Sustainability of Digital Formats: Planning for Library of Congress Collections
Sustainability of Digital Formats: Planning for Library of Congress Collections |
|
|
|
| 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), Baseline Profile |
|---|---|
| Description | Baseline is the least complex of the three original MPEG-4_AVC profiles (Baseline, Main, and Extended), i.e., it places the least demand on a decoder. The Baseline Profile is constrained in several ways, including a limit to intra (I) and predicted (P) 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, MPEG-4, Advanced Video Coding (Part 10) (H.264) |
| Used by | MP4_FF_2_AVC_BP, MPEG-4 File Format, V.2, with AVC, Baseline Profile |
| LC experience or existing holdings | |
|---|---|
| LC preference |
| Disclosure | Open standard. See MPEG-4_AVC. |
|---|---|
| Documentation | See MPEG-4_AVC. |
| Adoption | The specifications for the video-capable iPod introduced by Apple in late 2005 state that device will play "H.264 video" in the Baseline Profile up to Level 1.3, i.e., MPEG-4_AVC_BP (the encoding described on this page). Added picture specifications state that the data rate can rise to 768 kbps, picture size of 320 x 240 pixels, frame rate of 30 fps. Sound specifications call for AAC_MP4_LC up to 160 kbps, sampling to 48 Khz, stereo audio. Adoption of these iPod-oriented specifications was reinforced in early 2006, when Google began to offer downloadable videos that include files with an .mp4 extension and an encoding variously listed as "H.264" or "avc1," i.e., MPEG-4_AVC_BP. |
| 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 | |
|---|---|
| Normal rendering | Good support. |
| Clarity (high image resolution) | See MPEG-4_AVC. Depends in part on the level and encoding algorithm selected. MPEG-4_AVC_MP (Main Profile) and MPEG-4_AVC_EP (Extended Profile) will produce greater clarity than the Baseline Profile at a given picture size and data rate. 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 |
|---|---|---|
| Filename extension | mp4 |
|
| Internet Media Type | Not applicable. | See MP4_FF_2 |
| Magic numbers | Not applicable. | 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. |
| Indicator for profile, level, version, etc. | 66 |
For profile_idc; Annex A of Part 10 of the standard, pp. 204-05. |
| Pronom PUID | See note. | PRONOM has no corresponding entry as of July 2022. |
| Wikidata Title ID | See related format. | See MPEG-4, Advanced Video Coding (Part 10) (H.264). |
| General | |
|---|---|
| History |
|
|