Patent ID: 12262064

DETAILED DESCRIPTION

FIG.1illustrates an example block-based video encoder. An input video signal102may be processed, for example block by block. A video block unit may comprise 16×16 pixels. Such a block unit may be referred to as a macroblock (MB). A video block unit size may be extended, for example to 64×64 pixels. Extended size video blocks may be used to compress high resolution video signals (e.g., 1080p video signals and beyond). Extended block sizes may be referred to as coding units (CUs). A CU may be partitioned into one or more prediction units (PUs), for which separate prediction methods may be applied.

For one or more input video blocks (e.g., each input video block), such as MBs or CUs, spatial prediction160and/or temporal prediction162may be performed. Spatial prediction160, which may be referred to as intra prediction, may use pixels from one or more already coded neighboring blocks in a video picture and/or slice, for example to predict a video block. Spatial prediction160may reduce spatial redundancy that may be inherent in a video signal. Temporal prediction162, which may be referred to as inter prediction and/or motion compensated prediction may use pixels from one or more already coded video pictures, for example to predict a video block. Temporal prediction may reduce temporal redundancy that may be inherent in a video signal. A temporal prediction signal for a video block may include one or more motion vectors and/or one or more reference picture indexes, for example if multiple reference pictures are used, in order to identify from which reference pictures in a reference picture store164the temporal prediction signal may originate.

After spatial prediction and/or temporal prediction are performed, a mode decision block180(e.g., in an encoder) may choose a prediction mode, for example based on a rate-distortion optimization method. A prediction block may be subtracted from a video block116. A prediction residual may be transformed104and/or quantized106. One or more quantized residual coefficients may be inverse quantized110and/or inverse transformed112, for example to form a reconstructed residual. The reconstructed residual may be added to a prediction block126, for example to form a reconstructed video block.

Further in-loop filtering, such as one or more deblocking filters and/or Adaptive Loop Filters166may be applied on the reconstructed video block, for example before it is stored in the reference picture store164and/or used to code subsequent video blocks. To form an output video bitstream120, a coding mode (e.g., inter or intra), prediction mode information, motion information, and/or quantized residual coefficients may be sent to an entropy coding unit108, for example to be further compressed and/or packed to form the bitstream120.

FIG.2illustrates an example block-based video decoder that may correspond to the block-based encoder depicted inFIG.1. A video bitstream202may be unpacked and/or entropy decoded, for example at an entropy decoding unit208. A coding mode and/or prediction information may be sent to a spatial prediction unit260(e.g., for intra coding) or a temporal prediction unit262(e.g., for inter coding), for example to form a prediction block. One or more residual transform coefficients may be sent to an inverse quantization unit210and/or an inverse transform unit212, for example to reconstruct a residual block. The prediction block and the residual block may be added together at226, for example to form a reconstructed block. The reconstructed block may be processed through in-loop filtering (e.g., using a loop filter266), for example before being added to a reconstructed output video220to be transmitted (e.g., to a display device) and/or before being stored in a reference picture store264, for example for use in predicting one or more subsequent video blocks.

Video may be consumed on devices with varying capabilities in terms of computing power, memory and/or storage size, display resolution, display frame rate, etc., for example by smart phones and/or tablets. Network and/or transmission channels may have varying characteristics in terms of packet loss rate, available channel bandwidth, burst error rate, etc. Video data may be transmitted over a combination of wired networks and/or wireless networks, which may complicate one or more underlying video transmission channel characteristics. In such scenarios, scalable video coding may improve a video quality provided by video applications, for instance video quality provided by video applications running on devices with different capabilities over heterogeneous networks.

Scalable video coding may encode a video signal in accordance with a highest representation (e.g., temporal resolution, spatial resolution, quality, etc.), but may enable decoding from respective subsets of one or more video streams, for example in accordance with a specified rate and/or representation employed by one or more applications running on a client device. Scalable video coding may enable bandwidth and/or storage savings.

FIG.3illustrates an example two-layer scalable video coding system having one base layer (BL) and one enhancement layer (EL). Spatial resolutions between the two layers may be different, such that spatial scalability may be applied. A base layer encoder (e.g., a High Efficiency Video Coding (HEVC) encoder) may encode a base layer video input, for example block by block, and may generate a base layer bitstream (e.g., in accordance with the block diagram depicted inFIG.1). An enhancement layer encoder may encode an enhancement layer video input, for example block by block, and may generates an enhancement layer bitstream (e.g., in accordance with the block diagram depicted inFIG.1). A coding efficiency of a scalable video coding system (e.g., the coding efficiency of enhancement layer coding) may be improved. For example, signal correlation from a base layer reconstructed video may be used to improve prediction accuracy.

A base layer reconstructed video may be processed such that at least portions of one or more processed base layer pictures may be inserted into an enhancement layer Decoded Picture Buffer (EL DPB) and/or used to predict an enhancement layer video input. A base layer video and an enhancement layer video may be substantially the same video source represented in respective different spatial resolutions, such that they correspond to each other via a downsampling process, for example. Inter-layer prediction (ILP) processing may be carried out by an inter-layer processing and/or management unit, such as an upsampling operation that may be used to align a spatial resolution of a base layer reconstruction with that of an enhancement layer video. A scalable video coding bitstream may include a base layer bitstream, an enhancement layer bitstream produced by the base and enhancement layer encoders, and/or inter-layer prediction information.

Inter-layer prediction information may be produced by the ILP processing and management unit. For example, ILP information may include one or more of the following: a type of inter-layer processing applied; one or more parameters used in the processing (e.g., which upsampling filters are used); which of one or more processed base layer pictures should be inserted into an EL DPB; etc. The base and enhancement layer bitstreams and/or the ILP information may be multiplexed together, for example to form a scalable bitstream (e.g., an SHVC bitstream).

FIG.4illustrates an example two-layer scalable video decoder that may correspond to the scalable encoder depicted inFIG.3. The decoder may perform one or more operations, for example in a reverse order relative to the encoder. The scalable bitstream may be de-multiplexed into a base layer bitstream, an enhancement layer bitstream, and/or the ILP information. The base layer decoder may decode a base layer bitstream and/or may produce a base layer reconstruction.

The ILP processing and management unit may receive the ILP information and/or may process the base layer reconstruction, for example in accordance with the received ILP information. The ILP processing and management unit may selectively insert one or more processed base layer pictures into an EL DPB, for example in accordance with the received ILP information. An enhancement layer decoder may decode the enhancement layer bitstream, for example with a combination of temporal reference pictures and/or inter-layer reference pictures (e.g., one or more processed base layer pictures), in order to reconstruct an enhancement layer video. For the purposes of the instant disclosure, the terms “inter layer reference picture” and “processed base layer pictures” may be used interchangeably.

FIG.5depicts an example inter-layer prediction and processing management unit, for example as may be implemented in the example two-layer spatial scalable video encoder depicted inFIG.3and/or the example two-layer spatial scalable video decoder depicted inFIG.4. The inter-layer prediction and processing management unit may include one or more stages (e.g., three stages as depicted inFIG.5). In a first stage (e.g., Stage1), the BL reconstructed picture may be enhanced (e.g., before it is upsampled). In a second stage (e.g., Stage2), upsampling may be performed (e.g., when a resolution of the BL is lower than a resolution of the EL in spatial scalability). An output of the second stage may have a resolution that is substantially the same as that of the EL with a sampling grid aligned. An enhancement may be performed in a third stage (e.g., Stage3), for example before the upsampled picture is put in the EL DPB, which may improve inter-layer reference picture quality.

None, one, or more of the above-described three stages may be performed by the inter-layer prediction and processing management unit. For example, in signal-to-noise ratio (SNR) scalability, where a BL picture may have substantially the same resolution as an EL picture but with lower quality, one or more of the above-described three stages (e.g., all the stages) may not be performed, for example such that the BL reconstructed picture may be inserted into EL DPB directly for inter-layer prediction. In spatial scalability, the second stage may be performed, for example to make an upsampled BL reconstructed picture have an aligned sampling grid relative to an EL picture. The first and third stages may be performed to improve inter-layer reference picture quality, which may help achieve higher efficiency in EL coding, for example.

Performing picture level ILP in a scalable video coding system (e.g., as illustrated inFIGS.3and4) may reduce implementation complexity, for example because respective base layer and/or enhancement layer encoder and/or decoder logics, for example at a block level, may be at least partially reused without changes. High level (e.g., picture and/or slice level) configurations may implement insertion of one or more respective processed base layer pictures into an enhancement layer DPB. To improve coding efficiency, one or more block level changes may be allowed in the scalable system, for example in order to facilitate block-level inter-layer prediction, which may be in addition to picture level inter-layer prediction.

