Patent Publication Number: US-10785483-B2

Title: Modified coding for a transform skipped block for CABAC in HEVC

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Patent Application No. PCT/JP2014/003723 filed on Jul. 14, 2014, which claims priority to U.S. Provisional Application No. 61/858,010 filed on Jul. 24, 2013. 
     International Patent Application No. PCT/JP2014/003723 also claims priority to U.S. patent application Ser. No. 13/942,616 filed on Jul. 15, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 13/857,366 filed on Apr. 5, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 13/457,272 filed on Apr. 26, 2012, which is a continuation-in-part of U.S. patent application Ser. No. 13/444,710 filed on Apr. 11, 2012 (issued as U.S. Pat. No. 8,552,890 on Oct. 8, 2013), which is a continuation-in-part of U.S. patent application Ser. No. 13/365,215 filed on Feb. 2, 2012, which is a continuation-in-part of U.S. patent application Ser. No. 13/360,615 filed on Jan. 27, 2012 (issued as U.S. Pat. No. 8,581,753 on Nov. 12, 2013), which is a continuation-in-part of U.S. patent application Ser. No. 13/354,272 filed on Jan. 19, 2012, each of which is hereby incorporated by reference herein in its entirety. 
     Each of the above-referenced patent applications is hereby incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to electronic devices. More specifically, the present disclosure relates to electronic devices utilizing enhanced Context Adaptive Binary Arithmetic Coding (CABAC) for encoding and/or decoding. 
     BACKGROUND ART 
     Many decoders (and encoders) receive (and encoders provide) encoded data for blocks of an image. Typically, the image is divided into blocks and each of the blocks is encoded in some manner, such as using a discrete cosine transform (DCT), and provided to the decoder. A block may denote a rectangular region in an image and consist of pixels, for example a 16×16 block is a region 16× pixels in width and 16× pixels in height. The decoder receives the encoded blocks and decodes each of the blocks in some manner, such as using an inverse discrete cosine transform. 
     Video coding standards, such as MPEG-4 part 10 (H.264), compress video data for transmission over a channel with limited frequency bandwidth and/or limited storage capacity. These video coding standards include multiple coding stages such as intra prediction, transform from spatial domain to frequency domain, quantization, entropy coding, motion estimation, and motion compensation, in order to more effectively encode and decode frames. 
     The Joint Collaborative Team on Video Coding (JCT-VC) of the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Study Group (SG16) Working Party 3 (WP3) and International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) Joint Technical Committee 1/Subcommittee 29/Working Group 11 (JTC1/SC29/WG11) has launched a standardization effort for a video coding standard called the High Efficiency Video Coding standard (HEVC). Similar to some prior video coding standards, HEVC is block-based coding. An example of a known HEVC encoder is shown in  FIG. 1 . HEVC decoders are also known. 
     In HEVC, Context-Adaptive Binary Arithmetic Coding (CABAC) is used to compress Transformed and Quantized Coefficients (TQCs) without loss. The TQCs are determined at the encoder by processing image blocks with a forward transform to generate transform coefficients that are then quantized using an operation that maps multiple transform coefficient values to TQCs values. The TQCs values are then communicated to the decoder as Coefficient Level values, or level values, and the level value for each coefficient is then mapped to a transform coefficient value that is similar, but not necessarily identical to, the transform coefficient value computed at the encoder. CABAC based encoding and/or decoding technique is generally context adaptive which refers to (i) adaptively coding symbols based on the values of previous symbols encoded and/or decoded in the past, and (ii) context, which identifies the set of symbols encoded and/or decoded in the past used for adaptation. The past symbols may be located in spatial and/or temporal adjacent blocks. In many cases, the context is based upon symbol values of neighboring blocks. 
     As mentioned above, CABAC may be used to compress TQCs without loss. By way of background, TQCs may be from different block sizes according to transform sizes (e.g., 4×4, 8×8, 16×16, 32×32, 16×32). Two-dimensional (2D) TQCs may be converted into a one-dimensional (1D) array before entropy coding. In an example, 2D arrayed TQCs in a 4×4 block may be arranged as illustrated in Table (1). 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                   
                 4 
                 0 
                 1 
                 0 
               
               
                   
                 3 
                 2 
                 −1 
                 . . . 
               
               
                   
                 −3 
                 0 
                 . . . 
                 . . . 
               
               
                   
                 0 
                 . . . 
                 . . . 
                 . . . 
               
               
                   
               
            
           
         
       
     
     When converting the 2D TQCs into a 1D array, the block may be scanned in a diagonal zig-zag fashion. Continuing with the example, the 2D arrayed TQCs illustrated in Table (1) may be converted into 1D arrayed TQCs [4, 0, 3, −3, 2, 1, 0, −1, 0, . . . ] by scanning the first row and first column, first row and second column, second row and first column, third row and first column, second row and second column, first row and third column, first row and fourth column, second row and third column, third row and second column, fourth row and first column and so on. 
     The 1D array of TQCs is represented by a sequence of Syntax Elements (SEs) in CABAC. An example of the sequence of SEs for the example 1D array of TQCs is shown in  FIG. 2 . The SEs represent the following parameters: Last position X/Y, Significance Map, and the attributes Greater than 1, Greater than 2, Sign Information, and Absolute −3. The last position X/Y represents the position (X/Y) of the last non-zero coefficient in the corresponding block. Significance map represents the significance of each coefficient. Greater than 1 indicates whether the coefficient amplitude is larger than one for each non-zero coefficient (i.e. with significant flag as 1). Greater than 2 indicates whether the coefficient amplitude is larger than two for each coefficient with amplitude larger than one (i.e. with greater than 1 flag as 1). 
     In CABAC in HEVC, the representative SEs are coded.  FIG. 3  shows the CABAC framework used for coding SEs. The CABAC coding technique includes coding symbols using stages. In the first stage, the CABAC uses a “binarizer” to map input symbols to a string of binary symbols, or “bins”. The input symbol may be a non-binary valued symbol that is binarized or otherwise converted into a string of binary (1 or 0) symbols prior to being coded into bits. The bins can be coded into bits using either a “bypass encoding engine” or a “regular encoding engine”. 
     For the regular encoding engine in CABAC, in the second stage a probability model is selected. The probability model is used to arithmetic encode one or more bins of the binarized input symbols. This model may be selected from a list of available probability models depending on the context, which is a function of recently encoded symbols. The probability model stores the probability of a bin being “1” or “0”. In the third stage, an arithmetic encoder encodes each bin according to the selected probability model. There are two sub-ranges for each bin, corresponding to a “0” and a “1”. The fourth stage involves updating the probability model. The selected probability model is updated based on the actual encoded bin value (e.g., if the bin value was a “1”, the frequency count of the “1”s is increased). The decoding technique for CABAC decoding reverses the process. 
     For the bypass encoding engine in CABAC, the second stage involves conversion of bins to bits omitting the computationally expensive context estimation and probability update stages. The bypass encoding engine assumes a fixed probability distribution for the input bins. The decoding technique for CABAC decoding reverses the process. 
     The CABAC encodes the symbols conceptually using two steps. In the first step, the CABAC performs a binarization of the input symbols to bins. In the second step, the CABAC performs a conversion of the bins to bits using either the bypass encoding engine or the regular encoding engine. The resulting encoded bit values are provided in the bit stream to a decoder. 
     The CABAC decodes the symbols conceptually using two steps. In the first step, the CABAC uses either the bypass decoding engine or the regular decoding engine to convert the input bits to bin values. In the second step, the CABAC performs de-binarization to recover the transmitted symbol value for the bin values. The recovered symbol may be non-binary in nature. The recovered symbol value is used in remaining aspects of the decoder. 
     As previously described, the encoding and/or decoding process of the CABAC includes at least two different modes of operation. In a first mode, the probability model is updated based upon the actual coded bin value, generally referred to as a “regular coding mode”. The regular coding mode requires several sequential serial operations together with its associated computational complexity and significant time to complete. In a second mode, the probability model is not updated based upon the actual coded bin value, generally referred to as a “bypass coding mode”. In the second mode, there is no probability model (other than perhaps a fixed probability) for decoding the bins, and accordingly there is no need to update the probability model. 
     When utilizing CABAC coding in HEVC, throughput performance can differ depending on different factors such as but not limited to: total number of bins/pixels, number of bypass bins/pixels, and number of regular (or context) coded bins/pixels. Generally speaking, throughput for the case of high bit-rate encoding (low Quantization Parameter (QP) value) is significantly less than throughput in other cases. Therefore, throughput in high bit-rate cases may consume a significant amount of processing resources and/or may take a significant amount of time to encode/decode. The disclosure that follows solves this and other problems. 
     It is also known that CABAC can be used in a lossless coding mode to compress a residual sample. In one example, a residual sample is a value corresponding to a specific location in an image. Typically, a residual sample corresponds to the difference between a value corresponding to a specific location in an image and a prediction value corresponding to the same, specific location in an image. Alternatively, a residual sample is a value corresponding to a specific location in an image that has not been processed with a transformation operation, or a transformation operation that is not typically used to create TQCs. A residual sample can be from different block sizes according to its sample size (4×4, 8×8, 16×16, 32×32, 16×32, etc.) A 2D residual sample block is first converted into a 1D array before entropy coding, similar to TQC encoding. In an example, 2D arrayed residual sample in a 4×4 block may be arranged as illustrated in Table (2). 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                   
                 4 
                 0 
                 1 
                 0 
               
               
                   
                 3 
                 2 
                 −1 
                 . . . 
               
               
                   
                 −3 
                 0 
                 . . . 
                 . . . 
               
               
                   
                 0 
                 . . . 
                 . . . 
                 . . . 
               
               
                   
               
            
           
         
       
     
