MKV vs AVI
MKV is the modern, flexible one: it holds any codec, several audio tracks, subtitles and chapters. AVI holds one video and one audio track with older codecs. Unless a device demands AVI, MKV is better, and MP4 is better still for sharing.
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Choose MKV when
- Films with several languages or subtitle tracks.
- Archiving, where nothing should be thrown away.
Choose AVI when
- Old DVD players with DivX support and legacy editing software.
What MKV actually is
Matroska will hold essentially any combination of video, audio and subtitle streams, in any codec, in unlimited numbers, with chapters and attachments alongside. That is why it is the format of choice for archived films with several language tracks and subtitle sets.
MKV and WEBM share a signature because WEBM is a restricted Matroska, so tools sometimes report one as the other. What matters is the codecs inside.
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.
MKV and AVI side by side
| MKV | AVI | |
|---|---|---|
| Extension | .mkv | .avi |
| Media type | video/x-matroska | video/x-msvideo |
| Inside the file | H.264 video with AAC sound | MPEG-4 Part 2 (Xvid) video with MP3 sound |
| Compression | Lossy | Lossy |
| Carries sound | Yes | Yes |
| Plays on | VLC, Plex, most smart TVs and Android, but not the iPhone Photos app or QuickTime | Windows Media Player, VLC and old DVD players with DivX support |
| We can write it | Yes | Yes |
Questions
Can I convert MKV to AVI?
Yes, but extra audio and subtitle tracks will not survive, and the file usually grows. MP4 is a better target unless something requires AVI.