OBS writes the index last
An MP4 needs its index, the moov atom, before a player can open it. The index lists where each frame and audio packet sits, so OBS writes it at the end, after you press Stop Recording. A crash or a power cut stops OBS before that step, and so does a disk that fills up mid-recording. Ending a frozen OBS in Task Manager has the same effect.
OBS warns about this in its own output settings. Pick MP4 or MOV there and OBS tells you the recording will be unrecoverable if OBS can't finalize the file. File > Remux Recordings can't open such a file either, because remuxing reads the same index.
The tool on this page writes a new index around the footage OBS saved. It re-encodes nothing, so the repaired file holds the encoder's own video and sound, byte for byte, at the bitrate and resolution you recorded.
Check your recording format and codec
Before you try to recover an OBS recording after a crash, check which format OBS wrote. Open Settings > Output and look at Recording Format. File > Show Recordings opens the folder that holds your files, which is your Videos folder on Windows unless you changed it. OBS names each file by the date and time the recording started, such as 2026-10-07 18-30-05.mp4, so you can match the broken file to the session that crashed.
| Recording Format | After a crash | Next step |
|---|---|---|
| MP4 or MOV | No index, won't play | Repair it with the checker on this page |
| Hybrid MP4 or Hybrid MOV | Stays a valid fragmented file | Remux it in OBS with File > Remux Recordings |
| MKV | Keeps the footage up to the crash | Remux it in OBS; this tool can't open MKV yet |
The tool reads H.264 and HEVC (H.265) video with AAC sound. That covers OBS's default encoders, and NVENC, AMD and QuickSync when you set them to H.264 or HEVC. AV1 recordings are outside what it handles.
Repair the broken MP4
- In OBS, choose File > Show Recordings and copy the broken file somewhere safe. Work on the copy.
- Open the copy in the checker on this page. Your browser reads it from your disk and never uploads it, which matters when your desktop or private chats were on screen.
- Read the result. The checker tells you, for free, whether it can rebuild the index.
- If it asks for a reference clip, record ten seconds in OBS with the same profile and settings, and give it that file. If you've since switched OBS to MKV or Hybrid MP4, set it back to MP4 for this one clip. The tool takes the encoder settings from the healthy clip, and the clip brings the sound back when needed.
- Watch the free 5-second preview. It plays at reduced quality with a watermark.
- Download the full recording with a paid plan: one video, 3 months or 1 year, cancel anytime. If the repaired video doesn't play, you get a refund.
Set up OBS so the next crash leaves a playable file
OBS 30.2 added Hybrid MP4 as a beta recording format. While OBS records, a Hybrid MP4 is a fragmented MP4 that survives a crash. After you press stop, OBS turns it into a regular MP4 that editors and players open. OBS 32.0 took the format out of beta and made it the default for new profiles on Windows and Linux, with the new Hybrid MOV as the default on macOS. If you picked plain MP4 in an older version, OBS keeps that choice after the update, so check Recording Format before your next long session.
The older route works too: record to MKV, then use File > Remux Recordings to repackage the file as MP4 without re-encoding. If you'd rather keep plain MP4 selected, tick "Automatically remux to mp4" under Settings > Advanced. OBS then records MKV behind the scenes and remuxes it to MP4 as soon as you stop.
Any of these setups leaves you a file you can open after a crash.
What this tool can't fix
- A file of 0 bytes, or one filled with zeros. OBS never wrote footage into it.
- A deleted recording. The tool repairs files you still have; it doesn't undelete.
- MKV, AVI, TS and WebM files, which it can't open yet.
- AV1 video, from any encoder.
If the checker says it can't rebuild your file, you haven't paid anything.