Convert AVI to MP4

AVI to MP4の使い方

1. 1

   Add the AVI files

   Drop up to 3 .avi videos of up to 500 MB and 10 minutes each: old camera clips, DivX or Xvid files, webcam captures.

2. 2

   Wait for the engine the first time

   Browsers can't open AVI themselves, so a 31 MB video engine is downloaded once, with a progress bar, and cached for next time.

3. 3

   Choose quality and size

   High is preselected; lower the resolution or pick Balanced to make big DV or MJPEG files much smaller.

4. 4

   Convert and download

   Press Convert to MP4 and save name.mp4, which plays on phones, smart TVs and every website.

AVI to MP4 について

AVI is Microsoft's video container from 1992, still found on old digital cameras, camcorder transfers, DivX and Xvid downloads from the 2000s, CCTV exports and some webcam software. Modern devices handle it badly: iPhones, Android galleries, Chrome and Safari can't play it, and many editors refuse it. AVI also lacks features newer formats rely on, such as reliable B-frame timing and streaming from the first byte.

No browser can read AVI on its own, so this page uses ffmpeg.wasm, the FFmpeg engine compiled to WebAssembly, which is downloaded once (31 MB) and kept in the browser cache. It opens the AVI, decodes the video — Xvid and DivX (MPEG-4 Part 2), Motion JPEG, DV, old Windows codecs — and encodes it as H.264, because copying MPEG-4 Part 2 into an MP4 would produce a file phones and browsers still can't play. MP3 sound, the usual partner of Xvid, is copied unchanged; PCM, ADPCM and AC-3 sound is converted to AAC.

This conversion runs on your processor rather than a hardware encoder, so it is slower than other conversions: roughly real time for standard-definition clips on a recent laptop, slower on phones. Interlaced camcorder footage isn't deinterlaced, so fast motion may show fine combing, as it did before. Old AVI files with damaged indexes usually still convert, but a truncated recording ends where the data stops.

AVI to MP4：よくある質問