How to recover an OBS recording after a crash

By the FixMP4 engineering team · Updated October 9, 2026 · Tested on real H.264, HEVC and AAC recordings

If OBS Studio crashed or the PC lost power while recording, what you can do depends on the recording format. MKV, fragmented MP4 and hybrid MP4 recordings are designed to survive crashes and usually play up to the crash point; remux them if you need a standard MP4. A plain MP4 or MOV recording has no index after a crash, but its frames are intact: rebuild the index using a 10-second reference recorded with exactly the same OBS output settings. The FixMP4 repair tool does that rebuild locally in your browser and shows a free preview.

Find out what you recorded

Open Settings, Output, Recording in OBS and look at Recording Format, or simply look at the file extension in your recording folder:

Our blog post OBS recording corrupted after a crash explains the background in more detail.

Why plain MP4 breaks

A plain MP4 stores its index, the moov atom, at the end of the file; OBS can only write it once recording stops cleanly. If OBS crashes, Windows restarts, the game takes the GPU driver down, the disk fills or the power drops, the index is never written and players report "moov atom not found" or show 0:00. More: what the moov atom is.

Make a reference that matches

Without changing any settings, record ten seconds and stop. The reference must match:

• Encoder: x264, NVENC H.264, NVENC HEVC, QuickSync H.264/HEVC, AMF H.264/HEVC.
• Output (scaled) resolution and FPS from Settings, Video.
• Rate control, profile and keyframe interval if you changed them.
• Colour format and colour space (NV12/P010, Rec. 709/Rec. 2100), especially for HDR or 10-bit recordings.
• Audio: AAC encoder, sample rate (44.1 or 48 kHz) and the number of audio tracks.

If you have already changed settings since the broken recording, change them back. Profiles in OBS (Profile menu) make this easier for streamers who switch setups.

Rebuild the index

1. Open the repair tool.
2. Add the broken recording and the reference.
3. Press Repair and watch the free preview.
4. Export the full recording with a subscription.

Large recordings are fine: the file is read directly from your disk by the browser and never uploaded. A two-hour 1080p60 recording at 15 Mbps is about 13 GB; make sure you have that much free space for the export.

Supported OBS setups

Reading the preview

Smooth motion and correct colours mean the full export will match. Blocks everywhere usually mean the reference used a different encoder; this happens when NVENC was unavailable and OBS silently fell back to x264 for one of the recordings. Audio drifting out of sync over a long recording suggests a different audio sample rate between the two files. Fix the setting, make a new reference and preview again; previews are free.

How the rebuild works

FixMP4 scans the media data of the broken MP4 from start to end. It recognises H.264 and HEVC frames by their NAL unit structure and parses each AAC audio frame to measure its length, which separates the interleaved video and audio again. Stream parameters come from the reference; timestamps come from the frame rate and the audio sample rate; B-frame reordering and keyframes are restored; and a new index is written. Frames are not re-encoded, so quality is unchanged.

Streamers: the VOD is a second copy

If you were streaming and recording at the same time, the platform's VOD (Twitch past broadcasts, YouTube live archive) is a complete, independent copy of the stream output. It is encoded at your stream bit rate rather than your recording quality, but it does not depend on the local file. Download it before it expires if the local recording turns out to be beyond repair, or use it to fill the last minutes that the crashed recording did not capture.

Recordings on a second PC or capture card

Dual-PC setups and capture-card software (Elgato 4K Capture Utility and similar) write their own files. If they record plain MP4 with H.264 or HEVC and AAC, the same rebuild applies; use a reference made by the same software with the same preset.

Never again: crash-proof settings

1. Set Recording Format to MKV and enable Automatically remux to MP4 in Settings, Advanced, or use hybrid MP4 if your OBS version offers it.
2. Record to a fast internal SSD with plenty of free space, not to a USB drive or network share.
3. Pause Windows Update during long sessions and set active hours.
4. Keep GPU drivers current; encoder crashes are a common cause of OBS freezes.
5. For important streams, keep the platform VOD as a second copy.

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