Abstract:
A motion compensation method and apparatus. The method includes retrieving data relating to a reference bock, performing a transpose on the retrieved data, performing vertical filtering on the transposed retrieved data, performing one or more transpose on the vertically filtered data, performing horizontal filtering on the transposed vertically filtered dad, and generating an interpolated bock and storing the interpolated block.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of U.S. provisional patent application Ser. No. 61/559,948, filed Oct. 15, 2011, and 61/543,168, filed Oct. 4, 2011, which are herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the present invention generally relate to a method and apparatus for prediction unit size dependent motion compensation filtering order. 
         [0004]    2. Description of the Related Art 
         [0005]    The motion compensation order is fixed for all prediction unit block sizes in HM 4.0 for high efficiency setting. Horizontal filtering is carried out first and the output of the horizontal filtering is rounded to fit within 16 bits. The rounded output from the first stage is then vertically filtered. 
         [0006]      FIG. 1  is an embodiment of a motion compensation apparatus. As shown in  FIG. 1 , Transpose  1  and Transpose  2  are used for row access from input memory and row access to output memory. Transpose  1  reads in row at a time and writes out column at a time. Transpose  2  reads in column at a time and writes out row at a time. Several multiplexers are used to bypass different blocks for special cases of filtering, such as, H subpel, V subpel, Integer pel, etc. 
         [0007]    Table 1 lists the number of motion compensation operations when the motion compensation filtering order is fixed and modified depending on the prediction unit (PU) size. In Table 1, motion vectors are assumed to be fractional in both x- and y-directions. As shown in Table 1, motion compensation computation cycle reduction is in the range from 5% for 64×32 block to 35% for 16×4 block. At time, such as in High Efficiency Video Coding (HEVC), the system may not support 4×4 PU. Hence, 8×4 PU becomes worst case block size from motion compensation cycles point of view. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Comparison of MC cycles for fixed MC filtering order and PU size dependent MC filtering 
               
               
                 order. Motion vectors are assumed to be fractional in both x- and y-directions 
               
             
          
           
               
                 Block 
                 Block 
                 Fixed MC filter order 
                 PU size dependent MC filter order 
                 Percent 
               
             
          
           
               
                 width 
                 height 
                 Filtering 
                 Num MC 
                 Num MC 
                 Filtering 
                 Num MC 
                 Num MC 
                 savings in 
               
               
                 (w) 
                 (h) 
                 order 
                 filterings 
                 filterings 
                 order 
                 filterings 
                 filterings 
                 computations 
               
               
                   
               
             
          
           
               
                 8 
                 4 
                 H first 
                 (h + 7)*w + w*h 
                 120 
                 V first 
                 (w + 7)*h + w*h 
                 92 
                 23%  
               
               
                 16 
                 4 
                 H first 
                 (h + 7)*w + w*h 
                 240 
                 V first 
                 (w + 7)*h + w*h 
                 156 
                 35%  
               
               
                 16 
                 8 
                 H first 
                 (h + 7)*w + w*h 
                 368 
                 V first 
                 (w + 7)*h + w*h 
                 312 
                 15%  
               
               
                 32 
                 8 
                 H first 
                 (h + 7)*w + w*h 
                 736 
                 V first 
                 (w + 7)*h + w*h 
                 568 
                 23%  
               
               
                 32 
                 16 
                 H first 
                 (h + 7)*w + w*h 
                 1248 
                 V first 
                 (w + 7)*h + w*h 
                 1136 
                 9% 
               
               
                 64 
                 16 
                 H first 
                 (h + 7)*w + w*h 
                 2496 
                 V first 
                 (w + 7)*h + w*h 
                 2160 
                 13%  
               
               
                 64 
                 32 
                 H first 
                 (h + 7)*w + w*h 
                 4544 
                 V first 
                 (w + 7)*h + w*h 
                 4320 
                 5% 
               
               
                 4 
                 8 
                 H first 
                 (h + 7)*w + w*h 
                 92 
                 H first 
                 (h + 7)*w + w*h 
                 92 
                 0% 
               
               
                 4 
                 16 
                 H first 
                 (h + 7)*w + w*h 
                 156 
                 H first 
                 (h + 7)*w + w*h 
                 156 
                 0% 
               
