Reverse, Sub-Pixel Block Matching: Applications within H.264 and Analysis of Limitations

In this paper the concept of reverse block matching is introduced based on the relativity of motion, especially, the translational motion. As one of the main applications for this technique, sub-pixel motion estimation is revisited to achieve faster, yet efficient video coding when it is to be deployed on a system with limited memory and data caching requirements. Analysis of direct (conventional) and reverse (proposed) sub-pixel motion estimation at the encoder is provided to identify the sources of mismatch between these two techniques. Finally, experimental results are provided for sub-pixel motion estimation, using the reverse block matching scheme within the H.264 encoder. These results show a significant increase in speed and a reduction of required memory at a reasonable cost, in terms of PSNR degradation, when compared to the fastest direct sub-pixel motion estimation methods currently implemented in the reference H.264 codec by HHI.