The herein described single and/or multi-layer video coding systems may be used for coding color videos. In a color video, each pixel carrying luminance and chrominance information may be made of a combination of respective intensities of primary colors (e.g., YCbCr, RGB, or YUV). Each video frame of a color video may be composed of three rectangular arrays, corresponding to three color channels. One or more samples in a color channel (e.g., each color channel) may have discrete and/or finite magnitudes, which in digital video applications may be represented using 8-bit values. The red, green, and blue (RGB) primary may be used in video capture and/or display systems.

In video coding and/or transmission, video signals in the RGB space may be converted into one or more other color spaces (e.g., with luminance and/or chrominance coordinates), such as YUV, for PAL and SECAM TV systems, and YIQ for NTSC TV systems, for example to reduce bandwidth consumption and/or for compatibility with monochrome video applications. A value of a Y component may represent a brightness of a pixel, while the other two components (e.g., Cb and Cr) may bear chrominance information. A digital color space (e.g., YCbCr) may be a scaled and/or shifted version of an analog color space (e.g., YUV). A transformation matrix for deriving a YCbCr coordinate from an RGB coordinate may be represented as equation (1).

[YC⁢bC⁢r[=[0.2⁢5⁢70.5⁢0⁢40.0⁢9⁢8-0.1⁢4⁢8-0.2⁢9⁢10.4⁢3⁢90.4⁢3⁢9-0.3⁢6⁢8-0.0⁢7⁢1][RGB]+[1⁢61⁢2⁢81⁢2⁢8](1)

Because the human vision system (HVS) may be less sensitive to color than to brightness, the chrominance components Cb and Cr may be subsampled with little degradation of perceived video quality. A color subsampling format may be indicated by a triplet of digits separated by colons. For example, in accordance with a 4:2:2 color subsampling format, a horizontal sampling rate for chrominance components may reduce to half while a vertical sampling rate may be unchanged. In accordance with a 4:2:0 color subsampling format, in order to reduce an associated data rate the sampling rate for chrominance components may be reduced to half in both horizontal and vertical directions. In accordance with a 4:4:4 color subsampling format that may be used for applications using very high video quality, the chrominance components may have sampling rates substantially identical to the sampling rate used for the luminance component. Example sampling grids illustrating luminance and chrominance samples for the above-described color subsampling formats are depicted inFIGS.6A-6C, respectively.

The Y, Cb, and Cr color planes of a frame in a video sequence may be correlated in content (e.g., highly correlated), but the two chroma planes may exhibit fewer textures and/or edges than the luma plane. The three color planes may share a same motion. When a block-based hybrid video coding system (e.g., in accordance withFIGS.1and2) is applied to a color block, the three planes within the block may not be coded separately. If the color block is coded by inter prediction, the two chroma blocks may reuse motion information of the luma block, such as a motion vector and/or a reference index. If the color block is coded by intra prediction, the luma block may have more prediction directions to choose than do one or both of the two chroma blocks, for instance because luma blocks may have more diverse and/or stronger edges.

For example, in accordance with H.264/AVC intra prediction, luma blocks may have nine candidate directions, whereas chroma blocks may have four candidate directions. In accordance with HEVC intra prediction, chroma blocks may have four candidate directions, and luma blocks may have more than four candidate directions (e.g., thirty five candidate directions). Respective transform and/or quantization processes for the luma and/or chroma prediction errors may be performed separately, for example after intra or inter prediction. At low bit-rates (e.g., where a QP for a luma is larger than thirty four) a chroma may have a lighter quantization (e.g., a smaller quantization stepsize) than a corresponding luma, for example because the edges and/or textures in chroma planes may be more delicate and may suffer more from heavy quantization, which may cause visible artifacts, such as color bleeding.

A device that is configured to perform video coding (e.g., to encode and/or decode video signals) may be referred to as a video coding device. Such video coding devices may include video-capable devices, for example a television, a digital media player, a DVD player, a Blu-ray™ player, a networked media player device, a desktop computer, a laptop personal computer, a tablet device, a mobile phone, a video conferencing system, a hardware and/or software based video encoding system, or the like. Such video coding devices may include wireless communications network elements, such as a wireless transmit/receive unit (WTRU), a base station, a gateway, or other network elements.

A video coding device may be configured to receive video signals (e.g., video bitstreams) via a network interface. A video coding device may have a wireless network interface, a wired network interface, or any combination thereof. For example, if the video coding device is a wireless communications network element (e.g., a wireless transmit receive unit (WTRU)), the network interface may be a transceiver of the WTRU. In another example, if the video coding device is a video-capable device that is not configured for wireless communication (e.g., a back-end rack encoder) the network interface may be a wired network connection (e.g., a fiber optic connection). In another example, the network interface may be an interface that is configured to communicate with a physical storage medium (e.g., an optical disk drive, a memory card interface, a direct connection to a video camera, or the like). It should be appreciated that the network interface is not limited to these examples, and that the network interface may include other interfaces that enable a video coding device to receive video signals.

A video coding device may be configured to perform cross-plane filtering on one or more video signals (e.g., a source video signal received by a network interface of the video coding device).

Cross-plane filtering may be used, for example, to restore blurred edges and/or textures in one or both chroma planes using information from a corresponding luma plane. Adaptive cross-plane filters may be implemented. Cross-plane filter coefficients may be quantized and/or signaled such that overhead in a bitstream reduces (e.g., minimizes) performance degradation, for example in accordance with a threshold level of transmission performance of a bitstream associated with the video signal. Cross-plane filter coefficients may be transmitted in the bitstream (e.g., an output video bitstream) and/or may be transmitted out of band with respect to the bitstream.

One or more characteristics of a cross-plane filter (e.g., size, separability, symmetry, etc.) may be determined such that overhead in a bitstream is affordable, without performance degradation. Cross-plane filtering may be applied to videos with various color subsampling formats (e.g., including 4:4:4, 4:2:2, and 4:2:0). Cross-plane filtering may be applied to select regions of a video image (e.g., to edge areas and/or to one or more that may be signaled in the bitstream). Cross-plane filters may be implemented in single-layer video coding systems. Cross-plane filters may be implemented in multi-layer video coding systems.

A luma plane may be used as guidance to improve the quality of one or both chroma planes. For example, one or more portions of information pertaining to a luma plane may be blended into corresponding chroma planes. For the purposes of the instant disclosure, the three color planes of an original (e.g., uncoded) video image may be denoted as Y_org, Cb_org, and Cr_org, respectively, and the three color planes of a coded version of the original video image may be denoted as Y_rec, Cb_rec, and Cr_rec, respectively.

FIG.7illustrates an example of cross-plane filtering that may be used, for example, to transform Y_rec, Cb_rec, and Cr_rec back to an RGB space, where the three planes are denoted as R_rec, G_rec, and B_rec, respectively, using an inverse process (e.g., process (1) depicted above). Y_org, Cb_org, and Cr_org may be transformed back to an RGB space (e.g., at substantially the same time), such that respective original RGB planes may be obtained, denoted as R_org, G_org, and B_org. A least square (LS) training method may take plane pairs (R_org, R_rec), (G_org, G_rec), and (B_org, B_rec) as a training data set to train three filters for the R, G, and B planes, respectively, denoted as filter_R, filter_G, and filter_B. By using filter_R, filter_G, and filter_B to filter R_rec, G_rec, and B_rec, respectively, three improved RGB planes may be obtained, denoted as R_imp, G_imp, and B_imp, and/or distortions between R_org and R_imp, G_org and G_imp, and B_org and B_imp, respectively, may be reduced (e.g., minimized), compared with respective distortions between R_org and R_rec, G_org and G_rec, and B_org and B_rec. R_imp, G_imp, and B_imp may be transformed to the YCbCr space, and Y_imp, Cb_imp, and Cr_imp may be obtained, where Cb_imp and Cr_imp may be an output of the cross-plane filtering process.

Converting a color space, for example back and forth as illustrated inFIG.7, may consume computational resources (e.g., an undesirably large amount of computational resources) of one or both of the encoder and/or decoder sides. Because the space converting processes and filtering processes are both linear, at least a portion of the illustrated cross-plane filtering procedure may be approximated, for example using a simplified process where one or more of the operations (e.g., all of the operations) are performed in the YCbCr space.

