Your download, explained
The file format should match the file.
Your browser does the encoding. This recorder checks what it can support and gives the saved file its actual extension.
What Auto does
Auto first checks browser support for MP4 recording, including an H.264 and AAC combination. If that is unavailable, it checks WebM options such as VP8 or VP9 with Opus audio. If no listed type is reported as supported, the browser’s default encoder is used.
A support check is a capability hint. Recording can still fail if the browser lacks resources. Once data arrives, the recorder checks the first saved piece for an MP4 or WebM container signature. A browser that returns WebM receives a .webm filename, even if MP4 was your preference.
| Choice | What to expect |
|---|---|
| Auto | MP4 if reported as supported, otherwise a supported WebM option. |
| WebM | Prefer a supported WebM encoder. Useful when your workflow accepts WebM. |
| MP4 if supported | Prefer MP4; show the WebM fallback before recording when MP4 is unavailable. |
Why not rename WebM to MP4?
MP4 and WebM are containers. Their contents and codecs determine what players can read. Renaming a file changes its label, not its container or encoding. A renamed WebM can fail in software expecting MP4.
This website does not upload your video for conversion and does not run a large in-browser transcoder. If a workflow requires MP4 and your browser cannot record it, convert the downloaded WebM using software you trust. Keep the original until you have checked the converted file.
What about resolution and audio?
The quality setting requests a maximum of 1080p or 720p after the source has been selected, where the browser accepts those constraints. It cannot invent detail from a smaller source or guarantee an exact output resolution. The saved preview shows the video track’s reported width and height when available.
Shared audio and microphone inputs are mixed into one output audio track. With both sources off or absent, the video has no audio track. That is why the source check matters more than a format label.
Before you send the file
Play the downloaded file in its destination software. Confirm that the picture, sound and duration are correct. Interrupted recordings can have incomplete container metadata; retaining pieces locally does not guarantee every partial file is playable.
Technical references: MediaRecorder format support and the recorder’s MIME type.
Make a short test recording ↗