AVI to MP4
AVI is from another era. Convert old camcorder or DVD rips to a modern MP4.
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Why convert AVI to MP4?
AVI is a 1990s Microsoft container. It's everywhere in old video archives — camcorder dumps, DVD rips, downloaded TV episodes from before YouTube existed. It works on Windows but is a hassle elsewhere: iPhones don't play AVI, Android players need codec packs, and modern editors prefer MP4.
Converting AVI to MP4 brings your file into the modern era: smaller, plays on every device, accepted by every editor.
What's inside an AVI?
Usually MPEG-4 ASP (DivX, Xvid), Cinepak, or Indeo video with MP3 or PCM audio. We re-encode everything to H.264 + AAC for maximum compatibility.
What is in an AVI, and why it matters
AVI is a container from 1992, and the reason AVI files are unpredictable is that the container says almost nothing about what is inside it. One AVI might hold DivX or Xvid video from the 2000s, another might hold uncompressed frames from a capture card, another MJPEG from an old camera. Two files with the same extension can behave completely differently.
That is the actual problem with AVI today: not that the format is unreadable, but that modern phones, browsers and editors support MP4 with H.264 universally and support the older codecs inside AVI only sometimes. Converting to MP4 gives you a file that plays everywhere.
What to expect
The video is re-encoded to H.264 and the audio to AAC, which is the combination every device understands. Because the source is usually an older, less efficient codec, the MP4 is often smaller than the AVI it came from despite looking the same.
Re-encoding is not lossless, but going from an old codec to a modern one at a sensible bitrate rarely shows. What it cannot do is recover quality the AVI had already lost.
Other legacy containers have their own pages: WMV for Windows Media files, FLV for old Flash video, and MKV for the modern equivalent.
FAQ
Will the quality be the same?
If you pick High quality, very close. Old AVI files were often already heavily compressed; re-encoding adds slight generation loss but nothing dramatic.
Does the file get uploaded anywhere?
No. Nothing is uploaded. Open your browser's network tab while you convert and you will see your file never leaves the page. Once the converter itself has downloaded, it keeps working on this device even with no connection.
What's the maximum file size?
Browser memory is the limit. WebAssembly caps at 2–4 GB per file. Most laptops handle 1080p videos under a gigabyte comfortably.
Why is it slow on my phone?
FFmpeg-WASM runs on your CPU, not hardware video encoders. Phones have less CPU, so encoding takes longer.
Can I cancel mid-encode?
Yes. The Cancel button terminates the worker immediately. You'll wait a few seconds the next time you start.