As shown inFIG.8A, in order to improve the quality of Cb_rec, an LS training module may take Y_rec, Cb_rec, Cr_rec, and Cb_org as a training data set and optimal filters filter_Y4Cb, filter_Cb4Cb, and filter_Cr4Cb, which may be jointly derived, may be applied to Y_rec, Cb_rec, and Cr_rec, respectively. Respective outputs of the filtering on the three planes may be added together, for example, to obtain an improved Cb plane, denoted as Cb_imp. The three optimal filters may be trained by the LS method such that distortion between Cb_imp and Cb_org may be minimized, for example in accordance with equation (2).
(filterγ4Cb,filterCb4Cb,filterCr4Cb)=arg minE[(Yrec⊗filterγ4Cb+Cbrec⊗filterCb4Cb+Crrec⊗filterCr4Cb−Cborg)2]  (2)
where ⊗ represents two dimensional (2-D) convolution, + and − represent matrix addition and subtraction, respectively, and E[(X)2] represents the mean of the square of each element in matrix X.

As shownFIG.8B, in order to improve the quality of Cr_rec, an LS training module may take Y_rec, Cb_rec, Cr_rec, and Cr_org as a training data set and optimal filters filter_Y4Cr, filter_Cb4Cr, and filter_Cr4Cr, which may be jointly derived, may be applied to Y_rec, Cb_rec, and Cr_rec, respectively. Respective outputs of the filtering on the three planes may be added together, for example, to obtain an improved Cr plane, denoted as Cr_imp. The three optimal filters may be trained by the LS method such that distortion between Cr_imp and Cr_org may be minimized, for example in accordance with equation (3).
(filterγ4Cr,filterCb4Cr,filterCr4Cr)=arg minE[(Yrec⊗filterγ4Cr+Cbrec⊗filterCb4Cr+Crrec⊗filterCr4Cr−Crorg)2]  (3)

Cr may contribute little to improving Cb. Cb may contribute little to improving Cr.

The cross-plane filtering techniques illustrated inFIGS.8A and8Bmay be simplified. For example, as shown inFIG.9A, the quality of a Cb plane may be improved by employing the Y and Cb planes, but not the Cr plane, in LS training, such that two filters, filter_Y4Cb and filter_Cb4Cb, may be jointly derived and may be applied to Y and Cb, respectively. Respective outputs of the filters may be added together, for example to obtain an improved Cb plane, denoted Cb_imp.

As shown inFIG.9B, the quality of a Cr plane may be improved by employing the Y and Cr planes, but not the Cb plane, in LS training, such that two filters, filter_Y4Cr and filter_Cr4Cr, may be jointly derived and may be applied to Y and Cr, respectively. Respective outputs of the filters may be added together, for example to obtain an improved Cr plane, denoted Cr_imp.

The cross-plane filtering techniques illustrated inFIGS.9A and9Bmay reduce respective computational complexities of training and/or filtering, and/or may reduce overhead bits transmitting the cross-plane filter coefficients to the decoder side, such that performance degradation may be marginal.

In order to implement cross-plane filtering in a video coding system, one or more of the following may be addressed: cross-plane filter size determination; cross-plane filter coefficient quantization and/or transmission (e.g., signaling); or adapting cross-plane filtering to one or more local areas.

In order to train optimal cross-plane filters, suitable filter sizes may be determined. The size of a filter may be roughly proportional to the size of overhead associated with the filter and/or a computational complexity of the filter. For example, a 3×3 filter may have nine filter coefficients to be transmitted, and may employ nine multiplications and eight additions to accomplish filtering one pixel. A 5×5 filter may have twenty five filter coefficients to be transmitted and may employ twenty five multiplication and twenty four additions to filter one pixel. Larger size filters may achieve lower minimum distortion (e.g., as in equations (2) and (3) and/or may provide better performance. Filter size may be selected in order balance of computational complexity, overhead size, and/or performance, for example.

Trained filters that may be applied to a plane itself, such as filter_Cb4Cb and filter_Cr4Cr, may be implemented as low-pass filters. Trained filters that may be used for cross-planes, such as filter_Y4Cb, filter_Y4Cr, filter_Cb4Cr, and filter_Cr4Cb, may be implemented as high-pass filters. Using different filters of differing sizes may have little influence on the performance of a corresponding video coding system. The size of a cross-plane filter may be kept small (e.g., as small as possible), for example such that performance penalties are negligible. For example, cross-plane filter size may be selected such that substantially no performance loss is observed. Large size cross-plane filters may be implemented (e.g., M×N cross-plane filters, where M and N may be integers).

For example, for low-pass filters, such as filter_Cb4Cb and filter_Cr4Cr, the filter size may be implemented as 1×1, such that the filter has one coefficient multiplied to respective pixels to be filtered. The filter coefficient of the 1×1 filter_Cb4Cb and filter_Cr4Cr may be fixed to be 1.0, such that the filter_Cb4Cb and filter_Cr4Cr may be saved (e.g., not applied and/or not signaled).

For high-pass filters, such as filter_Y4Cb and filter_Y4Cr, the filter size may be dependent on or independent of the color sampling format. Cross-plane filter size may depend on the color sampling format. For example, a size and/or support region of a cross-plane filter (e.g., filter_Y4Cb and filter_Y4Cr) may be implemented for a select chroma pixel, for example as illustrated inFIGS.10A-10C, where circles may represent respective positions of luma samples, solid triangles may represent respective positions of chroma samples, and luma samples used to filter a select chroma sample (e.g., as represented by an outline triangle) may be represented by grayed circles. As illustrated, the filter size of filter_Y4Cb and filter_Y4Cr may be 3×3 for 4:4:4 and 4:2:2 color formats, and may be 4×3 for 4:2:0 color format. The filter size may be independent of the color format, for example as depicted inFIGS.11A-11C. The filter size may be 4×3, for example in accordance with the size for 4:2:0 format.

A cross-plane filtering process may apply a trained high-pass filter on a Y plane and may take the filtering result, denoted Y_offset4Cb and Y_offset4Cr, as an offset that may be added to a corresponding pixel in a chroma plane, for example in accordance with equations (4) and (5).
Y_offset4Cb=Y_rec⊗filter_Y4Cb andY_offset4Cr=Y_rec⊗filter_Y4Cr  (4)
Cb_imp=Cb_rec+Y_offset4Cb and Cr_imp=Cr_rec+Y_offset4Cr  (5)

Cross-plane filter coefficients may be quantized. Trained cross-plane filters may have real-value coefficients that may be quantized, for example before transmission. For example, filter_Y4Cb may be roughly approximated by an integer filter, denoted as filter_int. Elements in filter_int may have small dynamic range (e.g., from −8 to 7 in accordance with a 4-bit representation). A second coefficient, denoted as coeff., may be used in order to make filter_int approach filter_Y4Cb more accurately, for example in accordance with equation (6).
filter_Y4Cb≈filter_int×coeff.  (6)

In equation (6), coeff., a real-valued number, may be approximated by M/2N, where M and N are integers, for example in accordance with equation (7).
filter_Y4Cb≈filter_int×M/2N(7)

To transmit filter_Y4Cb, the coefficients in filter_int, together with M and N, may be coded in the bitstream, for example. The above-described quantization technique may be extended, for example, in order to quantize filter_Y4Cr.

Cross-plane filters (e.g., the filter_Y4Cb and/or the filter_Y4Cr) may have flexible separability and/or symmetries. Cross-plane filter properties introduced herein may be described in relation to an example 4×3 cross-plane filter (e.g., in accordance withFIGS.10A-10C or11A-11C), but may be applicable to other filter sizes.

Cross-plane filters may have various symmetry properties, for example as depicted inFIGS.12A-12E. A cross-plane filter may have no symmetry, for example as depicted inFIG.12A. Each square may represent one filter coefficient, and may be labeled with a unique index, which may indicate that its value may be different from those of the remaining filter coefficients. A cross-plane filter may have horizontal and vertical symmetry, for example as depicted inFIG.12B, such that a coefficient may have the same value as one or more corresponding coefficients in one or more other quadrants. A cross plane filter may have vertical symmetry, for example as depicted inFIG.12C. A cross plane filter may have horizontal symmetry, for example as depicted inFIG.12D. A cross plane filter may have point symmetry, for example as depicted inFIG.12E.

Cross-plane filters are not limited to the symmetries illustrated inFIGS.12A-12E, and may have one or more other symmetries. A cross plane filter may have a symmetry if at least two coefficients in a filter have the same value (e.g., at least two coefficients may be labeled with the same index). For example, for high pass cross-plane filters (e.g., filter_Y4Cb and filter_Y4Cr), it may be beneficial to enforce no symmetry on one or more (e.g., all) coefficients along the boundaries of the filter support region, but enforce some symmetry (e.g., horizontal and vertical, horizontal, vertical, or point symmetry) on one or more (e.g., all) of the inner coefficients of the filter support region.

A cross-plane filter may be separable. For example cross-plane filtering using a 4×3 two dimensional filter may be equivalent to applying a 1×3 horizontal filter to the lines (e.g., during the first stage) and applying a 4×1 vertical filter to the columns of the output of the first stage (e.g., during the second stage). The order of the first and second stages may be changed. Symmetry may be applied to the 1×3 horizontal filter and/or the 4×1 vertical filter.FIGS.13A and13Bdepict two one dimensional filters without and with symmetry, respectively.

