Convert AVI to MP4
AVI is a 1992 Microsoft container. Modern players tolerate it inconsistently. Wave repackages the streams into MP4 - usually with no re-encode - so the same video plays on iOS, streams over Chromecast, and uploads to social platforms without complaint.
What actually changes
AVI can wrap almost anything: MPEG-4 ASP (DivX / Xvid), older MPEG-2, or occasionally H.264 (though the format wasn't designed for it). H.264 and DivX / Xvid both go into MP4 without re-encoding - DivX and Xvid are literally MPEG-4 Part 2, a codec MP4 accepts natively - so Wave rewrites the container and copies the streams. Older MPEG-2 AVIs are the one exception, and those re-encode through the browser's WebCodecs H.264 encoder (or the LGPL MPEG-4 fallback where WebCodecs isn't available).
The bigger practical issue with AVI is that its audio and video tracks aren't strictly synchronized by design; some old files drift. Wave preserves the source timing, so if drift exists in the input it will exist in the output. If your AVI plays cleanly locally, the MP4 will too.
Three steps.
-
01
Step 1
Drop your AVI file onto the card.
-
02
Step 2
Wave inspects the codecs and picks fast-copy or transcode automatically.
-
03
Step 3
Convert and save.
Answers, specifically.
Why does my AVI file look old?
AVI is one of the oldest containers still in the wild. Files from 2000s-era ripping tools often use Xvid, which shows its age against modern encoders.
Can I convert without losing quality?
Almost always yes. H.264 inside an AVI copies losslessly. DivX and Xvid - the actual codec in most 2000s-era AVIs - are MPEG-4 Part 2, which MP4 also accepts, so those copy too with no re-encode. Only the rare MPEG-2-in-AVI needs a real transcode, and even then Wave targets a bitrate that keeps the picture close to the source.
Why do modern apps refuse AVIs?
Streaming platforms and mobile OSes standardized on MP4 and HEVC. AVI's variable-block structure doesn't fit their pipelines.
What happens to subtitle tracks?
AVIs rarely carry proper subtitle tracks. When they do (MicroDVD-style), Wave drops them - MP4 subtitle mux support in the current build is limited.
Are there size limits?
About 1.5 GB comfortably. Most AVIs from the era are well under this.