AVI File Format (.avi)
An AVI file interleaves video and audio in chunks of Microsoft's RIFF structure, the container Windows has used for video since 1992 and the one most video from the DivX and Xvid years is stored in.
AVI at a glance#
| Full name | Audio Video Interleave |
|---|---|
| File extension | .avi |
| Category | Video Files |
| Developer | Microsoft |
| First released | 1992 |
| MIME types | video/x-msvideovideo/avivideo/msvideo |
| Compression | Varies from file to file |
| Specification | AVI RIFF File Reference (Microsoft) |
| FileFlip support | FileFlip reads and writes this format |
What a .avi file can hold#
These are the things a AVI file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Lossless compression | Yes |
|---|---|
| Embedded metadata | Yes |
| Audio | Yes |
| Video | Yes |
| Subtitle tracks | No |
| Chapters | No |
| Streaming | No |
Strengths and limitations of AVI#
What AVI does well
- Read by nearly every video tool written since 1992, including software far older than MP4
- Simple RIFF chunk layout that is easy to index, cut and repair without decoding the video
- Carries uncompressed and lossless video cleanly, which is why old capture and editing setups used it
- The DivX and Xvid files that filled hard drives through the 2000s are AVIs, so old archives are full of them
Where AVI falls short
- The original design runs out at 2GB, lifted only by the unofficial OpenDML extension added in the mid nineties
- The stream header declares a single fixed frame rate, so variable frame rate footage drifts out of sync with its audio
- No subtitle or attachment tracks, so subtitles travel in a separate SRT file or get burned into the picture
- No practical way to carry H.265 or AV1, both of which arrived decades after the format was designed
- No browser plays AVI, and macOS dropped its last route to it when Perian was discontinued in 2012
Keep a file as AVI when it is going into software old enough to predate MP4, which is the one situation where the format's age helps.
Convert AVI to MP4 to get the video playing on phones, browsers and TVs, and to shrink it, since what is inside an AVI is usually a codec generation or two behind.
How to open a .avi file#
A .avi file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts AVI into a format your machine already opens, and it does it in the browser tab rather than on a server.
| Platform | Programs that open it |
|---|---|
| Windows | VLC, MPC-HC, PotPlayer |
| macOS | VLC, IINA, mpv |
| Linux | VLC, mpv, GNOME Videos |
| iOS | VLC, Infuse |
| Android | VLC, MX Player |
| Web | FileFlip |
AVI questions people ask#
Why won't my AVI file play?
An AVI that will not play is usually encoded with a codec the machine does not have. AVI identifies its video by a four character code and leaves the decoder to the operating system, which is why Windows users spent years installing codec packs. Old DivX, Xvid, Indeo and Cinepak files all hit this. VLC ships its own decoders and plays most of them, and converting to MP4 removes the problem permanently.
Is AVI a codec or a container?
AVI is a container, and an unusually open-ended one. Any codec that registers a four character code can go inside, so AVI files from different eras hold wildly different things: MJPEG from a camera, Cinepak from a CD-ROM, DivX or Xvid from a download. That is why one AVI plays instantly and the next one shows a black screen on the same computer.
Does converting AVI to MP4 lose quality?
Converting AVI to MP4 nearly always re-encodes the video, so some quality is lost. AVI predates H.264 and H.265, which is what MP4 players expect, so the old DivX or Xvid stream cannot simply be rewrapped the way an MKV can. Encoding at a generous bitrate keeps the loss invisible in practice, and the result usually still ends up smaller than the AVI.
Why is my AVI file so large?
AVI files are big because of what is inside them rather than the container itself. The codecs of the era, MJPEG and DivX among them, need several times the bitrate H.265 does for the same picture, and MJPEG stores every frame as a separate JPEG with no saving between frames at all. Re-encoding the same footage to H.264 or H.265 in an MP4 commonly cuts the file to a fraction of its size.
Can AVI files have subtitles?
AVI has no subtitle track, so subtitles for an AVI live in a separate SRT or SUB file sitting next to it with a matching filename, and the player pairs them up. Move the video without the sidecar file and the subtitles are gone. Converting to MKV or MP4 lets the subtitles be embedded in the video file itself, which is the usual reason people move AVIs into a newer container.
Converting AVI files#
Convert AVI to another format
Convert another format to AVI
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.