MP4 file format (.mp4)
H.264 video, AAC audio. Plays on absolutely everything.
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What is an MP4 file?
In short: An MP4 file (.mp4) is a video file in the MP4 format. 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. It can be converted to MOV or GIF for free in a web browser with iHateFiles, without uploading it.
Standardised in 2001 by MPEG, based on Apple's QuickTime file format.
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.
What MP4 is good at
- Plays on effectively every device and platform
- Hardware decoding, so battery drain and heat stay low
- Streams well, and can start playing before it has finished downloading
Where MP4 falls short
- H.264 is less efficient than newer codecs like AV1
- Licensing applies to commercial encoders
- The container tells you little about what is inside it
When to use MP4
Use MP4 when the video has to work everywhere with no thought required. It is the right default.
How to open a MP4 file
Every phone, every browser, every television, every editor.
| Windows | Opens everywhere on Windows without extra software. |
|---|---|
| macOS | Opens in QuickTime, Preview and Photos without extra software. |
| Linux | Every player handles it. |
| Phone | The default video format on both iPhone and Android. |
| In a browser | Every browser plays MP4 holding H.264 and AAC. This is the safest format on the web. |
The thing that usually goes wrong
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.
Questions
What is a MP4 file?
H.264 video, AAC audio. Plays on absolutely everything. Files use the .mp4 extension.
How do I open a MP4 file?
Most video software opens MP4 directly. If yours does not, convert it here to something more common. It takes a few seconds and nothing is uploaded.
Can I convert MP4 for free?
Yes. Every conversion here is free and unlimited, because your own device does the work rather than a server we have to pay for.
Is MP4 lossless?
That depends on the codec inside the container rather than the container itself. Everything written here is re-encoded, so expect one generation of loss.