Whether or not the cross-plane filter is separable and/or symmetric, the coding of filter coefficients into the bitstream may be limited to filter coefficients having unique values. For example, in accordance with the cross-plane filter depicted inFIG.12A, twelve filter coefficients (indexed with 0 to 11) may be coded. In accordance with the cross-plane filter depicted inFIG.12B, four filter coefficients (indexed with 0 to 3) may be coded. Implementing symmetry in a cross-plane filter may reduce overhead size (e.g., in a video signal bitstream).

A summation of the filter coefficients of a cross-plane filter may equal to zero, for example if the cross-plane filters (e.g., filter_Y4Cb and filter_Y4Cr) are high-pass filters. In accordance with this property, which may be a constraint, a coefficient (e.g., at least one coefficient) in a cross-plane filter may have a magnitude equal to the summation of the other coefficients but may have the opposite sign. If a cross-plane filter has X coefficients to be transmitted (e.g., with X equal to 12 as depicted inFIG.12A), X−1 coefficients may be coded into the bitstream (e.g., explicitly coded). A decoder may receive the X−1 coefficients and may derive (e.g., implicitly derive) the value of the remaining coefficient, for example based on the zero-summation constraint.

Cross-plane filtering coefficients may be signaled, for example in a video bitstream. The example syntax table ofFIG.14illustrates an example of signaling a set of two dimensional, non-separable, asymmetric cross-plane filter coefficients for a chroma plane (e.g., Cb or Cr). The following may apply to entries in the example syntax table. The entry num_coeff_hori_minus1 plus one (+1) may indicate a number of coefficients in a horizontal direction of the cross-plane filter. The entry num_coeff_vert_minus1 plus one (+1) may indicate a number of coefficients in a vertical direction of the cross-plane filter. The entry num_coeff_reduced_flag equal to 0 may indicate that a number of the cross-plane filter coefficients may be equal to (num_coeff_hori_minus1+1)×(num_coeff_vert_minus1+1), for example as depicted inFIG.15A. As shown inFIG.15A, num_coeff_hori_minus1 is equal to 2 and num_coeff_vert_minus1 is equal to 3.

The entry num_coeff_reduced_flag equal to 1 may indicate that a number of cross-plane filter coefficients, which may typically be equal to (num_coeff_hori_minus1+1)×(num_coeff_vert_minus1+1), may be reduced to (num_coeff_hori_minus1+1)×(num_coeff_vert_minus1+1)−4, for example by removing the four corner coefficients, for instance as depicted inFIG.15B. The support region of a cross-plane filter may be reduced, for example, by removing the four corner coefficients. Employing the num_coeff_reduced_flag entry may provide enhanced flexibility, for example in whether or not filter coefficients are reduced.

The entry filter_coeff_plus8[i] minus 8 may correspond to an ith cross-plane filter coefficient. The value of filter coefficients may be in a range, for example, of −8 to 7. In such a case, the entry filter_coeff_plus8[i] may be in the range of 0 to 15, and may be coded, for example, in accordance with 4-bit fixed-length coding (FLC). The entries scaling_factor_abs_minus1 and scaling_factor_sign may together specify a value of a scaling factor (e.g., M in equation (7) as follows:
M=(1−2*scaling_factor_sign)*(scaling_factor_abs_minus1+1)  (7)

The entry bit_shifting may specify a number of bits to be right shifted after a scaling process. This entry may represent N in equation (7).

Different regions of a picture may have different statistical properties. Deriving cross-plane filter coefficients for one or more such regions (e.g., for each such region) may improve chroma coding performance. To illustrate, different sets of cross-plane filer coefficients may be applied to different regions of a picture or a slice, for which multiple sets of cross-plane filter coefficients may be transmitted at the picture level (e.g., in an adaptive picture set (APS)) and/or at the slice level (e.g., in a slice header).

If cross-plane filtering is used in a post-processing implementation, for example applied to a reconstructed video before the video is displayed, one or more sets of filter coefficients may be transmitted as a supplemental enhancement information (SEI) message. For each color plane, a total number of filter sets may be signaled. If the number is greater than zero, one or more sets of cross-plane filter coefficients may be transmitted, for example sequentially.

The example syntax table ofFIG.16illustrates an example of signaling multiple sets of cross-plane filter coefficients in an SEI message that may be named cross_plane_filter( ). The following may apply to entries in the example syntax table. The entry cross_plane_filter_enabled_flag equal to one (1) may specify that cross-plane filtering is enabled. In contrast, the entry cross_plane_filter_enabled_flag equal to zero (0) may specify that cross-plane filtering is disabled.

The entry cb_num_of_filter_sets may specify a number of cross-plane filter coefficients sets that may be used for coding the Cb plane of a current picture. The entry cb_num_of_filter_sets equal to zero (0) may indicate that cross-plane filtering is not applied on the Cb plane of the current picture. The entry cb_filter_coeff[i] may be the ith set of cross-plane filter coefficients for the Cb plane. The entry cb_filter_coeff may be a data construct, and may include one or more of num_coeff_hori_minus1, num_coeff_vert_minus1, num_coeff_reduced_flag, filter_coeff_plus8, scaling_factor_abs_minus1, scaling_factor_sign, or bit_shifting.

The entry cr_num_of_filter_sets may specify a number of cross-plane filter coefficients sets that may be used for coding the Cr plane of a current picture. The entry cr_num_of_filter_sets equal to zero (0) may indicate that cross-plane filtering is not applied on the Cr plane of the current picture. The entry cr_filter_coeff[i] may be the ith set of cross-plane filter coefficients for Cr plane. The entry cr_filter_coeff may be a data construct, and may include one or more of num_coeff_hori_minus1, num_coeff_vert_minus1, num_coeff_reduced_flag, filter_coeff_plus8, scaling_factor_abs_minus1, scaling_factor_sign, or bit_shifting.

Region-based cross-plane filtering may be implemented. Cross-plane filtering may be adapted for filtering one or more local areas in a video image, for instance if it is desired to recover a loss of high frequency information in associated chroma planes (e.g., with guidance of the luma plane). For example, cross-plane filtering may be applied to an area rich in edges and/or textures. Edge detection may be performed first, for example in order to find one or more regions where cross-plane filter may be applied. A high-pass filter, such as filter_Y4Cb and/or filter_Y4Cr, may first be applied to the Y plane.

A magnitude of a filtering result may imply whether a filtered pixel is in a high frequency area. A large magnitude may indicate sharp edges in a region of the filtered pixel. A magnitude close to zero may indicate that the filtered pixel is in a homogeneous region. A threshold may be employed to measure a filtering output by filter_Y4Cb and/or filter_Y4Cr. The filtering output may be added to a corresponding pixel in the chroma plane, for example if it is greater than the threshold. For example, respective chroma pixels in smooth regions may not be changed, which may avoid random filtering noise. Region-based cross-plane filtering may reduce video coding complexity while maintaining coding performance. For example, region information, which may include one or more regions, may be signaled to a decoder.

In an implementation of region-based cross-plane filtering, one or more regions with different statistical properties (e.g., smooth, colorful, texture, and/or edge-rich areas) may be detected, for example on the encoder side. A plurality of cross-plane filters may be derived and applied to corresponding ones of the one or more regions. Information pertaining to respective ones of the one or more regions may be transmitted to the decoder side. Such information may include, for example, the area of the region, the location of the region, and/or a specific cross-plane filter to apply to the region.

The example syntax table ofFIG.17illustrates an example of signaling information pertaining to a particular region. The following may apply to entries in the example syntax table. The entries top_offset, left_offset, right_offset, and bottom_offset may specify an area and/or location of a current region. The entries may be representative of respective distances, for example in terms of pixels, from the top, left, right, and bottom sides of a current region to the corresponding four sides of an associated picture, for example as depicted inFIG.18.

The cross_plane_filtering_region_info( ) may include information pertaining to cross-plane filtering of a specified region of a Cb plane, cross-plane filtering of a specified region of a Cr plane, or to cross-plane filtering of respective specified regions of a Cb plane and a Cr plane.

The entry cb_filtering_enabled_flag equal to one (1) may indicate that cross-plane filtering for a current region of the Cb plane is enabled. The entry cb_filtering_enabled_flag equal to zero (0) may indicate that cross-plane filtering for the current region of the Cb plane is disabled. The entry cb_filter_idx may specify that the cross-plane filtercb_filter_coeff[cb_filter_idx] (e.g., signaling cb_filter_coeff as depicted inFIG.16) may be applied to the current region of the Cb plane.

