About this tool
Old camcorder footage and legacy downloads often live in AVI files that phones and modern editors refuse. Converting to MP4 with H.264 makes them playable on anything and usually shrinks them substantially at the same time.
About the formats: AVI is Microsoft's 1992 video container. It is still common for old camcorder footage and legacy downloads, but the files are large and mobile support is poor. MP4 is the universal video container, usually holding H.264 video and AAC audio. It plays on every phone, browser, TV, and editing program, which is why most platforms ask for it.
AVI and MP4, side by side
| .avi in | .mp4 out | |
|---|---|---|
| Usual codecs | Anything, often DivX or Xvid | H.264 video, AAC audio |
| Plays on | Windows, VLC; browsers no | Everything |
| Subtitles | External files only | Limited |
| Best for | Old recordings, camera output | Sharing and uploading |
Rows where the two differ are marked. The full story on each: AVI files and MP4 files.
How to use it
- Drop your AVI files into the box above, or click to browse. Nothing is uploaded.
- Adjust the options if you want; the defaults suit most files.
- Click Convert to MP4 and wait a moment.
- Download the results individually or all at once as a ZIP.
Questions
Will my AVI be re-encoded?
Usually yes, because AVI typically contains DivX/Xvid or DV video that MP4 players do not support. H.264 or HEVC streams are copied without re-encoding.
Why does re-encoding take so long?
Encoding video in the browser runs on a single CPU core, so a re-encode processes roughly real time or slower for 1080p footage. Container swaps (stream copy) are near instant. Keep clips short or lower the resolution when you need speed.
Is it free, are files uploaded, which browsers work: the general questions are answered once for the whole site.