AVI vs MP4
MP4 is the better choice for almost everything: it holds modern codecs, streams on the web and plays on every phone and TV. AVI is a 1990s Windows container kept alive by old cameras and archives. Convert AVI to MP4 to share it.
Last updated
Choose AVI when
- Old editing software, capture cards and hardware that only accept AVI.
- Keeping an archive in the form it was captured in.
Choose MP4 when
- Sharing, uploading, and playing on phones, TVs and browsers.
- Smaller files: MP4 with H.264 is usually a third of an old DivX or Xvid AVI.
What AVI actually is
AVI is a simple container from before modern video: it interleaves chunks of audio and video and does little else. It has no proper support for variable frame rates, modern subtitles or the metadata that newer containers take for granted, which is why it was replaced.
Audio drifting out of sync partway through an AVI is common, because the container assumes a fixed frame rate that the source did not actually have. Re-encoding to MP4 corrects the timing.
What MP4 actually is
MP4 is a container: it holds a video stream, usually H.264, an audio stream, usually AAC, and any subtitles or chapter data, and describes how they line up. Almost every device made in the last fifteen years plays that combination in hardware, which is why MP4 became the default.
Two MP4 files can behave completely differently depending on the codecs inside. A file that will not play is usually an unusual codec in an ordinary container, not a broken file.
AVI and MP4 side by side
| AVI | MP4 | |
|---|---|---|
| Extension | .avi | .mp4 |
| Media type | video/x-msvideo | video/mp4 |
| Inside the file | MPEG-4 Part 2 (Xvid) video with MP3 sound | H.264 video with AAC sound |
| Compression | Lossy | Lossy |
| Carries sound | Yes | Yes |
| Plays on | Windows Media Player, VLC and old DVD players with DivX support | every phone, laptop, TV, browser and messaging app |
| We can write it | Yes | Yes |
Questions
Is AVI better quality than MP4?
Neither container has a quality. What matters is the codec inside, and MP4 holds better ones.
Why will an AVI not play on my phone?
Phones do not support the Xvid and DivX codecs most AVIs use. Convert it to MP4.