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 | Information technology -- Coding of audio-visual objects (formal name)MPEG-4, Visual Coding, Core Profile |
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| Description | See also MP4_FF_2 and MPEG-4_V. Useful in higher-quality interactive services and supports mobile broadcast services.1 The Core Profile permits the use of the following visual object types: • Simple: rectangular video, uses intra (I) and predicted (P) video object planes (VOPs, the MPEG-4 term for frames). • Core: arbitrarily shaped video, uses a tool superset of Simple, adds bidirectional (B) video object planes (VOPs), binary shape coding, and supports temporal scalability based on sending extra P-VOPs. Two compression levels are permitted; Levels 1 (maximum bit rate 384 kbps) and 2 (maximum 2 Mbps). Uses typical session size depending upon level: Quarter Common Intermediate Format (QCIF; 176 pixels by 144 lines, 30 fps; 1.22:1) or Common Intermediate Format (CIF; 352 pixels by 288 lines, 30 fps; 1.22:1). |
| Production phase | Generally a final-state (end-user delivery) format. |
| Relationship to other formats | |
| Subtype of | MPEG-4_V, MPEG-4, Visual Coding (Part 2) |
| Used by | MP4_FF_2_V, MPEG-4 File Format, V.2, with Visual Coding (All Profiles) |
| LC experience or existing holdings | |
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| LC preference |
| Disclosure | Open standard. See MP4_FF_2. |
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| Documentation | See MP4_FF_2. |
| Adoption | Actual adoption not known to the compilers of this document. |
| Licensing and patents | See MP4_FF_2. |
| Transparency | See MP4_FF_2. |
| Self-documentation | See MP4_FF_2. |
| External dependencies | See MP4_FF_2. |
| Technical protection considerations | See MP4_FF_2. |
| Moving Image | |
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| Normal rendering | Good support. |
| Clarity (high image resolution) | See MPEG-4and MPEG-4_V. Potential for greater clarity at a given picture size, data rate, and encoding algorithm, than some other MPEG-4 profiles, e.g., Simple and Simple Scalable Profiles. May offer slightly less clarity at a given picture size, data rate, and encoding algorithm than the Main Profile. |
| Functionality beyond normal rendering | See MPEG-4. |
| Tag | Value | Note |
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| Filename extension | mp4 |
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| Internet Media Type | see note |
See MP4_FF_2 |
| Magic numbers | See note |
See MP4_FF_2 |
| Other | See note |
Indicated in file wrapper and relates to "brands" defined in ISO_BMFF. Wrapping MPEG-4_V bitstreams in MP4_FF_1 would occasion the use of mp41; in MP4_FF_2, use mp42. See Part 15 of the standard, pp. 2-9, 13. |
| Indicator for profile, level, version, etc. | 00100001, 00100010 |
For profile_and_level_indication for Core Profile, levels 1 and 2. From Annex G of Part 2 of the standard, pp. 454-55. |
| General | |
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| History |
1Pereira, Fernando, and Touradj Ebrahimi, The MPEG-4 Book, Upper Saddle River, NJ: IMSC Press, 2002, p. 599.
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