mpeg header 구조

[출처] http://dvd.sourceforge.net/dvdinfo/mpeghdrs.html

[참고] http://andrewduncan.net/mpeg/mpeg-2.html

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			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
temperal 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

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

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	Aspect Ratio	Frame Rate
0	forbidden	forbidden
1	1:1	24000/1001 (23.976)
2	4:3	24
3	16:9	25
4	2.21:1(not used in DVD)	30000/1001 (29.97)
5	reserved	30
6	reserved	50
7	reserved	60000/1001 (59.94)
8	reserved	60
9	reserved	reserved
:
15	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.

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
0010				video format			color description flag =0	(not present)
							=1	color primaries								transfer characteristics								matrix coefficients

byte 5 byte 8								byte 6 byte 9								byte 7 byte 10								byte 8 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
display horizontal size														1	display vertical size														0 0 0

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)
	=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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