Convert AVI to MP4
Bring old AVI files back to life. DivX, Xvid, MJPEG, Microsoft MPEG-4 and Motion JPEG video are all decoded and re-encoded as H.264 in an MP4 — the one format phones, tablets, browsers and TVs all play.
- Never stored
- No queue, no waiting
- No signup, no watermark
How it works
Add your AVI
Drop the file. The video and sound codecs inside are named for you — often a surprise in a twenty-year-old file.
Let it convert
The picture is re-encoded as H.264 and the sound as AAC, at the original size and frame rate.
Download the MP4
A file that plays on anything made this decade.
A 1992 container meeting a modern one
AVI predates almost everything about how video works now. Microsoft designed it in 1992, before B-frames, before variable frame rates, before modern timestamp handling — and it was never meaningfully updated. Whatever is inside your AVI is therefore not something an MP4 can hold, so unlike an MKV or a MOV this is always a real re-encode: every frame is decoded and encoded again. It takes time proportional to the length of the video, and it costs one generation of quality.
What is usually inside is DivX or Xvid — implementations of MPEG-4 Part 2, the codec that made video sharing practical around 2001 — or motion JPEG from an older camera. H.264 is roughly twice as efficient as either, which is why the MP4 typically comes out noticeably smaller than the AVI while looking much the same. That is a genuine gain rather than a trick: you are paying one generation of loss to switch to a far better codec.
Interlacing is the thing to look for in the result. Video from that era was frequently made for cathode-ray televisions, which drew alternate lines in alternate passes — so each frame contains two different moments in time, and on a modern screen fast movement shows as a comb of horizontal stripes. The conversion carries the video across as it is rather than deinterlacing it, so stripes in the AVI are stripes in the MP4. Fixing that needs a filter, and the tools below have one.
The rest is small print worth knowing. Old AVI files were often split at two or four gigabytes because early implementations could not exceed it, so a film may exist as several parts that need joining rather than converting one at a time. Audio is frequently MP3 or AC-3 and is re-encoded to AAC. Only the main video and sound track come across, and the page says when something was left behind.
When you want something else
For interlaced footage, ffmpeg does the job properly: ffmpeg -i in.avi -vf yadif -c:v libx264 -crf 20 -c:a aac out.mp4 deinterlaces as it converts, and bwdif is a better filter again on difficult material. Handbrake offers the same thing with a preview and no command line, which for a one-off is genuinely easier.
For an archive of old AVIs, the practical concern is doing it once and doing it well — every re-encode is permanent. Convert at -crf 18 rather than a size target, deinterlace where needed, and keep the originals until you have checked the results. Handbrake and ffmpeg both process a folder unattended; a browser tab converting one file at a time is the wrong tool for a shelf of them.
Frequently asked questions
Why does AVI have to be re-encoded?
Because the video inside is usually DivX or Xvid — MPEG-4 Part 2 — which an MP4 can technically hold but almost no phone or browser can decode. Re-encoding to H.264 is what actually makes the file playable, so it is done at high quality rather than avoided.
Is my file stored anywhere?
No. The AVI is read and converted here, with nothing stored. Nothing is sent anywhere.
Will it look worse?
Very slightly, as with any re-encode, but H.264 is far more efficient than DivX: at the quality used here the difference is hard to see, and the file is usually smaller than the original.
My AVI has no sound after other converters.
Old AVI files often store sound as MP3, PCM, ADPCM, or Windows Media Audio, and many tools quietly drop what they cannot read. Every one of those is decoded, and if a sound track really cannot be read you are told rather than handed a silent film.
How long does a full-length film take?
Roughly real time to a few times faster on a modern laptop. The progress bar keeps count, and you can cancel at any point.
Can I convert several AVIs at once?
One at a time. For a long conversion, leave the tab open — the page stays usable while it works.
Good to know: Only the main video and sound track are kept; a second language track or embedded subtitles are left out, and you are told when that happens. Interlaced video is converted as it is, without deinterlacing.
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