The entry cr_filtering_enabled_flag equal to one (1) may indicate that cross-plane filtering for a current region of the Cr plane is enabled. The entry cr_filtering_enabled_flag equal to zero (0) may indicate that cross-plane filtering for the current region of the Cr plane is disabled. The entry cr_filter_idx may specify that the cross-plane filter cr_filter_coeff[cr_filter_idx] (e.g., signaling cr_filter_coeff as depicted inFIG.16) may be applied to the current region of the Cr plane.

Information pertaining to one or more regions may be transmitted at the picture level (e.g., in an APS or an SEI message) or at the slice level (e.g., in a slice header). The example syntax table ofFIG.19illustrates an example of signaling multiple regions together with multiple cross-plane filters in an SEI message that may be named cross_plane_filter( ) Information pertaining to regions is italicized.

The following may apply to entries in the example syntax table. The entry cb_num_of_regions_minus1 plus 1 (+1) may specify a number of regions in the Cb plane. Each region may be filtered by a corresponding cross-plane filter. The entry cb_num_of_regions_minus1 equal to zero (0) may indicate that an entirety of the Cb plane may be filtered by one cross-plane filter. The entry cb_region_info[i] may be the ith region information in the Cb plane. The entry cb_region_info may be a data construct, and may include one or more of top_offset, left_offset, right_offset, bottom_offset, cb_filtering_enabled_flag, or cb_filter_idx.

The entry cr_num_of_regions_minus1 plus 1 (+1) may specify a number of regions in the Cr plane. Each region may be filtered by a corresponding cross-plane filter. The entry cr_num_of_regions_minus1 equal to zero (0) may indicate that an entirety of the Cr plane may be filtered by one cross-plane filter. The entry cr_region_info[i] may be the ith region information in the Cr plane. The entry cr_region_info may be a data construct, and may include one or more of top_offset, left_offset, right_offset, bottom_offset, cr_filtering_enabled_flag, or cr_filter_idx.

Cross-plane filtering may be used in single-layer video coding systems, and/or in multi-layer video coding systems. In accordance with single-layer video coding (e.g., as illustrated inFIGS.1and2), cross-plane filtering may be applied, for example to improve reference pictures (e.g., pictures stored in reference picture stores164and/or264), such that one or more subsequent frames may be better predicted (e.g., with regard to the chroma planes).

Cross-plane filtering may be used as a post-processing method. For example, cross-plane filtering may be applied to a reconstructed output video220(e.g., before it is displayed). Although such filtering may not be a part of an MCP loop, and thus may not influence coding of subsequent pictures, the post-processing may improve (e.g., directly) quality of a video for display. For example, cross-plane filtering may be applied in HEVC postprocessing with supplemental enhancement information (SEI) signaling. Cross-plane filter information estimated at an encoder side may be delivered, for example, in an SEI message.

In accordance with an example of using multi-layer video coding (e.g., as illustrated inFIGS.3and4), cross-plane filtering may be applied to one or more upsampled BL pictures, for example before the one or more pictures are placed in the EL DPB buffer (e.g., a reference picture list) for predicting higher layer pictures. As depicted inFIG.5, cross-plane filtering may be performed in the third stage. To improve the quality of one or both chroma planes in an upsampled base layer reconstruction picture (e.g., an ILP picture), a corresponding luma plane involved in training and/or filtering may be one from the same ILP picture, where the training and/or filtering processes may be the same as used in single-layer video coding.

In accordance with another example of using multi-layer video coding, a corresponding luma plane may be used (e.g., directly) in the base layer reconstruction picture, without upsampling, to support cross-plane training and/or filtering, for example to enhance the chroma planes in the ILP picture. For example, in accordance with a 2× spatial SVC with a 4:2:0 video source, the size of a base layer luma plane may be substantially the same (e.g., exactly the same) as a size of one or both corresponding chroma planes in the ILP picture. The sampling grids of the two types of planes may be different. The luma plane in the base layer picture may be filtered by a phase-correction filter, for instance in order to align (e.g., exactly align) with a sampling grid of the chroma planes in the ILP picture. One or more following operations may be the same as those described elsewhere herein, for example for single-layer video coding. The color format may be considered as 4:4:4 (e.g., in accordance withFIG.10AorFIG.11A). Using the base layer luma plane to support cross-plane filtering for the chroma planes in an ILP picture may be extended to other ratios of spatial scalability and/or other color formats, for example by simple derivation.

In accordance with another example of using multi-layer video coding, cross-plane filtering may be applied to a reconstructed base layer picture that has not been upsampled. An output of the cross-plane filtering may be upsampled. As depicted inFIG.5, cross-plane filtering may be performed in the first stage. In a spatial scalability case (e.g., where the BL has lower resolution than the EL), cross-plane filtering may be applied to fewer pixels, which may involve lower computational complexity than one or more of the other multi-layer video coding examples described herein. The equations (2) and (3) may not be directly applied, for example because, with reference to equation (2),

Yrec⊗filterY4Cb+Cbrec⊗filterCb4Cb+Crrec⊗filterCr4Cband Cborgmay have different dimensions and may not subtract directly. Yrec, Cbrec, and Crrecmay have the same resolution as in a base layer picture. Cborgmay have the same resolution as in an enhancement layer picture. The derivation of cross-plane filter coefficients in accordance with this example of multi-layer video coding may be achieved using equations (8) and (9).
(filterγ4Cb,filterCb4Cb,filterCr4Cb)=arg minE[(U(Yrec⊗filterγ4Cb+Cbrec⊗filterCb4Cb+Crrec⊗filterCr4Cb)−Cborg)2]  (8)
(filterγ4Cr,filterCb4Cr,filterCr4Cr)=arg minE[(U(Yrec⊗filterγ4Cr+Cbrec⊗filterCb4Cr+Crrec⊗filterCr4Cr)−Crorg)2]  (9)
where U may be an upsampling function that may take a base layer picture as an input, and may output an upsampled picture with the enhancement layer resolution.

In accordance with the cross-plane filtering technique illustrated inFIGS.9A and9B, a chroma plane may be enhanced by the luma plane and by itself (e.g., excluding the other chroma plane), and equations (8) and (9) may be simplified, for example as illustrated in equations (10) and (11).
(filterγ4Cb,filterCb4Cb)=arg minE[(U(Yrec⊗filterγ4Cb+Cbrec⊗filterCb4Cb)−Cborg)2]  (10)
(filterγ4Cr,filterCr4Cr)=arg minE[(U(Yrec⊗filterγ4Cr+Crrec⊗filterCr4Cr)−Crorg)2]  (11)

Based on the cross-plane filtering technique illustrated inFIGS.9A and9B, the size of filter_Cb4Cb and/or filter_Cr4Cr may be reduced to 1×1 and the value of the filter coefficient may be set to 1.0. Equations (10) and (11) may be simplified, for example as illustrated in equations (12) and (13).
filterγ4Cb=arg minE[(U(Yrec⊗filterγ4Cb+Cbrec)−Cborg)2]  (12)
filterγ4Cr=arg minE[(U(Yrec⊗filterγ4Cr+Crrec)−Crorg)2]  (13)

Cross-plane filtering may be adaptively applied. For example, when applied to multi-layer video coding, cross-plane filtering may be adaptively applied, for instance in the first and/or third stages as depicted inFIG.5.

Cross-plane filtering may be adaptively applied to one or more coding levels, for example including one or more of a sequence-level, a picture-level, a slice-level, or a block-level. In accordance with sequence-level adaptation, for example, an encoder may determine to employ cross-plane filtering in the first stage and/or the third stage for coding a portion of a video sequence (e.g., the entirety of the video sequence). Such a determination may be represented, for example as a binary flag that may be included in a sequence header and/or in one or more sequence-level parameter sets, such as a video parameter set (VPS) and/or a sequence parameter set (SPS).

In accordance with picture-level adaptation, for example, an encoder may determine to employ cross-plane filtering in the first stage and/or the third stage for coding one or more EL pictures (e.g., each EL picture of a video sequence). Such a determination may be represented, for example as a binary flag that may be included in a picture header and/or in one or more picture-level parameter sets, such as an adaptive parameter set (APS) and/or a picture parameter set (PPS).

In accordance with slice-level adaptation, for example, an encoder may determine to employ cross-plane filtering in the first stage and/or the third stage for coding one or more EL video slices (e.g., each EL slice). Such a determination may be represented, for example as a binary flag that may be included in a slice header. Signaling mechanisms, such as the above-described, may be implemented in accordance with (e.g., extended to) one or more other level adaptations.

