## MPEG-2 Pack Header

byte 0 | byte 1 | byte 2 | byte 3
--- | --- | --- | ---
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
0000 0000 0000 0000 0000 0001 start code | 1011 1010 PACK identifier

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
01 | SCR 32..30 | 1 | SCR 29..15 | 1 | SCR 14..00 | 1 | SCR_ext | 1

byte 10 | byte 11 | byte 12 | byte 13
--- | --- | --- | ---
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
Program_Mux_Rate | 1 | 1 | reserved | pack_stuffing_length

PACK identifier -- 0xBA

- SCR and SCR_ext together are the System Clock Reference, a counter driven at 27MHz, used as a reference to synchronize streams. The clock is divided by 300 (to match the 90KHz clocks such as PTS/DTS), the quotient is SCR (33 bits), the remainder is SCR_ext (9 bits)
- Program_Mux_Rate -- This is a 22 bit integer specifying the rate at which the program stream target decoder receives the Program Stream during the pack in which it is included. The value of program_mux_rate is measured in units of 50 bytes/second. The value 0 is forbidden.
- pack_stuffing_length -- A 3 bit integer specifying the number of stuffing bytes which follow this field.
- stuffing byte -- This is a fixed 8-bit value equal to '1111 1111' that can be inserted by the encoder, for example to meet the requirements of the channel. It is discarded by the decoder.

### MPEG-1 Pack Header

The MPEG-1 Pack header is shown for reference only, it is NOT used in DVD-Video.

byte 0 | byte 1 | byte 2 | byte 3
--- | --- | --- | ---
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
0000 0000 0000 0000 0000 0001 start code | 1011 1010 PACK identifier

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 | SCR 32..30 | 1 | SCR 29..15 | 1 | SCR 14..00 | 1

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
1 | Program_Mux_Rate | 1

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