     When converting the 2D residual sample into a 1D array, the block may be scanned in a diagonal zig-zag fashion. Continuing with the example, the 2D arrayed residual sample illustrated in Table (2) may be converted into 1D arrayed residual sample [4, 0, 3, −3, 2, 1, 0, −1, 0, . . . ] by scanning the first row and first column, first row and second column, second row and first column, third row and first column, second row and second column, first row and third column, first row and fourth column, second row and third column, third row and second column, fourth row and first column and so on. 
     The 1D array of the residual sample is represented by a sequence of Syntax Elements (SEs) in CABAC. An example of a sequence of SEs for the example 1D array of the residual sample is shown in  FIG. 11 . The SEs represent the following parameters: Last position X/Y, Significance Map, and the attributes Greater than 1, Greater than 2, Sign Information, and Absolute −3. 
     In the lossless coding mode of CABAC in HEVC, the representative SEs are coded. The CABAC framework of  FIG. 3  may be used for coding the SEs. The CABAC coding technique includes coding symbols using stages. In the first stage, the CABAC uses a “binarizer” to map input symbols to a string of binary symbols, or “bins”. The input symbol may be a non-binary valued symbol that is binarized or otherwise converted into a string of binary (1 or 0) symbols prior to being coded into bits. The bins can be coded into bits using the previously described “regular encoding engine”. 
     For the regular encoding engine in the lossless coding mode of CABAC, in the second stage a probability model (also known as a “context model” in the lossless encoding mode of CABAC) is selected. The model is used to arithmetic encode one or more bins of the binarized input symbols. This model may be selected from a list of available models depending on the context, which is a function of recently encoded symbols. The model stores the probability of a bin being “1” or “0”. In the third stage, an arithmetic encoder encodes each bin according to the selected model. There are two sub-ranges for each bin, corresponding to a “0” and a “1”. The fourth stage involves updating the model. The selected model is updated based on the actual encoded bin value (e.g., if the bin value was a “1”, the frequency count of the “1”s is increased). The decoding technique for CABAC decoding reverses the process. 
     The number of models used as described in the previous paragraph may be 184. Specifically: 36 models used for Last position X/Y (18 models for Last_position_X, 18 models for Last_position_Y); 48 models used for Significance Map (4×4 block: 9 luma, 6 chroma; 8×8 block: 11 luma, 11 chroma; 16×16 or 32×32 block: 7 luma, 4 chroma); and 100 models used for the attributes Greater than 1, Greater than 2, Sign Information, and Absolute −3 (Greater_than_1 flag of luma: 30; Greater_than_1 flag of chroma 20, Greater_than_2 flag of luma: 30; and Greater_than_2 flag of chroma 20). 
     When utilizing CABAC encoding in HEVC in the lossless coding mode, encoding/decoding is computationally complex. One reason for the computation complexity is the use of 184 models, as explained above. Due to this computation complexity, encoding/decoding may consume a significant amount of processing resources and/or may take a significant amount of time to complete. The disclosure that follows solves this and other problems. 
     SUMMARY OF INVENTION 
     One embodiment of the present invention discloses a system, comprising: an electronic device of a decoder, the electronic device configured to: obtain a bit stream; recover a binary symbol from the obtained bit stream; the binary symbol is dequantized and inverse transformed to recover video data wherein if inverse transform is not applied to the transform block for higher bit depth coding then scaling operation is performed to dequantized coefficient values based on TS_Shift as follows: Residue=(Dequantized coefficient values)&lt;&lt;TS_Shift and Residue is calculated based on bdShift as follows: 
     Residue=(Residue+(1&lt;&lt;(bdShift−1)))&gt;&gt;bdShift wherein TS_Shift is a left bit shift for scaling operation, bdShift is a right bit shift for scaling operation and TS_Shift is smaller than or equal to bdShift. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of an HEVC encoder. 
         FIG. 2  is a table showing a sequence of syntax elements according to CABAC. 
         FIG. 3  is a block diagram of the CABAC framework for a sequence of syntax elements. 
         FIG. 4  is a block diagram illustrating an example of an encoder and a decoder. 
         FIG. 5  is a flow diagram illustrating one configuration of a method for high throughput binarization mode on an electronic device. 
         FIG. 6  is a flow diagram illustrating one configuration of encoder processing using high throughput binarization mode. 
         FIG. 7  is a flow diagram illustrating one configuration of a method for high throughput binarization mode on an electronic device at the decode-side. 
         FIG. 8  is a flow diagram illustrating one configuration of decoder processing using high throughput binarization mode. 
         FIG. 9  illustrates a mapping table that may be used for determining an input value in high throughput binarization mode. 
         FIG. 10  illustrates a plurality of binarization tables that may be used for adaptive binarization in high throughput binarization mode. 
         FIG. 11  is a table showing a sequence of syntax elements according to a lossless coding mode in CABAC. 
         FIG. 12  is a block diagram illustrating an example of an encoder and a decoder for a lossless coding technique. 
         FIG. 13  is a flow diagram illustrating one configuration of a method for lossless coding on an electronic device. 
         FIG. 14  is a table showing a sequence of syntax elements according to the configuration illustrated in  FIG. 13 . 
         FIG. 15  is a flow diagram illustrating one configuration of a method for lossless decoding on an electronic device at the decode-side. 
         FIG. 16  is a flow diagram illustrating another configuration of a method for lossless coding on an electronic device. 
         FIG. 17  is a flow diagram illustrating another configuration of a method for lossless coding on an electronic device at the decode-side. 
         FIG. 18  is a flow diagram illustrating yet another configuration of a method for lossless coding on an electronic device. 
         FIG. 19  is a flow diagram illustrating yet another configuration of a method for lossless coding on an electronic device at the decode-side. 
         FIG. 20A  is flow diagram illustrating example configurations of an encoder or a decoder to 
         FIG. 20B  is flow diagram illustrating example configurations of an encoder or a decoder to determine whether the high throughput binarization mode condition is met. 
         FIG. 20C  is flow diagram illustrating example configurations of an encoder or a decoder to determine whether the high throughput binarization mode condition is met. 
         FIG. 20D  is flow diagram illustrating example configurations of an encoder or a decoder to determine whether the high throughput binarization mode condition is met. 
         FIG. 20E  is flow diagram illustrating example configurations of an encoder or a decoder to determine whether the high throughput binarization mode condition is met. 
         FIG. 21  is a flow diagram illustrating one configuration of a method for determining whether a high throughput mode condition is met on an electronic device at the decode-side. 
         FIG. 22  is a flow diagram illustrating another configuration of a method for determining whether a high throughput mode condition is met on an electronic device at the decode-side. 
         FIG. 23  is a block diagram illustrating an example of an encoder and a decoder. 
         FIG. 24  is a flow diagram illustrating a configuration of a method for high throughput significance map decoding on an electronic device at the decode-side. 
         FIG. 25  is a flow diagram illustrating another configuration of a method for high throughput significance map decoding on an electronic device at the decode-side. 
         FIG. 26  is a flow diagram illustrating a configuration of a method for high throughput significance map decoding with a decode-bypass feature on an electronic device at the decode-side. 
         FIG. 27  is a flow diagram illustrating a configuration of a method for high throughput significance map decoding with a decode-method-switching feature on an electronic device at the decode-side. 
         FIG. 28  is a table used for updating a Rice parameter according to a lossless coding mode in CABAC. 
         FIG. 29  is a block diagram illustrating an example of an encoder and a decoder. 
         FIG. 30  is a flow diagram illustrating one configuration of a method for lossless coding with different parameter selection on an electronic device. 
         FIG. 31  is a flow diagram illustrating one configuration of a method for lossless coding with different parameter selection on an electronic device at the decode-side. 
         FIG. 32  is an example syntax element generated according to CABAC. 
         FIG. 33  is a block diagram illustrating an example of an encoder and a decoder. 
         FIG. 34  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device. 
         FIG. 35  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device at the decode-side. 
         FIG. 36  is an example syntax element generated according to the configuration of  FIG. 34 . 
         FIG. 37  is an illustration of a reduced Rice parameter update table. 
         FIG. 38  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device at the decode-side. 
         FIG. 39  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device at the decode-side. 
         FIG. 40  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device at the decode-side. 
         FIG. 41  is a block diagram illustrating an example of an encoder and a decoder. 
         FIG. 42  is a flow diagram illustrating one configuration of a method for high throughput residual coding. 
         FIG. 43  is a flow diagram illustrating one configuration of a method for high throughput residual coding at the decode-side. 
         FIG. 44  is a flow diagram illustrating one configuration of a method for high throughput residual coding at the decode-side. 
         FIG. 45A  is a flow diagram illustrating one configuration of applying a Rice parameter update function. 
         FIG. 45B  is an example table used for updating a Rice parameter. 
         FIG. 46  is a block diagram illustrating an example of an encoder and a decoder. 
         FIG. 47  is a flow diagram illustrating one configuration of a method for using a modified transform skip mode. 
         FIG. 48  is a flow diagram illustrating one configuration of a method for using a modified transform skip mode at the decode-side. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 4  is a block diagram illustrating an example of an encoder and a decoder. 
     The system  400  includes an encoder  411  to generate encoded blocks to be decoded by a decoder  412 . The encoder  411  and the decoder  412  may communicate over a network. 
     The encoder  411  includes an electronic device  421  configured to encode using high throughput binarization mode. The electronic device  421  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable by the processor to perform the operations shown in  FIGS. 5 and 6 . 
     The decoder  412  includes an electronic device  422  configured to decode using the high throughput binarization mode. The electronic device  422  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable to perform the operations shown in  FIGS. 7 and 8 . 
       FIG. 5  is a flow diagram illustrating one configuration of a method for high throughput binarization mode on an electronic device. 
     In block  511 , the electronic device  421  obtains a block of transformed and quantized coefficients (TQCs). In diamond  512 , the electronic device  421  determines whether a high throughput binarization mode condition is met. If the condition is not met in diamond  512 , then in block  513  the electronic device  421  codes the block by selectively using a regular coding mode and a bypass coding mode (according to conventional CABAC selection schemes). 
     If the condition is met in diamond  512 , then in block  514  the electronic device  421  uses high throughput binarization mode and bypass coding mode to code the block. The electronic device  421  transmits the generated bit stream over a network and/or stores the generated bit stream in a memory device in block  515 . 
     HTB mode uses bypass coding mode for coding the level values. In contrast to regular encoding mode, bypass coding omits the computationally expensive context estimation and probability update stages because bypass coding mode assumes a fixed probability distribution for the input bins. 
     In addition to using bypass coding mode for coding, by way of contrast to conventional CABAC, HTB mode uses simplified signing structure for coding. For example, conventional CABAC requires four sub-parts for coding, including Greater_than_1, Greater_than_2, Sign information, and Absolute −3. 
       FIG. 6  is a flow diagram illustrating one configuration of encoder processing using high throughput binarization mode. 
     The blocks  612 - 615  illustrate operations performed in block  514  in more detail. In block  612 , the electronic device  421  generates sign and level information for any non-zero values from the block of TQCs by applying an absolute value minus one function to each non-zero value and checking the sign of each non-zero value. For ease of explanation, consider the values for the 1D arrayed TQC from the background section of the present application[4, 0, 3, −3, 2, 1, 0, −1, 0, . . . ]. Applying the absolute value minus one function to each non-zero value and checking the sign of each non-zero value generates six combinations of sign and level information as follows: +3, +2, −2, +1, +0, and −0. 
     In block  613 , the electronic device  421  maps an input value to each generated combination of sign and level information using a mapping table. An example mapping table is shown in  FIG. 9 .  FIG. 9  also shows an equation for determining an input value according to blocks  612  and  613 . 
     In block  614 , the electronic device  421  performs adaptive binarization of the input values using a plurality of binarization tables, e.g. the VLC tables of Context Adaptive Variable Length Coding (CAVLC). An example of the VLC tables of CAVLC is shown in  FIG. 10 .  FIG. 10  also shows an equation for updating the binarization tables based on previous input information. 
     In an example, block  614  may include initially using values from the column VLC-Table-0 ( FIG. 10 ) to binarize at least the first input value. The VLC table number may be monotomically increased when a previous value is larger than the given threshold values, e.g. 3, 5, 13, 27. Accordingly, subsequent adaptive binarization after the first monotomical increase may use values from the column VLC-Table-1, subsequent adaptive binarization after the second monotomical increase may use values from the column VLC-Table-2, etc. 
     In block  615 , the electronic device  421  encodes the resultant values of the adaptive binarization using the CABAC bypass coding mode. 
     (High Throughput Binarization Mode Condition) 
     In an example, if a characteristic corresponding to a block of image data is greater than a preset threshold, then the high throughput binarization mode condition is met, e.g. the electronic device  421  may set a high throughput binarization mode indicator, e.g. an HTB mode flag, to a value of 1 (which of course may include changing a default value of the HTB mode flag or leaving the HTB mode flag at a default value depending on design preference). 
     In an example, the electronic device  421  determines whether a bit rate for a coding is greater than a preset threshold. If the bit rate is greater than the preset threshold, then the high throughput binarization mode condition is met. In an example, the preset bit rate threshold corresponds to QP 16; however, a preset threshold corresponding to different QP values may be used. 
     In an example, the determination (by the electronic device  421  or the electronic device  422 ) of whether the high throughput binarization mode condition is met is based on whether the transform unit level (for example but not limited to the level values generated by a transform unit) of a corresponding block of image data is greater than a preset threshold. 
     In an example, the high throughput binarization mode condition can be met when the number of level values of a corresponding block of image data and with magnitude greater than zero is greater than a preset threshold, e.g. 8. In another example, the high throughput binarization mode condition is met when the number of level values of a corresponding block of image data and with magnitude greater than a first preset threshold is greater than a second preset threshold. In yet an example, the high throughput binarization mode condition is met when a level value of a corresponding block of image data is greater than a preset threshold. 
     The  FIGS. 20A-E  show some examples of configurations that may be used for an encoder or decoder in example systems operating according to at least some of the principles described in the immediately preceding two paragraphs.  FIG. 20A  illustrates processes  1611 - 1616 , as shown.  FIG. 20B  illustrates processes  1711 - 1716 , as shown.  FIG. 20C  illustrates processes  1801 - 1805  and  1814 - 1820 .  FIG. 20D  illustrates processes  1901 - 1905  and  1914 - 1920 . In  FIG. 20E , the processes of  FIG. 20C  are performed up until process  1816 , as shown. If the counter is greater than the threshold in process  1816 , then the configuration continues as shown in  FIG. 20E . 
     In an example, the determination (by the electronic device  421  or the electronic device  422 ) of whether the high throughput binarization mode condition is met is based on whether the slice level of a corresponding block of image data is greater than a preset threshold. 
     (High Throughput Binarization Mode Indicator) 
     In an example, the electronic device  421  is configured to set a high throughput binarization indicator, e.g. an HTB mode flag, in a header, e.g. the slice header. The high throughput binarization indicator may be used to determine whether or not the process shown in  FIG. 5  is executed for block(s) corresponding to the slice header. 
     In an example, setting the HTB mode flag to “1” causes the electronic device  421  to perform the process shown in the flowchart of  FIG. 5  for block(s) corresponding to the slice header in response to observing the HTB mode flag value of “1”. Setting the HTB mode flag to “0” causes the electronic device  421  to encode block(s) corresponding to the slice header according to a conventional CABAC technique in response to observing the HTB mode flag value of “0”. 
     The HTB mode flag value may also be observed by the electronic device  422  for decoding. In an example, the electronic device  422  decodes block(s) corresponding to a slice header having the HTB mode flag value of “1” according to the process shown in the flowchart of  FIG. 7  for block(s) corresponding to the slice header in response to observing the HTB mode flag value of “1”. The electronic device  422  decodes block(s) corresponding to a slice header having the HTB mode flag value of “0” according to a conventional CABAC technique in response to observing the HTB mode flag value of “0”. 
       FIG. 7  is a flow diagram illustrating one configuration of a method for high throughput binarization mode on an electronic device at the decode-side. 
     In block  710 , the electronic device  422  obtains a bit stream. In block  711 , the electronic device  422  recovers a binary symbol from the obtained bit stream. 
     In diamond  712 , the electronic device  422  determines whether a high throughput binarization mode condition is met. In an example, the determination may include checking a header, such as a slice header, corresponding to the received bit stream. Checking the header may further comprise checking a slice header corresponding to the obtained bit stream for a value of a high throughput binarization mode indicator. If the condition is not met in diamond  712 , then in block  713  the electronic device  422  decodes the binary symbol by selectively using regular decoding mode and bypass coding mode. 
     If the condition is met in diamond  712 , then in block  714  the electronic device  421  uses high throughput binarization mode and bypass decoding mode to decode the binary symbol. The electronic device  422  may store an obtained block of TQCs in a memory device and/or may recover video data in block  715 . 
       FIG. 8  is a flow diagram illustrating one configuration of decoder processing using high throughput binarization mode. 
     The blocks  812 - 815  illustrate operations performed in block  714  in more detail. In block  812 , the electronic device  422  bypass decodes the encoded binary symbol. In block  813 , the electronic device  422  de-binarizes a result of the bypass decoding. In block  814 , the electronic device  422  maps recovered input values from the de-binarization to sign and level information using a mapping table. In block  815 , the electronic device  422  decodes a block of transformed and quantized coefficients (TQCs) using the sign and level information. 
     In an example, an electronic device including a processor and a memory in electronic communication with the processor is provided. Stored in the memory are instructions executable by the processor to perform operations. 
     In an example, an operation may include obtaining a block of transformed and quantized coefficients (TQCs). Another operation may include determining whether a high throughput binarization mode condition is met. Another operation may include generating a first bit stream using the high throughput binarization mode in response to determining that the high throughput binarization mode condition is met. Another operation may include generating a second bit stream in response to determining that the high throughput binarization mode condition is not met. Another operation may include transmitting the generated first or second bit stream to a decoder. 
     In an example, the generation of the first bit stream using the high throughput binarization mode may include additional operations. One operation may include generating sign and level information for any non-zero values from the block by applying an absolute value minus one function to each non-zero value and checking the sign of each non-zero value. Another operation may include mapping an input value to each generated combination of sign and level information using a mapping table. Another operation may include performing adaptive binarization of the mapped input values using a plurality of binarization tables. Another operation may include encoding a result of the adaptive binarization. 
     In an example, the plurality of binarization tables include VLC tables of CAVLC. Encoding the result of the adaptive binarization may further include the operation of utilizing a CABAC bypassing coding mode. 
     In an example, the adaptive binarization of the mapped input values using a plurality of binarization tables may include additional operations. One operation may include determining whether one of the mapped input values is greater than a preset threshold. Another operation may include performing a table update responsive to determining that said mapped input value is greater than the preset threshold. In an example, table update selection comprises selection of a table from a set of tables. 
     In an example, the generation of the first bit stream may include additional operations. One operation may include coding the block by selectively utilizing a regular coding mode and a bypass coding mode according to CABAC. Another operation may include generating the first bit stream utilizing only the bypass coding mode. 
     In an example, the determination of whether the high throughput binarization mode condition is met is based on whether a characteristic corresponding to a block of image data is greater than a preset threshold. 
     In an example, the determination of whether the high throughput binarization mode condition is met is based on whether the slice level of a corresponding block of image data is greater than a preset threshold. 
     In an example, the determination of whether the high throughput binarization mode condition is met is based on whether the transform unit level of a corresponding block of image data is greater than a preset threshold. 
     (Lossless Coding Technique for CABAC in HEVC) 
       FIG. 12  is a block diagram illustrating an example of an encoder and a decoder for a lossless coding technique. 
     The system  1400  includes an encoder  1411  to generate encoded blocks to be decoded by a decoder  1412 . The encoder  1411  and the decoder  1412  may communicate over a network. 
     The encoder  1411  includes an electronic device  1421  configured to encode using a lossless coding technique for CABAC in HEVC. The electronic device  1421  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable by the processor to perform the operations shown in  FIGS. 13, 16, and 18 . 
     The decoder  1412  includes an electronic device  1422  configured to decode using a lossless coding technique for CABAC in HEVC. The electronic device  1422  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable to perform the operations shown in  FIGS. 15, 17, and 19 . 
       FIG. 13  is a flow diagram illustrating one configuration of a method for lossless coding on an electronic device. 
     In block  911 , the electronic device  1421  obtains a block representing a residual sample. In one example, zig-zag scanning direction may be redefined to fit the direction of intra prediction that is used to remove the spatial redundancies between neighboring pixels. There are several intra prediction modes available in lossless intra coding mode. In one example, in vertical intra prediction mode, upper pixels become the prediction value of the current pixel value and the difference between the current value and the prediction value (upper pixel value in vertical mode) become the residual sample value. Context model selection may also depend on the direction of intra prediction and the corresponding block size. 
     In block  912 , the electronic device  1421  generates a significance map to be used in a sequence of syntax elements. In block  913 , the electronic device  1421  populates a significance map field that corresponds to the last scanning position of the block with a value corresponding to the level of the last position of the block. 
     In block  914 , the electronic device  1421  generates a sequence of syntax elements including the significance map having said value. Generating the sequence of syntax elements excludes the last position coding step of conventional CABAC lossless coding mode. 
       FIG. 14  is a table showing a sequence of syntax elements according to the configuration illustrated in  FIG. 13 . 
     Several differences can be observed by way of contrast of the sequence of syntax elements shown in  FIG. 14  as compared to the sequence of syntax elements shown in  FIG. 11 . The sequence of syntax elements shown in  FIG. 11  includes a Last_position_X field and a Last_position_Y field because the conventional CABAC lossless coding mode includes a last position coding step. In contrast, the sequence of syntax elements shown in  FIG. 14  does not include a Last_position_X field and a Last_position_Y field because the configuration of  FIG. 14  omits the last position coding step. 
     While both of the sequence of syntax elements include significance maps, there are differences between the significance maps. In the significance map of the sequence of syntax elements of  FIG. 11 , a significance map field is unpopulated to correspond with the field of Last_position_X/Last_position_Y that is populated. In contrast, in  FIG. 14  a significance map field that corresponds to the last scanning position of the block is populated with a value, i.e. “0” for the example block, corresponding to the level of the last position of the block. 
       FIG. 15  is a flow diagram illustrating one configuration of a method for lossless decoding on an electronic device at the decode-side. 
     In block  1011 , the electronic device  1422  recovers, from a bit stream, a sequence of syntax elements having a significance map field containing a number of values corresponding to a last scanning position of a block. In block  1012 , the electronic device  1422  decodes the levels of the block using the significance map and using said value of the significance map. In block  1013 , the electronic device  1422  stores an obtained block corresponding to a residual value in a memory device and/or recovers video data. 
       FIG. 16  is a flow diagram illustrating another configuration of a method for lossless coding on an electronic device. 
     In block  1111 , the electronic device  1421  obtains a sequence of syntax elements representing level information for a block of a residual sample. In block  1112 , the electronic device  1421  performs adaptive binarization on values of the Absolute −3 portion of the sequence of syntax elements using a plurality of binarization tables, e.g. the VLC tables of CAVLC ( FIG. 10 ), wherein the values of the Absolute −3 portion of the sequence of syntax elements are used as input values for the plurality of binarization tables. An equation for updating the binarization tables based on previous input information is shown below:
 
