MP4 has to be finalised at the end of the write before it is playable at all. OBS's documentation is explicit about it: if the write is interrupted for any reason, the file may not be recoverable — which is why OBS tells you not to record to MP4/MOV directly in the first place.
This is not a community theory. OBS documents it in its own words — and the search results for this problem are almost entirely forum threads where nobody quotes it.
What "corrupted" actually means here
From OBS's own knowledge base, in the Audio/Video Formats Guide, describing the MP4 and MOV containers:
"MP4 is the de-facto standard for internet video. MOV is its sister format with slight differences in codec compatibility, mostly favoured on Mac platforms. MP4/MOV require "finalisation" of a file to be playable, if the writing is interrupted for any reason the file may not be recoverable. It is therefore not recommended to record to MP4/MOV directly."
Three things in that quote deserve to be read slowly:
- Finalisation is required for playability, not for tidiness. Until it happens, the file is not a video file yet in the sense a player cares about.
- "If the writing is interrupted for any reason." Not just crashes. A power cut, a forced quit, killing the process — anything that stops OBS from finishing the write lands you in the same place.
- "May not be recoverable." OBS is not promising recovery, and it is not ruling it out either. That hedge is doing real work.
The last sentence is a flat recommendation from the people who wrote the recorder: do not record to MP4/MOV directly.
The contrast with MKV is documented on the same page:
"MKV is a very flexible container that is compatible with every audio and video encoder supported in OBS Studio. It is failsafe, i.e. an unfinished recording due to power loss or other causes will remain playbale and recoverable. However, it is not well supported in editing software and may require remuxing for use in editing software."
(The spelling of "playbale" is OBS's, not ours.) The Standard Recording Output Guide repeats it from the settings side: "MKV is recommended in case of unforeseen issues arising, since MKV will not corrupt the whole file if there is no graceful stoppage of recording."
The two containers fail in opposite directions. MKV survives an ungraceful stop and annoys your editor. MP4 pleases your editor and does not survive an ungraceful stop.
About repairing the file you already lost
The honest answer is worth more here than an optimistic one: OBS's knowledge base contains no repair procedure for an interrupted MP4 or MOV. No "recover recording" step, no supported tool, no documented parameter. The only thing the official documentation says about the situation is the sentence quoted above.
The same gap applies to Hybrid MP4, which OBS describes as remaining recoverable after an aborted write: the documentation states the property but does not describe what the user is supposed to click. If you need a recovery path for a specific file, check the official documentation and OBS's own support channels rather than trusting the first repair utility a forum thread recommends.
The fix: stop asking OBS to finalise an MP4
OBS ships three containers that are designed not to have this failure mode. All three are in Settings → Output → Recording Format.
MKV. The Formats Guide calls it failsafe and says it is "compatible with every audio and video encoder supported in OBS Studio". The cost is stated just as plainly: "Poor support in editing software." You record safely and convert afterwards.
Fragmented MP4 / MOV. In OBS's words: "Fragmentation is a method of writing MP4/MOV files in self-contained chunks so that a file does not require finalisation to be usable, allowing it to offer higher compatibility than MKV while being similarly fault-resistant. May require remuxing to work properly in some editing suites when using lossless or uncompressed audio." Editing support is rated "Good".
Hybrid MP4 / Hybrid MOV. The newest option, and the closest thing to having it both ways:
"Hybrid MP4 and Hybrid MOV are the names of new output formats introduced in OBS 30.2 (Hybrid MP4) and OBS 32.0 (Hybrid MOV), that aim to provide reliable and compatible output without the drawbacks of traditional or fragmented MP4/MOV. It remains recoverable even if writing the file is aborted, e.g. due to system crashes or power outages, while still maintaining wide compatibility."
The mechanism is documented too: the file is written fragmented, then "finalised like a regular MP4/MOV in a process we call "soft-remux", which hides the fragmentation within, so that MP4/MOV-compatible software will treat is like a regular file." Editing support is rated "Excellent".
One limit before you treat Hybrid MP4 as crash-proof: OBS notes that chapter markers "are written during the finalisation process, i.e. they are not recoverable in the event of a crash." The video survives; the chapters you dropped with a hotkey do not.
Straight recommendation
- On OBS 30.2 or newer, recording for an editor: Hybrid MP4 (Hybrid MOV on macOS from OBS 32.0). Resilient write, excellent editing support, no conversion step.
