Is so-and-so really MPEG compliant ?
A. At the very least, there are two areas of conformance/compliance in MPEG: 1. Compliant bitstreams 2. compliant decoders. Technically speaking, video bitstreams consisting entirely of I-frames (such as those generated by Xing software) are syntactically compliant with the MPEG specification. The I-frame sequence is simply a subset of the full syntax. Compliant bitstreams must obey the range limits (e.g. motion vectors limited to +/-128, frame sizes, frame rates, etc.)and syntax rules (e.g. all slices must commence and terminate with a non-skipped macroblock, no gaps between slices, etc.). Decoders, however, cannot escape true conformance. For example, a decoder that cannot decode P or B frames are *not* legal MPEG. Likewise, full arithmetic precision must be obeyed before any decoder can be called “MPEG compliant.” The IDCT, inverse quantizer, and motion compensated predictor must meet the specification requirements… which are fairly rigid (e.g. no more than 1 least significant bit
At the very least, there are two areas of conformance/compliance in MPEG: 1. Compliant bitstreams 2. compliant decoders. Technically speaking, video bitstreams consisting entirely of I-frames (such as those generated by Xing software) are syntactically compliant with the MPEG specification. The I-frame sequence is simply a subset of the full syntax. Compliant bitstreams must obey the range limits (e.g. motion vectors limited to +/-128, frame sizes, frame rates, etc.) and syntax rules (e.g. all slices must commence and terminate with a non-skipped macroblock, no gaps between slices, etc.). Decoders, however, cannot escape true conformance. For example, a decoder that cannot decode P or B frames are *not* legal MPEG. Likewise, full arithmetic precision must be obeyed before any decoder can be called “MPEG compliant.” The IDCT, inverse quantizer, and motion compensated prediction must meet the specification requirements… which are fairly rigid (e.g. no more than 1 least significant bit
