Convert MKV to MP4
MKV (Matroska) is an open container that takes almost any codec, plus subtitles and several audio tracks. OBS Studio users record to it because a crash doesn't ruin the file. When the video inside is H.264 and the sound AAC, the MP4 is made by rewrapping, not re-encoding.
Your file never leaves this device. Everything runs in your browser.
How it works
- Drop your video.
- Pick the format you need. The tool says which parts it copies and which it re-encodes.
- Press Convert and download the new file.
Questions
Is this the same as OBS's Remux Recordings?
For an MKV of H.264 and AAC, yes: both copy the video and the sound into an MP4 without re-encoding. OBS has it under File › Remux Recordings; this does it in a browser, with nothing to install.
What if my MKV holds something else?
HEVC or AV1 video is re-encoded to H.264, and Opus, FLAC or MP3 sound to AAC. Subtitle tracks and extra audio languages are left out: the MP4 gets the main video and the main sound.
Which formats can I convert to?
MP4 and MOV with H.264 video and AAC sound, and WebM with VP9 video and Opus sound: the formats a browser can write. AVI, FLV and WMV aren't offered, because no browser can make them.
Does converting lose quality?
Not when the video is copied: a MOV or MKV holding H.264 becomes an MP4 without its picture being touched. When the codec has to change, the video is re-encoded at high quality, and like any re-encode it isn't bit-for-bit the original.
Is there a length limit?
Files up to 2 GB. A conversion that copies the video has no length limit; one that re-encodes it takes videos up to 15 minutes.
What happens to subtitles and extra audio tracks?
The new file gets the main video and the main sound. Subtitle tracks and extra languages, which an MKV often carries, are left out.
Does my video get uploaded?
No. It's converted in your browser, on your device.
Which browsers does it work in?
Current Chrome, Edge, Safari and Firefox. Re-encoding to MP4 or MOV needs a browser that can encode H.264, which Chrome, Edge and Safari can. Making a WebM needs VP9 and Opus encoders, which Chrome and Edge have. If yours can't, the tool says so before it starts.