Picture-based cross-plane filtering may be implemented for multi-layer video coding, for example. Information related to such cross-plane filtering may be signaled. For example, one or more flags, such as uplane_filtering_flag and/or vplane_filtering_flag, may be coded, for example once per picture, and may be transmitted to a decoder. The flags uplane_filtering_flag and/or vplane_filtering_flag may indicate, for example, whether cross-plane filtering should be applied to the Cb plane and/or to the Cr plane, respectively. An encoder may determine whether to enable or disable cross-plane filtering for either chroma plane of one or more pictures (e.g., on a picture-by-picture basis). An encoder may be configured to make such a determination, for example, to improve coding performance and/or in accordance with desired levels of coding performance and complexity (e.g., turning on cross-plane filtering may increase decoding complexity).

An encoder may be configured to employ one or more techniques to determine whether to apply picture-based cross-plane filtering to one or more chroma planes. For example, in accordance with an example of performing picture-level selection, Cb planes before and after filtering, for example Cb_rec and Cb_imp, may be compared with an original Cb plane, for example Cb_org, in an EL picture. Mean square error (MSE) values before and after the filtering, that may be denoted as MSE_rec and MSE_imp, respectively, may be calculated and may be compared. In an example, MSE_imp may be smaller than MSE_rec, which may indicate that applying cross-plane filtering may reduce distortion, and cross-plane filtering may be enabled on the Cb plane. If MSE_imp is not smaller than MSE_rec, cross-plane filtering may be disabled on the Cb plane. In accordance with this technique, MSE may be calculated on a whole picture basis, which may mean that a single weighting factor may be applied to one or more pixels (e.g., each pixel) in the MSE calculation.

In accordance with another example of performing picture-level selection, MSE may be calculated based on one or more pixels involved in ILP, for example based on only those pixels involved in ILP. When the encoder determines whether to apply cross-plane filtering on the Cb plane, the ILP map for the picture may not be available yet. For example, the determination may be made before coding the EL picture, whereas the ILP map may be unavailable until the EL picture has been coded.

In accordance with another example of performing picture-level selection, a multi-pass encoding strategy may be employed. In a first pass, the EL picture may be encoded and the ILP map may be recorded. In a second pass, the determination of whether to use cross-plane filtering may be made, for example in accordance with an MSE calculation that may be limited to ILP blocks marked by the ILP map. The picture may be encoded in accordance with this determination. Such multi-pass encoding may be time-consuming, and may involve greater computational complexity when compared to single-pass encoding.

One or more moving objects in respective pictures (e.g., respective pictures of a video sequence) may be more likely to be coded by the ILP picture than non-moving objects. The ILP maps of successive pictures (e.g., successive pictures of a video sequence) may be correlated (e.g., may exhibit a high degree of correlation). Such successive ILP maps may exhibit one or more displacements (e.g., relatively small displacements) relative to each other. Such displacements may be attributed to respective different time instances of the pictures, for example.

In accordance with another example of performing picture-level selection, the ILP maps of one or more previously coded EL pictures may be used to predict an ILP map of a current EL picture to be coded. The predicted ILP map may be used to locate one or more blocks that may be likely to be used for ILP in coding the current EL picture. Such likely to be used blocks may be referred to as potential ILP blocks. One or more potential ILP blocks may be included in calculating the MSE (e.g., as described above) and/or may be used in determining whether to apply cross-plane filtering, for example based on the calculated MSE.

The dimension of the ILP map may depend, for example, on a granularity that an encoder selects. If the dimension of the picture is W×H (e.g., in terms of luma resolution), for example, the dimension of the ILP map may be W×H, in which an entry may represent whether a corresponding pixel is used for ILP. The dimension of the ILP map may be (W/M)×(H/N), in which an entry may represent whether a corresponding block of size M×N is used for ILP. In accordance with an example implementation, M=N=4 may be selected.

An accurate ILP map, for example recorded after the EL picture is coded, may be a binary map, such that entries (e.g., each entry) may be limited to one of two possible values (e.g., zero (0) or one (1)) that may indicate whether the entry is used for ILP. The values of 0 and 1 may indicate for example, that the entry is used for ILP or is not used for ILP, respectively.

The predicted ILP map may be a multi-level map. In accordance with such an ILP map, each entry may have multiple possible values that may represent multiple-level confidence in predicting the block to be used for ILP. Larger values may be indicative of higher confidence. In accordance with an example implementation, possible values of the predicted ILP map from 0 to 128 may be used, where 128 represents a highest confidence and 0 represents a lowest confidence.

FIG.20depicts an example picture-level selection algorithm2000for cross-plane filtering. The illustrated picture-level selection algorithm may be applied to, for example, the Cb plane and/or the Cr plane. At2010, for example before encoding a first picture, a predicted ILP map, denoted as PredILPMap, may be initialized. In accordance with the depicted algorithm, it may be assumed that each block may have an equal chance to be used for ILP, and the value of each entry of the PredILPMap may be set to 128.

At2020, the encoder may determine whether to apply cross-plane filtering. An enhanced Cb plane, Cb_imp, may be generated by cross-plane filtering. A weighted MSE may be calculated, using equations (14) and (15) for example.

WeightedMSEimp=4Width×Height⁢∑x=0Width/2-1∑y=0Height/2-1PredILPMap⁡(x4,y4)⁢(Cbimp(x2,y2)-Cborg(x2,y2))2(14)WeightedMSErec=4Width×Height⁢∑x=0Width/2-1∑y=0Height/2-1PredILPMap⁡(x4,y4)⁢(Cbrec(x2,y2)-Cborg(x2,y2))2(15)

In equations (14) and (15), Cb_rec and Cb_imp may represent the Cb plane before and after cross-plane filtering, Cb_org may represent an original Cb plane of the current EL picture to be coded, and (x,y) may represent a position of a certain pixel in the grid of the luma plane. As shown, equations (14) and (15) assume 4:2:0 color subsampling and that an entry of the ILP map represents a 4×4 block size, so the corresponding positions in the Cb plane and PredILPMap may be (x/2, y/2) and (x/4, y/4), respectively. For each pixel, the squared error (Cb_imp(x/2,y/2)−Cb_org(x/2,y/2))2or (Cb_rec(x/2,y/2)−Cb_org(x/2,y/2))2may be weighted by a corresponding factor in PredILPMap, for example before the error is accumulated into Weighted_MSE_imp or Weighted_MSE_rec. This may mean that distortion on one or more pixels that are more likely to be used for ILP may have higher weight in the weighted MSE.

Alternatively or additionally at2020, an enhanced Cr plane, Cr_imp, may be generated by cross-plane filtering. A weighted MSE may be calculated, using equations (16) and (17) for example.

WeightedMSEimp=4Width×Height⁢∑x=0Width/2-1∑y=0Height/2-1PredILPMap⁡(x4,y4)⁢(Crimp(x2,y2)-Crorg(x2,y2))2(16)WeightedMSErec=4Width×Height⁢∑x=0Width/2-1∑y=0Height/2-1PredILPMap⁡(x4,y4)⁢(Crrec(x2,y2)-Crorg(x2,y2))2(17)

In equations (16) and (17), Cr_rec and Cr_imp may represent the Cr plane before and after cross-plane filtering, Cr_org may represent an original Cr plane of the current EL picture to be coded, and (x,y) may represent a position of a certain pixel in the grid of the luma plane. As shown, equations (16) and (17) assume 4:2:0 color subsampling and that an entry of the ILP map represents a 4×4 block size, so the corresponding positions in the Cr plane and PredILPMap may be (x/2, y/2) and (x/4, y/4), respectively. For each pixel, the squared error (Cr_imp(x/2,y/2)−Cr_org(x/2,y/2)2or (Cr_rec(x/2,y/2)−Cr_org(x/2,y/2)2may be weighted by a corresponding factor in PredILPMap, for example before the error is accumulated into Weighted_MSE_imp or Weighted_MSE_rec. This may mean that distortion on one or more pixels that are more likely to be used for ILP may have higher weight in the weighted MSE.

Weighted_MSE_imp and Weighted_MSE_rec may be compared to one another. If Weighted_MSE_imp is smaller than Weighted_MSE_rec, which may indicate that cross-plane filtering may reduce distortion (e.g., distortion of one or more of the potential ILP blocks) cross-plane filtering may be enabled. If Weighted_MSE_imp is not smaller than Weighted_MSE_rec, cross-plane filtering may be disabled.

Once the determination is made at2020, the current EL picture may be encoded at2030, and the current ILP map, which may be denoted as CurrILPMap, may be recorded at2040. The current ILP map may be used, for example, with an EL picture subsequent to the current EL picture. The current ILP map may be accurate, rather than predicted, and may be binary. If a corresponding block is used for ILP, the value of the entry for that block may be set to 128. If the corresponding block is not used for ILP the value of the entry for that block may be set to zero (0).

