MPEG-4 Part 2 (MPEG-4 Simple Profile)
The MPEG-4 standard was defined by the ISO/IEC Moving Picture Experts Group (MPEG) in 1998 under the formal standard ISO/IEC 14496. MPEG-4 Part 2 is a codec defined under MPEG-4 for visual data. The most commonly used profiles for MPEG-4 Part 2 are the Simple Profile (MPEG-4 SP) and Advanced Simple Profile (MPEG-4 ASP).
MPEG-4 SP is most commonly used for applications such as mobile phones and video conferencing, where degradation in quality is acceptable. MPEG-4 ASP offers support for features such as B-frames, Qpel, Interlaced Video and Global Motion Compensation, which ensure better quality for home applications. While MPEG-4 Part 2 provides superior efficiency compared to older codecs, such as MPEG-2, it comes at a high price of speed and complexity.
Windows Media Video (WMV) & VC-1
The WMV & VC-1 video codec are standards developed by Microsoft. The Simple and Main profiles in WMV9 are compatible with the same profiles in VC-1 and are an evolution of the codec design found in earlier codecs such as MPEG-2 ASP. VC-1 provides support for features such as VBSMC, Qpel, B-frames, Global Motion Compensation, two-dimensional Motion Vectors for each block and Deblocking filters.
VC-1 Advanced Profile is implemented in the Windows Media Video Advanced Profile. It provides greater efficiency and allows the codec to be contained in an RTP packet format to provide greater streaming support.
MPEG-4 Part 10 (H.264)
MPEG-4 Part 10, or H.264, is the latest codec standard jointly instituted by MPEG and the VCEG. It provides compression efficiency that is twice or greater than earlier codecs, such as MPEG-2 and MPEG-4 Part 2, at a relatively small increase in complexity. H.264 uses context-aware binary arithmetic coding (CABAC) for greater efficiency at main and higher profiles and allows prediction based on B-frames.
H.264 also uses the Network Abstraction Layer, which allows a “network-friendly” video representation that can cater to both interactive applications such as telephony and non-interactive applications including broadcast, storage or streaming. NAL allows the mapping of the Video Coding Layer of H.264 to transport layers such as RTP/IP (for streaming), file formats (for storage) and H.323 systems (for wireless and wireline communication).
Other features available in H.264 include support for B-frames, Variable Block-Size Motion Compensation (VBSMC), two-dimensional Motion Vectors for each block, Deblocking filters and Data partitioning (DP).
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