Audio Video Interleave

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Audio Video Interleave
Filename extension
.avi
Internet media type
video/vnd.avi [1]
video/avi
video/msvideo
video/x-msvideo
Type code 'Vfw '
Uniform Type Identifier (UTI) public.avi
Developed by Microsoft
Initial releaseNovember 10, 1992;31 years ago (1992-11-10)
Type of format Container format
Container for Audio, video
Extended from Resource Interchange File Format
Open format?No
Free format?Yes [2]
Website https://docs.microsoft.com/en-us/windows/win32/directshow/avi-file-format

Audio Video Interleave (also Audio Video Interleaved and known by its initials and filename extension AVI, usually pronounced /ˌeɪ.viːˈaɪ/ [3] ) is a proprietary multimedia container format and Windows standard [4] introduced by Microsoft in November 1992 as part of its Video for Windows software. AVI files can contain both audio and video data in a file container that allows synchronous audio-with-video playback. Like the DVD video format, AVI files support multiple streaming audio and video, although these features are seldom used.

Contents

Many AVI files use the file format extensions developed by the Matrox OpenDML group in February 1996. [5] These files are supported by Microsoft, and are unofficially called "AVI 2.0". [6] In 2010 the US government's National Archives and Records Administration defined AVI as the official wrapper for preserving digital video. [7]

History

Publishers faced a predicament regarding how they should distribute videos on CD-ROMs. Thirty seconds of video displayed in 24-bit color and at thirty frames per second and Super VGA resolutions could take up 680 megabytes of space—the storage capacity of most CD-ROMs in 1992. Lossily compressing the videos would save a lot of space, but not without degrading the quality of the videos. Publishers who were more concerned about video quality instead were searching for an ideal compression algorithm that would compress the video files while still preserving the quality. [8]

Microsoft recognized the problem and sought to develop a standard that would losslessly compress the video files. They also recognized that because of the hardware requirements for playing the videos in uncompressed quality, which at the time were demanding, it needed to allow users of low-end computers to play the videos in compressed quality. They developed and published the Audio Video Interleave format on November 10, 1992, as part of their Video for Windows, and included support for codecs to satisfy those users. [8] [9] [10]

Format

AVI is a subformat of the Resource Interchange File Format (RIFF), which divides a file's data into blocks, or "chunks". Each chunk is identified by a FourCC tag. [11]

An AVI file takes the form of a RIFF header, which is then divided into two mandatory chunks and one optional chunk. The first chunk is identified by the "hdrl" tag, which stores the information required by the codec to decompress the AVI file for viewing. The second sub-chunk is identified by the "movi" tag, containing the actual audio and visual data that make up the AVI video. The third optional chunk is identified by the "idx1" tag, which indexes the offsets of the data chunks within the file. [11]

By way of the RIFF format, the audio and visual data contained in the "movi" chunk can be encoded or decoded by software called a codec, which is an abbreviation for (en)coder/decoder. Upon creation of the file, the codec translates between raw data and the (compressed) data format used inside the chunk. An AVI file may carry audio and visual data inside the chunks in virtually any compression scheme, including Full Frame (Uncompressed), Indeo, run-length encoding, and Microsoft Video 1. [10]

Some programs, like VLC, complain when the "idx1" index sub-chunk is not found, as it is required for efficient moving among timestamps. They offer to "fix" the file by building an index temporarily or permanently. [12] [ better source needed ]

Metadata

As a derivative of the Resource Interchange File Format (RIFF), AVI files are commonly tagged with metadata in the INFO chunk. In addition, AVI files can embed Extensible Metadata Platform. [13] By design, any RIFF file can legally include additional chunks of data, each identified by a four-character code; [11] software which does not understand that particular code should skip the chunk. As such, it is theoretically possible to expand any RIFF file format, including AVI, to support almost any conceivable metadata. Some of the limitations of AVI in modern use relate to a lack of standardization in this metadata (see Limitations below).

Limitations

Since its introduction in the early 90s, new computer video techniques have been introduced which the original AVI specification did not anticipate.

More recent container formats (such as Matroska, Ogg and MP4) solve all these problems, although software is freely available to both create and correctly replay AVI files which use the techniques described here.

DV AVI

DV AVI is a type of AVI file where the video has been compressed to conform with DV standards. There are two types of DV-AVI files:

Type 1 is actually the newer of the two types. Microsoft made the "type" designations, and decided to name their older VfW-compatible version "Type 2", which only furthered confusion about the two types. In the late 1990s through early 2000s, most professional-level DV software, including non-linear editing programs, only supported Type 1. One notable exception was Adobe Premiere, which only supported Type 2. High-end FireWire controllers usually captured to Type 1 only, while "consumer" level controllers usually captured to Type 2 only. Software is and was available for converting Type 1 AVIs to Type 2, and vice versa, but this is a time-consuming process.