At2050, the current ILP map may be used to update the predicted ILP map, for example as shown in equation (18). In accordance with an example updating process, a sum of the previously predicted ILP map (e.g., PredILPMap(x,y)) and the current ILP map (e.g., CurrILPMap(x,y)) may be divided by two, which may mean that an ILP map associated with another picture may have a relatively small impact on the updated predicted ILP map.

PredILPMap⁡(x,y)=PredILPMap⁢(x,y)+CurrILPMap⁢(x,y)2⁢0≤x<Width4,0≤y<Height4(18)

At2060, it may be determined whether an end of the video sequence has been reached. If the end of the video sequence has not been reached, one or more of the above-described operations (e.g.,2020to2060) may be repeated, for example to code successive EL pictures. If the end of the video sequence has been reached, the example picture-level selection algorithm2000may terminate at2070.

The herein described video coding techniques, for example employing cross-plane filtering, may be implemented in accordance with transporting video in a wireless communication system, such as the example wireless communication system2100, and components thereof, depicted inFIGS.21A-21E.

FIG.21Ais a diagram of an example communications system2100in which one or more disclosed embodiments may be implemented. For example, a wireless network (e.g., a wireless network comprising one or more components of the communications system2100) may be configured such that bearers that extend beyond the wireless network (e.g., beyond a walled garden associated with the wireless network) may be assigned QoS characteristics.

The communications system2100may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system2100may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems2100may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and the like.

As shown inFIG.21A, the communications system2100may include at least one wireless transmit/receive unit (WTRU), such as a plurality of WTRUs, for instance WTRUs2102a,2102b,2102c, and2102d, a radio access network (RAN)2104, a core network2106, a public switched telephone network (PSTN)2108, the Internet2110, and other networks2112, though it should be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs2102a,2102b,2102c,2102dmay be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs2102a,2102b,2102c,2102dmay be configured to transmit and/or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, consumer electronics, and the like.

The communications systems2100may also include a base station2114aand a base station2114b. Each of the base stations2114a,2114bmay be any type of device configured to wirelessly interface with at least one of the WTRUs2102a,2102b,2102c,2102dto facilitate access to one or more communication networks, such as the core network2106, the Internet2110, and/or the networks2112. By way of example, the base stations2114a,2114bmay be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and the like. While the base stations2114a,2114bare each depicted as a single element, it should be appreciated that the base stations2114a,2114bmay include any number of interconnected base stations and/or network elements.

The base station2114amay be part of the RAN2104, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station2114aand/or the base station2114bmay be configured to transmit and/or receive wireless signals within a particular geographic region, which may be referred to as a cell (not shown). The cell may further be divided into cell sectors. For example, the cell associated with the base station2114amay be divided into three sectors. Thus, in one embodiment, the base station2114amay include three transceivers, i.e., one for each sector of the cell. In another embodiment, the base station2114amay employ multiple-input multiple output (MIMO) technology and, therefore, may utilize multiple transceivers for each sector of the cell.

The base stations2114a,2114bmay communicate with one or more of the WTRUs2102a,2102b,2102c,2102dover an air interface2116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface2116may be established using any suitable radio access technology (RAT).

More specifically, as noted above, the communications system2100may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station2114ain the RAN2104and the WTRUs2102a,2102b,2102cmay implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface2116using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink Packet Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station2114aand the WTRUs2102a,2102b,2102cmay implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface2116using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station2114aand the WTRUs2102a,2102b,2102cmay implement radio technologies such as IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

The base station2114binFIG.21Amay be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, and the like. In one embodiment, the base station2114band the WTRUs2102c,2102dmay implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, the base station2114band the WTRUs2102c,2102dmay implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station2114band the WTRUs2102c,2102dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell. As shown inFIG.21A, the base station2114bmay have a direct connection to the Internet2110. Thus, the base station2114bmay not be required to access the Internet2110via the core network2106.

The RAN2104may be in communication with the core network2106, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs2102a,2102b,2102c,2102d. For example, the core network2106may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown inFIG.21A, it should be appreciated that the RAN2104and/or the core network2106may be in direct or indirect communication with other RANs that employ the same RAT as the RAN2104or a different RAT. For example, in addition to being connected to the RAN2104, which may be utilizing an E-UTRA radio technology, the core network2106may also be in communication with another RAN (not shown) employing a GSM radio technology.

The core network2106may also serve as a gateway for the WTRUs2102a,2102b,2102c,2102dto access the PSTN2108, the Internet2110, and/or other networks2112. The PSTN2108may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet2110may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and the internet protocol (IP) in the TCP/IP internet protocol suite. The networks2112may include wired or wireless communications networks owned and/or operated by other service providers. For example, the networks2112may include another core network connected to one or more RANs, which may employ the same RAT as the RAN2104or a different RAT.

Some or all of the WTRUs2102a,2102b,2102c,2102din the communications system2100may include multi-mode capabilities, i.e., the WTRUs2102a,2102b,2102c,2102dmay include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU2102cshown inFIG.21Amay be configured to communicate with the base station2114a, which may employ a cellular-based radio technology, and with the base station2114b, which may employ an IEEE 802 radio technology.

FIG.21Bis a system diagram of an example WTRU2102. As shown inFIG.21B, the WTRU2102may include a processor2118, a transceiver2120, a transmit/receive element2122, a speaker/microphone2124, a keypad2126, a display/touchpad2128, non-removable memory2130, removable memory2132, a power source2134, a global positioning system (GPS) chipset2136, and other peripherals2138. It should be appreciated that the WTRU2102may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

The processor2118may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Array (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor2118may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU2102to operate in a wireless environment. The processor2118may be coupled to the transceiver2120, which may be coupled to the transmit/receive element2122. WhileFIG.21Bdepicts the processor2118and the transceiver2120as separate components, it should be appreciated that the processor2118and the transceiver2120may be integrated together in an electronic package or chip.

The transmit/receive element2122may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station2114a) over the air interface2116. For example, in one embodiment, the transmit/receive element2122may be an antenna configured to transmit and/or receive RF signals. In another embodiment, the transmit/receive element2122may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element2122may be configured to transmit and receive both RF and light signals. It should be appreciated that the transmit/receive element2122may be configured to transmit and/or receive any combination of wireless signals.

In addition, although the transmit/receive element2122is depicted inFIG.21Bas a single element, the WTRU2102may include any number of transmit/receive elements2122. More specifically, the WTRU2102may employ MIMO technology. Thus, in one embodiment, the WTRU2102may include two or more transmit/receive elements2122(e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface2116.

The transceiver2120may be configured to modulate the signals that are to be transmitted by the transmit/receive element2122and to demodulate the signals that are received by the transmit/receive element2122. As noted above, the WTRU2102may have multi-mode capabilities. Thus, the transceiver2120may include multiple transceivers for enabling the WTRU2102to communicate via multiple RATs, such as UTRA and IEEE 802.11, for example.

The processor2118of the WTRU2102may be coupled to, and may receive user input data from, the speaker/microphone2124, the keypad2126, and/or the display/touchpad2128(e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor2118may also output user data to the speaker/microphone2124, the keypad2126, and/or the display/touchpad2128. In addition, the processor2118may access information from, and store data in, any type of suitable memory, such as the non-removable memory2130and/or the removable memory2132. The non-removable memory2130may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory2132may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor2118may access information from, and store data in, memory that is not physically located on the WTRU2102, such as on a server or a home computer (not shown).

The processor2118may receive power from the power source2134, and may be configured to distribute and/or control the power to the other components in the WTRU2102. The power source2134may be any suitable device for powering the WTRU2102. For example, the power source2134may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

The processor2118may also be coupled to the GPS chipset2136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU2102. In addition to, or in lieu of, the information from the GPS chipset2136, the WTRU2102may receive location information over the air interface2116from a base station (e.g., base stations2114a,2114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It should be appreciated that the WTRU2102may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

The processor2118may further be coupled to other peripherals2138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals2138may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, and the like.

FIG.21Cis a system diagram of an embodiment of the communications system2100that includes a RAN2104aand a core network2106athat comprise example implementations of the RAN2104and the core network2106, respectively. As noted above, the RAN2104, for instance the RAN2104a, may employ a UTRA radio technology to communicate with the WTRUs2102a,2102b, and2102cover the air interface2116. The RAN2104amay also be in communication with the core network2106a. As shown inFIG.21C, the RAN2104amay include Node-Bs2140a,2140b,2140c, which may each include one or more transceivers for communicating with the WTRUs2102a,2102b,2102cover the air interface2116. The Node-Bs2140a,2140b,2140cmay each be associated with a particular cell (not shown) within the RAN2104a. The RAN2104amay also include RNCs2142a,2142b. It should be appreciated that the RAN2104amay include any number of Node-Bs and RNCs while remaining consistent with an embodiment.

