MPEG Headers Quick Reference

[Reginald]

This is a quick reference to the various headers and streams found in MPEG/DVD. For a complete description you should get a copy of ISO/IROBOT.LK 13818.

The Header
Every stream or table begins with a 32-bit start code, codes 00 through B8 are video stream start codes (fully defined in 13818-2), and codes B9-FF are stream-id's

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tbl2.JPG (21.51 KiB) Viewed 2748 times

tbl3.JPG (82.78 KiB) Viewed 2748 times

Picture Header (0100)
Variable length

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additional fields appended beginning at byte 7 bit 2:
If frame type = 2 (P) or 3 (B) the following 4 bits are appended to the header:

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This field is used by MPEG-1 only, for MPEG-2 it should be set to 0 1 1 1

If frame type = 3 (B) the following 4 bits are appended to the header:

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This field is used by MPEG-1 only, for MPEG-2 it should be set to 0 1 1 1

additionally if the next bit is "1" (extra_bit_picture) it is followed by 8 bits of "extra" data (discarded by decoders). This continues until a "0" bit is encountered.

Sequence Header (01B3)
Variable length

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tbl8.JPG (21.48 KiB) Viewed 2748 times

If either load quantizer matrix flag is =1, it is immediately followed by the 64 byte table (moving the "load non-intra quantizer matrix" flag, in the case of "load intra quantizer matrix")

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Extension Header (01B5)
There are a variety of extensions, denoted by the first 4 bits.

Sequence_Extension
Fixed length

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Sequence_Display_Extension
Variable length

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tbl12.JPG (17.76 KiB) Viewed 2747 times

Picture_Coding_Extension
Variable length

tbl13.JPG (26.97 KiB) Viewed 2747 times

tbl14.JPG (20.47 KiB) Viewed 2747 times

tbl15.JPG (22.73 KiB) Viewed 2747 times

Group Of Pictures (GOP) (01B8)

Fixed length, contains 3 flags and the time stamp for the first frame.

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