MPEG headers Quick Reference

MPEG Headers Quick Reference

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/IEC 13818.
This is an incomplete work-in-progress

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

byte 0	byte 1	byte 2	byte 3
0000 0000 0000 0000 0000 0001 Start code prefix			Start Code -or-Stream ID

Start Code	used for
0x00	Picture
0x01 - 0xAF	slice
0xB0	reserved
0xB1	reserved
0xB2	user data
0xB3	Sequence header
0xB4	sequence error
0xB5	extension
0xB6	reserved
0xB7	sequence end
0xB8	Group of Pictures

Stream ID	used for
0xB9	Program end (terminates a program stream)
0xBA	Pack header
0xBB	System Header
0xBC	Program Stream Map
0xBD	Private stream 1
0xBE	Padding stream
0xBF	Private stream 2
0xC0 - 0xDF	MPEG-1 or MPEG-2 audio stream
0xE0 - 0xEF	MPEG-1 or MPEG-2 video stream
0xF0	ECM Stream
0xF1	EMM Stream
0xF2	ITU-T Rec. H.222.0 \| ISO/IEC 13818-1 Annex A or ISO/IEC 13818-6_DSMCC_stream
0xF3	ISO/IEC_13522_stream
0xF4	ITU-T Rec. H.222.1 type A
0xF5	ITU-T Rec. H.222.1 type B
0xF6	ITU-T Rec. H.222.1 type C
0xF7	ITU-T Rec. H.222.1 type D
0xF8	ITU-T Rec. H.222.1 type E
0xF9	ancillary_stream
0xFA - 0xFE	reserved
0xFF	Program Stream Directory

Picture header (0100)

Variable length.

byte 4								byte 5								byte 6								byte 7
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
temporal sequence number										frame type 1=I, 2=P 3=B, 4=D			VBV delay																---

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:

3 2 1 0

full_pel_forward_vector forward_f_code

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

3	2	1	0
full_pel_forward_vector	forward_f_code

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

3 2 1 0

full_pel_backward_vector backward_f_code

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

3	2	1	0
full_pel_backward_vector	backward_f_code

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.

byte 4								byte 5								byte 6								byte 7
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
horizontal size												vertical size												aspect ratio				frame rate

byte 8								byte 9								byte 10								byte 11
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
bit rate																		1	VBV buffer size										constrained parameters flag	load intra quantiser matrix	(load non-intra quantiser matrix)

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

Code	MPEG-1 Aspect Ratio (PAR) height / width	MPEG-2 Aspect Ratio (DAR)	Frame Rate
0	forbidden	forbidden	forbidden
1	1.0000	SAR 1:1 (Square Samples)	24000/1001 (23.976)
2	0.6735	4:3	24
3	0.7031 PAL 16:9	16:9	25
4	0.7615	2.21:1	30000/1001 (29.97)
5	0.8055	reserved	30
6	0.8437 NTSC 16:9	reserved	50
7	0.8935	reserved	60000/1001 (59.94)
8	0.9375 PAL 4:3	reserved	60
9	0.9815	reserved	reserved
10	1.0255	reserved	reserved
11	1.0695	reserved	reserved
12	1.1250 NTSC 4:3	reserved	reserved
13	1.1575	reserved	reserved
14	1.2015	reserved	reserved
15	reserved	reserved	reserved

extension header (01B5)

There are a variety of extensions, denoted by the first 4 bits.

Sequence_Extension

Fixed length.

byte 4								byte 5								byte 6								byte 7								byte 8								byte 9
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0001				profile and level								progressive_sequence	chroma_format		horizontal size extension		vertical size extension		bit rate extension												1	vbv buffer size extension								low delay	frame rate extension n		frame rate extension d

Sequence_Display_Extension

Variable length.
With no color description information, the last 3 bits of byte 8 are not part of this table.

byte 4								byte 5								byte 6								byte 7								byte 8
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0010				video format			color description flag =0	display horizontal size														1	display vertical size

With color description information, the last 3 bits of byte 11 are not part of this table.

byte 4								byte 5								byte 6								byte 7								byte 8								byte 9								byte 10								byte 11
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0010				video format			color description flag =1	color primaries								transfer characteristics								matrix coefficients								display horizontal size														1	display vertical size

Picture_Display_Extension

Variable length, depending on number of offsets encoded (see section 6.3.12 of ISO/IEC 13818-2).
For a single offset (the last 2 bits of byte 8 are not part of this table).

byte 4								byte 5								byte 6								byte 7								byte 8
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0111				frame_center_horizontal_offset[1]																1	frame_center_vertical_offset[1]																1

For two offsets.

byte 4								byte 5								byte 6								byte 7								byte 8								byte 9								byte 10								byte 11								byte 12
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0111				frame_center_horizontal_offset[1]																1	frame_center_vertical_offset[1]																1	frame_center_horizontal_offset[2]																1	frame_center_vertical_offset[2]																1

For three offsets (the maximum, the last 6 bits of byte 17 are not part of this table).

byte 4								byte 5								byte 6								byte 7								byte 8								byte 9								byte 10								byte 11								byte 12								byte 13								byte 14								byte 15								byte 16								byte 17
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
0111				frame_center_horizontal_offset[1]																1	frame_center_vertical_offset[1]																1	frame_center_horizontal_offset[2]																1	frame_center_vertical_offset[2]																1	frame_center_horizontal_offset[3]																1	frame_center_vertical_offset[3]																1

Picture_Coding_Extension

Variable length.

byte 4								byte 5								byte 6
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
1000				f_code[0][0] (forward horizontal)				f_code[0][1] (forward vertical)				f_code[1][0] (backward horizontal)				f_code[1][1] (backward vertical)				intra_DC_precision		picture_structure

byte 7
7	6	5	4	3	2	1	0
Top_Field_First	frame_pred_frame_dct	concealment_motion_vectors	q_scale_type	intra_vlc_format	alternate_scan	Repeat_First_Field	chroma_420_type

byte 8								byte 9								byte 10
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
progressive_frame	composite_display =0	0 0 0 0 0 0						(not present)
progressive_frame	=1	v_axis	field_sequence			sub_carrier	burst_amplitude							sub_carrier_phase								0 0

Group Of Pictures (GOP) (01B8)

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

byte 4								byte 5								byte 6								byte 7
7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0	7	6	5	4	3	2	1	0
drop frame flag	hour (0-23)					minute (0-59)						1	second (0-59)						frame (0-59)						closed GOP	broken GOP	0 0 0 0 0

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