MP4 to AVI
Convert MP4 video files into AVI format with browser-side FFmpeg.
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Quick Tip
Select the .mp4 file.
About This Tool
Why use MP4 to AVI?
Repackage an MP4 as an AVI. FFmpeg runs in your browser and re-encodes the streams into AVI's container using its default codecs, producing a file that older Windows software, some editing suites and a good deal of legacy hardware will actually open.
AVI is a Microsoft container from 1992 and it has been comprehensively superseded — MP4 is smaller, more efficient and supported practically everywhere. The only reason to convert this direction is compatibility with something that will not take MP4: an old editing program, a hardware player, a piece of industrial or broadcast equipment with fixed requirements. Expect the AVI to be noticeably larger, because its codecs are much less efficient than H.264.
Key Benefits
Legacy compatibility
Produces a file that older Windows software, editing suites and hardware players will open when they reject MP4.
Runs in the browser
FFmpeg is compiled to WebAssembly and executes in the tab, so the video is never uploaded.
No software to install
Useful on a locked-down machine where installing a desktop encoder is not an option.
How to use MP4 to AVI
- 1
Select the .mp4 file.
- 2
Convert; the streams are re-encoded into the AVI container.
- 3
Expect this to take longer than an audio conversion — video re-encoding is the slow part.
- 4
Download the .avi and test it in the software that needed it.
Best use cases
Feed a video into an old editing program that only reads AVI.
Play a file on legacy hardware with fixed format requirements.
Meet a submission requirement that specifies AVI.
Work with equipment that predates widespread MP4 support.
MP4 to AVI FAQs
Why is the AVI so much bigger than the MP4?
AVI's default codecs are far less efficient than the H.264 in a modern MP4. The same content in AVI is routinely several times larger. That is the cost of the compatibility.
Should I convert MP4 to AVI at all?
Only if something specific requires AVI. MP4 is smaller, better supported and better quality at the same size. This is a compatibility conversion, not an upgrade.
Why is it slow?
Video has to be decoded and re-encoded frame by frame, and a browser tab is slower at that than a native application. Long files take a while.
Is there a size limit?
No fixed limit, but the tab's memory ceiling is real. Very large files can fail; trim them first or use a desktop encoder.
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