Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | ISO/IEC 11172. Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s (formal name) MPEG-1 (common name) |
| Description | Encoding for compressed video bitstreams that may be accompanied by audio, originally developed to store video on media like CDs; later widely used in online environments. |
| Production phase | Generally a final-state (end-user delivery) format. |
| Relationship to other formats | |
| Other | Identical to the ITU-T standard H.261 |
| Supertype of | MP3_ENC MP3 audio encoding |
| Used by | QTV_MPEG, QuickTime MPEG |
| LC experience or existing holdings | Used extensively for American Memory reformatted moving image content. |
| LC preference | For file-based compressed video, the Library prefers formats other than MPEG-1, e.g., MPEG-2, Main Profile and MPEG-2, 4:2:2 Profile. Uncompressed or losslessly compressed copies are preferred to compressed (for future development). |
| Disclosure | Open standard. Developed by ISO technical program JTC 1/SC 29 (WG11), aka the Motion Pictures Expert Group (MPEG), Coding of audio, picture, multimedia and hypermedia information. |
| Documentation | ISO/IEC 11172; first approvals in 1991. Five parts have been published; parts 1, 2, and 3 are central. See list of ISO documents in Format specifications below. |
| Adoption | Widely adopted for filemaking and World Wide Web access. Many software tools exist for encoding and decoding. MPEG-1 and MPEG-2 are recommended data formats in the list of FCLA recommended formats (PDF) (Florida Center for Library Automation; www.fcla.edu/digitalArchive/pdfs/recFormats.pdf), although no profiles or levels are specified. |
| Licensing and patent claims | None known |
| Transparency | Depends upon algorithms and tools to read; will require sophistication to build tools. |
| Self-documentation | Technical (coding) information is contained in the MPEG-1 bitstream in various headers. Image height and width, for example, are embedded within the sequence header. The lack of metadata of the type called bibliographic by librarians motivated the MPEG group to develop MPEG-7, a separately standardized structure for metadata to support discovery and other purposes. |
| External dependencies | None |
| Technical protection considerations | None |
| Normal rendering | Good support. |
| Clarity (support for high image resolution) | Moderate. Typical files have a picture size of 352x240 pixels (non-square pixels) and a data rate of 1.5 Mb/s, which means that only field of each video frame is captured. One commentator (http://www.faqs.org/faqs/mpeg-faq/part1/) reports that the source input format (SIF) for MPEG-1 "is CCIR-601 [component video] decimated by 2:1 in the horizontal direction, 2:1 in the time direction, and an additional 2:1 in the chrominance vertical direction. And some lines are cut off to make sure things divide by 8 or 16 where needed." Outcome will depend on the type and extent of compression, and the encoder used. |
| Fidelity (support for high audio resolution) | Moderate, given that this is a format for compression. Audio layer three encoding in the standard is also known as MP3_ENC. Outcome will depend on the type and extent of compression, and the encoder used. |
| Support for multiple sound channels | MP3 supports five main channels and an optional LFE (Low Frequency Encoding or Effects) channel, i.e., 5.1 surround sound. |
| Functionality beyond normal video rendering | None |
| Tag type | Value | Note |
| Filename Extension | mpg, mpeg | There is no explicit MPEG-1 file format; MPEG-1 content "ready to be delivered" is exchanged in a de facto file format that may carry one of these extensions. |
| Internet Media Type | video/mpeg | From IETF (Internet Engineering Task Force) RFC 2046 |
| Internet Media Type | video/mpv video/mp1s | From IETF (Internet Engineering Task Force) RFC 3555; these subtypes are glossed as "MPEG-1 or -2 Elementary Streams" and "MPEG-1 Systems Streams." |
| Internet Media Type | video/mpg video/x-mpg application/x-pn-mpg video/x-mpeg | Additional examples selected from The File Extension Source. |
| Magic numbers | Hex: 00 00 01 Bx ASCII: .... | From Gary Kessler's File Signatures Table. |
| General | |
| History | MPEG stands for the Motion Pictures Expert Group, which began developing video compression standards in the 1980s. The group was founded by two men described by one commentator as "the fiery Leonardo Chiariglione (CSELT, Italy)" and "the peaceful Hiroshi Yasuda (JVC, Japan)." MPEG's initial development was partly inspired by the H.261 video coding standard published by the ITU (International Telecom Union). |
URLs
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• ISO/IEC 11172-1:1993 Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s -- Part 1: Systems
• ISO/IEC 11172-1:1993/Cor 1:1996
• ISO/IEC 11172-1:1993/Cor 2:1999
• ISO/IEC 11172-2:1993 Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s -- Part 2: Video
• ISO/IEC 11172-2:1993/Cor 1:1996
• ISO/IEC 11172-2:1993/Cor 2:1999
• ISO/IEC 11172-2:1993/Cor 3:2003
• ISO/IEC 11172-3:1993 Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s -- Part 3: Audio
• ISO/IEC 11172-3:1993/Cor 1:1996
• ISO/IEC 11172-4:1995 Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s -- Part 4: Compliance testing
• ISO/IEC TR 11172-5:1998 Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s -- Part 5: Software simulation
URLs
• http://www.chiariglione.org/mpeg/
• http://www.mpeg.org/
• http://www.faqs.org/faqs/mpeg-faq/
• JTC 1/SC 29 (WG11), the ISO technical program aka the Motion Pictures Expert Group (MPEG; http://www.iso.org/iso/en/CatalogueListPage.CatalogueList?COMMID=148&scopelist=PROGRAMME).
• RFC 2046 (http://www.rfc-editor.org/rfc/rfc2046.txt) from the IETF (Internet Engineering Task Force, http://www.ietf.org/)
• RFC 3555 (http://www.rfc-editor.org/rfc/rfc3555.txt) from the IETF (Internet Engineering Task Force, http://www.ietf.org/)
• Gary Kessler's File Signatures Table (http://www.garykessler.net/library/file_sigs.html).
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