AVI File (.avi): What It Is, How It Works + Sample Files

The basics

What is an AVI file?

AVI is the video format Microsoft introduced in 1992 with Video for Windows. For more than a decade it was the default for video on PCs: captures from camcorders and TV cards, webcam and early digital camera clips, CD-ROM video, and the DivX and Xvid films that circulated online in the 2000s. You'll still find it in archives, on old hard drives, from security cameras and in some scientific and industrial equipment.

Like MP4 and MKV, AVI is a container: it stores one or more streams, usually one video and one audio, and leaves the compression to a codec. AVI's own structure is very simple, which made it easy to support and lets it carry almost any codec, but it lacks things modern formats take for granted: timestamps on each frame, B-frame support, subtitles, chapters and a standard way to stream it.

In short

AVI still works for playing and archiving old material, but it isn't a good choice for anything new. For sharing, use MP4; for keeping several audio or subtitle tracks, use MKV.

Anatomy

What's inside an AVI file

An AVI file is a RIFF file, like a WAV: a tree of chunks, each with a 4-letter ID, a 4-byte size and its data. A LIST chunk holds other chunks. All numbers are little-endian. Here is the chunk tree of sample-xvid-mp3.avi, our 10-second sample, as read from the file. Offsets and sizes are in bytes.

sample-xvid-mp3.avi (chunk tree)

offset   chunk            size       content
0        RIFF 'AVI '      1,007,432  the whole file
                          52 49 46 46 48 5F 0F 00 41 56 49 20
12         LIST 'hdrl'    8,906      the headers
24           avih         56         33,333 µs per frame, 301 frames,
                                     2 streams, 640×360
88           LIST 'strl'  4,320      stream 0: video
100            strh       56         type "vids", handler "XVID"
164            strf       40         640×360, compression "XVID"
212            JUNK       4,120      space for an OpenDML index
4,340          vprp       68         video properties (OpenDML)
4,416        LIST 'strl'  4,234      stream 1: audio
4,428          strh       56         type "auds"
4,492          strf       30         format 0x0055 (MP3), 2 ch, 48 kHz
4,530          JUNK       4,120      space for an OpenDML index
8,658        JUNK         260        space for the OpenDML header
8,926      LIST 'INFO'    190        INAM, IART, ICMT, ISFT tags
9,124      JUNK           1,016      padding
10,148     LIST 'movi'    985,772    the media
10,160       01wb         384        stream 1, audio: MP3
10,552       00dc         13,530     stream 0, video: a keyframe
             …            719 chunks in all: 301 × 00dc, 418 × 01wb
995,928    idx1           11,504     index: 719 entries of 16 bytes

152 49 46 46 · 48 5F 0F 00 · 41 56 49 20
The RIFF header
RIFF, then the size of the rest of the file (0x000F5F48 = 1,007,432 bytes, read backwards because it's little-endian), then the form type AVI with a trailing space. WAV and WebP files start with RIFF too; the form type is what tells them apart.
2LIST 'hdrl' / avih
The main header
How long each frame lasts (33,333 microseconds, so 30 fps), the number of frames and streams, and the picture size. AVI has a single fixed frame rate: there are no timestamps on individual frames.
3LIST 'strl' / strh
A stream header
One strl list per stream. The stream header gives its type (vids for video, auds for audio) and a FourCC naming the codec: XVID here. A player looks this code up to find a decoder, which is why a missing codec was the classic AVI error.
4strf
The stream format
For video, a Windows BITMAPINFOHEADER with the size and compression code; for audio, a WAVEFORMATEX with a format tag, here 0x0055 for MP3 (0x0001 would be PCM), the channels and the sample rate.
5JUNK, vprp
Room for OpenDML
JUNK chunks are filler that readers skip. FFmpeg leaves these ones empty so it can write OpenDML indexes into them if the file grows past about 1 GB; vprp is OpenDML's video properties chunk, with the aspect ratio.
6LIST 'INFO'
Metadata
Title (INAM), artist (IART), comment (ICMT) and software (ISFT), the same INFO tags WAV files use.
7LIST 'movi' / 00dc, 01wb
The interleaved media
The audio and video data, in small chunks that alternate so a player reading from start to end always has both: that's the "interleave" in the name. The ID gives the stream number and the kind of data: 00dc is a compressed video frame from stream 0, 01wb is audio from stream 1 (db would be an uncompressed frame).
8idx1
The index
At the very end: one 16-byte entry per chunk, giving its ID, a keyframe flag, its position and its size. Players use it to seek. If a recording stops before the index is written, the file still plays from the start, but seeking fails until a player rebuilds the index.

