Updated August 11, 2026

Video formats & codecs reference

A video file is a container (the wrapper, e.g. MP4) holding streams encoded with a codec (e.g. H.264). This sheet separates the two so you can pick a target, then convert or compress locally.

Containers

The container is the file wrapper. The same codec can live in different containers.

Container	Typical codecs	Best for
`MP4`	H.264, H.265, AAC	Universal sharing and playback; the safe default
`WebM`	VP9, AV1, Opus	The web; royalty-free codecs, small files
`MOV`	H.264, H.265, ProRes	Apple/QuickTime editing workflows
`MKV`	Almost any	Flexible archiving; multiple tracks and subtitles

Codecs

The codec decides how the video is compressed. Newer codecs are smaller at the same quality but need more compute and have patchier support.

Codec	Efficiency	Support
`H.264 (AVC)`	Baseline	Everywhere — browsers, phones, editors
`H.265 (HEVC)`	~50% smaller than H.264	Good on Apple; patchy in browsers; licensing
`VP9`	Similar to H.265, royalty-free	Most browsers; common on the web (WebM)
`AV1`	Best; smaller than VP9/H.265	Growing; slower to encode

Container vs codecChanging the container (MP4 to MKV) can be a fast remux without re-encoding. Changing the codec (H.264 to AV1) re-encodes every frame — slower, and it loses a little quality each time.

When in doubt, use MP4 + H.264MP4 with H.264 plays almost everywhere. Reach for H.265, VP9, or AV1 when you specifically need smaller files and control the playback target.

References

Questions

What is the difference between a container and a codec?

The container (MP4, WebM, MOV, MKV) is the file wrapper that holds the streams; the codec (H.264, H.265, VP9, AV1) is how the video itself is compressed. A file needs both.

Which video format is most compatible?

MP4 with the H.264 codec. It plays in virtually every browser, phone, and editor, which is why it is the safe default for sharing.

Is AV1 better than H.264?

For file size, yes — AV1 is much more efficient. But it is slower to encode and not supported everywhere yet, so H.264 remains the compatibility choice.