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) 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]
| MPEG Program Stream | |
|---|---|
| Internet media type |
video/MP2P, video/MP1S |
| Developed by | MPEG |
| Type of format | Media container |
| Container for | Audio, video, data |
| Standard | ISO/IEC 11172-1, ISO/IEC 13818-1 |
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 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. 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.[3]
Program streams are used on DVD-Video discs and HD DVD video discs, but with some restrictions and extensions.[4][5] The filename extensions are VOB and EVO respectively. Blu-ray Disc Video contain streams in BD-AV container, which is based on a MPEG-2 transport stream (TS) format[6][7][8] with an additional 4 byte time code added to the beginning of each TS packet (modification of TS for random-access media).
Coding structure
If you open up an unencrypted VOB file or other program stream with a hex editor you will see the following structure.
| 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 |
| 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
- ^ a b c d ISO (2000-12-01) ISO/IEC 13818-1 : 2000, Second edition Page X, Retrieved on 2009-07-25
- ^ Data Broadcasting, MPEG-2 Transport Basics, MPEG-2 Program Stream, Retrieved on 2009-07-25
- ^ SMPTE Registration Authority, LLC - registration authority for MPEG-2 format identifiers Retrieved on 2009-07-06
- ^ DVD - MPeg differences, Retrieved on 2009-07-24
- ^ MPEG.org (July 21, 1996) DVD Technical Notes - Video Data Specifications, Retrieved on 2009-07-25
- ^ AfterDawn.com Glossary - BDAV container, Retrieved on 2009-07-26
- ^ AfterDawn.com Glossary - BD-MV (Blu-ray Movie) and BDAV container, Retrieved on 2009-07-26
- ^ Videohelp.com What is Blu-ray Disc and HD DVD?, Retrieved on 2009-07-26
- ^ Pack Header
See also
External links
- MPEG-2
- Official MPEG web site
- BBC On MPEG
- RFC 3555 - MIME Type Registration of RTP Payload Formats (video/MP2P, video/MP1S)
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