Limits

The 1 GB and 2 GB limits, and OpenDML (AVI 2.0)

Every RIFF chunk stores its size as a 32-bit number, so in theory one RIFF file can reach 4 GB. In practice the original AVI format stopped well short of that. Video for Windows files were first limited to 1 GB, later to 2 GB, and FAT16, the usual Windows file system of the time, couldn't store a file over 2 GB anyway. For video capture, where an hour of DV is about 13 GB, that wasn't enough.

The fix was the OpenDML extension, written in 1995–96 by the OpenDML committee working with the capture-card maker Matrox, and supported by Microsoft. It's often called AVI 2.0:

After the first RIFF 'AVI ' chunk, the file continues with further RIFF 'AVIX' chunks, each with its own movi list, so the file can grow as large as the file system allows.
A two-level index (indx chunks pointing to smaller indexes spread through the file) replaces the single idx1 at the end, which also makes seeking in big files faster.
A dmlh header records the true total number of frames.

To stay readable by old software, writers keep the first RIFF chunk small and still give it an idx1. Old players then show only the first part of a big OpenDML file, often around the first gigabyte, which is the usual explanation when a long AVI "stops early" in one program and plays in full in another.

Codecs

What's inside: codecs and FourCC codes

The strh and strf chunks name the video codec with a four-character code (FourCC) and the audio codec with a numeric format tag. Knowing the common ones tells you what era a file is from and what will play it.

Common codes in AVI files
Code	Codec	Where it comes from
`XVID`, `DIVX`, `DX50`, `FMP4`	MPEG-4 Part 2 (Xvid, DivX)	Films and TV shared online in the 2000s, DVD rips
`MJPG`	Motion JPEG: every frame a JPEG	Webcams, early digital cameras, security cameras
`dvsd`	DV	Camcorders captured over FireWire
`cvid`, `IV32`, `IV50`	Cinepak, Intel Indeo	CD-ROM games and encyclopaedias of the 1990s
`H264`, `X264`	H.264	Later screen recorders and cameras. Works, but MP4 or MKV is a better home for it
`HFYU`, `UYVY`, uncompressed	Huffyuv (lossless), raw video	Capture and editing intermediates
`0x0001`, `0x0055`, `0x2000`	PCM, MP3, AC-3 audio	PCM for captures, MP3 for shared films, AC-3 for DVD rips

Why codecs with B-frames are awkward in AVI

AVI stores frames in the order they're shown, at a fixed rate. Codecs with B-frames have to store frames out of order, so DivX and Xvid used a trick called packed bitstream, putting two frames in one chunk and an empty placeholder in the next. Many players cope, but it causes stutter and sync problems in others. Our samples avoid B-frames for this reason.

On the web

Why browsers won't play AVI files

No current browser plays AVI in a <video> element. Open an .avi link and the browser downloads it instead. There are two reasons:

The container. Browsers support MP4, WebM and, increasingly, Matroska. AVI was never added: it can't be streamed efficiently (the index is at the end and frames have no timestamps) and it offers nothing those formats don't.
The codecs. Most AVI files hold codecs browsers don't decode at all, such as MPEG-4 Part 2, Motion JPEG, DV or Indeo. Even moving the streams into MP4 wouldn't make those play.

To show an AVI on a web page, convert it: ffmpeg -i in.avi -c:v libx264 -crf 20 -c:a aac -movflags +faststart out.mp4. If the AVI already holds H.264, you can keep the video as it is with -c:v copy and only convert the audio.

