Convert AVI to MP4
Free online converter for AVI files. H.264/AAC video that plays on virtually any device. Nothing to install, no watermark, and every file is deleted automatically.
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Upload a AVI file to convert it to MP4. Up to 3 files at once, 100 MB each.
Free · up to 3 files · 100 MB each · files deleted automatically after 1 hour.
About AVI and MP4
AVI .avi
A Microsoft container from 1992. Still readable everywhere, but it predates modern streaming, subtitles and variable bitrate audio.
Good for
- Opens in very old software
- Simple, well-understood structure
Trade-offs
- Much larger than MP4 for the same quality
- No native subtitle support
- Poor handling of variable bitrate audio and modern codecs
video/x-msvideo
MP4 .mp4
The universal video container, normally holding H.264 video and AAC audio. If a device plays video at all, it plays MP4.
Good for
- Plays on effectively every device, browser and editor
- Excellent compression at high quality
- Streams well, and seeks quickly
Trade-offs
- H.264 carries patent licensing obligations
- Lossy — quality drops each time it is re-encoded
- Less flexible than MKV for subtitles and multiple tracks
video/mp4
AVI and MP4 side by side
| AVI | MP4 | |
|---|---|---|
| Compression | Container — usually older codecs | Lossy (usually H.264) |
| Transparency | No | No |
| Typically used for | Legacy video files | Everything — the safe default for video |
What changes when you convert AVI to MP4
AVI and MP4 are unrelated containers
AVI is built on RIFF, Microsoft's chunk format from 1992. MP4 is the ISO base media format, derived from QuickTime. A container is a box, not a compression method: what decides how a video looks and how large it is, is the codec stored inside, and these two boxes accept different ones.
This is a re-encode, not a repackage
Some tools can move a stream into a different container untouched when the codecs happen to line up. We do not — every job here is decoded and encoded again, so the conversion takes time in proportion to the length of the file and costs a small amount of quality even where a repackage would have been possible. In exchange the output is predictable: it plays everywhere, rather than inheriting whatever the source happened to contain.
What your MP4 will contain
The output is H.264 video with AAC audio — the index is moved to the front of the file so it can start playing before it has finished downloading, and the colour is written as 8-bit 4:2:0, which is what phones, browsers and TVs all agree on. Quality is set by a constant-quality target rather than a fixed bitrate, so a still interview compresses small and a fast-moving clip is allowed the bits it needs.
Other AVI conversions
Other ways to get MP4
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