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MPEG Program Stream
Filename extension .mpg, .mpeg
Internet media type video/MP2P, video/MP1S
Developed by MPEG
Type of format Media container
Container for Audio, video, data
Extended to VOB, EVO, MOD
Standard(s) ISO/IEC 11172-1, ISO/IEC 13818-1

Program stream (PS or MPEG-PS) is a container format for multiplexing digital audio, video and more. The PS format is specified in MPEG-1 Part 1 (ISO/IEC 11172-1) and MPEG-2 Part 1, Systems (ISO/IEC standard 13818-1). The MPEG-2 Program Stream is analogous and similar to ISO/IEC 11172 Systems layer and it is forward compatible.[1] [2]

Program streams are created by combining one or more Packetized Elementary Streams (PES), which have a common time base, into a single stream. It is designed for reasonably reliable media such as disks, in contrast to MPEG transport stream which is for data transmission in which loss of data is likely. Program streams have variable size records and minimal use of start codes which would make over the air reception difficult, but has less overhead. Program stream coding layer allows only one program of one or more elementary streams to be combined into a single stream, in contrast to transport stream, which allows multiple programs.[1]

MPEG-2 Program stream can contain MPEG-1 Part 2 video, MPEG-2 Part 2 video, MPEG-1 Part 3 audio (MP3, MP2, MP1) or MPEG-2 Part 3 audio.[1] It can also contain MPEG-4 Part 2 video, MPEG-2 Part 7 audio (AAC) or MPEG-4 Part 3 (AAC) audio,[1] but they are rarely used. The MPEG-2 Program stream has provisions for non-standard data (e.g. AC-3 audio or subtitles) in the form of so-called private streams.[3] International Organization for Standardization authorized SMPTE Registration Authority, LLC as the registration authority for MPEG-2 format identifiers. It publishes list of compression formats which can be encapsulated in MPEG-2 transport stream and program stream.[4]

Program streams are used on DVD-Video discs and HD DVD video discs, but with some restrictions and extensions.[5][6] The filename extensions are VOB and EVO respectively. Blu-ray Video discs contain streams in BDAV container, which is based on the MPEG transport stream (TS) format[7][8][9] with an additional 4 byte time code added to the beginning of each TS packet (modification of TS for random-access media).

Contents

Coding structure

If you open up an unencrypted VOB file or other program stream with a hex editor you will see the following structure.

Partial Program Stream Pack header format[10]
Name Number
of bits
Description
sync bytes 32 0x000001BA
marker bits 2 01b
System clock [32..30] 3 System Clock Reference (SCR) bits 32 thru 30
marker bit 1 1 Bit always set.
System clock [29..15] 15 System clock bits 29 thru 15
marker bit 1 1 Bit always set.
System clock [14..0] 15 System clock bits 14 thru 0
marker bit 1 1 Bit always set.
SCR extension 9
marker bit 1 1 Bit always set.
bit rate 22 In units of 50 bytes per second.
marker bits 2 11 Bits always set.
reserved 5 reserved for future use
stuffing length 3
stuffing bytes 8*stuffing length
system header (optional) 0 or more if system header start code follows: 0x000001BB
Partial system header format
Name Number
of bytes
Description
sync bytes 4 0x000001BB
header length 2
rate bound and marker bits 3
audio bound and flags 1
flags, market bit, and video bound 1
Packet rate restriction and reserved byte 1

References

  1. ^ a b c d ISO (2000-12-01) ISO/IEC 13818-1 : 2000, Second edition Page X, Retrieved on 2009-07-25
  2. ^ Data Broadcasting, MPEG-2 Transport Basics, MPEG-2 Program Stream, Retrieved on 2009-07-25
  3. ^ What is a VOB file, Retrieved on 2009-07-26
  4. ^ SMPTE Registration Authority, LLC - registration authority for MPEG-2 format identifiers Retrieved on 2009-07-06
  5. ^ DVD - MPeg differences, Retrieved on 2009-07-24
  6. ^ MPEG.org (July 21, 1996) DVD Technical Notes - Video Data Specifications, Retrieved on 2009-07-25
  7. ^ AfterDawn.com Glossary - BDAV container, Retrieved on 2009-07-26
  8. ^ AfterDawn.com Glossary - BD-MV (Blu-ray Movie) and BDAV container, Retrieved on 2009-07-26
  9. ^ Videohelp.com What is Blu-ray Disc and HD DVD?, Retrieved on 2009-07-26
  10. ^ Pack Header

See also

External links

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