By Demin Wang, Senior Scientist, Video Coding and Processing, Andr Vincent, Manager, Advanced Video Systems Group, and Liang Zhang, ResearcherCommunications Research Center, Canada
December 08, 2006 -- videsignline.com
The structure and algorithms of a new wavelet-based video codec called CRC-WVC with compression efficiency that can perform better than H.264/MPEG-4, and with room for further improvements.
Exploding demand for video services, such as HDTV broadcasting, IPTV, mobile TV, and D-cinema, creates a sustained need for more efficient video coding in order to reduce storage and transmission bandwidth. All the existing video coding standards are based on the hybrid coding scheme of motion compensation (MC) and discrete cosine transform (DCT). The latest video coding standard, H.264/MPEG-AVC, is a well-refined and optimized version of this hybrid scheme. Its compression efficiency is up to 50% higher than that of the widely used MPEG-2 standard. But is the hybrid MC/DCT scheme able to offer even higher compression efficiency to fulfill the requirements of the future video services? A number of experts don't think that the hybrid scheme still has significant potential to exploit, considering the fact that this scheme has been well refined and optimized during the last two decades. Therefore, they turn their attention to other schemes.
Wavelet-based video coding has recently received much attention and emerged as a powerful competitor against the traditional hybrid coding scheme. Many experimental results have shown that wavelet-based video coding is able to provide higher compression efficiency than the traditional hybrid coding. In addition, wavelet-based video coding has another advantage. Once a video is encoded at a given resolution and quality, video with various lower resolutions and qualities can be easily decoded using portions of the bit streams. This feature, called scalability, enables delivery of video over heterogeneous networks and to serve clients with various display and processing capabilities.
In this article we will describe the structure and algorithms of a wavelet-based video codec called CRC-WVC. Then we will present the compression efficiency of the codec and explain the reasons why it can perform better than H.264.
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