               
                 8 
                 16 
                 H first 
                 (h + 7)*w + w*h 
                 312 
                 H first 
                 (h + 7)*w + w*h 
                 312 
                 0% 
               
               
                 8 
                 32 
                 H first 
                 (h + 7)*w + w*h 
                 568 
                 H first 
                 (h + 7)*w + w*h 
                 568 
                 0% 
               
               
                 16 
                 32 
                 H first 
                 (h + 7)*w + w*h 
                 1136 
                 H first 
                 (h + 7)*w + w*h 
                 1136 
                 0% 
               
               
                 16 
                 64 
                 H first 
                 (h + 7)*w + w*h 
                 2160 
                 H first 
                 (h + 7)*w + w*h 
                 2160 
                 0% 
               
               
                 32 
                 64 
                 H first 
                 (h + 7)*w + w*h 
                 4320 
                 H first 
                 (h + 7)*w + w*h 
                 4320 
                 0% 
               
               
                 8 
                 8 
                 H first 
                 (h + 7)*w + w*h 
                 184 
                 H first 
                 (h + 7)*w + w*h 
                 184 
                 0% 
               
               
                 16 
                 16 
                 H first 
                 (h + 7)*w + w*h 
                 624 
                 H first 
                 (h + 7)*w + w*h 
                 624 
                 0% 
               
               
                 32 
                 32 
                 H first 
                 (h + 7)*w + w*h 
                 2272 
                 H first 
                 (h + 7)*w + w*h 
                 2272 
                 0% 
               
               
                 64 
                 64 
                 H first 
                 (h + 7)*w + w*h 
                 8640 
                 H first 
                 (h + 7)*w + w*h 
                 8640 
                 0% 
               
               
                   
               
             
          
         
       
     
