OBS Recording Saves as MKV - How to Change to MP4

OBS Recording Saves as MKV: How to Change to MP4

OBS saved your recording as .mkv and your editor will not open it. The setting that controls this exists, it is one dropdown, and it is not where most people look for it.

It is also worth two minutes of your time to understand why OBS chose MKV, because on current OBS versions there is a third option that gives you an MP4 file and keeps the protection MKV was there to provide. Most guides written before 2024 do not mention it.

This page is the configuration reference: where the setting lives, which value to choose, what each one costs you, and why the change sometimes appears not to work. If you have MKV files already sitting on disk that you need converted right now, that is a separate job covered in How to Convert OBS MKV to MP4.

Why OBS Picked MKV Without Asking

An MP4 file keeps its index, the table that tells a player where every frame lives, in a block written at the very end of the file. OBS builds that block when you click Stop Recording.

If OBS crashes, the machine loses power, or a driver fault kills the process before you press stop, that block is never written. The file on disk contains all of your video, but no player can navigate it, so it reports as corrupt and plays as nothing.

MKV writes self-contained clusters continuously throughout the recording. Interrupt it at any moment and the file remains playable right up to that moment.

That is the entire reason for the default. OBS assumes losing a recording is worse than an inconvenient file extension, which is the correct assumption if you are streaming a live event and the wrong one if you are making a two-minute product demo on a stable desktop.

Where the Format Setting Actually Lives

The path differs depending on which output mode you are in, which is the single most common reason people cannot find it.

In Simple mode:

1. Open Settings > Output.
2. Leave Output Mode on Simple.
3. In the Recording section, find Recording Format.
4. Choose your format, then click Apply and OK.

In Advanced mode:

1. Open Settings > Output.
2. Set Output Mode to Advanced.
3. Click the Recording sub-tab. Simple mode has no sub-tabs, Advanced does, and this is where people get lost.
4. Find Recording Format near the top of that tab.
5. Click Apply and OK.

Changing the setting in one mode does not change it in the other. The two modes keep independent recording configurations, so if you set MP4 in Simple mode and then switch to Advanced, you are looking at a completely different set of values.

The Option You Probably Want: Hybrid MP4

OBS Studio 30.2 added Hybrid MP4 to that dropdown, and for most people it is now the correct answer.

Hybrid MP4 writes recovery information as the recording progresses rather than only at the end. If OBS dies mid-take, the file stays playable. It also carries the .mp4 extension, so editors and browsers accept it without any conversion step.

That is the trade-off that used to force the MKV decision, removed. If your OBS version offers Hybrid MP4, select it and you are finished.

If your dropdown does not list it, you are on an older build. Update OBS, or use the record-and-remux setup below.

What Plain MP4 Costs You

If you select the standard MP4 entry rather than Hybrid MP4, you are accepting two real limitations.

No crash protection. Any interruption before you press stop leaves an unplayable file. Recovering one is possible but tedious, and the process is documented in OBS File Corrupted After Crash: Recovery Guide.

Multi-track audio becomes unreliable. OBS can record up to six separate audio tracks so you can keep your microphone and your desktop audio independently editable. MKV handles all six without complaint. Plain MP4 will usually carry them, but most editors and nearly every player expose only the first track, so in practice you lose the separation you set them up for.

If you never separate your audio and your machine is stable, plain MP4 is a perfectly reasonable choice. If either of those is untrue, pick Hybrid MP4 or the remux workflow instead.

The Alternative: Record MKV, Get MP4 Automatically

If Hybrid MP4 is unavailable on your version, this gives you the same practical result.

1. Set Recording Format to MKV.
2. Go to Settings > Advanced.
3. Scroll to the Recording section.
4. Tick Automatically remux to mp4.
5. Click Apply and OK.

You record into MKV, so a crash cannot cost you the take. The instant you press stop, OBS rewraps the file into MP4 in the same folder, typically in under three seconds, with zero change to the video because nothing is re-encoded.

The one thing to know is that this leaves both files. The MKV stays as your safety copy and the MP4 appears next to it, so your recordings folder grows at double the rate until you clear the originals out.

"I Changed It and It Still Saves MKV"

Four causes, in the order they are worth checking.

You edited the wrong output mode. As above, Simple and Advanced keep separate recording settings. Confirm which mode the Output Mode dropdown is showing, then check the format value in that mode.

You are looking at the auto-remux leftovers. If Automatically remux to mp4 is enabled, the MKV is supposed to remain. Sort the folder by date and check whether an MP4 with the same timestamp is sitting right beside it.

You are using the Replay Buffer. The replay buffer has its own output settings and does not necessarily follow your recording format. Check its configuration separately in Settings > Output.

You switched profiles. OBS profiles each carry their own complete output configuration. If you changed format under one profile and later loaded another, the old value came back with it. The active profile name is shown under Profile in the top menu bar.

Choosing

The Version With No Container Decision

Every option above is you making an engineering trade-off between losing your work and being able to open your work. That trade-off exists because OBS is a broadcast tool that hands you the raw pipeline.

Cubix Capture has no format dropdown. It writes a finished, editor-ready file when you press stop, on Windows and Mac, and there is a free Starter plan with no account required.

If you are staying on OBS, set Hybrid MP4 and you will not have to revisit this page.

Keep Reading

• How to Convert OBS MKV to MP4 for the files already sitting in your folder, including batch conversion.
• OBS MKV vs MP4: Which Should You Use? goes deeper on the container decision and fragmented MP4.
• Where Do OBS Recordings Go on Windows and Mac? is the reference for output paths and filename tokens.
• OBS File Corrupted After Crash: Recovery Guide if plain MP4 already cost you a take.