Advanced Simple Profile (ASP)
Advanced Simple Profile's notable technical features relative to the Simple Profile, which is roughly similar to H.263, include:
- Support for "MPEG"-style quantization
- Support for interlaced video
- Support for B pictures (a.k.a. B Frames)
- Quarter Pixel motion compensation (Qpel)
- Global motion compensation (GMC)
The MPEG quantization and interlace support are designed in basically similar ways to the way it is found in MPEG-2 Part 2. The B picture support is designed in a basically similar way to the way it is found in MPEG-2 Part 2 and H.263v2.
The quarter-pixel motion compensation feature of ASP was innovative, and was later also included (in somewhat different forms) in MPEG-4 Part 10 and VC-1. Some implementations omit support for this feature, because it has a significantly harmful effect on speed and it is not always beneficial for quality.
The global motion compensation feature is not actually supported in most implementations although the standard officially requires decoders to support it. Most encoders do not support it either, and some experts say that it does not ordinarily provide any benefit in compression. When used, ASP's global motion compensation has a large unfavorable impact on speed and adds considerable complexity to the implementation.