Drop MKV videos to convert to MP4Add MKV videos to convert to MP4
OBS recordings and other MKV videos as MP4, remuxed in seconds.
or paste with CtrlCommandV MKV
Your files never leave your deviceAbout this tool
Remux MKV to MP4 without re-encoding
This tool remuxes MKV videos into MP4 right in your browser: the picture and every sound track are copied into the new file exactly as they are, with nothing re-encoded. The MP4 has the original quality and is ready in seconds, even for a long recording. Your videos never leave your device.
OBS recordings, ready to edit
OBS records to MKV by default, because an MKV survives a crash: everything recorded up to that moment stays playable. Editors, phones and many players would rather have an MP4. Remuxing moves the recording’s H.264, HEVC or AV1 picture and its AAC sound into an MP4 unchanged, which is what OBS’s own Remux Recordings does, without OBS.
Recorded your game, microphone and music to separate tracks? Each sound track comes along as its own track in the MP4, so an editor can still mix them.
A remux takes seconds
Nothing is decoded or encoded, so the time is what it takes to read the file once and write it once. A 655 MB, 4-minute 1080p MKV is remuxed in about 2 seconds on a recent laptop.
The MKV is read in pieces and the MP4 streamed to your browser’s private storage, so the file never has to fit in memory. Chromium-based browsers such as Chrome and Edge use about 300 MB more memory while it runs, and a file twice the size needs no more. Firefox uses more, up to about 1.5 GB. We haven’t measured phones.
Films, subtitles and sound formats
An MKV film often carries subtitle tracks. They stay behind, as an MP4 here can’t carry them yet, and the film says so before you press Convert. Every language of its sound that an MP4 can carry comes along.
Sound in DTS, which most MP4 players can’t play, is left out when the film has another sound track, and the film says so; when DTS is its only sound, the film is left alone rather than turned into a silent MP4. Video in VP8, from older files, can’t go into an MP4 as it is, so it says so too. Changing a picture or sound format is a job this tool doesn’t do yet.
How it works
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Step 1:Add your MKV files
Drop OBS recordings or other MKV videos here, or choose them. Each one lists its tracks.
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Step 2:Remux
Press Convert. Picture and sound are copied into an MP4 as they are, in seconds.
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Step 3:Save the MP4
Save it, or save several as a .zip. Nothing was sent anywhere.
Questions, answered
What is the difference between remuxing and converting MKV to MP4?
Remuxing copies the picture and sound into the MP4 as they are; converting usually means re-encoding them, which takes far longer and loses some quality. This tool remuxes, so the MP4 is identical in quality.
Will all my OBS audio tracks be kept?
Yes. Each sound track in the MKV that an MP4 can carry becomes its own track in the MP4, so separate game, microphone and music tracks stay separate.
Why are the subtitles missing from my MP4?
Subtitle tracks can’t be carried into the MP4 yet, so they stay behind. The film says so in its row before you press Convert. The picture and every sound track come along.
My MKV says it can’t be converted. Why?
Its picture is in a format an MP4 can’t carry as it is, such as VP8, or its only sound is DTS, which most MP4 players can’t play. The row names the format. Re-encoding it is something this tool doesn’t do yet.
More video conversions
MP4, with the same picture and sound: nothing is re-encoded.
Picture and sound copied as they are: nothing is re-encoded.MP4 · copied as it is