Related formats

AVI vs MP4, MKV and MOV

	AVI	MP4	MKV
Introduced	1992	2003 (MPEG-4 Part 14)	2002
Frame timestamps	No: fixed frame rate	Yes	Yes
B-frames	Only with workarounds	Yes	Yes
Subtitles, chapters	No standard way	Limited	Yes, many tracks
Streaming over the web	No	Yes	Partly
Plays in browsers	No	Yes, everywhere	Chrome, Edge, Firefox
Good for today	Reading old files	Sharing and the web	Archiving, films with several tracks

Troubleshooting

Why won't my AVI play? Common problems and fixes

Symptom	Usual cause	Fix
"Codec not found", or sound with no picture	No decoder for the video FourCC on this computer.	Play it in VLC or mpv, which include decoders for almost every AVI codec. Don't install random "codec packs".
Plays, but you can't skip ahead	The `idx1` index is missing or damaged, usually because recording or copying stopped early.	VLC offers to rebuild the index when it opens such a file. `ffmpeg -i in.avi -c copy out.avi` writes a new one.
Audio drifts out of sync	Variable-bit-rate MP3 audio, or packed-bitstream video, which some players handle badly.	Convert to MP4 with FFmpeg, re-encoding the audio to AAC (`-c:a aac`).
A long recording stops early	An OpenDML (AVI 2.0) file opened in a program that only reads the first RIFF chunk, or an old 2 GB limit.	Use VLC, mpv or FFmpeg, which read OpenDML.
Won't open on a Mac	QuickTime Player can't open most AVI files.	Use VLC or IINA, or convert to MP4.

How to

How to open, edit and convert an AVI file

Windows: the Media Player app plays AVI files with common codecs such as Xvid, Motion JPEG and DV. For anything else, VLC.
macOS: VLC or IINA. QuickTime Player and iMovie don't open most AVIs.
Linux: VLC or mpv.
Phones: VLC for Android and iOS plays AVI files; the built-in players usually don't.
Convert to MP4: HandBrake (free, with presets) or ffmpeg -i in.avi -c:v libx264 -crf 20 -c:a aac out.mp4.
Inspect it: ffprobe in.avi lists the FourCC, frame rate and audio format; MediaInfo shows the same in a window.

Archiving old AVIs

Keep the original file when you convert: re-encoding loses a little quality each time. For long-term preservation, archives often move old video into lossless FFV1 in Matroska; our MKV page has a sample.

Security

Is an AVI file safe?

Fake codec downloads. A website or a file that says you need to install a special codec to watch a video is a classic way to spread malware. Real players don't ask for that; VLC plays nearly every AVI as it is.
Disguised programs. film.avi.exe is a program. Windows hides known extensions by default, so turn on file name extensions in File Explorer.
Old decoders. An AVI can't run code, but a crafted file can exploit bugs in decoders, and AVI often means old, unmaintained codecs installed years ago. Uninstall codec packs you don't need and keep your player updated.

Free downloads

Sample AVI files to download

Free sample AVI files for testing players, converters, upload forms and media pipelines. All are made from FFmpeg test patterns and generated tones, with the format written on screen. Each was checked with ffprobe and fully decoded without errors. Browsers can't play AVI, so these download rather than preview.

sample-xvid-mp3.avi · 983.8 KBDownload

Browsers can't show this kind of file in a page. Download it to open it in the app it belongs to.

What's inside sample-xvid-mp3.avi

A 10-second, 640×360 AVI at 30 fps in the classic 2000s combination: Xvid (MPEG-4 Part 2) video and MP3 stereo audio. Open it in VLC or mpv to see the parts below.

The label
The bottom band names the resolution, frame rate and codecs, so you can see at a glance if a converter changed something.
Timecode and frame counter
Burned into the top of each frame. Skipped or repeated frames show up as jumps in the counter.
The flash and the beep
A white square flashes in the top right for 3 frames on every whole second, in step with a 1 kHz beep. AVI files are prone to drift, so check they stay together to the end.
Stereo test tones
440 Hz on the left channel and 660 Hz on the right, so swapped or mixed-down channels are easy to hear.
FourCC and format tag
The video is tagged XVID and the audio 0x0055 (MP3), the two codes a player needs to find decoders.
No B-frames
Encoded without B-frames, so there's no packed bitstream and it plays smoothly in every AVI player.
Metadata and index
Title, artist and a comment naming this page in the INFO list, and a complete idx1 index at the end, so seeking works.

