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Convert MP4 to AVI

Turn MP4, MOV, WebM and MKV files into AVI files on this device, as Motion JPEG for the widest player support or as smaller H.264.

Converts MP4, MOV, WebM and MKV videos to AVI. It is free, needs no account and adds no watermark, and your video is not uploaded: your browser re-encodes the picture and writes the AVI inside this tab. The size and frame rate stay as they were (up to 60 fps) and the sound is kept. An AVI here cannot be larger than 1.9 GB, and the page works offline after one visit and a short wait.

Drop MP4, MOV, WebM or MKV files to convert to AVIor click to choose files. Batches welcome.

    On: every frame is a JPEG picture with uncompressed sound. QuickTime, VLC and old AVI players open it, but the file is many times larger. Off: H.264 video, much smaller, which VLC opens and QuickTime does not.

    Working…

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    Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.

    AVI is an old Microsoft container that some DVD players, car stereos, older editing programs and hardware media players still ask for. A modern MP4 is not a file they open, so this page re-encodes the video into an AVI that they can.

    Nothing can be copied across, unlike MP4 to MOV: an AVI cannot hold the AAC sound an MP4 has, and the picture has to be rewritten for the AVI container. Your browser re-encodes it at the same size (rounded to an even number) and the same frame rate, up to 60 frames a second.

    By default the picture is written as Motion JPEG (MJPEG): every frame is a separate JPEG, with uncompressed 16-bit PCM sound. We chose it because it is the kind of AVI that opened in every player we tried, QuickTime included. The price is size: an MJPEG AVI is many times larger than the MP4.

    Untick Maximum compatibility for a much smaller AVI with H.264 video. Sound is then PCM for clips under 2 minutes and MP3 for longer ones. We checked those files in VLC, which plays them, and in the QuickTime playback engine on a Mac, which does not open H.264 inside an AVI. We have not been able to test Windows players, so if you need one of those, convert a short clip first.

    An AVI cannot be bigger than 1.9 GB here, and a video that would pass it is refused before anything is encoded, with a message that says so. To go the other way, use AVI to MP4: the two are separate jobs.

    How it works

    1. Drop one or more MP4, MOV, WebM or MKV files, or tap to pick them.
    2. Leave Maximum compatibility ticked for the widest player support, untick it for a smaller H.264 file, or tick Remove the sound for a silent AVI.
    3. Press Convert to AVI. One file downloads straight away; several download as a zip.

    In your browser, not on a server

    Mediabunny (MPL-2.0), a media toolkit written in TypeScript, reads the MP4, MOV, WebM or MKV container in your tab. With Maximum compatibility, each frame is drawn on a canvas and saved as a JPEG by your browser, and the sound is written as uncompressed 16-bit PCM. Without it, your browser’s own video encoder (WebCodecs) writes H.264 with no B-frames at a constant frame rate, and the page’s MP3 encoder (LAME, LGPL, compiled to WebAssembly) writes the sound; clips under 2 minutes keep PCM instead. A small AVI writer in this page’s own code then lays the frames and the index into a RIFF file in memory.

    Compared with upload-based tools: The video is read from your disk and the AVI is written in memory on your device, so there is no upload to wait for. An AVI of this kind cannot hold more than 1.9 GB, and a job that would pass it is refused before any encoding starts.

    Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.

    Questions

    How do I convert MP4 to AVI?

    Drop the .mp4 file on this page and press Convert to AVI. Your browser re-encodes the picture and writes an AVI with the same name and a .avi ending. Nothing needs installing, and you can drop several files at once.

    How do I play an AVI, and which players open these files?

    Browsers cannot play AVI files, so open the file in a desktop player. On a Mac we tested VLC 3.0, which plays both kinds of file this page writes, and the QuickTime playback engine, which plays the Maximum compatibility (MJPEG) file and does not open the H.264 one. We have not tested Windows players. If a player refuses the file, keep Maximum compatibility ticked and try again.

    Why is the AVI so much bigger than the MP4?

    AVI is an older container, and MP4 video is compressed by comparing each frame with its neighbours. The Maximum compatibility file stores every frame as its own JPEG picture and the sound uncompressed, so it is many times larger. Untick it for H.264, which is far smaller but is not opened by QuickTime.

    Why is there a 1.9 GB limit?

    This is the classic AVI layout, which is written in one piece and cannot be larger than 2 GB, and the page keeps a margin. The size is estimated before encoding starts, so a long or large video is refused at once instead of failing after a long wait. Trim it first, untick Maximum compatibility for a smaller file, or pick MP4 or MOV, which have no such limit.

    Can I convert MP4 to AVI without uploading the file?

    Yes. Your browser reads the MP4 from your disk, re-encodes it with its own video encoder and writes the AVI with code running in this tab. Open the network tab, run a conversion, and your video is not among the requests. After one visit and a short wait the page works offline.

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