AVI (Audio Video Interleave)
Microsoft's original Windows video container, built in 1992, still readable everywhere three decades later.
| Full name | Audio Video Interleave |
| Extension | .avi |
| MIME type | video/x-msvideo |
| Developer | Microsoft |
| Released | November 10, 1992 |
| Type | Video container format |
| Based on | RIFF (Resource Interchange File Format) |
| Max file size (original) | ~2 GB (4 GB with OpenDML extension) |
What is a AVI file?
AVI is a video container format created by Microsoft and released on November 10, 1992, as part of the Video for Windows package. It stores audio and video data in the same file, played back in sync. Despite its age, AVI remains one of the most universally recognized video formats on Windows systems.
AVI is a container, not a codec. It wraps video and audio streams together in a single file without dictating how those streams are compressed. The actual image and sound quality depend on the codecs used inside the container, such as DivX, Xvid, or uncompressed PCM audio. One AVI file might be raw, uncompressed footage; another might be a heavily compressed video using a third-party codec. The format itself just holds the pieces together and tells the player how to synchronize them.
History
Microsoft introduced AVI on November 10, 1992, bundled with Video for Windows, which was designed to bring video playback to everyday Windows 3.1 computers. The format is built on top of RIFF, a chunked binary file structure that Microsoft and IBM had introduced in 1991. In February 1996, the Matrox-led OpenDML group published AVI 2.0 extensions, raising the practical file-size ceiling from roughly 2 GB to 4 GB and adding better timestamp and aspect-ratio support; Microsoft later endorsed these extensions.
Container vs codec
An AVI file is a RIFF file divided into chunks, each tagged with a four-character code that identifies its type. The top-level chunk is labeled 'AVI ', and inside it sit two main lists: 'hdrl' (the header list, which describes the streams and their properties) and 'movi' (the movie data, which contains the actual interleaved audio and video frames). An optional index chunk at the end of the file lets players jump to any frame without scanning the whole file. OpenDML files add extra index chunks scattered through the data so players can seek accurately in very large files.
What it is used for
- Storing uncompressed or losslessly captured video for video editing workflows
- Archiving older Windows video content that was originally produced in AVI
- Distributing video with codecs like DivX or Xvid, common in the early 2000s
- Playing back legacy camcorder recordings and screen-capture software output
How to open it
AVI files open natively in Windows Media Player and File Explorer on Windows. On macOS and Linux, VLC Media Player handles nearly every AVI variant regardless of the codec used inside.
Pros and cons
Strengths
- Supported by virtually every video player and editing application
- Simple structure makes it easy for software to read and write
- Codec-agnostic: works with hundreds of different video and audio codecs
- Stable format with no DRM complications or proprietary lock-in
Trade-offs
- No native support for modern features like chapters, multiple subtitle tracks, or variable frame rates
- Original 2 GB size limit is a problem for long recordings (OpenDML raises it but compatibility varies)
- Larger file sizes than modern containers like MP4 or MKV at equivalent quality
- Codec dependency means a file can be unplayable if the right codec is not installed
Convert AVI files
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From AVI
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AVI FAQ
Is AVI better than MP4?
Not for most uses today. MP4 supports more modern codecs, smaller file sizes, subtitles, chapters, and wider device compatibility. AVI made sense in 1992 but MP4 is the safer choice for sharing or streaming video now.
Why won't my AVI file play?
The container opened fine but the codec inside is probably missing. AVI does not bundle the codec with the file. Installing a codec pack like K-Lite (Windows) or using VLC, which includes its own decoders, usually fixes this.
Can AVI files contain HD or 4K video?
Yes, technically. The AVI container can hold high-resolution video streams. The practical problem is file size: uncompressed 4K footage will hit the 2 GB limit in seconds, and even the OpenDML 4 GB cap is tight. MKV or MOV are better containers for large HD files.
Does converting AVI to MP4 lose quality?
It depends on the settings. If you re-encode the video stream, some quality is lost. If the video inside the AVI is already H.264, a remux (container swap without re-encoding) copies it to MP4 with no quality loss at all.