if (‘abs[coefficient( i )]−3’&gt;(Table[ vlc ])) vlc++;  
         where Table [vlc]={3, 5, 13, 27};   ‘i’ represents scanning position and ‘vlc’ represents the current vlc table number   *vlc is first set to zero (or one for intra slice) because there is no available previous ‘Absolute −3’ vlc Table updated is stopped when vlc is equal to 4       

     In an example, block  1111  may include initially using values from the column VLC-Table-0 ( FIG. 10 ) for inter slice and the column VLC-Table-1 for intra slice to binarize at least the first input value. The VLC table number may be monotomically increased when a previous value is larger than the given threshold values, e.g. 3, 5, 13, 27. Accordingly, subsequent adaptive binarization after the first monotomical increase may use values from the column VLC-Table-1, subsequent adaptive binarization after the second monotomical increase may use values from the column VLC-Table-2, etc. 
     In block  1113 , the electronic device  1421  encodes the resultant values of the adaptive binarization using CABAC bypass coding mode. 
       FIG. 17  is a flow diagram illustrating another configuration of a method for lossless coding on an electronic device at the decode-side. 
     In block  1211 , the electronic device  1422  recovers a binary symbol from a bit stream. In block  1212 , the electronic device  1422  bypass decodes the binary symbol. In block  1213 , the electronic device  1422  adaptively de-binarizes a result of the bypass decoding. In block  1214 , the electronic device  1422  recovers a block representing residual information using a result of the adaptive de-binarization. 
       FIG. 18  is a flow diagram illustrating yet another configuration of a method for lossless coding on an electronic device. 
     In block  1311 , the electronic device  1421  accesses only a subset of the context models of CABAC. The number of context models of CABAC may be 184. In order to generate the subset, these context models may be filtered based on associated characteristics of the context models, e.g. based on which context models are associated with a frequency component, based on which context models are associated with a scan position, based on which context models are associated with the last position coding step of CABAC, or the like, or any combination thereof. The filtering may be performed by the electronic device  1421  in one example, but in other examples the subset may be provided to the electronic device  1421  so that the electronic device  1421  may access the provided subset for lossless coding mode. In an example, in order to generate the subset, the context models of CABAC may be classified based on associated characteristics of the context models, e.g. based on which context models are associated with to frequency component, based on which context models are associated with a scan position, based on which context models are associated with the last position coding step of CABAC, or the like, or any combination thereof. In an example, frequency component and scan position may be equal and interchangeable. 
     In one example, a subset may not contain CABAC context models with a frequency component not equal to a first frequency component. In an example, the resulting subset would include 26 context models, i.e. two context models (one is for a first luma frequency component and the other is for a first chroma frequency component) for coding the significance map, and 6 context models for coding the first luma frequency component of the Greater_than_1 flag, coding the first chroma frequency component of the Greater_than_1 flag, coding the first luma frequency component of the Greater_than_2 flag of luma, and coding the first chroma frequency component of the Greater_than_2 flag, respectively. Therefore, total 24 context models are used for Greater_than_1 and Greater_than_2. In an example, said first frequency component is only accessed when coding the significance map in block  1312 . 
     As shown In Table (3), the 6 context models for coding the first luma frequency of a flag may depend on the sub-block type and the LargerT1 value, where the LargerT1 value is the number of coefficient level values greater than one in the previous sub-block. In an example, the term “sub-block” refers to a partitioning of the residual samples (or block to TQCs). For example, for a sub-block size of 4×4, residual sample with a size of 8×8 are divided into four 4×4 sub-blocks. Similarly, for a sub-block size of 8×4, residual samples with a size of 32×8 are divided into eight 8×4 sub-blocks. Sub-blocks are identified by coding order, where sub-block 0 denotes the first coded sub-block. In an example, the first coded sub-block is the sub-block located at the bottom right of the block. In another example, the first coded sub-block is the sub-block located in the middle of the block. 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 6 context models based on sub-block type and 
               
               
                 LargerT1 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 0 
                 Sub-block 
                 0 LargerT1 in previous subset 
               
               
                   
                 1 
                 0 
                 1-3 LargerT1 in previous subset 
               
               
                   
                 2 
                   
                 &gt;3 LargerT1 in previous subset 
               
               
                   
                 3 
                 Other sub- 
                 0 LargerT1 in previous subset 
               
               
                   
                 4 
                 blocks 
                 1-3 LargerT1 in previous subset 
               
               
                   
                 5 
                   
                 &gt;3 LargerT1 in previous subset 
               
               
                   
               
            
           
         
       
     
