What is a MP4 file?
MP4 (MPEG-4 Part 14) is a container: a wrapper that holds a video track, one or more audio tracks, and sometimes subtitles and chapter marks. It was standardised by MPEG in 2003 and is based on Apple's QuickTime format.
The container does not decide the quality; the codecs inside do. Most MP4 files carry H.264 video with AAC audio, the combination that plays on practically every device made in the last fifteen years. Newer phones also record H.265 (HEVC) into MP4, which halves the size but does not play everywhere. When people say "convert to MP4", they usually mean "make it H.264 and AAC in an MP4 file", which is what the converters here do.
MP4 at a glance
| Full name | MPEG-4 Part 14 |
|---|---|
| File extensions | .mp4, .m4v |
| Created by | MPEG (ISO/IEC 14496-14) |
| Introduced | 2003 |
| Compression | Depends on the codec inside; usually lossy |
| Codecs inside | Usually H.264 or H.265 video with AAC audio |
| Opens on | Every phone, computer, TV, browser, editor and social network |
| Best for | Sharing, uploading and playing video anywhere |
How to open a MP4 file
MP4 plays in every browser, in the Photos or Films & TV app on Windows, in QuickTime on a Mac and in the gallery on any phone. If a file will not play, its codec is the problem, not the container: re-encode it with the Video Converter. To shrink it, use the Video Compressor.