As shown inFIG.21C, the Node-Bs2140a,2140bmay be in communication with the RNC2142a. Additionally, the Node-B2140cmay be in communication with the RNC2142b. The Node-Bs2140a,2140b,2140cmay communicate with the respective RNCs2142a,2142bvia an lub interface. The RNCs2142a,2142bmay be in communication with one another via an lur interface. Each of the RNCs2142a,2142bmay be configured to control the respective Node-Bs2140a,2140b,2140cto which it is connected. In addition, each of the RNCs2142a,2142bmay be configured to carry out or support other functionality, such as outer loop power control, load control, admission control, packet scheduling, handover control, macrodiversity, security functions, data encryption, and the like.

The core network2106ashown inFIG.21Cmay include a media gateway (MGW)2144, a mobile switching center (MSC)2146, a serving GPRS support node (SGSN)2148, and/or a gateway GPRS support node (GGSN)2150. While each of the foregoing elements is depicted as part of the core network2106a, it should be appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

The RNC2142ain the RAN2104amay be connected to the MSC2146in the core network2106avia an luCS interface. The MSC2146may be connected to the MGW2144. The MSC2146and the MGW2144may provide the WTRUs2102a,2102b,2102cwith access to circuit-switched networks, such as the PSTN2108, to facilitate communications between the WTRUs2102a,2102b,2102cand traditional land-line communications devices.

The RNC2142ain the RAN2104amay also be connected to the SGSN2148in the core network2106avia an luPS interface. The SGSN2148may be connected to the GGSN2150. The SGSN2148and the GGSN2150may provide the WTRUs2102a,2102b,2102cwith access to packet-switched networks, such as the Internet2110, to facilitate communications between and the WTRUs2102a,2102b,2102cand IP-enabled devices.

As noted above, the core network2106amay also be connected to the networks2112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

FIG.21Dis a system diagram of an embodiment of the communications system2100that includes a RAN2104band a core network2106bthat comprise example implementations of the RAN2104and the core network2106, respectively. As noted above, the RAN2104, for instance the RAN2104b, may employ an E-UTRA radio technology to communicate with the WTRUs2102a,2102b, and2102cover the air interface2116. The RAN2104bmay also be in communication with the core network2106b.

The RAN2104bmay include eNode-Bs2140d,2140e,2140f, though it should be appreciated that the RAN2104bmay include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs2140d,2140e,2140fmay each include one or more transceivers for communicating with the WTRUs2102a,2102b,2102cover the air interface2116. In one embodiment, the eNode-Bs2140d,2140e,2140fmay implement MIMO technology. Thus, the eNode-B2140d, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU2102a.

Each of the eNode-Bs2140d,2140e, and2140fmay be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink and/or downlink, and the like. As shown inFIG.21D, the eNode-Bs2140d,2140e,2140fmay communicate with one another over an X2 interface.

The core network2106bshown inFIG.21Dmay include a mobility management gateway (MME)2143, a serving gateway2145, and a packet data network (PDN) gateway2147. While each of the foregoing elements is depicted as part of the core network2106b, it should be appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

The MME2143may be connected to each of the eNode-Bs2140d,2140e, and2140fin the RAN2104bvia an S1 interface and may serve as a control node. For example, the MME2143may be responsible for authenticating users of the WTRUs2102a,2102b,2102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs2102a,2102b,2102c, and the like. The MME2143may also provide a control plane function for switching between the RAN2104band other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

The serving gateway2145may be connected to each of the eNode Bs2140d,2140e,2140fin the RAN2104bvia the S1 interface. The serving gateway2145may generally route and forward user data packets to/from the WTRUs2102a,2102b,2102c. The serving gateway2145may also perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when downlink data is available for the WTRUs2102a,2102b,2102c, managing and storing contexts of the WTRUs2102a,2102b,2102c, and the like.

The serving gateway2145may also be connected to the PDN gateway2147, which may provide the WTRUs2102a,2102b,2102cwith access to packet-switched networks, such as the Internet2110, to facilitate communications between the WTRUs2102a,2102b,2102cand IP-enabled devices.

The core network2106bmay facilitate communications with other networks. For example, the core network2106bmay provide the WTRUs2102a,2102b,2102cwith access to circuit-switched networks, such as the PSTN2108, to facilitate communications between the WTRUs2102a,2102b,2102cand traditional land-line communications devices. For example, the core network2106bmay include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the core network2106band the PSTN2108. In addition, the core network2106bmay provide the WTRUs2102a,2102b,2102cwith access to the networks2112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

FIG.21Eis a system diagram of an embodiment of the communications system2100that includes a RAN2104cand a core network2106cthat comprise example implementations of the RAN2104and the core network2106, respectively. The RAN2104, for instance the RAN2104c, may be an access service network (ASN) that employs IEEE 802.16 radio technology to communicate with the WTRUs2102a,2102b, and2102cover the air interface2116. As described herein, the communication links between the different functional entities of the WTRUs2102a,2102b,2102c, the RAN2104c, and the core network2106cmay be defined as reference points.

As shown inFIG.21E, the RAN2104cmay include base stations2140g,2140h,2140i, and an ASN gateway2141, though it should be appreciated that the RAN2104cmay include any number of base stations and ASN gateways while remaining consistent with an embodiment. The base stations2140g,2140h,2140imay each be associated with a particular cell (not shown) in the RAN2104cand may each include one or more transceivers for communicating with the WTRUs2102a,2102b,2102cover the air interface2116. In one embodiment, the base stations2140g,2140h,2140imay implement MIMO technology. Thus, the base station2140g, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU2102a. The base stations2140g,2140h,2140imay also provide mobility management functions, such as handoff triggering, tunnel establishment, radio resource management, traffic classification, quality of service (QOS) policy enforcement, and the like. The ASN Gateway2141may serve as a traffic aggregation point and may be responsible for paging, caching of subscriber profiles, routing to the core network2106c, and the like.

The air interface2116between the WTRUs2102a,2102b,2102cand the RAN2104cmay be defined as an R1 reference point that implements the IEEE 802.16 specification. In addition, each of the WTRUs2102a,2102b, and2102cmay establish a logical interface (not shown) with the core network2106c. The logical interface between the WTRUs2102a,2102b,2102cand the core network2106cmay be defined as an R2 reference point, which may be used for authentication, authorization, IP host configuration management, and/or mobility management.

The communication link between each of the base stations2140g,2140h,2140imay be defined as an R8 reference point that includes protocols for facilitating WTRU handovers and the transfer of data between base stations. The communication link between the base stations2140g,2140h,2140iand the ASN gateway2141may be defined as an R6 reference point. The R6 reference point may include protocols for facilitating mobility management based on mobility events associated with each of the WTRUs2102a,2102b,2102c.

As shown inFIG.21E, the RAN2104cmay be connected to the core network2106c. The communication link between the RAN2104cand the core network2106cmay defined as an R3 reference point that includes protocols for facilitating data transfer and mobility management capabilities, for example. The core network2106cmay include a mobile IP home agent (MIP-HA)2154, an authentication, authorization, accounting (AAA) server2156, and a gateway2158. While each of the foregoing elements is depicted as part of the core network2106c, it should be appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

The MIP-HA may be responsible for IP address management, and may enable the WTRUs2102a,2102b, and2102cto roam between different ASNs and/or different core networks. The MIP-HA2154may provide the WTRUs2102a,2102b,2102cwith access to packet-switched networks, such as the Internet2110, to facilitate communications between the WTRUs2102a,2102b,2102cand IP-enabled devices. The AAA server2156may be responsible for user authentication and for supporting user services. The gateway2158may facilitate interworking with other networks. For example, the gateway2158may provide the WTRUs2102a,2102b,2102cwith access to circuit-switched networks, such as the PSTN2108, to facilitate communications between the WTRUs2102a,2102b,2102cand traditional landline communications devices. In addition, the gateway2158may provide the WTRUs2102a,2102b,2102cwith access to the networks2112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

Although not shown inFIG.21E, it should be appreciated that the RAN2104cmay be connected to other ASNs and the core network2106cmay be connected to other core networks. The communication link between the RAN2104cthe other ASNs may be defined as an R4 reference point, which may include protocols for coordinating the mobility of the WTRUs2102a,2102b,2102cbetween the RAN2104cand the other ASNs. The communication link between the core network2106cand the other core networks may be defined as an R5 reference point, which may include protocols for facilitating interworking between home core networks and visited core networks.

Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element may be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read-only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, terminal, base station, RNC, or any host computer. Features and/or elements described herein in accordance with one or more example embodiments may be used in combination with features and/or elements described herein in accordance with one or more other example embodiments.