     In block  1312 , the electronic device  1421  uses the subset of the context models to code the significance map. 
     As described in paragraph 0120, context models with a frequency component (or scanning position) not equal to a first frequency component (or scanning position) may not be used in a lossless coding mode. This has the benefit of reducing computational complexity and memory for the lossless coding mode. A first subset of context models may be used for significance map processing. A second subset of context models may be used for level coding, e.g. Greater_than_1 coding and/or Greater_than_2 coding. The first subset may be different than the second subset. 
     In an example applying at least some of the principles described above, the first subset of context models used in significance map processing may comprise only one context model. In another example applying at least some of the principles described above, the first subset of context models used in significance map processing may comprise more than one context model, e.g. two or three context models, based on color information (luma/chroma). In yet another example applying at least some of the principles described above, the first subset of context models used in significance map processing may comprise more than one context model, e.g. several context models, based on prediction type, e.g. the use of intra-frame or inter-frame prediction within a block. In another example applying at least some of the principles described above, the first subset of context models used in significance map processing may comprise more than one context model, e.g. two or three context models, based on block size. In another example applying at least some of the principles described above, the first subset of context models used in significance map processing may comprise more than one context model, e.g. two or three context models, based on sub-block type. 
     In an example applying at least some of the principles described above, the second subset of context models used in level coding may comprise only one context model. In another example applying at least some of the principles described above, the second subset of context models used in level coding may comprise more than one context model, e.g. two or three context models, based on color information (luma/chroma). In yet another example applying at least some of the principles described above, the second subset of context models used in level coding may comprise more than one context model, e.g. several context models, based on block prediction type, e.g. the use of intra-frame or inter-frame prediction within a block. In another example applying at least some of the principles described above, the first subset of context models used in level coding may comprise more than one context model, e.g. two or three context models, based on block size. In another example applying at least some of the principles described above, the first subset of context models used in level coding processing may comprise more than one context model, e.g. two or three context models, based on sub-block type. 
       FIG. 19  is a flow diagram illustrating yet another configuration of a method for lossless coding on an electronic device at the decode-side. 
     In block  1511 , the electronic device  1422  accesses only a subset of the context models of CABAC. In block  1512 , the electronic device  1422  recovers a binary symbol from a bit stream using the subset of context models. In block  1513 , the electronic device  1422  recovers video data using a result of the decoding. 
     In the foregoing, configurations that may be implemented by the electronic device  1421  are illustrated in  FIGS. 13, 16, and 18 . Configuring an encoder with all of these configurations improves coding performance compared to known CABAC lossless coding mode. Nevertheless, configuring an encoder with less than all of these configurations in any combination, e.g. one of these configurations or any two of these configurations, is also possible and practical, and also improves coding performance compared to known CABAC lossless coding mode. 
     In the foregoing, configurations that may be implemented by the electronic device  1422  are illustrated in  FIGS. 14, 17, and 19 . Configuring a decoder with all of these configurations improves coding performance compared to known CABAC lossless coding mode. Nevertheless, configuring a decoder with less than all of these configurations in any combination, e.g. one of these configurations or any two of these configurations, is also possible and practical, and also improves coding performance compared to known CABAC lossless coding mode. 
     In an example, an electronic device including a processor and a memory in electronic communication with the processor is provided. Stored in the memory are instructions executable by the processor to perform operations. 
     In an example, an operation may include obtaining a block representing a residual sample for lossless encoding. Another operation may include generating a significance map, wherein the generating includes populating a significance map field that corresponds to the last scanning position of the block with a value corresponding to a level of the last scanning position of the block. Another operation may include generating a sequence of syntax elements including the significance map having the value. Another operation may include transmitting a bit stream representing the generated sequence of syntax elements to a decoder. 
     In an example, the sequence of syntax elements is generated without performing the last position coding step of Context Adaptive Binary Arithmetic Coding (CABAC). 
     In an example, another operation may include performing perform adaptive binarization using a plurality of binarization tables, wherein values of an Absolute −3 portion of the sequence of syntax elements are used as input values for the plurality of binarization tables. Another operation may include encoding a result of the adaptive binarization. The plurality of binarization tables may be VLC tables of CAVLC. 
     In an example, encoding the result of the adaptive binarization may include additional operations. An additional operation may include utilizing a CABAC bypassing coding mode. 
     In an example, the adaptive binarization of the input values using the plurality of binarization tables may include additional operations. An additional operation may include determining whether one of the input values is greater than a preset threshold. An additional operation may include performing a table update responsive to determining that said input value is greater than the preset threshold. 
     In an example, another operation may include accessing only a subset of the context models of CABAC. Another operation may include using the subset of the context models to code the significance map. The subset may comprise the context models of CABAC with a frequency component not equal to a first frequency. 
     In an example, an electronic device including a processor and a memory in electronic communication with the processor is provided. Stored in the memory are instructions executable by the processor to perform operations. 
     In an example, an operation may include obtaining a block representing a residual sample for lossless encoding. Another operation may include generating a sequence of syntax elements to represent the block. Another operation may include performing adaptive binarization using a plurality of binarization tables, wherein values of an Absolute −3 portion of the sequence of syntax elements are used as input values for the plurality of binarization tables. Another operation may include encoding a result of the adaptive binarization. Another operation may include transmitting the encoding to a decoder. 
     In an example, the plurality of binarization tables are VLC tables of CAVLC. 
     In an example, encoding the result of the adaptive binarization may include additional operations. An additional operation may include utilizing a Context Adaptive Binary Arithmetic Coding (CABAC) bypassing coding mode. 
     In an example, the adaptive binarization of the input values using the plurality of binarization tables may include additional operations. An additional operation may include determining whether one of the input values is greater than a preset threshold. An additional operation may include performing a table update responsive to determining that said input value is greater than the preset threshold. 
     In an example, another operation may include generating a significance map, wherein the generating includes populating a significance map field that corresponds to the last scanning position of the block with a value corresponding to a level of the last scanning position of the block. Another operation may include generating the sequence of syntax elements using the generated significance map. 
     In an example, the sequence of syntax elements is generated without performing the last position coding step of CABAC. 
     In one example, a method is provided. The method may be performed using a decoder. One operation of the method may include filtering the context models of Context Adaptive Binary Arithmetic Coding (CABAC) based on which context models are associated with frequency component. Another operation of the method may include obtaining a bit stream. Another operation of the method may include recovering a binary symbol from the bit stream. Another operation of the method may include decoding the binary symbol using the filtered context models. Another operation of the method may include recovering video data using a result of the decoding. 
     In an example, another operation may include recovering, from the bit stream, a sequence of syntax elements having a significance map populated with a value corresponding to a last scanning position of a block representing a residual sample. Another operation may include decoding the levels of the block using the significance map and using said value of the significance map. 
     In an example, the decoding of the levels of the block may be performed without performing the last position decoding step of CABAC. 
     In an example, another operation may include bypass decoding the recovered binary symbol. Another operation may include adaptively de-binarizing a result of the bypass decoding. Another operation may include recovering a block representing residual information using a result of the de-binarization. 
     In an example, another operation may include using a plurality of VLC tables of CAVLC for the adaptive de-binarization. 
     In an example, the bypass decoding may include utilizing a CABAC bypass decoding mode. 
       FIG. 21  is a flow diagram illustrating one configuration of a method for determining whether a high throughput mode condition is met on an electronic device at the decode-side. 
     In block  2611 , the electronic device  422  obtains a bit stream. In block  2612 , the electronic device  422  obtains a block of level values. In an example, the block comprises a block of TQCs. 
     In block  2613 , the electronic device  422  determines the number of level values that are not equal to zero. In diamond  2614 , the electronic device  422  determines whether the number is greater than a preset threshold. In an example, the preset threshold may be 8, which is half of the number of values of a 4×4 block. In examples with a block size having N level values, the threshold may correspond to 50% of N. In an example, the electronic device  422  receives signaling from the electronic device  421 . The signaling transmitted by the electronic device  421  may specify the preset threshold or include information that may be used by the electronic device  421  for determining the preset threshold. 
     If the number is not greater than the preset threshold in diamond  2614 , then in block  2615  the electronic device  422  decodes level values not equal to zero with a first binarization method. If the number is greater than the preset threshold in diamond  2614 , then in block  2616  the electronic device  422  decodes level values not equal to zero with a second binarization method that is different than the first binarization method. In an example, the second binarization method may comprise a high throughput debinarization mode, such as the previously described HTB mode. In an example, the first binarization method may comprise binarization of conventional CABAC. 
       FIG. 22  is a flow diagram illustrating another configuration of a method for determining whether a high throughput mode condition is met on an electronic device at the decode-side. 
     In block  2711 , the electronic device  422  obtains a bit stream. In block  2712 , the electronic device  422  obtains a block of level values. In an example, the block comprises a block of TQCs. 
     In block  2713 , the electronic device  422  determines the number of level values with an absolute value greater than a first preset threshold. In an example, the first preset threshold may be either  1  or  2 , although other first preset thresholds may be used in other examples. In diamond  2714 , the electronic device  422  determines whether the number is greater than a second preset threshold. In an example, the second preset threshold may be 8, which is half of the number of values of a 4×4 block. In examples with a block size having N level values, the second preset threshold may correspond to 50% of N. 
     In an example, the electronic device  422  receives signaling from the electronic device  421 . The signaling transmitted by the electronic device  421  may specify the first preset threshold and/or the second present threshold, or include information that may be used by the electronic device  421  for determining the first preset threshold and/or the second present threshold. 
     If the number is not greater than the second preset threshold in diamond  2714 , then in block  2715  the electronic device  422  decodes level values not equal to zero with a first binarization method. If the number is greater than the preset threshold in diamond  2714 , then in block  2716  the electronic device  422  decodes level values not equal to zero with a second binarization method that is different than the first binarization method. In an example, the second binarization method may comprise a high throughput debinarization mode, such the previously described HTB mode. In an example, the first binarization method may comprise binarization of known CABAC decoding. 
       FIG. 23  is a block diagram illustrating an example of an encoder and a decoder. 
     The system  2400  includes an encoder  2411  to generate encoded blocks to be decoded by a decoder  2412 . The encoder  2411  and the decoder  2412  may communicate over a network. 
     The decoder  2412  includes an electronic device  2422  configured to decode using the high throughput significance map processing. The electronic device  2422  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable to perform the operations shown in  FIGS. 24-27 . 
     The encoder  2411  includes an electronic device  2421 , which may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable by the processor to perform operations that will be understood by one of ordinary skill in the art from the description of the configurations shown in  FIGS. 24-27  and the corresponding description thereof. 
       FIG. 24  is a flow diagram illustrating a configuration of a method for high throughput significance map decoding on an electronic device at the decode-side. 
     In block  2801 , the electronic device  2422  obtains a bit stream. In block  2802 , the electronic device  2422  obtains a block of level values. In an example, the block comprises a block of TQCs. In block  2803 , the electronic device  2422  obtains a level value of the block, e.g. the first level value of the block or a next level value of the block. 
     In diamond  2804 , the electronic device  2422  determines whether the obtained level value is the last level value of the block. If the obtained level value is not the last level value in diamond  2804 , then the electronic device  2422  proceeds to diamond  2814 . If the obtained level value is the last level value in diamond  2804 , then in block  2805  the electronic device  2422  decodes magnitudes of the level values (which may include determining both sign information and absolute magnitude for each level value). 
     Referring again to diamond  2814 —the electronic device  2422  determines whether the obtained level value is not zero using a first decoding method. If the obtained level value is not zero in diamond  2814 , the electronic device  2422  proceeds to block  2815 ; otherwise, the electronic device  2422  returns to block  2803 . In block  2815 , the electronic device  2422  increments a counter. 
     In diamond  2816 , the electronic device  2422  determines whether a current count of the counter is greater than a preset threshold. In an example, the preset threshold may comprise the preset threshold described with reference to  FIG. 21 . If the current count of the counter is greater than the preset threshold in diamond  2816 , the electronic device  2422  proceeds to block  2817 ; otherwise, the electronic device  2422  returns to block  2803 . 
     In block  2817 , the electronic device  2422  obtains the next level value of the block. In diamond  2818 , the electronic device  2422  determines whether the obtained level value is the last level value of the block. If the obtained level value is not the last level value in diamond  2818 , then the electronic device  2422  proceeds to block  2819 ; otherwise, in block  2820  the electronic device  2422  decodes magnitudes of the level values. 
     In block  2819 , the electronic device  2422  determines whether the obtained level value is not zero using a second decoding method that is different than the first decoding method. In an example, the second decoding method comprises a high throughput decoding method, a bypass decoding method, or the like. In an example, the first decoding method is comprises the regular decoding mode of CABAC. 
     According to the above, a significance map may be decoded element-by-element, e.g. significance map field-by-significance map field. When the preset threshold is reached, the electronic device  2422  may change the decoding of the remaining significance map portion. A high throughput or bypass significance map decoding mode may be used for the remaining significance map portion. Therefore, decoding performance may be improved over conventional CABAC significance map decoding. 
       FIG. 25  is a flow diagram illustrating another configuration of a method for high throughput significance map decoding on an electronic device at the decode-side. 
     In the method shown in  FIG. 25 , processes  2901 - 2905  may be performed as shown, similar to processes  2801 - 2805  ( FIG. 24 ). In diamond  2914 , the electronic device  2422  determines whether the absolute value of the obtained level value is greater than a first threshold using a first decoding method. In an example, the first threshold may be either  1  or  2 , although other first thresholds may be used in other examples. If the absolute value of the obtained level value is greater than the first threshold in diamond  2914 , the electronic device  2422  proceeds to block  2915 ; otherwise, the electronic device  2422  returns to block  2903 . In block  2915 , the electronic device  2422  increments a counter. 
