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, Advanced Video Coding (part 10), Main Profile |
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| Description | Main is the middle of the three original MPEG-4_AVC profiles (Baseline, Main, and Extended) in terms of complexity and the demands it places on a decoder. The Main Profile is constrained in several ways, but may include intra (I), predicted (P), and bidirectional (B) slice types (slice is the MPEG-4_AVC term for a single macroblock or a set of macroblocks that make up a portion of an individual picture.) For a discussion of additional contraints and the levels that may be used in this profile, see Appendix A in Part 10 of the standard, pp. 204-211. |
| Production phase | Generally a final-state (end-user delivery) format. |
| Relationship to other formats | |
| Subtype of | MPEG-4_AVC, |
| Used by | MP4_FF_2_AVC_MP, MPEG-4 File Format, V.2, with AVC, Main Profile |
| LC experience or existing holdings | |
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| LC preference |
| Disclosure | Open standard. See MPEG-4_AVC. |
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| Documentation | See MPEG-4_AVC. |
| Adoption | See MPEG-4_AVC. |
| 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-4_AVC. Depends in part on the level and encoding algorithm selected. The Main Profile will produce greater clarity than the MPEG-4_AVC_BP (Baseline Profile) at a given picture size and data rate but less than the MPEG-4_AVC_EP (Extended Profile). The clarity in all three of the original profiles is surpassed by the four FRExt (Fidelity Range Extension) profiles: MPEG-4_AVC_HP, MPEG-4_AVC_H10P, MPEG-4_AVC_H422P, and MPEG-4_AVC_H444P. |
| Functionality beyond normal rendering | See MP4_FF_2. |
| Tag | Value | Note |
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| Filename extension | mp4 |
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| Internet Media Type | See MP4_FF_2 |
**See MP4_FF_2 |
| Magic numbers | See MP4_FF_2 |
**See MP4_FF_2 |
| File type brand (ISO Base Media File Format) | See note |
Indicated in file wrapper and relates to "brands" defined in ISO_BMFF. Wrapping MPEG-4_AVC bitstreams in MP4_FF_1 would occasion the use of mp41; in MP4_FF_2, use mp42. |
| Other | 77 |
Profile indicators. For profile_idc; Annex A of Part 10 of the standard, pp. 204-05. |
| General | |
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| History |
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