         [0008]    Therefore, there is a need for a method and/or apparatus for a more efficient motion compensation. 
       SUMMARY OF THE INVENTION 
       [0009]    Embodiments of the present invention relate to a method and apparatus for motion compensation method and apparatus. The method includes retrieving data relating to a reference bock, performing a transpose on the retrieved data,performing vertical filtering on the transposed retrieved data, performing one or more transpose on the vertically filtered data, performing horizontal filtering on the transposed vertically filtered dad, and generating an interpolated bock and storing the interpolated block. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
           [0011]      FIG. 1  is an embodiment of a motion compensation apparatus; 
           [0012]      FIG. 2  is a block diagram of a digital system; 
           [0013]      FIG. 3  is a block diagram of a video encoder; 
           [0014]      FIG. 4  is a block diagram of a video decoder; 
           [0015]      FIG. 5  is an embodiment of a motion compensation apparatus in accordance with the present invention; and 
           [0016]      FIG. 6  is a flow diagram of a method for performing motion compensation in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Discussed herein are improved method and apparatus for reducing motion compensation (MC) cycles of prediction units (PU) by modifying motion compensation filtering order. For example, for prediction unit width is less than the prediction unit height, vertical filtering maybe carried out first and then horizontal filtering. The filtering order may not change for square prediction units and rectangular prediction units with prediction unit width greater than the prediction unit height. In cases, when using the modified filtering order, it has been shown that the motion compensation computation cycles reduction ranges between 5% for 64×32 block and 35% for 16×4 block, which when the motion vector is fractional in both x- and y-directions. The computation cycles for square prediction units and rectangle prediction units with prediction unit width greater than the prediction unit height may not change. 
         [0018]      FIG. 2  is a block diagram of a digital system.  FIG. 2  shows a block diagram of a digital system that includes a source digital system  200  that transmits encoded video sequences to a destination digital system  202  via a communication channel  216 . The source digital system  200  includes a video capture component  204 , a video encoder component  206 , and a transmitter component  208 . The video capture component  204  is configured to provide a video sequence to be encoded by the video encoder component  206 . The video capture component  204  may be, for example, a video camera, a video archive, or a video feed from a video content provider. In some embodiments, the video capture component  204  may generate computer graphics as the video sequence, or a combination of live video, archived video, and/or computer-generated video. 
         [0019]    The video encoder component  206  receives a video sequence from the video capture component  204  and encodes it for transmission by the transmitter component  208 . The video encoder component  206  receives the video sequence from the video capture component  204  as a sequence of pictures, divides the pictures into largest coding units (LCUs), and encodes the video data in the LCUs. An embodiment of the video encoder component  206  is described in more detail herein in reference to  FIG. 3 . 
         [0020]    The transmitter component  208  transmits the encoded video data to the destination digital system  202  via the communication channel  216 . The communication channel  216  may be any communication medium, or combination of communication media suitable for transmission of the encoded video sequence, such as, for example, wired or wireless communication media, a local area network, or a wide area network. 
         [0021]    The destination digital system  202  includes a receiver component  210 , a video decoder component  212  and a display component  214 . The receiver component  210  receives the encoded video data from the source digital system  200  via the communication channel  216  and provides the encoded video data to the video decoder component  212  for decoding. The video decoder component  212  reverses the encoding process performed by the video encoder component  206  to reconstruct the LCUs of the video sequence. 
         [0022]    The reconstructed video sequence is displayed on the display component  214 . The display component  214  may be any suitable display device such as, for example, a plasma display, a liquid crystal display (LCD), a light emitting diode (LED) display, etc. 
         [0023]    In some embodiments, the source digital system  200  may also include a receiver component and a video decoder component and/or the destination digital system  202  may include a transmitter component and a video encoder component for transmission of video sequences both directions for video steaming, video broadcasting, and video telephony. Further, the video encoder component  206  and the video decoder component  212  may perform encoding and decoding in accordance with one or more video compression standards. The video encoder component  206  and the video decoder component  212  may be implemented in any suitable combination of software, firmware, and hardware, such as, for example, one or more digital signal processors (DSPs), microprocessors, discrete logic, application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), etc. 
         [0024]      FIG. 3  is a block diagram of a video encoder.  FIG. 3  shows a block diagram of the LCU processing portion of an example video encoder. A coding control component (not shown) sequences the various operations of the LCU processing, i.e., the coding control component runs the main control loop for video encoding. The coding control component receives a digital video sequence and performs any processing on the input video sequence that is to be done at the picture level, such as determining the coding type (I, P, or B) of a picture based on the high level coding structure, e.g., IPPP, IBBP, hierarchical-B, and dividing a picture into LCUs for further processing. The coding control component also may determine the initial LCU CU structure for each CU and provides information regarding this initial LCU CU structure to the various components of the video encoder as needed. The coding control component also may determine the initial prediction unit and TU structure for each CU and provides information regarding this initial structure to the various components of the video encoder as needed. 
         [0025]    The LCU processing receives LCUs of the input video sequence from the coding control component and encodes the LCUs under the control of the coding control component to generate the compressed video stream. The CUs in the CU structure of an LCU may be processed by the LCU processing in a depth-first Z-scan order. The LCUs  300  from the coding control unit are provided as one input of a motion estimation component  320 , as one input of an intra-prediction component  324 , and to a positive input of a combiner  302  (e.g., adder or subtractor or the like). Further, although not specifically shown, the prediction mode of each picture as selected by the coding control component is provided to a mode selector component and the entropy encoder  334 . 
         [0026]    The storage component  318  provides reference data to the motion estimation component  320  and to the motion compensation component  322 . The reference data may include one or more previously encoded and decoded CUs, i.e., reconstructed CUs. 
