Sustainability of Digital Formats
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Identification and description

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
Used by	MP4_FF_2_AVC_BP, MPEG-4 File Format, V.2, with AVC, Baseline Profile

Local use

LC experience or existing holdings
LC preference

Sustainability factors

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 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.

Quality and functionality factors (video)

Normal rendering	Good support.
Clarity (support for 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.
Fidelity (support for high audio resolution)	See MP4_FF_2.
Support for multiple sound channels	See MP4_FF_2.
Functionality beyond normal video rendering	See MP4_FF_2.

File type signifiers

Tag type	Value	Note
Filename Extension	mp4
Internet Media Type	See MP4_FF_2
Magic numbers	See MP4_FF_2
Profile indicators	66	For profile_idc; Annex A of Part 10 of the standard, pp. 204-05.
File type brand	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.

Notes

General
History

Format specifications

URLs

Print
From the ISO web site (http://www.iso.ch/ISO/en/):
• ISO/IEC 14496-10:2003 Information technology -- Coding of audio-visual objects -- Part 10: Advanced Video Coding
• ISO/IEC 14496-15:2003 Information technology -- Coding of audio-visual objects -- Part 15: Advanced Video Coding (AVC) file format

Useful references

URLs
• See MP4_FF_2.

Print
• See MP4_FF_2.