Many FireWire controllers only captured to one or the other type. However, almost all relevant software supports both Type 1 and Type 2 editing and rendering, including Adobe Premiere. Thus, many users are unaware of the fact that there are two types of DV AVI files.

See also

Related Research Articles

<span class="mw-page-title-main">Audio file format</span> Computer format for digital audio

An audio file format is a file format for storing digital audio data on a computer system. The bit layout of the audio data is called the audio coding format and can be uncompressed, or compressed to reduce the file size, often using lossy compression. The data can be a raw bitstream in an audio coding format, but it is usually embedded in a container format or an audio data format with defined storage layer.

A codec is a device or computer program that encodes or decodes a data stream or signal. Codec is a portmanteau of coder/decoder.

<span class="mw-page-title-main">Ogg</span> Open container format maintained by the Xiph.Org Foundation

Ogg is a free, open container format maintained by the Xiph.Org Foundation. The authors of the Ogg format state that it is unrestricted by software patents and is designed to provide for efficient streaming and manipulation of high-quality digital multimedia. Its name is derived from "ogging", jargon from the computer game Netrek.

Waveform Audio File Format is an audio file format standard for storing an audio bitstream on personal computers. The format was developed and published for the first time in 1991 by IBM and Microsoft. It is the main format used on Microsoft Windows systems for uncompressed audio. The usual bitstream encoding is the linear pulse-code modulation (LPCM) format.

<span class="mw-page-title-main">DV (video format)</span> Digital video codecs and tape formats

DV is a family of codecs and tape formats used for storing digital video, launched in 1995 by a consortium of video camera manufacturers led by Sony and Panasonic. It includes the recording or cassette formats DV, MiniDV, DVCAM, Digital8, HDV, DVCPro, DVCPro50 and DVCProHD. DV has been used primarily for video recording with camcorders in the amateur and professional sectors.

A video file format is a type of file format for storing digital video data on a computer system. Video is almost always stored using lossy compression to reduce the file size.

Audio Interchange File Format (AIFF) is an audio file format standard used for storing sound data for personal computers and other electronic audio devices. The format was developed by Apple Inc. in 1988 based on Electronic Arts' Interchange File Format and is most commonly used on Apple Macintosh computer systems.

<span class="mw-page-title-main">FLAC</span> Lossless digital audio coding format

FLAC is an audio coding format for lossless compression of digital audio, developed by the Xiph.Org Foundation, and is also the name of the free software project producing the FLAC tools, the reference software package that includes a codec implementation. Digital audio compressed by FLAC's algorithm can typically be reduced to between 50 and 70 percent of its original size and decompresses to an identical copy of the original audio data.

Resource Interchange File Format (RIFF) is a generic file container format for storing data in tagged chunks. It is primarily used for audio and video, though it can be used for arbitrary data.

Motion JPEG is a video compression format in which each video frame or interlaced field of a digital video sequence is compressed separately as a JPEG image.

<span class="mw-page-title-main">Advanced Systems Format</span> File format

Advanced Systems Format is Microsoft's proprietary digital audio/digital video container format, especially meant for streaming media. ASF is part of the Media Foundation framework.

8-Bit Sampled Voice (8SVX) is an audio file format standard developed by Electronic Arts for the Amiga computer series. It is a data subtype of the IFF file container format. It typically contains linear pulse-code modulation (LPCM) digital audio.

A FourCC is a sequence of four bytes used to uniquely identify data formats. It originated from the OSType or ResType metadata system used in classic Mac OS and was adopted for the Amiga/Electronic Arts Interchange File Format and derivatives. The idea was later reused to identify compressed data types in QuickTime and DirectShow.

A container format or metafile is a file format that allows multiple data streams to be embedded into a single file, usually along with metadata for identifying and further detailing those streams. Notable examples of container formats include archive files and formats used for multimedia playback. Among the earliest cross-platform container formats were Distinguished Encoding Rules and the 1985 Interchange File Format.

These tables compare features of multimedia container formats, most often used for storing or streaming digital video or digital audio content. To see which multimedia players support which container format, look at comparison of media players.

Flash Video is a container file format used to deliver digital video content over the Internet using Adobe Flash Player version 6 and newer. Flash Video content may also be embedded within SWF files. There are two different Flash Video file formats: FLV and F4V. The audio and video data within FLV files are encoded in the same way as SWF files. The F4V file format is based on the ISO base media file format, starting with Flash Player 9 update 3. Both formats are supported in Adobe Flash Player and developed by Adobe Systems. FLV was originally developed by Macromedia. In the early 2000s, Flash Video was the de facto standard for web-based streaming video. Users include Hulu, VEVO, Yahoo! Video, metacafe, Reuters.com, and many other news providers.