         [0027]    The motion estimation component  320  provides motion data information to the motion compensation component  322  and the entropy encoder  334 . More specifically, the motion estimation component  320  performs tests on CUs in an LCU based on multiple inter-prediction modes (e.g., skip mode, merge mode, and normal or direct inter-prediction) and transform block sizes using reference picture data from storage  318  to choose the best motion vector(s)/prediction mode based on a rate distortion coding cost. To perform the tests, the motion estimation component  320  may begin with the CU structure provided by the coding control component. The motion estimation component  320  may divide each CU indicated in the CU structure into prediction units according to the unit sizes of prediction modes and into transform units according to the transform block sizes and calculate the coding costs for each prediction mode and transform block size for each CU. The motion estimation component  320  may also compute CU structure for the LCU and PU/TU partitioning structure for a CU of the LCU by itself. 
         [0028]    For coding efficiency, the motion estimation component  320  may also decide to alter the CU structure by further partitioning one or more of the CUs in the CU structure. That is, when choosing the best motion vectors/prediction modes, in addition to testing with the initial CU structure, the motion estimation component  320  may also choose to divide the larger CUs in the initial CU structure into smaller CUs (within the limits of the recursive quadtree structure), and calculate coding costs at lower levels in the coding hierarchy. If the motion estimation component  320  changes the initial CU structure, the modified CU structure is communicated to other components that need the information. 
         [0029]    The motion estimation component  320  provides the selected motion vector (MV) or vectors and the selected prediction mode for each inter-predicted prediction unit of a CU to the motion compensation component  322  and the selected motion vector (MV), reference picture index (indices), prediction direction (if any) to the entropy encoder  334   
         [0030]    The motion compensation component  322  provides motion compensated inter-prediction information to the mode decision component  326  that includes motion compensated inter-predicted PUs, the selected inter-prediction modes for the inter-predicted PUs, and corresponding transform block sizes. The coding costs of the inter-predicted prediction units are also provided to the mode decision component  326 . 
         [0031]    The intra-prediction component  324  provides intra-prediction information to the mode decision component  326  that includes intra-predicted prediction units and the corresponding intra-prediction modes. That is, the intra-prediction component  324  performs intra-prediction in which tests based on multiple intra-prediction modes and transform unit sizes are performed on CUs in an LCU using previously encoded neighboring prediction units from the buffer  328  to choose the best intra-prediction mode for each prediction unit in the CU based on a coding cost. 
         [0032]    To perform the tests, the intra-prediction component  324  may begin with the CU structure provided by the coding control. The intra-prediction component  324  may divide each CU indicated in the CU structure into prediction units according to the unit sizes of the intra-prediction modes and into transform units according to the transform block sizes and calculate the coding costs for each prediction mode and transform block size for each PU. For coding efficiency, the intra-prediction component  324  may also decide to alter the CU structure by further partitioning one or more of the CUs in the CU structure. That is, when choosing the best prediction modes, in addition to testing with the initial CU structure, the intra-prediction component  324  may also chose to divide the larger CUs in the initial CU structure into smaller CUs (within the limits of the recursive quadtree structure), and calculate coding costs at lower levels in the coding hierarchy. If the intra-prediction component  324  changes the initial CU structure, the modified CU structure is communicated to other components that need the information. Further, the coding costs of the intra-predicted prediction units and the associated transform block sizes are also provided to the mode decision component  326 . 
         [0033]    The mode decision component  326  selects between the motion-compensated inter-predicted prediction units from the motion compensation component  322  and the intra-predicted prediction units from the intra-prediction component  324  based on the coding costs of the prediction units and the picture prediction mode provided by the mode selector component. The decision is made at CU level. Based on the decision as to whether a CU is to be intra- or inter-coded, the intra-predicted prediction units or inter-predicted prediction units are selected, accordingly. 
         [0034]    The output of the mode decision component  326 , i.e., the predicted PU, is provided to a negative input of the combiner  302  and to a delay component  330 . The associated transform block size is also provided to the transform component  304 . The output of the delay component  330  is provided to another combiner (i.e., an adder)  338 . The combiner  302  subtracts the predicted prediction unit from the current prediction unit to provide a residual prediction unit to the transform component  304 . The resulting residual prediction unit is a set of pixel difference values that quantify differences between pixel values of the original prediction unit and the predicted PU. The residual blocks of all the prediction units of a CU form a residual CU block for the transform component  304 . 
         [0035]    The transform component  304  performs block transforms on the residual CU to convert the residual pixel values to transform coefficients and provides the transform coefficients to a quantize component  306 . The transform component  304  receives the transform block sizes for the residual CU and applies transforms of the specified sizes to the CU to generate transform coefficients. 
         [0036]    The quantize component  306  quantizes the transform coefficients based on quantization parameters (QPs) and quantization matrices provided by the coding control component and the transform sizes. The quantize component  306  may also determine the position of the last non-zero coefficient in a TU according to the scan pattern type for the TU and provide the coordinates of this position to the entropy encoder  334  for inclusion in the encoded bit stream. For example, the quantize component  306  may scan the transform coefficients according to the scan pattern type to perform the quantization, and determine the position of the last non-zero coefficient during the scanning/quantization. 
         [0037]    The quantized transform coefficients are taken out of their scan ordering by a scan component  308  and arranged sequentially for entropy coding. The scan component  308  scans the coefficients from the highest frequency position to the lowest frequency position according to the scan pattern type for each TU. In essence, the scan component  308  scans backward through the coefficients of the transform block to serialize the coefficients for entropy coding. As was previously mentioned, a large region of a transform block in the higher frequencies is typically zero. The scan component  308  does not send such large regions of zeros in transform blocks for entropy coding. Rather, the scan component  308  starts with the highest frequency position in the transform block and scans the coefficients backward in highest to lowest frequency order until a coefficient with a non-zero value is located. Once the first coefficient with a non-zero value is located, that coefficient and all remaining coefficient values following the coefficient in the highest to lowest frequency scan order are serialized and passed to the entropy encoder  334 . In some embodiments, the scan component  308  may begin scanning at the position of the last non-zero coefficient in the TU as determined by the quantize component  306 , rather than at the highest frequency position. 