     In diamond  2916 , the electronic device  2422  determines whether a current count of the counter is greater than a second preset threshold. In an example, the second preset threshold may be 8, which is half of the number of values of a 4×4 block. In examples with a block size having N level values, the second preset threshold may correspond to 50% of N. If the current count of the counter is greater than the second threshold in diamond  2916 , the electronic device  2422  proceeds to block  2917 ; otherwise, the electronic device  2422  returns to block  2903 . 
     In block  2917 , the electronic device  2422  obtains the next level value of the block. In diamond  2918 , the electronic device  2422  determines whether the obtained level value is the last level value of the block. If the obtained level value is not the last level value in diamond  2918 , then the electronic device  2422  proceeds to block  2919 ; otherwise, in block  2920  the electronic device  2422  decodes magnitudes of the level values. 
     In block  2919 , the electronic device  2422  determines whether the absolute value of the obtained level value is greater than the first threshold using a second decoding method that is different than the first decoding method. In an example, the second decoding method comprises a high throughput decoding method, a bypass decoding method, or the like. In an example, the first decoding method is comprises the regular decoding mode of CABAC. 
     According to the above, a significance map may be decoded element-by-element, e.g. significance map field-by-significance map field. When the preset threshold is reached, the electronic device  2422  may change the decoding of the remaining significance map portion. A high throughput or bypass significance map decoding mode may be used for the remaining significance map portion. Therefore, decoding performance may be improved over conventional CABAC significance map decoding. 
       FIG. 26  is a flow diagram illustrating a configuration of a method for high throughput significance map decoding with a decode-bypass feature on an electronic device at the decode-side. 
     In the method shown in  FIG. 26 , processes  3001 - 3004  and  3014 - 3016  may be performed as shown, similar to processes  2801 - 2804  and  2814 - 2816  ( FIG. 24 ). In block  3005 , the electronic device  2422  recovers magnitudes of the level values using a third decoding method, e.g. a binarization method. In block  3020 , the electronic device  2422  recovers magnitudes of a first portion of the level values using the third decoding method, and recovers magnitudes of a second portion of the level values using a fourth decoding method, e.g. a different binarization method. 
     In an example, the first portion of the level values comprises the level values processed with the first decoding method. The second portion of the level values comprises the level values not processed with the first decoding method. 
     It should be apparent that other configurations of a method for high throughput significance map decoding with a decode-bypass feature on an electronic device at the decode-side similar to the configuration shown in  FIG. 26  may be possible and practical. For example, in another configuration, the electronic device  2422  determines if the absolute value of the obtained level value is greater than a first preset threshold using a first decoding method, similar to diamond  2914  ( FIG. 25 ). Also, the electronic device  2422  determines whether the counter is greater than the second preset threshold, similar to diamond  2916  ( FIG. 25 ). 
     According to the above, a significance map may be decoded element-by-element, e.g. significance map field-by-significance map field. When the preset threshold is reached, the electronic device  2422  may stop decoding the significance map (the remaining elements of the significance map are not decoded). Thereafter, the level values that correspond to the decoded elements are processed using a binarization method (e.g. a binarization method that can send the value zero), while the remaining elements are processed using a different binarization method (e.g. a binarization method that cannot send the value zero). Therefore, decoding performance may be improved over conventional CABAC significance map decoding. 
       FIG. 27  is a flow diagram illustrating a configuration of a method for high throughput significance map decoding with a decode-method-switching feature on an electronic device at the decode-side. 
     In the method shown in  FIG. 27 , processes  3801 - 3804  and  3814 - 3819  may be performed as shown, similar to processes  2801 - 2804  and  2814 - 2819  ( FIG. 24 ). In block  3805 , the electronic device  2422  recovers magnitudes of the level values using the third decoding method (the third decoding method of  FIG. 26 ). In block  3820 , the electronic device  2422  recovers magnitudes of a first portion of the level values using the third decoding method, and recovers magnitudes of a second portion of the level values using the fourth decoding method (the fourth decoding method of  FIG. 26 ). In an example, the first portion of the level values comprises the level values obtained in block  3803 , while the second portion of the level values comprises the level values obtained in block  3817 . 
     It should be apparent that other configurations of a method for high throughput significance map decoding with a decode-bypass feature on an electronic device at the decode-side similar to the configuration shown in  FIG. 27  may be possible and practical. For example, in another configuration, the electronic device  2422  determines if the absolute value of the obtained level value is greater than a first preset threshold using a first decoding method, similar to diamond  2914  ( FIG. 25 ). Also, the electronic device  2422  determines whether the counter is greater than the second preset threshold, similar to diamond  2916  ( FIG. 25 ). 
     In an example, a first electronic device including a processor and a memory in electronic communication with the processor is provided. Stored in the memory are instructions executable by the processor to perform operations. 
     In an example, an operation may include receiving a bit stream. Another operation may include obtaining a block of level values based on the received bit stream. Another operation may include identifying a portion of the level values according to a threshold. Another operation may include, after identifying the portion, processing any remaining ones of the level values using a high throughput significance map processing mode. Another operation may include recovering video data based on the processing. 
     In an example, a second electronic device including a processor and a memory in electronic communication with the processor is provided. Stored in the memory are instructions executable by the processor to perform operations. An operation may include transmitting signaling to the first electronic device, wherein the signaling identifies the threshold. 
     According to the above, a significance map may be decoded element-by-element, e.g. significance map field-by-significance map field. When the preset threshold is reached, the electronic device  2422  may stop decoding the significance map (the remaining elements of the significance map are not decoded). Thereafter, the level values that correspond to the decoded elements are processed using a binarization method (e.g. a binarization method that can send the value zero), while the remaining elements are processed using a different binarization method (e.g. a binarization method that cannot send the value zero). Therefore, decoding performance may be improved over conventional CABAC significance map decoding. 
     (Lossless Coding with Different Parameter Selection Technique for CABAC in HEVC) 
     When utilizing CABAC encoding in HEVC in the lossless coding mode, encoding/decoding is computationally complex. One reason for the computation complexity is the encoding of the syntax element “Absolute-3”. In known CABAC coding, the Exponential-Golomb-Rice coding method is used to encode the syntax element. 
     By way of background, the Exponential-Golomb-Rice (G-R) coding method utilizes the Rice parameter update table shown in  FIG. 28 . The G-R coding method is applied to code syntax element “Absolute-3” (i.e. the last line of the table of  FIG. 2 ) in known lossless coding mode of CABAC, as explained in more detail in the next paragraph. 
     The Rice parameter controls the conversion of symbols to bins. To illustrate by way of example, consider using the table of  FIG. 28  and G-R coding to convert the symbols 0, 11, 4 . . . , where “0” (the first symbol) is the initial symbol in a sub-block. The Rice parameter is initialized at zero for the first symbol, because the first symbol is the initial symbol in the sub-block. The first symbol “0” is coded using the current Rice parameter of zero. In one example, the process of coding a symbol with a Rice parameter of RP consists of calculating the value Quotient=floor((symbol−1)/RP) and generating an output containing a Quotient string of bins equal to 1 followed by a bin equal to 0. Here, Quotient is an integer and floor( ) is an operation that maps a value containing an integer and fractional component to the integer component. For illustration, coding a symbol of “5” with Rice parameter 3, would result in a Quotient value of 1 and the output bins of “01”. Similarly, coding a symbol of “100” with Rice parameter 33 would result in a Quotient value of 3 and the output bins of “0001”. In an alternative example, the process of coding a symbol with a Rice parameter of RP consists of calculating the value Quotient=floor((symbol−1)/RP) and generating an output containing a Quotient string of bins equal to 0 followed by a bin equal to 1. In yet another example, the process of coding a symbol with Rice parameter of RP consists of selecting an RP-th lookup table that defines a mapping between symbols and a sequence of bins from a set of lookup tables. Given that the lookup result is zero according to the table of  FIG. 28 , the Rice parameter does not update for the next symbol. The second symbol “11” is thus coded using the current Rice parameter of zero. Given that the lookup result (“2”) for the second symbol “11” and Rice parameter “0” is different than the current Rice parameter value (i.e. zero), the Rice parameter is updated from zero to two. The third symbol “4” is then coded with the current Rice parameter of two. Given that the lookup result is not a different value than the current Rice parameter, the Rice parameter of two is used for the next symbol. 
     Due to the computation complexity of G-R coding the “Absolute-3” value according to known CABAC, encoding/decoding may consume a significant amount of processing resources and/or may take a significant amount of time to complete. The disclosure that follows solves this and other problems. 
       FIG. 29  is a block diagram illustrating an example of an encoder and a decoder. 
     The system  2900  includes an encoder  2911  to generate encoded blocks to be decoded by a decoder  2912 . The encoder  2911  and the decoder  2912  may communicate over a network. 
     The encoder  2911  includes an electronic device  2921  configured to encode using a lossless coding with different parameter selection for CABAC in HEVC. The electronic device  2921  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable by the processor to perform the operations shown in  FIG. 30 . 
     The decoder  2912  includes an electronic device  2922  configured to decode using a lossless coding with different parameter selection for CABAC in HEVC. The electronic device  2922  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable to perform the operations shown in  FIG. 31 . 
       FIG. 30  is a flow diagram illustrating one configuration of a method for lossless coding with different parameter selection on an electronic device. 
     In block  3011 , the electronic device  2921  obtains a block of data to be encoded using an arithmetic based encoder, e.g. a CABAC based encoder. In diamond  3012 , the electronic device  2921  determines whether the block is to be encoded using lossless encoding. If the block is not to be encoded using lossless encoding, then in block  3013  the electronic device  2921  uses a first Absolute-3 coding technique to encode the block of data. 
     If the block is to be encoded using lossless encoding, then in block  3014  the electronic device  2921  uses a second different Absolute-3 coding technique to encode the block of data. In block  3015 , the electronic device  2921  transmits the generated bit stream over a network and/or stores the generated bit stream in a memory device. 
     In an example, the first Absolute-3 coding technique comprises an R-G coding technique of CABAC coding, i.e. the Rice parameter initializes to zero at each sub-block coding stage, and the five Rice parameters of the table shown in  FIG. 28  are considered. In an example, the second different Absolute-3 coding technique does not initialize at zero at each sub-block coding stage, i.e. is differently initialized, and/or uses a different Rice parameter update table, e.g. a reduced Rice parameter update table. 
     In an example, the different initialization may comprise initializing the Rice parameter to zero at each block and not at each sub block. In an example, the different initialization may comprise using the last Rice parameter used in a previous sub-block as the initial Rice parameter of a current sub-block. 
     In an example, the different initialization may comprise initializing based on statistics of residual samples. In an example, the different initialization may comprise initializing at a predefined Rice parameter value based on block type, block size, or color information (luma/chroma), or the like, or any combination thereof. Block type is a value to represent the block based on block size of the block, prediction information (intra/inter) of the block, and color information of the block (luma/chroma). In an example, the different initialization may comprise initializing the Rice parameter at the predefined value “1” when current block type is equal to certain predefined value(s), e.g. “2” and/or “5”. 
     In an example, the different Rice parameter update table comprises fewer Rice parameters than the Rice parameter update table used for the first Absolute-3 coding technique. In an example, the different Rice parameter update table includes only the first two cases (Rice parameter is equal to “0” and “1”). An illustration of such a Rice parameter update table is included in  FIG. 37 . 
     In an example, if the second different Absolute-3 coding technique is used, the electronic device  2921  may set a corresponding indicator, e.g. a flag associated with the second different Absolute-3 coding technique, to a value of 1 (which of course may include changing a default value of said flag or leaving said flag at a default value depending on design preference). 
       FIG. 31  is a flow diagram illustrating one configuration of a method for lossless coding with different parameter selection on an electronic device at the decode-side. 
     In block  3110 , the electronic device  2922  obtains a bit stream. In block  3111 , the electronic device  2922  recovers a binary symbol from the obtained bit stream. 
     In diamond  3112 , the electronic device  2922  determines whether the binary symbol is to be decoded using lossless decoding. In an example, the determination may include checking a header, such as a slice header, corresponding to the received bit stream. Checking the header may further comprise checking a slice header corresponding to the obtained bit stream for a value of a flag associated with a second different Absolute-3 coding technique. In another example, the determination may include checking a previously decoded symbol associated with a block, such as block type or quantization parameter that controls the conversion of coefficient levels to TQCs. If the condition is not met in diamond  3112 , then in block  3113  the electronic device  2922  uses a first Absolute-3 coding technique to obtain a block of TQCs. 
     If the condition is met in diamond  3112 , then in block  3114  the electronic device  2921  uses a second different Absolute-3 coding technique to obtain a residual sample. The electronic device  2922  may store the obtained block of TQCs or the obtained residual sample in a memory device and/or may recover video data in block  3115 . 
     (High Throughput Coding for CABAC in HEVC) 
     When utilizing CABAC coding in HEVC, throughput performance can differ depending on different factors such as but not limited to: total number of bins/pixels, number of bypass bins/pixels, and number of regular (or context) coded bins/pixels. Therefore, depending on these factors, coding may consume a significant amount of processing resources and/or may take a significant amount of time. The disclosure that follows solves this and other problems. 
     By way of background, according to known CABAC, up to twenty five level code flags of a syntax element are context coded. The remaining level code flags are bypass coded. A predefined (and fixed) number of Greater_than_1 flags are context coded, namely eight Greater_than_1 flags. A predefined (and fixed) number of Greater_than_2 flags are context coded, namely one. All of the significance map flags are context coded, namely up to sixteen (a syntax element may have less than sixteen significance map flags depending on the last position information of the block. Therefore, a maximum of twenty five context coded bins are needed for a given subset block (25 bins/16 pixels=1.56 bins/pixel). The above example is when using a 4×4 sub-block. 
       FIG. 34  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device. 
     In block  3411 , the electronic device  3321  obtains a block of data to be encoded using an arithmetic based encoder, e.g. a CABAC based encoder. In block  3412 , the electronic device  3321  context codes a first amount of level code flags of a syntax element, e.g. Greater_than_1 and Greater_than_2 flags of a CABAC syntax element. The first amount comprises a first predefined number, e.g. nine, namely eight Greater_than_1 flags and one Greater_than_2 flag. 
     In block  3413 , the electronic device  3321  identifies a number of actually coded bins in the significance map of the syntax element. In block  3414 , the electronic device  3321  determines a difference of a second predefined number, e.g. sixteen in CABAC, and the identified number. In block  3415 , the electronic device  3321  context codes a second amount of the level code flags, wherein the second amount comprises the determined difference. In block  3416 , the electronic device  3321  transmits the generated bit stream over a network and/or stores the generated bit stream in a memory device. 
