MKV to MP4 converts Matroska videos, for example OBS recordings, into MP4 files that play and edit everywhere. When the video inside is already H.264 it is copied without re-encoding, so the conversion is quick and the quality unchanged. The file stays on your device.
Typical MKV files
| From | After converting |
|---|---|
| OBS recordings | Open in any editor |
| Camera or capture-card files | Share on phones |
| Downloaded videos | Play on TVs and in browsers |
Why OBS and capture cards use MKV
OBS Studio writes MKV by default because MKV can survive a crash: if the recording stops suddenly, the file is still playable. MP4 is less forgiving, which is why OBS avoids it until you are done. After a session, converting to MP4 is the usual next step so you can:
- Drop the file into Premiere, DaVinci Resolve, iMovie or CapCut
- Upload it to YouTube, Vimeo or a course platform
- Play it on a phone, a TV stick or a USB drive
- Send it to someone whose computer has no MKV player
The same is true of many capture cards and TV recorders: they write MKV because it can hold several tracks, then you convert when you need a single, widely accepted file.
Copy or re-encode
H.264 video is copied as-is, so a 20-minute OBS recording usually finishes in a few seconds. HEVC, VP9 or other codecs are re-encoded at the original bitrate, which takes longer and looks the same for normal viewing. Sound that has to be re-encoded is written at 160 kbit/s. Keep the original MKV until you have checked the MP4.
Tips
- Convert first, then compress. Copying H.264 does not shrink the file; Video Compressor does.
- Cut the recording down with Trim Video if you only need a highlight; a smaller source converts faster.
- Tick Remove sound for a silent screen capture, for example a tutorial you will narrate later.
- OBS can also remux to MP4 itself (File → Remux Recordings) if you have it open; this page is for when you don’t, or are on another computer.
The output is MP4 with no watermark. Keep the tab open until it finishes.