         [0038]    The ordered quantized transform coefficients for a CU provided via the scan component  308  along with header information for the CU are coded by the entropy encoder  334 , which provides a compressed bit stream to a video buffer  336  for transmission or storage. The header information may include the prediction mode used for the CU. The entropy encoder  334  also encodes the CU and prediction unit structure of each LCU. 
         [0039]    The LCU processing includes an embedded decoder. As any compliant decoder is expected to reconstruct an image from a compressed bit stream, the embedded decoder provides the same utility to the video encoder. Knowledge of the reconstructed input allows the video encoder to transmit the appropriate residual energy to compose subsequent pictures. To determine the reconstructed input, i.e., reference data, the ordered quantized transform coefficients for a CU provided via the scan component  308  are returned to their original post-transform arrangement by an inverse scan component  310 , the output of which is provided to a dequantize component  312 , which outputs a reconstructed version of the transform result from the transform component  304 . 
         [0040]    The dequantized transform coefficients are provided to the inverse transform component  314 , which outputs estimated residual information which represents a reconstructed version of a residual CU. The inverse transform component  314  receives the transform block size used to generate the transform coefficients and applies inverse transform(s) of the specified size to the transform coefficients to reconstruct the residual values. 
         [0041]    The reconstructed residual CU is provided to the combiner  338 . The combiner  338  adds the delayed selected CU to the reconstructed residual CU to generate an unfiltered reconstructed CU, which becomes part of reconstructed picture information. The reconstructed picture information is provided via a buffer  328  to the intra-prediction component  324  and to an in-loop filter component  316 . The in-loop filter component  316  applies various filters to the reconstructed picture information to improve the reference picture used for encoding/decoding of subsequent pictures. The in-loop filter component  316  may, for example, adaptively apply low-pass filters to block boundaries according to the boundary strength to alleviate blocking artifacts causes by the block-based video coding. The filtered reference data is provided to storage component  318 . 
         [0042]      FIG. 4  shows a block diagram of an example video decoder. The video decoder operates to reverse the encoding operations, i.e., entropy coding, quantization, transformation, and prediction, performed by the video encoder of  FIG. 3  to regenerate the pictures of the original video sequence. In view of the above description of a video encoder, one of ordinary skill in the art will understand the functionality of components of the video decoder without detailed explanation. 
         [0043]    The entropy decoding component  400  receives an entropy encoded (compressed) video bit stream and reverses the entropy coding to recover the encoded PUs and header information such as the prediction modes and the encoded CU and PU structures of the LCUs. If the decoded prediction mode is an inter-prediction mode, the entropy decoder  400  then reconstructs the motion vector(s) as needed and provides the motion vector(s) to the motion compensation component  410 . 
         [0044]    The inverse scan and inverse quantization component  402  receives entropy decoded quantized transform coefficients from the entropy decoding component  400 , inverse scans the coefficients to return the coefficients to their original post-transform arrangement, i.e., performs the inverse of the scan performed by the scan component  308  of the encoder to reconstruct quantized transform blocks, and de-quantizes the quantized transform coefficients. The forward scanning in the encoder is a conversion of the two dimensional (2D) quantized transform block to a one dimensional (1D) sequence; the inverse scanning performed here is a conversion of the 1D sequence to the two dimensional quantized transform block using the same scanning pattern as that used in the encoder. 
         [0045]    The inverse transform component  404  transforms the frequency domain data from the inverse scan and inverse quantization component  402  back to the residual CU. That is, the inverse transform component  404  applies an inverse unit transform, i.e., the inverse of the unit transform used for encoding, to the de-quantized residual coefficients to produce the residual CUs. 
         [0046]    A residual CU supplies one input of the addition component  406 . The other input of the addition component  406  comes from the mode switch  408 . When an inter-prediction mode is signaled in the encoded video stream, the mode switch  408  selects predicted PUs from the motion compensation component  410  and when an intra-prediction mode is signaled, the mode switch selects predicted PUs from the intra-prediction component  414 . 
         [0047]    The motion compensation component  410  receives reference data from storage  412  and applies the motion compensation computed by the encoder and transmitted in the encoded video bit stream to the reference data to generate a predicted PU. That is, the motion compensation component  410  uses the motion vector(s) from the entropy decoder  400  and the reference data to generate a predicted PU. 
         [0048]    The intra-prediction component  414  receives reference data from previously decoded PUs of a current picture from the picture storage  412  and applies the intra-prediction computed by the encoder as signaled by the intra-prediction mode transmitted in the encoded video bit stream to the reference data to generate a predicted PU. 
         [0049]    The addition component  406  generates a decoded CU by adding the predicted PUs selected by the mode switch  408  and the residual CU. The output of the addition component  406  supplies the input of the in-loop filter component  416 . The in-loop filter component  416  performs the same filtering as the encoder. The output of the in-loop filter component  416  is the decoded pictures of the video bit stream. Further, the output of the in-loop filter component  416  is stored in storage  412  to be used as reference data. 
         [0050]      FIG. 5  is an embodiment of a motion compensation apparatus in accordance with the present invention. As shown in  FIG. 5 , the order to support PU size dependent MC filtering order is different from  FIG. 1 . Some additional Multiplexer maybe used to rewire the blocks. However, the horizontal filtering will need to support larger bit-widths. In one embodiment, for 10-bit inputs, horizontal interpolation may support 15×6 multiplication instead of 10×6 multiplication, as in HM-4.0. 
         [0051]    In another embodiment, additional transpose operation may be introduced before the first filtering stage. Table 2 details the operation of motion compensation filtering with 3 transpose operations to support PU-size dependent motion compensation filtering order. Here the first filtering stage will still operate on data at the same bit-width. Thus, the complexity does not increase in the actual filtering blocks. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Architecture 2: Supporting PU-size dependent filtering order with 3 
               