     In an example, if the configuration shown in  FIG. 34  is used, the electronic device  3321  may set a corresponding indicator, e.g. a flag, to a value of 1 (which of course may include changing a default value of the flag or leaving the flag at a default value depending on design preference). In an example, the indicator may identify a number of the additional Greater_than_1 and/or Greater_than_2 flags that are context coded. 
     An example of a syntax element generated according to the configuration described above is shown in  FIG. 36 . In the example, a number of actually coded bins in the significance map of the example syntax element is twelve. The determined difference between sixteen and twelve is four. The first amount of the level code flags that are context coded is nine (eight Greater_than_1 flags and one Greater_than_2 flag). The second amount of level code flags that are context coded is four. In this particular example, these four are all Greater_than_1 flags, but in other examples these four may include one or more Greater_than_1 flag and one or more Greater_than_2 flag, or four Greater_than_2 flags. The remaining level code flags are bypass encoded. 
       FIG. 35  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device at the decode-side. 
     In block  3510 , the electronic device  3322  obtains a bit stream. In block  3511 , the electronic device  3322  recovers a binary symbol from the obtained bit stream. 
     In block  3512 , the electronic device  3322  context decodes a first amount of level code flags of a syntax element, e.g. Greater_than_1 and Greater_than_2 flags of a CABAC syntax element, wherein the first amount is equal to a first predefined number, e.g. nine, namely eight Greater_than_1 flags and one Greater_than_2 flag. In diamond  3513 , the electronic device  3322  determines whether additional level code flags of the syntax element are context coded. In an example, the determination may include checking a header, such as a slice header, corresponding to the received bit stream. Checking the header may further comprise checking a slice header corresponding to the obtained bit stream for a value of an indicator, e.g. a flag. If the electronic device  3322  determines that additional level code flags are not context coded in diamond  3513 , then in block  3514  the electronic device  3322  bypass decodes the remaining level code flags of the syntax element. 
     If the electronic device  3322  determines that additional level code flags are context coded in diamond  3513 , then in block  3515  the electronic device  3322  context decodes a second amount of the level code flags of the syntax element. In an example, the electronic device  3322  may identify a number of the additional Greater_than_1 and/or Greater_than_2 flags that are context coded based on information from the slice header. In block  3514 , the electronic device  3322  bypass decodes any remaining level code flags. In block  3516 , the electronic device  3322  stores the obtained block of TQCs or the obtained residual sample in a memory device and/or recovers video data. 
       FIG. 38  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device at the decode-side. 
     In block  3850 , the electronic device  3322  obtains a bit stream. In block  3851 , the electronic device  3322  obtains a block of level values from the obtained bit stream. 
     In block  3853 , the electronic device  3322  determines a position of a last significant coefficient of the block. In block  3854 , the electronic device  3322  context decodes significant coefficients from the obtained block, and determines a maximum number of symbols to context decode as a function of the determined position. 
     In block  3855 , the electronic device  3322  resets a counter, e.g. sets the counter to zero. In diamond  3856 , the electronic device  3322  determines whether a level code flag remains to be decoded. If no level code flag is remaining in diamond  3856 , then in block  3857  the electronic device  3322  stores the obtained block of TQCs or the obtained residual sample in a memory device and/or recovers video data. 
     If a level code flag is remaining (diamond  3856 ), then in diamond  3858  the electronic device  3322  determines whether the counter is greater than a threshold. In an example, the threshold may be associated with the determined maximum. In an example, the threshold may correspond to a difference of the determined maximum and a number of significance map flags of the block. If the counter is greater than the threshold in diamond  3858 , then in block  3859  the electronic device  3322  bypass decodes the level code flag. If the counter is not greater than the threshold in diamond  3858 , then in block  3860  the electronic device  3322  context decodes the level code flag. The electronic device  3322  increments the counter in block  3861 . 
       FIG. 39  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device at the decode-side. 
     In block  3950 , the electronic device  3322  obtains a bit stream. In block  3951 , the electronic device  3322  obtains a block of level values from the obtained bit stream. 
     In block  3953 , the electronic device  3322  determines a position of a last significant coefficient. In block  3954 , the electronic device  3322  context decodes significant coefficients from the obtained block, and determines a maximum number of symbols to context decode as a function of both the determined position and sub-block position. Processes  3955 - 3961  may correspond to processes  3855 - 3861 . 
       FIG. 40  is a flow diagram illustrating one configuration of a method for high throughput coding for CABAC in HEVC on an electronic device at the decode-side. 
     In block  4050 , the electronic device  3322  obtains a bit stream. In block  4051 , the electronic device  3322  obtains a block of level values from the obtained bit stream. 
     In block  4053 , the electronic device  3322  determines a position of a last significant coefficient. In block  4054 , the electronic device  3322  context decodes significant coefficients from the obtained block, and determines a maximum number of symbols to context decode as a function of a property of the block, e.g. a number of significant coefficients of the block. Processes  4055 - 4061  may correspond to processes  3855 - 3861 . 
     In one example, a system is provided. The system may comprise an electronic device configured to obtain a block of level values from a bit stream; context decode a level code flag of the block; check whether there is a next level code flag of the block; if there is a next level code flag, determine whether a count of context-coded level code flags is greater than a threshold; in response to determining that the count is not greater than the threshold, bypass decode the next level code flag; in response to determining that the count is greater than the threshold, context decode the next level code flag; recover a block of TQCs or a residual sample using the decoded level code flags; and store the recovered block in a memory device and/or recover video data. 
     The electronic device may be configured to increment the count responsive to context coding the next level code flag. The electronic device may be configured to repeat the checking, the determining, the decoding, and the incrementing until all level code flags of the block are decoded. The electronic device may be configured to increment the count response to context coding the first level code flag. 
     The electronic device may be configured to determine a position of the last significant coefficient of the block; and determine a maximum number of symbols to context decode based at least in part on a property of the block. The electronic device may be configured to set the threshold according to a result of the maximum number determination. 
     The electronic device may be configured to determine a position of the last significant coefficient of the block; and determine a maximum number of symbols to context decode based at least in part on the determined position. The electronic device may be configured to determine the maximum number of symbols to context decode based at least in part on the determined position and based at least in part on the sub-block position. 
     The electronic device may be configured to context decode a first amount of level code flags of a syntax element associated with the block, wherein the first amount is equal to a first predefined number; identify a number of actually coded bins in the significance map of the syntax element; determine a difference of a second predefined number and the identified number; and context decode a second amount of the level code flags of the syntax element, wherein the second amount comprises the determined difference. In an example, the first predefined number may comprise nine. In an example, the second predefined number may comprise sixteen. In an example, the level code flags corresponding to the first amount of context coded level code flags comprise eight “greater than 1” flags and one “greater than 2” flag. In an example, the level code flags corresponding to the second amount of context coded level code flags comprises only “greater than 1” flags. In an example, the level code flags corresponding to the second amount of context coded level code flags comprises only “greater than 2” flags. In an example, the level code flags correspond to the second amount of context coded flags comprises a third predefined number of “greater than 2” flags and a dynamic number of “greater than 1” flags, wherein the dynamic number comprises a difference of the second amount and the third predefined number. 
     In one example, a system is provided. The system may comprise a first electronic device of an encoder, the first electronic device configured to: obtain a block of data to be encoded using an arithmetic based encoder; determine whether the block of data is to be encoded using lossless encoding; in response to determining that the block of data is not to be encoded using lossless encoding, use a first Absolute-3 coding technique to encode the block of data; in response to determining that the block of data is to be encoded using lossless encoding, use a second Absolute-3 coding technique to encode the block of data; wherein the second Absolute-3 coding technique is different than the first Absolute-3 coding technique; and cause the encoding to be stored in a memory device. 
     The system may further comprise a second electronic device of a decoder, the second electronic device configured to: determine whether a received binary symbol is to be decoded using lossless decoding; in response to determining that the binary symbol is not to be decoded using lossless decoding, using the first Absolute-3 coding technique to obtain a block of TQCs; and in response to determining that the binary symbol is to be decoded using lossless decoding, use the second Absolute-3 coding technique to obtain a residual sample. 
     The first electronic device may be configured to: in response to determining that the block of data is not to be encoded using lossless encoding, initialize a Rice parameter at zero for an initial value of a sub-block; and in response to determining that the block of data is to be encoded using lossless encoding, use a Rice parameter from a last value of a previous sub-block for an initial value of the sub-block. 
     The first electronic device may be configured to: in response to determining that the block of data is not to be encoded using lossless encoding, initialize a Rice parameter at zero for an initial value of a sub-block; and in response to determining that the block of data is to be encoded using lossless encoding, bypass initialization of the Rice parameter at zero for the initial value of the sub-block. 
     The first electronic device may be configured to: in response to determining that the block of data is to be encoded using lossless encoding, initialize the Rice parameter at a predefined value based on at least one selected from the group comprising block type, block size, and color information (luma/chroma). 
     The first electronic device may be configured to: in response to determining that the block of data is to be encoded using lossless encoding, initialize the Rice parameter at one when current block type is equal to two or five. 
     The first electronic device may be configured to: in response to determining that the block of data is not to be encoded using lossless encoding, initialize a Rice parameter at zero for an initial value of a sub-block; and in response to determining that the block of data is to be encoded using lossless encoding, bypass initialization of the Rice parameter at zero for the initial value of the sub-block. 
     The first electronic device may be configured to: in response to determining that the binary symbol is not to be decoded using lossless decoding, employ a first Rice parameter update table; and in response to determining that the binary symbol is to be decoded using lossless decoding, employ a second Rice parameter update table that is different that the first Rice parameter update table. 
     The second Rice parameter update table may comprise is a truncated version of the first Rice parameter update table. In one example, only the second Rice parameter update table is configured to prevent an update after a current Rice parameter is updated to, or initialized to, two, three, or four. 
     In one example, a system is provided. The system may comprise a first electronic device of an encoder, the first electronic device configured to: obtain a block of data to be encoded using an arithmetic based encoder; context code a first amount of level code flags of a syntax element, wherein the first amount is equal to a first predefined number; identify a number of actually coded bins in the significance map of the syntax element; determine a difference of a second predefined number and the identified number; context code a second amount of the level code flags of the syntax element, wherein the second amount comprises the determined difference; and cause a bit stream generated by the context coding to be stored in a memory device. 
     The arithmetic based encoded may comprise a CABAC encoder. The first predefined number may comprise nine. The second predefined number may comprise sixteen. The level code flags corresponding to the first amount of context coded level code flags may comprise eight “greater than 1” flags and one “greater than 2” flag. The level code flags corresponding to the second amount of context coded level code flags may comprise only “greater than 1” flags. The level code flags corresponding to the second amount of context coded level code flags may comprise only “greater than 2” flags. The level code flags corresponding to the second amount of context coded flags may comprise a third predefined number of “greater than 2” flags and a dynamic number of “greater than 1” flags, wherein the dynamic number comprises a difference of the second amount and the third predefined number. 
     (High Throughput Residual Coding for a Transform Skipped Block for CABAC in HEVC) 
       FIG. 41  is a block diagram illustrating an example of an encoder and a decoder. 
     The system  4100  includes an encoder  4111  to generate encoded blocks to be decoded by a decoder  4112 . The encoder  4111  and the decoder  4112  may communicate over a network. 
     The encoder  4111  includes an electronic device  4121  configured to encode using a high throughput residual coding mode. The electronic device  4121  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable by the processor to perform the operations shown in  FIG. 42 . 
     The decoder  4112  includes an electronic device  4122  configured to decode using the high throughput residual coding mode. The electronic device  4122  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable to perform the operations shown in  FIG. 43 . 
       FIG. 42  is a flow diagram illustrating one configuration of a method for high throughput residual coding. 
     In block  4211 , the electronic device  4121  obtains a block of data to be encoded using an arithmetic based encoder, e.g. a CABAC based encoder. In diamond  4212 , the electronic device  4121  determines whether the block is to be encoded using high throughput residual coding. If the block is not to be encoded using high throughput residual coding, then in block  4213  the electronic device  4121  uses a first coding technique to encode the block of data. In an example, the first coding technique may comprise an Absolute-3 coding technique, e.g. the coding technique described with reference to block  3013  of  FIG. 30 . 
     If the block is to be encoded using high throughput residual coding, then in block  4214  the electronic device  4121  uses a second coding technique that is different than the first coding technique to encode the block of data. In block  4215 , the electronic device  4121  transmits the generated bit stream over a network and/or stores the generated bit stream in a memory device. 
     In an example, the second coding technique includes only a subset of coding stages of the first coding technique. In an example, the first coding technique includes Greater_than_1 coding stage and Greater_than_2 coding stage, and the second coding technique does not include at least one of the Greater_than_1 coding stage and Greater_than_2 coding stage. 
     In an example, the first coding technique includes Absolute-3 coding after significance map coding, but the second coding technique does not include Absolute-3 coding after significance map coding. In an example of the second coding technique, after significance map coding, Absolute-1 or Absolute-2 values are coded. In an example, Absolute-1 values are coded if both of the Greater_than_1 coding stage and Greater_than_2 coding stage are skipped, whereas Absolute-2 values are coded if the Greater_than_2 coding stage is skipped and the Greater_than_1 coding stage is not skipped. Sign coding may be performed after Absolute-1 or Absolute-2 coding in one example, although in other examples sign coding may be performed before Absolute-1 or Absolute-2 coding. 
     In an example, the Absolute-1 or Absolute-2 value coding uses any Golomb-Rice (G-R) code described herein. For example, the Absolute-1 or Absolute-2 value coding may use the G-R coding technique described with reference to  FIG. 30 . In an example, the Absolute-1 or Absolute-2 coding uses the same G-R coding used for the first coding technique. 
     In an example, the G-R coding technique used for the Absolute-1 or Absolute-2 value coding may use comprise initializing at a predefined Rice parameter value based on block type, block size, or color information (luma/chroma), or the like, or any combination thereof. In an example, the predefined Rice parameter may depend on texture (luma/chroma). For example, the predefined Rice parameter value may be two for a luma block and may be one for a chroma block. In an example, the same G-R coding is used for Absolute-1 or Absolute-2 coding and Absolute-3 coding. 
