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, Main Profile |
Description | See also MP4_FF_2 and MPEG-4_V. Created to serve broadcast services, permitting the highest quality, and supporting arbitrarily shaped objects using grayscale coding.1 The Main 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. • Main: arbitrarily shaped video, adds to Core the coding of grayscale shapes, sprites (object in memory with all pixel information, e.g., the background of scene), and interlaced coding. • Scalable Texture: arbitrarily shaped still image with wavelet compression and incremental download. Three compression levels are permitted; the highest accepts up to 32 objects (Simple, Core, or Main) for a maximum total bit rate of 38 Mbps. |
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 | |
LC preference |
Disclosure | Open standard. See MP4_FF_2. |
Documentation | See MP4_FF_2. |
Adoption | Actual adoption not known to the compilers of this document. |
Licensing and patent claims | 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. |
Normal rendering | Good support. |
Clarity (support for high image resolution) | See MPEG-4 and 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, Simple Scalable, Advanced Simple, and Core Profiles. |
Fidelity (support for high audio resolution) | See MPEG-4. |
Support for multiple sound channels | See MPEG-4. |
Functionality beyond normal video rendering | See MPEG-4. |
Tag type | Value | Note |
Filename Extension | mp4 | |
Internet Media Type | See MP4_FF_2 | |
Magic numbers | See MP4_FF_2 | |
Profile and level indicators | 00110010, 00110011, 00110100 | For profile_and_level_indication for Main Profile, levels 2, 3, and 4. From Annex G of Part 2 of the standard, pp. 454-55. |
File type brand | 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. |
General | |
History |
URLs
Print
See MP4_FF_2.
URLs
• See MP4_FF_2.
Print
• See MP4_FF_2.
1 Pereira, Fernando, and Touradj Ebrahimi, The MPEG-4 Book, Upper Saddle River, NJ: IMSC Press, 2002, p. 599.
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