               
                 transpose logic. 
               
             
          
           
               
                   
                   
                   
                 Second 
                   
               
               
                   
                   
                 First MC filter 
                 MC 
                   
               
               
                 No. 
                 Sub-Pel Options 
                 input 
                 filter input 
                 Output 
               
               
                   
               
               
                 1 
                 No Sub-Pel 
                 No Transpose 
                 No 
                 No Transpose 
               
               
                   
                   
                   
                 Transpose 
               
               
                 2 
                 Horizontal Sub-Pel 
                 No Transpose 
                 No 
                 No Transpose 
               
               
                   
                   
                   
                 Transpose 
               
               
                 3 
                 Vertical Sub-Pel 
                 Transpose 
                 Transpose 
                 No Transpose 
               
               
                 4 
                 Sub-Pel in both 
                 Transpose 
                 Transpose 
                 No Transpose 
               
               
                   
                 directions - 2N × N, 
               
               
                   
                 2N × N/2 case 
               
               
                 5 
                 Sub-Pel in both 
                 No Transpose 
                 Transpose 
                 Transpose 
               
               
                   
                 directions -N × 2N, 
               
               
                   
                 N/2 × 2N case 
               
               
                   
               
             
          
         
       
     
         [0052]      FIG. 6  is a flow diagram of a method for performing motion compensation in accordance with the present invention. The method  600  starts at step  602  and proceeds to step  604 . At step  604 , the method  600  retrieves data relating to a reference bock. At step  606 , the method  600  performs a transpose. At step  608 , the method  600  performs vertical filtering. At step  610 , the method  600  performs one or more transpose. At step  612 , the method  600  performs horizontal filtering. At step  614 , the method  600 , as a result of the horizontal filtering, generates an interpolated bock. At step  616 , the method  600  stores into memory data relating to the interpolated bock. The method  600  ends at step  618 . 
         [0053]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.