     In an example, the electronic device  4121  may explicitly signal to the decode side initialization information. The initialization information may comprise a Rice parameter initialization value for the bit stream or for the current block, i.e. block-by-block basis. If the initialization information includes more than one Rice parameter initialization value for a block, the initialization information may also indicate a criterion for using the first value or the second value, i.e. the values may be two and one, and the condition may be 2 for luma block and/or 1 for chroma block. In an example, the additional information may comprise an additional syntax element. 
     In an example, diamond  4212  may comprise determining whether a Transform_skip_flag of the block of data or a Trans_quant_Bypass_flag is set. In an example, if the Transform_skip_flag or the Trans_quant_Bypass_flag is equal to one, high throughput residual coding is used for that block of data (conversely if neither of Transform_skip_flag and Trans_quant_Bypass_flag are set, high throughput residual coding is not used for that block of data). 
     By way of background, the Transform_skip_flag indicates whether or not the corresponding block is transformed. In known schemes, the Transform_skip_flag is equal to zero when the corresponding block is transformed. When the Transform_skip_flag is equal to one, the corresponding block is not transformed, i.e. the residual data represents the residual sample. 
     By way of background, the Trans_quant_Bypass_flag indicates whether or not the corresponding block is transformed and quantized. When the Trans_quant_Bypass_flag is equal to one, the corresponding block is not transformed and quantized, i.e. the residual data represents the residual sample. Also, because transformation is used in the regular coding mode but not the lossless coding mode, the Trans_quant_Bypass_flag is equal to one when encoding is by a lossless coding mode 
     It should be appreciated that, in an example, at least one level code stage, e.g. Greater_than_1 and/or Greater_than_2, may be selectively skipped for a block of data to be encoded. In an example, checking the Transform_skip_flag of the block of data is used to determine whether or not the at least one level code stage is skipped. In an example, the at least one level coding stage may be skipped if the block of data is to be encoded using a lossless coding mode. It should be appreciated that when the at least one level code stage is skipped, a throughput gain may be realized. 
     In an example, if the second different coding technique is used, the electronic device  4121  may set a corresponding indicator, e.g. a flag associated with the second different coding technique, to a value of 1 (which of course may include changing a default value of said flag or leaving said flag at a default value depending on design preference). However, in some examples, such an explicit signaling is not necessary as the decode side may check the Transform_skip_flag and/or the Trans_quant_Bypass_flag for a block and infer that the encode side used the second coding technique for the block if either one of the Transform_skip_flag and the Trans_quant_Bypass_flag is equal to one. 
       FIG. 43  is a flow diagram illustrating one configuration of a method for high throughput residual coding at the decode-side. 
     In block  4310 , the electronic device  4122  obtains a bit stream. In block  4311 , the electronic device  4122  recovers a binary symbol from the obtained bit stream. 
     In diamond  4312 , the electronic device  4122  determines whether the binary symbol is to be decoded using high throughput residual coding. In an example, diamond  4312  includes determining whether the recovered binary symbol represents transformed coefficients, e.g. determining whether a Transform_skip_flag associated with the recovered binary symbol is set, determining whether a Trans_quant_bypass_flag is set, and/or determining whether the bit stream was coded using a lossless coding mode. If the condition is not met in diamond  4312 , then in block  4313  the electronic device  4122  uses a first coding technique to obtain a block of TQCs. 
     If the condition is met in diamond  4312 , then in block  4314  the electronic device  4122  uses a second different coding technique to obtain a residual sample. The electronic device  4122  may store the obtained block of TQCs or the obtained residual sample in a memory device and/or may recover video data in block  4315 . 
     In an example, only the first coding technique of the first and second coding techniques comprises an Absolute-3 coding technique. In an example, the second coding technique comprises an Absolute-1 or Absolute-2 coding technique. 
     In an example, the first coding technique comprising coding a Greater_than_1 flag and a Greater_than_2 flag, i.e. a GR1 coding stage and a GR2 coding stage, and the second coding technique does not code any Greater_than_1 flag and/or Greater_than_2 flag, i.e. does not include the GR1 coding stage and/or does not include the GR2 coding stage. 
     In an example, the first coding technique comprises a Golomb-Rice (G-R) coding method to code an Absolute-3 value, and the second coding technique comprises the G-R coding method to code an Absolute-1 or Absolute-2 value. In an example, the G-R coding method comprises initializing a Rice parameter at a predefined value based on at least one selected from the group comprising block type, block size, and color information (luma/chroma). In an example, the predefined Rice parameter may depend on texture (luma/chroma). For example, the predefined Rice parameter value is two for a luma block and one for a chroma block. In an example, the same G-R coding is used for Absolute-1 or Absolute-2 coding and Absolute-3 coding. 
     In an example, a system comprises a first electronic device of a decoder configured to obtain a bit stream; recover a binary symbol from the obtained bit stream; determine whether the binary symbol is to be decoded using a high throughput residual coding mode; in response to determining that the binary symbol is not to be decoded using the high throughput residual coding mode, use a first coding technique to obtain a block of Transformed and Quantized Coefficients (TQCs); in response to determining that the binary symbol is to be decoded using the high throughput residual coding mode, use a second different coding technique to obtain a residual sample; and store the obtained block of TQCs or the obtained residual sample, or video data representative of the obtained block of TQCs or the obtained residual sample, in a memory device. 
     In an example, only the first coding technique of the first and second coding techniques comprises an Absolute-3 coding. In an example, the second coding technique comprises an Absolute-1 or Absolute-2 coding. 
     In an example, the first electronic device is configured to determine whether the recovered binary symbol represents transformed coefficients; and use the second different coding technique in response to determining that the recovered binary symbol does not represent the transformed coefficients. In an example, the first electronic device is configured to determine whether a transform skip flag or transform quantization bypass flag associated with the recovered binary symbol is set; and use the second different coding technique in response to determining that the transform skip flag or transform quantization bypass flag is set. In an example, the first electronic device is configured to determine whether a transform skip flag or transform quantization bypass flag associated with the recovered binary symbol is set; and use the second different coding technique in response to determining that the transform skip flag or the transform quantization bypass flag is set. In an example, determine whether the bit stream was coded using a lossless coding mode; and use the second different coding technique in response to determining that the bit stream was coding using the lossless coding mode. 
     In an example, the first coding technique comprises coding a Greater_than_1 flag and a Greater_than_2 flag, and wherein the second coding technique does not code any Greater_than_1 flag and/or Greater_than_2 flag. 
     In an example, the bit stream originates from a Context Adaptive Binary Arithmetic Coding (CABAC) based encoder. 
     In an example, the first coding technique comprises a Golomb-Rice (G-R) coding method to code an Absolute-3 value and the second coding technique comprises the G-R coding method to code an Absolute-1 or Absolute-2 value. 
     In an example, the C-R coding method comprises initializing a Rice parameter at a predefined value based on at least one selected from the group comprising block type, block size, and color information (luma/chroma). In an example, the electronic device  4121  may determine the predefined value for the bit stream or for the block based on initialization information of the bit stream. The initialization information may comprise a Rice parameter initialization value for the bit stream or for the current block, i.e. block-by-block basis. If the initialization information includes more than one Rice parameter initialization value for a block, the initialization information may also indicate a criterion for using the first value or the second value, i.e. the values may be two and one, and the condition may be 2 for luma block and/or 1 for chroma block. In an example, the additional information may comprise an additional syntax element. 
     In an example, the electronic device  4121  may determine a predefined value responsive to determining a number of non-zero coefficients of the current block. For example, the electronic device  4121  may use a first predefined value if the number of non-zero coefficients is greater than a threshold, and a second predefined value that is different than the first predefined value if the number of non-zero coefficients is not greater than the threshold. 
       FIG. 44  is a flow diagram illustrating one configuration of a method for high throughput residual coding at the decode-side. 
     In block  4410 , the electronic device  4122  obtains a bit stream. In block  4411 , the electronic device  4122  recovers a binary symbol from the obtained bit stream. 
     In diamond  4412 , the electronic device  4122  determines whether the binary symbol is to be decoded using high throughput residual coding. In an example, diamond  4412  includes determining whether the recovered binary symbol represents transformed coefficients, e.g. determining whether a Transform_skip_flag associated with the recovered binary symbol is set. 
     If the condition is not met in diamond  4412 , then in block  4413  the electronic device  4122  applies a Rice parameter update function to obtain a block of TQCs. For example, in block  4413  the electronic device  4122  may decode an initial level value using an initial Rice parameter value, apply the Rice parameter update function, such as the Rice parameter update function described by  FIG. 28 , to determine whether to increment the initial Rice parameter value prior to decoding a next level value, etc. 
     If the condition is met in diamond  4412 , then the electronic device  4122  decode the level values differently. For example, the electronic device  4122  may decode a Rice parameter value from the obtained bit stream. Also, the electronic device  4122  may use the decoded Rice parameter value to decode all level values for the block. 
     In an example, in block  4414  the electronic device  4122  determines whether the bit stream signals a Rice parameter value that is greater than a maximum value of the Rice parameter update function. If the bit stream does signal a Rice parameter value that is greater than the maximum value, then in block  4417  the electronic device  4122  uses a Rice parameter value that is greater than the maximum value of the Rice parameter update function. For example, the Rice parameter update function applied in block  4413  may range from zero to a maximum of four (if the Rice parameter update function described by  FIG. 28  is used). However, the bit stream may signal a Rice parameter value that is greater than a maximum value of the Rice parameter update function, e.g. five. 
     If the bit stream does not signal a Rice parameter value that is greater than the maximum value, then in block  4416  the electronic device  4122  may use a Rice parameter value that is not greater than the maximum value of the Rice parameter update function applied in block  4413 , e.g. 0-4. The Rice parameter value used in block  4416  may be signaled by the obtained bit stream. The electronic device  4122  may use the decoded Rice parameter value to decode all level values for the block. 
     The electronic device  4122  may store the obtained block of TQCs or the obtained residual sample in a memory device and/or may recover video data in block  4418 . 
     A flag or other indicator may be used to control whether block  4414  is to be performed by the electronic device  4122 . The encoder-side electronic device  4121  may set the flag or other indicator to a value of 1 (which of course may include changing a default value of said flag or leaving said flag at a default value depending on design preference) to cause block  4414  to be performed by the electronic device  4122 . The flag may be placed at any level in the bit stream, e.g. in sequence level, slice level, Coding Unit (CU) level, Prediction Unit (PU) level, or Transform Unit (TU) level, or the like. In an example, the electronic device  4122  may perform block  4414  only if bit depth of the content is greater than a threshold and the flag is set to one. 
     In the case where diamond  4414  is not to be performed (e.g. the block is not a transform skip block, the flag is set to zero, or the bit depth is not greater than the preset threshold), then a Rice parameter value may not be signaled in the bit stream or the Rice parameter value may be in the range of the Rice parameter update function. If a transform skip block is received but the flag is equal to zero or the bit depth is not greater than the preset threshold, the electronic device  4122  may apply the Rice parameter update function to obtain a residual sample. In an example, the Rice parameter update function may be different than the Rice parameter update function described by  FIG. 28 , for example, the maximum Rice parameter value may be greater than four, e.g. 6 or higher. 
       FIG. 45A  is a flow diagram illustrating one configuration of applying a Rice parameter update function. 
     In block  4510 , the electronic device  4122  initializes a Rice parameter. In block  4511 , the electronic device  4122  decodes a level value using the initialized Rice parameter. 
     In diamond  4512 , the electronic device  4122  determines whether to apply a first Rice parameter update function. In an example, the first Rice parameter update function is the same as the Rice parameter update function described in  FIG. 28 . If the condition is met in diamond  4512 , then in block  4514  the electronic device  4122  applies the first Rice parameter update function. 
     In an example, diamond  4512  includes determining whether the recovered binary symbol represents transformed coefficients, e.g. determining whether a Transform_skip_flag associated with the recovered binary symbol is set. In such example, the first Rice parameter update function is applied in response to determining that the Transform_skip_flag associated with the recovered binary symbol is set, e.g. is equal to a value of one. 
     A flag or other indicator may be used to control whether the first Rice parameter update function is to be applied by the electronic device  4122 . The encoder-side electronic device  4121  may set the flag or other indicator to a value of 1 (which of course may include changing a default value of said flag or leaving said flag at a default value depending on design preference) to cause the electronic device  4122  to use the second different Rice parameter update function. The flag may be placed at any level in the bit stream, e.g. in sequence level, slice level, CU level, PU level, or TU level, or the like. In an example, the electronic device  4121  may determine to apply the second Rice parameter update function only if bit depth of the content is greater than a threshold and the flag is set to one. 
     If the condition is not met in diamond  4512 , then in block  4513  the electronic device  4122  applies a second Rice parameter update function that is different than the first Rice parameter update function. The second Rice parameter update function may have a different maximum value than the first Rice parameter update function, e.g. a higher maximum value. In an example, the second Rice parameter update function has a maximum value of six or higher. 
     For example,  FIG. 45B  shows a table  4900  for an example second different Rice parameter update function having a maximum value of eight. In the table  4900 , the symbol may correspond to Absolute-1, Absolute-2, or Absolute-3. In another table with a maximum Rice parameter value of N, the thresholds may be 4, 7, 13, 25, 49, 97, 193, 385, . . . (3*2N+1). 
     In another example configuration of the electronic devices  4121  and  4122  that is different than the configurations described with respect to  FIGS. 44 and 45 , the electronic device  4122  applies a Rice parameter update function that has a maximum Rice parameter value of six or higher in a similar fashion that HEVC applies the Rice parameter update function that has the maximum Rice parameter value of four. In yet another example configuration of the electronic devices  4121  and  4122 , the electronic device  4121  sets a flag or other indicator to control whether the electronic device  4122  applies the Rice parameter update function that has a maximum Rice parameter value of six or higher or the Rice parameter update function that has the maximum Rice parameter value of four. If the flag or other indicator is set to one, the electronic device  4122  applies the Rice parameter update function that has a maximum Rice parameter value of six or higher. If the flag or other indicator is set to zero, the electronic device  4122  applies the Rice parameter update function that has a maximum Rice parameter value of four. In yet another example configuration of the electronic devices  4121  and  4122 , the electronic device  4122  applies the Rice parameter update function that has a maximum Rice parameter value of six or higher only if bit depth of the content is greater than a threshold and the flag is set to one. 
     (Modified Transform Skip Mode for Higher Bit-Depth Coding) 
     By way of background, in decoding according to HEVC, entropy decoding is followed by inverse quantization, which may be followed by inverse transform skip. In a system that uses known entropy decoding or any of the entropy decoding methods described herein, the inverse transform is not performed for a transform skip block. Instead, scaling may be applied to the result of the inverse quantization. The scaling operation is determined based on a derived variable TS_Shift. In HEVC the inverse transform skip operation corresponds to the following pseudo-code: 
     
