File formats
Use real MIME support rather than renaming a video extension.
On this page
Automatic prefers supported WebM encoders and then supported MP4. MediaRecorder.isTypeSupported is checked at runtime; it is a capability hint, not a guarantee that encoding will succeed under current resource limits. Audio MP4 files use the .m4a extension.
How to use it
- Start with Automatic. If you require MP4, select it and check that an encoder MIME type appears.
- Record a sample and verify it in the intended player or editor.
- Keep original committed segments. If another format is required, transcode locally with a trusted tool rather than renaming the file.
Limits and safety
Timeslice data chunks are not independent movies. Only a complete recorder stop and successfully closed file becomes a committed segment. The bounded WASM/JS probe recognizes a WebM or MP4 prefix; it does not validate all frames, indexes, duration metadata or playback compatibility.