All sample AVI files

Xvid + MP3
sample-xvid-mp3.avi · 983.8 KB (1,007,440 bytes)
10 seconds at 640×360, 30 fps. MPEG-4 Part 2 video tagged XVID, MP3 stereo at 128 kbps, with an idx1 index.
- Testing that a player or converter handles classic AVI files
- Checking how a site deals with video it can't preview
Download
Motion JPEG + PCM
sample-mjpeg-pcm.avi · 436.0 KB (446,418 bytes)
2 seconds at 320×240, 15 fps, Motion JPEG (MJPG) with uncompressed 16-bit PCM stereo audio at 22,050 Hz, like clips from webcams and older digital cameras.
- Testing import from camera-style AVI files
- Extracting individual frames as JPEGs
Download
H.264 + MP3
sample-h264-mp3.avi · 213.7 KB (218,854 bytes)
4 seconds at 640×360, H.264 Main profile without B-frames (FourCC H264) and MP3 audio: a modern codec in the old container.
- Testing a remux to MP4 without re-encoding the video
- Checking FourCC-based codec detection
Download
1 MB AVI file
sample-1mb.avi · 1 MB (1,048,576 bytes)
8 seconds at 640×360, Xvid + MP3, padded with a JUNK chunk to exactly 1,048,576 bytes (1 MiB). Players skip the padding.
- Upload and size-limit tests
- Checking that parsers skip unknown chunks
Download

Ways to test with them

Upload handling: browsers can't preview AVI, so sample-xvid-mp3.avi shows what your site does with video it can't play: a download, a placeholder or an error.
Conversion: run each sample through your converter; the frame counter, the flash and the beep should all survive into the MP4.
Remux vs re-encode: ffmpeg -i sample-h264-mp3.avi -c:v copy -c:a aac out.mp4 should keep the video untouched; the Xvid and Motion JPEG files need re-encoding.
Size limits: sample-1mb.avi is exactly 1 MiB, so you can test a limit at the boundary.

Free to use for testing, teaching and demos, commercially or not, with no attribution needed. A link back to this page is always appreciated.

Put it online

Have an AVI file? Give it a link.

Drop an AVI on 99helpers and it gets its own address to send instead of a large attachment. Browsers don't play AVI, so visitors download it; to have it play in the browser, convert it to MP4 first.

Put an AVI online

Questions

AVI files, frequently asked

What does AVI stand for?

Audio Video Interleave. "Interleave" refers to how the file alternates small chunks of audio and video so both can be read together.

How do I play an AVI file?

Use VLC or mpv, which play almost every AVI on Windows, macOS, Linux and phones. The Windows Media Player app plays the common ones. Web browsers don't play AVI.

How do I convert AVI to MP4?

Use HandBrake, or ffmpeg -i in.avi -c:v libx264 -crf 20 -c:a aac out.mp4. If the AVI already holds H.264, -c:v copy keeps the video without re-encoding.

Is AVI better quality than MP4?

Neither container has a quality of its own; it depends on the codec inside. Older AVIs often use older codecs that need larger files for the same quality, and an uncompressed AVI is huge but lossless.

Why can't I play an AVI in Chrome?

No current browser supports the AVI container, and most AVI files also use codecs browsers can't decode. Convert it to MP4 to play it in a browser.

What is the maximum size of an AVI file?

Original AVI files were limited to 1 GB, later 2 GB in practice. The OpenDML extension (AVI 2.0) chains several RIFF chunks together, so the size is limited only by the file system.

Is AVI still used?

Rarely for new video. It survives in old archives, some security and industrial cameras, and scientific instruments. MP4 and MKV have replaced it for nearly everything else.

Can an AVI file contain a virus?

It can't run code by itself, but a crafted file could exploit a decoder bug. The bigger risk is being told to install a "codec" to play it, which is a common malware trick.

Related formats

Other file types explained

MP4 file MKV file MOV file WAV file All file types

Keep going

Host an AVI file

Put an AVI online at its own address for others to download.

Share an AVI file

Send a video as a link instead of an attachment.

Hosting guides

How to put different kinds of files online.

Sources

Last reviewed 27 October 2026.