Media Foundation (MF) is a COM-based multimedia framework pipeline and infrastructure platform for digital media in Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows 10, and Windows 11. It is the intended replacement for Microsoft DirectShow, Windows Media SDK, DirectX Media Objects (DMOs) and all other so-called "legacy" multimedia APIs such as Audio Compression Manager (ACM) and Video for Windows (VfW). The existing DirectShow technology is intended to be replaced by Media Foundation step-by-step, starting with a few features. For some time there will be a co-existence of Media Foundation and DirectShow. Media Foundation will not be available for previous Windows versions, including Windows XP.

CineForm Intermediate is an open source video codec developed for CineForm Inc by David Taylor, David Newman and Brian Schunck. On March 30, 2011, the company was acquired by GoPro which in particular wanted to use the 3D film capabilities of the CineForm 444 Codec for its 3D HERO System.

A video coding format is a content representation format of digital video content, such as in a data file or bitstream. It typically uses a standardized video compression algorithm, most commonly based on discrete cosine transform (DCT) coding and motion compensation. A specific software, firmware, or hardware implementation capable of compression or decompression in a specific video coding format is called a video codec.

<span class="mw-page-title-main">Audio coding format</span> Digitally coded format for audio signals

An audio coding format is a content representation format for storage or transmission of digital audio. Examples of audio coding formats include MP3, AAC, Vorbis, FLAC, and Opus. A specific software or hardware implementation capable of audio compression and decompression to/from a specific audio coding format is called an audio codec; an example of an audio codec is LAME, which is one of several different codecs which implements encoding and decoding audio in the MP3 audio coding format in software.

References

  1. ↑ Fleischman, Eric (June 1998). WAVE and AVI Codec Registries. IETF. doi: 10.17487/RFC2361 . RFC 2361 . Retrieved December 6, 2009.
  2. ↑ AVI (Audio Video Interleaved) File Format (Full draft). Sustainability of Digital Formats. Washington, D.C.: Library of Congress. March 9, 2016. Retrieved December 13, 2021.
  3. ↑ Cudnik, Brian (2009). Lunar Meteoroid Impacts and How to Observe Them. Springer. p. 154. ISBN   978-1-4419-0324-2 . Retrieved September 19, 2021.
  4. ↑ Gavin, Brady (September 12, 2018). "What Is an AVI File (and How Do I Open One)?". How-To Geek. Retrieved September 19, 2021.
  5. ↑ "AVI File Format with OpenDML Extensions, Version 1.02". www.loc.gov. March 9, 2016. Retrieved September 1, 2019.
  6. ↑ stevewhims. "AVI RIFF File Reference - Windows applications". docs.microsoft.com. Retrieved September 1, 2019.
  7. ↑ "Video Digital Product Options". archives.gov. Archived from the original on May 6, 2019. Retrieved September 1, 2019.
  8. 1 2 Raskin, Robin (December 22, 1992). "27 Good Reasons To Buy A CD-ROM Player". PC Magazine . Vol. 11, no. 22. pp. 345–346. Retrieved September 19, 2021.
  9. ↑ Damore, Kelley; Corcoran, Cate (November 9, 1992). "Microsoft, vendors team up to air Video for Windows". InfoWorld . Vol. 14, no. 45. p. 3. Retrieved September 19, 2021.
  10. 1 2 Quain, John R. (January 12, 1993). "Microsoft Goes Hollywood With Video for Windows". PC Magazine . Vol. 12, no. 1. p. 39. Retrieved September 19, 2021.
  11. 1 2 3 Gloe, Thomas (April 16, 2014). "Forensic analysis of video file formats § AVI Container format". Digital Investigation. 11 (1). Elsevier. doi: 10.1016/j.diin.2014.03.009 . ISSN   1742-2876.
  12. ↑ "WindowsFAQ-1.1.x". VideoLAN Wiki.
  13. ↑ Altheide, Cory; Carley, Harvan (2011). Digital Forensics with Open Source Tools. Syngress. p. 190. ISBN   978-1-59749-586-8 . Retrieved September 19, 2021.
  14. ↑ "Determining the Shape of Pixels and Frames". Microsoft.com . May 2003. Archived from the original on January 13, 2008.
  15. ↑ Rhodes, Phil (December 12, 2014). "AVI and Timecode". FFmpeg-user (Mailing list).
  16. ↑ "AVI MetaEdit - Technical Metadata". mediaarea.net.
  17. ↑ "Using B-frames". Avidemux.
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