4. MPEG Video Bitstream

• 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.