       
         
           
               
             
               
                   
               
             
            
               
                 If (TS_Shift &gt; 0) { 
               
               
                  Residue = ( Dequantized coefficient values + (1&lt;&lt;(TS_Shift-1)) ) &gt;&gt; 
               
               
                 TS_Shift 
               
               
                 } else { 
               
               
                  Residue = ( Dequantized coefficient values ) &lt;&lt; TS_Shift 
               
               
                 } 
               
               
                   
               
            
           
         
       
         
         
           
             where, 
             x&gt;&gt;y corresponds to arithmetic right shift of a two&#39;s complement integer representation of x by y binary digits. This function is defined only for non-negative integer values of y. Bits shifted into the most significant bits (MSBs) as a result of the right shift have a value equal to the MSB of x prior to the shift operation. 
             x&lt;&lt;y corresponds to arithmetic left shift of a two&#39;s complement integer representation of x by y binary digits. This function is defined only for non-negative integer values of y. Bits shifted into the least significant bits (LSBs) as a result of the left shift have a value equal to 0. 
           
         
       
    
     A known scaling operation involves determining TS_Shift as MAX_TDR−Bit_Depth−Log 2TrSize. Max_TDR is the maximum dynamic range of the transform, which may be 15 in known systems. Bit_Depth is the bit depth of the sample values, which in known systems may range from 0 to 16. Log 2TrSize is the Log 2 of the transform size, which may be 2 in known systems where the transform skip is applied to 4×4 blocks (TrSize means the size of the block). For higher bit-depth coding, precision loss has been observed subsequent to applying the scaling operation where TS_Shift=MAX_TDR−Bit_Depth−Log 2TrSize. 
     To support higher bit-depth coding without precision loss observed that is known in the art, TS_Shift may be determined as MAX[(MAX_TDR−Bit_Depth−Log 2TrSize), 0]. The MAX operation returns the maximum values of the values between the parentheses, e.g. MAX_TDR−Bit_Depth−Log 2TrSize and 0. Therefore, TS_Shift is a non-negative integer, e.g. an integer that is not less than zero. 
     In another example, to support higher bit-depth coding without precision loss observed that is known in the art, TS_Shift may be determined as MAX_TDR−Bit_Depth−Log 2TrSize+A. The encoder may select the variable A to control whether TS_Shift can be less than zero, or not. The decoder may decode the value A from the bit stream for determining TS_Shift using MAX_TDR−Bit_Depth−Log 2TrSize+A. 
     In an example, the encoder may set A to 1 if bit depth of the input video data is greater than or equal to 14 bit, and A is set to 0 for other bit depths. Also, the encoder may set A to 3 if bit depth of the input video data is greater than or equal to 14 bit but not greater than 16 bit, and A is set to 0 for other bit depths. 
       FIG. 46  is a block diagram illustrating an example of an encoder and a decoder. 
     The system  4600  includes an encoder  4611  to generate encoded blocks to be decoded by a decoder  4612 . The encoder  4611  and the decoder  4612  may communicate over a network. 
     The encoder  4611  includes an electronic device  4621  configured to encode using a modified transform skip mode. The electronic device  4621  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable by the processor to perform the operations shown in  FIG. 47 . 
     The decoder  4612  includes an electronic device  4622  configured to decode using the modified transform skip mode. The electronic device  4622  may comprise a processor and memory in electronic communication with the processor, where the memory stores instructions being executable to perform the operations shown in  FIG. 48 . 
       FIG. 47  is a flow diagram illustrating one configuration of a method for using a modified transform skip mode. 
     In block  4701 , the electronic device  4621  obtains a block of data to be encoded using an arithmetic based encoded, e.g. a CABAC based encoder. In diamond  4702 , the electronic device  4621  determines whether an encoding of the block is to be decoded using a modified transform skip mode. 
     If the encoding of the block is to be decoded using a modified transform skip mode, in block  4703 , the electronic device  4621  signals decoder  4612  to employ a modified transform skip mode to determine TS_Shift. In an example, the signal may be a flag in the generated bit stream. The flag may be placed at any level in the bit stream, e.g. in sequence level, slice level, CU level, PU level, or TU level, or the like. If TS_Shift is to be computed as MAX_TDR−Bit_Depth−Log 2TrSize+A in the modified transform skip mode, electronic device  4621  may also signal a value for A in addition to setting the flag. 
     If the encoding of the block is not to be decoded using a modified transform skip mode, in block  4704 , the electronic device  4621  does not signal decoder  4612  to employ the modified transform skip mode to determine TS_Shift. 
     In block  4705 , the electronic device  4621  encodes the block of data and transmits the generated bit stream over a network and/or stores the generated bit stream in a memory device. 
       FIG. 48  is a flow diagram illustrating one configuration of a method for using a modified transform skip mode at the decode-side. 
     In block  4801 , the electronic device  4622  obtains a bit stream. In block  4802 , the electronic device  4622  recovers a binary symbol. 
     In diamond  4803 , the electronic device  4622  determines whether the binary symbol is to be decoded using a modified transform skip mode. In an example, the electronic device  4622  determines whether a flag in the obtained bit stream is set. 
     If the binary symbol is to be decoded using the modified transform skip mode, in block  4804 , the electronic device  4622  determines TS_Shift using a first algorithm, and recovers video data. In an example, the first algorithm is MAX[(MAX_TDR−Bit_Depth−Log 2TrSize), 0]. In another example, the first algorithm is MAX_TDR−Bit_Depth−Log 2TrSize+A. In the latter case, the electronic device  4622  may also determine the value A based on a signal from the encoder  4611 . Alternatively, in the latter case the electronic device  4622  may infer the value of A based on a property of the obtained bit stream. For example, the electronic device  4622  whether bit depth of the bit stream is greater than or equal to 14 bit, and if so, the value 1 is used for A. However, if the check indicates that the bit stream is less than 14 bit the value 0 is used for A. In another example, the electronic device  4622  determines whether bit depth of the bit stream is greater than equal to 14 bit but not greater than 16 bit, and if so, the value 3 is used for A. However, if the check indicates that the bit depth of bit stream is less than 14 bit or greater than 16 bit then the value 0 is used for A. 
     If the binary symbol is not to be decoded using the modified transform skip mode, in block  4805 , the electronic device  4622  determines TS_Shift using a second different algorithm, and recovers video data. For example, TS_Shift is determined as MAX_TDR−Bit_Depth−Log 2TrSize. In block  4806 , the electronic device  4622  stores the recovered video data in a memory device. 
     Within the HEVC specification the output r[x][y] of the inverse transform skip process for a set of dequantized input d[x][y] is specified as follows:
 
 r [ x ][ y ]= d [ x ][ y ]&lt;&lt;7
 
bdShift=(cIdx==0)?20−BitDepth Y :20−BitDepth C  
 
 r [ x ][ y ]=( r [ x ][ y ]+(1&lt;&lt;(bdShift−1)))&gt;&gt;bdShift
         where cIdx represents the color component index. Hence, BitDepth Y  and BitDepth C  indicate the luma source bit depth and the chroma source bit depth, respectively. bdShift is a shift factor that depends on the bit depth.   ==corresponds to the relational operator “Equal to”.       

     Determining TS_Shift as MAX[(MAX_TDR−Bit_Depth−Log 2TrSize), 0] may be associated with the following modified inverse transform skip process:
 
 r [ x ][ y ]= d [ x ][ y ]&lt;&lt;7
 
bdShift=(cIdx==0)?20−BitDepth Y :20−BitDepth C  
 
bdShift=MAX(7,bdShift)
 
 r [ x ][ y ]=( r [ x ][ y ]+(1&lt;&lt;(bdShift−1)))&gt;&gt;bdShift
         where x and y represents the array indices for the vertical and horizontal dimensions;   Expression x?y: z corresponds to the folllowing—If x is TRUE or not equal to 0, the expression evaluates to the value of y; otherwise, the expression evaluates to the value of z.       

     The overall scaling operation for inverse transform skip shift process which takes as input dequantized coefficients d[x][y] and outputs the residual sample values r[x][y] may contain an initial left bit-shift operation and a later right bit-shift operation. In some systems it may be desirable that the number of bits shifted by the left bit-shift operation must be smaller than or equal to the number of bits shifted by the right bit-shift operation. If the number of bits shifted by the left bit-shift operation is greater than the number of bits shifted by the right bit-shift operation then the resulting output may contain a subset of the least significant bits set to zero. This corresponds to a loss in fidelity in the inverse transform skip process. In an example implementation the restriction that the number of bits shifted by the left bit-shift operation be smaller than or equal to the number of bits shifted by the right bit-shift operation is achieved by limiting the minimum number of bits shifted by the right bit-shift operation, for e,g, the amount of right bit-shift may be calculated as MAX (a lower limit on the amount of right bit-shift, a derived value for the amount of right bit-shift). In another example implementation the restriction that the number of bits shifted by the left bit-shift operation be smaller than or equal to the number of bits shifted by the right bit-shift operation is achieved by limiting the maximum number of bits shifted by the left bit-shift operation, for e,g, the amount of left bit-shift may be calculated as MIN (an upper limit on the amount of left bit-shift, a derived value for the amount of left bit-shift). The MIN operation returns the minimum value of the values between the parentheses, for e.g., MIN(x,y) results in x if x&lt;=y, otherwise it results in y. In another example implementation the restriction that the number of bits shifted by the left bit-shift operation be smaller than or equal to the number of bits shifted by the right bit-shift operation is achieved by limiting both the minimum number of bits shifted by the right bit-shift operation and the maximum number of bits shifted by the left bit-shift operation. In another example implementation the restriction that the number of bits shifted by the left bit-shift operation be smaller than or equal to the number of bits shifted by the right bit-shift operation is achieved by any other appropriate mechanism. 
     When limiting the maximum number of bits shifted by the left bit-shift operation, the output r[x][y] of the inverse transform skip process for a set of dequantized input d[x][y] (note, d[x][y] may also be referred to as scaled transform coefficients), may be specified as follows:
         a. The variable bdShift is derived as follows:
 
bdShift=(cIdx==0)?20−BitDepth Y :20−BitDepth C  
   b. The (nTbS)×(nTbS) array of residual samples r is derived as follows:
           If transform_skip_flag_sh[xTbY][yTbY][cIdx] is equal to 1, the residual sample array values r[x][y] with x=0 . . . nTbS−1, y=0 . . . nTbS−1 are derived as follows:
 
 r [ x ][ y ]=( d [ x ][ y ]&lt;&lt;MIN(7,bdShift))
   
           Otherwise (transform_skip_flag_sh[xTbY][yTbY][cIdx] is equal to 0), the transformation process for scaled transform coefficients is invoked with the transform block location (xTbY, yTbY), the size of the transform block nTbS, the colour component variable cIdx, and the (nTbS)×(nTbS) array of scaled transform coefficients d as inputs, and the output is an (nTbS)×(nTbS) array of residual samples r.   c. The residual sample values r[x][y] with x=0 . . . nTbS−1, y=0 . . . nTbS−1 are modified as follows:
 
 r [ x ][ y ]=( r [ x ][ y ]+(1&lt;&lt;(bdShift−1)))&gt;&gt;bdShift
   Where,   (xTbY, yTbY) corresponds to a luma location specifying the top-left sample of the current luma transform block relative to the top-left luma sample of the current picture,   cIdx specifies the colour component of the current block,   nTbS specifies the size of the current transform block,   BitDepth Y  and BitDepth C  indicate the luma source bit depth and the chroma source bit depth, respectively.   transform_skip_flag_sh[x0][y0][cIdx] specifies whether a transform is applied to the associated transform block or not: The array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered transform block relative to the top-left luma sample of the picture. The array index cIdx specifies an indicator for the colour component; it is equal to 0 for luma, equal to 1 for Cb, and equal to 2 for Cr. transform_skip_flag_sh[x0][y0][cIdx] equal to 1 specifies that no transform is applied to the current transform block. transform_skip_flag_sh[x0][y0][cIdx] equal to 0 specifies that the decision whether transform is applied to the current transform block or not depends on other syntax elements. When transform_skip_flag_sh[x0][y0][cIdx] is not present, it is inferred to be equal to 0.       

     In an example embodiment, when limiting the maximum number of bits shifted by the left bit-shift operation, the derived value for the amount of left bit-shift is determined based on past data signaled in the bitstream for e.g. size of current transform block. If we denote the derived value for the amount of left bit-shift as derivedTSLeftShift, then the output r[x][y] of the inverse transform skip process for a set of dequantized input d[x][y] (also referred to as scaled transform coefficients), may be specified as follows:
         a. The variable bdShift is derived as follows:
 
bdShift=(cIdx==0)?20−BitDepth Y :20−BitDepth C  
   b. The (nTbS)×(nTbS) array of residual samples r is derived as follows:
           If transform_skip_flag_sh[xTbY][yTbY][cIdx] is equal to 1, the residual sample array values r[x][y] with x=0 . . . nTbS−1, y=0 . . . nTbS−1 are derived as follows:
 
 r [ x ][ y ]=( d [ x ][ y ]&lt;&lt;MIN(derived TS LeftShift,bdShift))
   
           Otherwise (transform_skip_flag_sh[xTbY][yTbY][cIdx] is equal to 0), the transformation process for scaled transform coefficients is invoked with the transform block location (xTbY, yTbY), the size of the transform block nTbS, the colour component variable cIdx, and the (nTbS)×(nTbS) array of scaled transform coefficients d as inputs, and the output is an (nTbS)×(nTbS) array of residual samples r.   c. The residual sample values r[x][y] with x=0 . . . nTbS−1, y=0 . . . nTbS−1 are modified as follows:
 
 r [ x ][ y ]=( r [ x ][ y ]+(1&lt;&lt;(bdShift−1)))&gt;&gt;bdShift
       

     In an example, transform_skip_flag_sh[xTbY][yTbY][cIdx] corresponds to the Transform_skip_flag. 
     The system and apparatus described above may use dedicated processor systems, micro controllers, programmable logic devices, microprocessors, or any combination thereof, to perform some or all of the operations described herein. Some of the operations described above may be implemented in software and other operations may be implemented in hardware. One or more of the operations, processes, and/or methods described herein may be performed by an apparatus, a device, and/or a system substantially similar to those as described herein and with reference to the illustrated figures. 
     A processing device may execute instructions or “code” stored in memory. The memory may store data as well. The processing device may include, but may not be limited to, an analog processor, a digital processor, a microprocessor, a multi-core processor, a processor array, a network processor, or the like. The processing device may be part of an integrated control system or system manager, or may be provided as a portable electronic device configured to interface with a networked system either locally or remotely via wireless transmission. 
     The processor memory may be integrated together with the processing device, for example RAM or FLASH memory disposed within an integrated circuit microprocessor or the like. In other examples, the memory may comprise an independent device, such as an external disk drive, a storage array, a portable FLASH key fob, or the like. The memory and processing device may be operatively coupled together, or in communication with each other, for example by an I/O port, a network connection, or the like, and the processing device may read a file stored on the memory. Associated memory may be “read only” by design (ROM) by virtue of permission settings, or not. Other examples of memory may include, but may not be limited to, WORM, EPROM, EEPROM, FLASH, or the like, which may be implemented in solid state semiconductor devices. Other memories may comprise moving parts, such as a conventional rotating disk drive. All such memories may be “machine-readable” and may be readable by a processing device. 
     Operating instructions or commands may be implemented or embodied in tangible forms of stored computer software (also known as “computer program” or “code”). Programs, or code, may be stored in a digital memory and may be read by the processing device. “Computer-readable storage medium” (or alternatively, “machine-readable storage medium”) may include all of the foregoing types of memory, as well as new technologies of the future, as long as the memory may be capable of storing digital information in the nature of a computer program or other data, at least temporarily, and as long at the stored information may be “read” by an appropriate processing device. The term “computer-readable” may not be limited to the historical usage of “computer” to imply a complete mainframe, mini-computer, desktop or even laptop computer. Rather, “computer-readable” may comprise storage medium that may be readable by a processor, a processing device, or any computing system. Such media may be any available media that may be locally and/or remotely accessible by a computer or a processor, and may include volatile and non-volatile media, and removable and non-removable media, or any combination thereof. 
     A program stored in a computer-readable storage medium may comprise a computer program product. For example, a storage medium may be used as a convenient means to store or transport a computer program. For the sake of convenience, the operations may be described as various interconnected or coupled functional blocks or diagrams. However, there may be cases where these functional blocks or diagrams may be equivalently aggregated into a single logic device, program or operation with unclear boundaries. 
     One of skill in the art will recognize that the concepts taught herein can be tailored to a particular application in many other ways. In particular, those skilled in the art will recognize that the illustrated examples are but one of many alternative implementations that will become apparent upon reading this disclosure. 
     Although the specification may refer to “an”, “one”, “another”, or “some” example(s) in several locations, this does not necessarily mean that each such reference is to the same example(s), or that the feature only applies to a single example.