- On an older build, or for the widest codec coverage: MKV, then convert. OBS's tables show MKV accepting H.264, HEVC, AV1 and ProRes, where MP4 has no ProRes column and MOV has no AV1 column.
- Never: plain MP4/MOV for a long session you cannot repeat.
If you already have finished, playable MP4 files and want them in the container OBS treats as failsafe, you can change the wrapper in your browser:
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
It rewraps a working file — it is not a repair tool and cannot rescue an MP4 that was never finalised. Changing the container is the job FFmpeg's documentation describes for stream copy: "Streamcopy is useful for changing the elementary stream count, container format, or modifying container-level metadata. Since there is no decoding or encoding, it is very fast and there is no quality loss." The converter has its own page at MP4 to MKV; the full set is on the tools page.
OBS has conversion built in too, per the Standard Recording Output Guide: "If you click on File then select Remux Recordings and press the … button to select which video(es) you'd like to remux. After that hit the Remux button and OBS will convert your videos for you". There is an unattended version — "Automatically remux to mp4" — which OBS says "will remux your video as soon as you stop recording". The guide only calls this a convert operation and never states whether it re-encodes, so do not assume either way from that page.
What the default actually is
The confusion here is in the source material, not in your head. OBS's formats guide calls MKV the default container, while the same page labels Hybrid MP4/MOV as the platform defaults — "Hybrid MP4 (Windows/Linux default) / Hybrid MOV (macOS default)". Both statements sit on the same page, and the documentation does not say which one governs.
So: do not assume your install records to a safe container because someone told you what the default is. Open Settings → Output and read what it actually says.
How to tell it worked
- Check Settings → Output → Recording Format and confirm it shows MKV, Fragmented MP4/MOV, or Hybrid MP4/MOV — not plain MP4 or MOV.
- Make a short test recording and stop it the normal way. OBS gives the same advice for sound problems, and it generalises: "Finally, be sure to record a session as you normally would and then listen back to the file before going live."
- Open the test file in the software that will actually consume it — your editor, or the player your viewers use. A container that is safe to write is worthless if the next tool refuses it, which is exactly the tradeoff MKV carries.
Do this after any OBS update, and before any session you cannot repeat.
FAQ
Why won't my OBS MP4 recording play? One documented cause is that the file was never finalised. OBS states that MP4/MOV "require "finalisation" of a file to be playable, if the writing is interrupted for any reason the file may not be recoverable." A crash, power loss, or force quit during recording leaves the file in that state.
Can I repair a corrupted OBS MP4 file? OBS's knowledge base documents no repair procedure — no official steps, tools, or settings for recovering an interrupted MP4/MOV. Check the official documentation and OBS support channels. Treat forum-recommended repair utilities with the caution you would give any unofficial tool handling your only copy.
Should I record in MKV or MP4 in OBS? MKV if you want the recording to survive an ungraceful stop; OBS calls it failsafe but rates its editing support as poor. Hybrid MP4 (OBS 30.2+) if you want both, since OBS says it "remains recoverable even if writing the file is aborted" while keeping excellent editing support. Plain MP4 is the one option OBS explicitly recommends against recording to directly.
What is Hybrid MP4 in OBS? A format introduced in OBS 30.2 (Hybrid MOV came in OBS 32.0) that writes the file fragmented and then finalises it through what OBS calls a "soft-remux", so MP4-compatible software sees a normal file while the write stays recoverable. Note that chapter markers are written during finalisation and are not recoverable after a crash.
Does converting MKV to MP4 lose quality? OBS's guide only says it will "convert your videos for you" and never describes what happens internally, so nothing can be concluded from that page. FFmpeg's documentation is explicit about stream copy specifically: changing container format with no decoding or encoding means "it is very fast and there is no quality loss." That guarantee covers stream copy, not conversion in general.
Is there a maximum recording length that causes corruption? OBS's knowledge base does not mention any file size or duration limit for recordings, so there is no official number to quote. If long recordings fail specifically, the finalisation issue above is still the first thing to rule out.
Quotes from OBS Studio's own knowledge base — the Audio/Video Formats Guide, Hybrid MP4 & Hybrid MOV Formats, and the Standard Recording Output Guide — checked 16 September 2026; start at OBS Help. Related: OBS recording has no audio, more fix guides, or all Clapr tools.
