Sustainability of Digital Formats
 Planning for Library of Congress Collections

Format Description Categories >> Browse Alphabetical List>> Back

Identification and description

Full name	AVI (Audio Video Interleaved), Indeo Video Codec
Description	File format that wraps an Indeo video bitstream with other data chunks, e.g., audio, in an AVI wrapper. Indeo versions 3.1 and 3.2 employ vector quantization; versions 4 and 5 use forms of wavelet compression.
Production phase	Generally a middle-state format (often used as the video source when producing lower-resolution streaming versions); may be used as a final-state format for enduser delivery.
Relationship to other formats
Subtype of	AVI,
May contain	Indeo_3, video codec
May contain	Indeo_4 video codec, not separately documented
May contain	Indeo_5, video codec
May contain	WAVE, audio (interleaved with video)
May contain	MP3_CBR, (constant bit rate) audio (interleaved with video)

Local use

LC experience or existing holdings	American Memory produced AVI_Indeo files in 1992 and 1993, using version 3.1 or 3.2 of the Indeo codec, options set at 15 fps and 320x240 pixels, and yielding a data rate of about 188 Kb/s. These AVI files were retired and replaced by MPEG-1 and QuickTime files in 1994 and 1995.
LC preference	See AVI.

Sustainability factors

Disclosure	See AVI, Indeo_3, and Indeo_5.
Documentation	See AVI, Indeo_3, and Indeo_5.
Adoption	AVI is widely adopted for video production and filemaking; commentator John McGowan writes, "Indeo R3.2 is one of the default Video for Windows codecs."
Licensing and patents	See AVI, Indeo_3, and Indeo_5.
Transparency	See Indeo_3 and Indeo_5.
Self-documentation	See AVI
External dependencies	See AVI
Technical protection considerations	See AVI

Quality and functionality factors

Moving Image
Normal rendering	Good support.
Clarity (high image resolution)	Moderate to very good, given that this is a format typically used for compression and does not support interlaced video. Outcome will depend on the version of Indeo employed, the extent of compression, and the encoder used. High resolution work is limited in the Windows environment due to file size limits (2 GB with FAT 16 technology; theoretical 8 GB with later technologies).
Functionality beyond normal rendering	See AVI

File type signifiers

Tag	Value	Note
Filename extension	avi
Internet Media Type	See related format.	See AVI
Magic numbers	See related format.	See AVI
Microsoft FOURCC	IV32 IV41 IV50	See the list of FOURCC codes, which also lists a number of additional IV FOURCCs. John McGowan states that IV32 is generally used for Indeo 3; IV41 for Indeo 4, and IV50 for Indeo 5. FOURCC codes are no longer managed by Microsoft, which has developed a new mechanism for identifying rich media types in general.

Notes

General
History

Format specifications

• See Disclosure under Sustainability factors.

Useful references

URLs

• John McGowan's AVI Overview (http://www.jmcgowan.com/avi.html).
• John McGowan's AVI Audio and Video Codecs (http://www.jmcgowan.com/avicodecs.html).
• List of FOURCC codes (http://www.fourcc.org/codecs.php). FOURCC codes were originally managed in a registry by Microsoft, but have been superseded by a more general mechanism to identify media types.
• Gary Kessler's File Signatures Table (http://www.garykessler.net/library/file_sigs.html).