An Irregular Search Window Reuse Scheme for MPEG-2 to H.264 Transcoding

Xiang-Hui WEI  Shen LI  Yang SONG  Satoshi GOTO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E91-A   No.3   pp.749-755
Publication Date: 2008/03/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e91-a.3.749
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Signal Processing for Audio and Visual Systems and Its Implementations)
Category: Image Coding and Video Coding
MPEG-2 to H.264 transcoding,  motion estimation,  search window reuse,  

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Motion estimation (ME) is a computation-intensive module in video coding system. In MPEG-2 to H.264 transcoding, motion vector (MV) from MPEG-2 reused as search center in H.264 encoder is a simple but effective technique to simplify ME processing. However, directly applying MPEG-2 MV as search center will bring difficulties on application of data reuse method in hardware design, because the irregular overlapping of search windows between successive macro block (MB). In this paper, we propose a search window reuse scheme for transcoding, especially for HDTV application. By utilizing the similarity between neighboring MV, overlapping area of search windows can be regularized. Experiment results show that our method achieves average 93.1% search window reuse-rate in HDTV720p sequence with almost no video quality degradation. Compared to transcoding method without any data reuse scheme, bandwidth of the proposed method can be reduced to 40.6% of that.