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The MPEG Video Bitstream is summarised as follows:
- Public domain
tool mpeg_stat and mpeg_bits will analyze a bitstream.
- Sequence Information
- 1.
- Video Params include width, height, aspect ratio of pixels, picture rate.
- 2.
- Bitstream Params are bit rate, buffer size, and constrained parameters flag (means bitstream can be decoded by most hardware)
- 3.
- Two types of QTs: one for intra-coded blocks (I-frames) and one for inter-coded blocks (P-frames).
- Group of Pictures (GOP) information
- 1.
- Time code: bit field with SMPTE time code (hours, minutes, seconds, frame).
- 2.
- GOP Params are bits describing structure of GOP. Is GOP closed? Does it have a dangling pointer broken?
- Picture Information
- 1.
- Type: I, P, or B-frame?
- 2.
- Buffer Params indicate how full decoder's buffer should be before starting decode.
- 3.
- Encode Params indicate whether half pixel motion vectors are used.
- Slice information
- 1.
- Vert Pos: what line does this slice start on?
- 2.
- QScale: How is the quantization table scaled in this slice?
- Macroblock information
- 1.
- Addr Incr: number of MBs to skip.
- 2.
- Type: Does this MB use a motion vector? What type?
- 3.
- QScale: How is the quantization table scaled in this MB?
- 4.
- Coded Block Pattern (CBP): bitmap indicating which blocks are coded.
Next: Decoding MPEG Video in
Up: MPEG Compression
Previous: Differences from H.261
Dave Marshall
10/4/2001