How to repair corrupted video files, step by step

1. Stop and protect what you have

If the file is still on the camera’s SD card, stop using the card. Don’t format it and don’t record anything new. Copy the file (and ideally the whole card) to your computer. If the file is missing entirely, read how to recover corrupted video files first, because you need recovery before repair.

2. Rule out the simple stuff

Try the file in VLC. A surprising number of “corrupted” videos are actually fine and just use a codec (often HEVC/H.265) that Windows Media Player or an older editor can’t decode. Windows error 0xc00d36c4 is often this. See the 0xc00d36c4 page. If VLC plays it perfectly, you need a codec or a conversion, not a repair.

3. Decide what kind of damage it is

Recording was interrupted (battery, crash, card removed): index missing. Copy or download was interrupted: end of file missing. Card errors: bits damaged mid-file. Each has a different fix, covered in broken video files: audio only, freezes, won’t open.

4. Try the lossless fix first

Always start with fixes that copy the video rather than re-compress it. For MP4/MOV that means remuxing with FFmpeg, then rebuilding the index with untrunc if needed. Lossless fixes keep full quality and you can still edit the result normally. The commands are in how to fix corrupted MP4 files with free tools.

5. Check the result properly

Don’t just watch the first few seconds. Skip to the middle, skip to the end, and check that the audio lines up. A repair that plays the first minute and dies is a partial repair. Also open it in whatever you’ll actually use, whether that’s Premiere, DaVinci, CapCut or your phone.

6. Or let us do it

FixCorruptVideo does steps 3 to 5 automatically, including the mid-file seek check, and shows you a 15-second preview before you pay. If the preview doesn’t look right, you walk away and pay nothing.

A professional repair workflow, start to finish

Video editors, wedding shooters, and documentary teams deal with corrupted files often enough to have a routine. It is worth borrowing even if you only need to fix one clip, because each step protects the next. The routine has five stages: preserve, recover, repair, verify, and archive.

The order matters. Repairing before preserving risks destroying the only copy. Repairing before recovering means you might fix a truncated file when a complete one was still on the card. Archiving before verifying means you might back up a file that only looks fixed.

Stage 1: Preserve the media

Stop using the card, drive, or phone the moment you notice a problem. Every new recording, thumbnail cache, or automatic file-system check can overwrite the space the lost data occupies.

If the media is a memory card, make a full image of it rather than just copying the files. An image captures deleted and partially written data that a normal copy ignores. On macOS and Linux, dd if=/dev/diskN of=card.img bs=4m (with the right disk number, checked carefully) creates one. On Windows, free tools such as Win32 Disk Imager or HDD Raw Copy do the same.

Work from the image from then on. If something goes wrong during recovery, you can start again from the image without touching the card. Keep the card itself in a labelled envelope until the job is complete.

Stage 2: Recover anything that isn’t visible

Before repairing, make sure you have the best possible raw material. If the camera crashed, it may have left the file with a wrong size in the directory, or not listed at all. File-carving tools scan the raw image for video signatures and pull out files the file system has lost track of.

PhotoRec (free, from the makers of TestDisk) is the standard choice. Point it at the card image, select only video file types to speed things up, and let it run. It names recovered files by position (f12345678.mp4), so you will need to identify them by size and preview.

Carved files are often bigger than the original clip, because the carver doesn’t know where the clip ended and includes trailing data. That is fine: a good repair ignores anything after the last valid frame. Carved files are also often missing their index, for the same reason the original was. Which brings us to repair.

Stage 3: Repair in increasing order of effort

Try the least invasive fix first and stop as soon as one works. A lossless remux (ffmpeg -i in.mp4 -c copy out.mp4) rewrites the container and fixes index errors and misplaced metadata. If FFmpeg reports that the index is missing, move on to a rebuild.

An index rebuild scans the raw frames and writes a new index. It works without help for many common formats, and with a reference clip from the same camera for nearly all of them. Choose a reference recorded with identical settings: resolution, frame rate, codec, bit depth, audio format, and picture profile.

If the rebuilt file shows damaged frames, decide whether to cut around them or re-encode with error concealment. Cutting keeps full quality but leaves a jump. Re-encoding hides the damage with repeated or blended frames but costs quality and render time.

Our repair page runs these stages automatically and reports which one worked, with a free 15-second preview before you unlock the full file for $9/month or $29/year.

Stage 4: Verify like an editor

Open the repaired file in at least two different players, for example VLC and QuickTime or Windows Media Player. Scrub through the whole timeline, not just the start, because damage often sits near the end where the recording was interrupted.

Run a full decode check: ffmpeg -v error -i repaired.mp4 -f null -. A clean run produces no output. Errors with timestamps tell you exactly where problems remain.

Import the file into your editor and drop it on a timeline. Editors are fussier than players about timestamps, variable frame rate, and audio sample alignment. If the editor drifts audio or refuses to conform the clip, a remux with -fflags +genpts or a constant-frame-rate re-encode usually settles it.

Check the audio separately by listening with headphones. Rebuilt audio sometimes has small clicks at chunk boundaries that are hard to hear on laptop speakers but obvious in a finished edit.

Repairing inside Premiere Pro, DaVinci Resolve, and Final Cut

Editors aren’t repair tools, but they can work around some problems. Premiere Pro will import a file with a damaged index if it can read the header, then show the clip as shorter than it should be or with media offline partway. Re-linking to a repaired version fixes the project without rebuilding edits.

DaVinci Resolve is stricter and often refuses files with any container error. That makes it a good test of a repair: if Resolve accepts the file and plays it cleanly, it will work almost anywhere. Resolve also offers clip attributes to force a frame rate, which can correct timing on files whose rebuilt index has a slightly wrong rate.

Final Cut Pro relies on AVFoundation, the same engine as QuickTime. If QuickTime can’t open a file, Final Cut won’t either. Repair the file first, then import. Final Cut’s transcode-to-ProRes option on import is a convenient way to normalise a repaired file with odd timing.

Stage 5: Archive and learn

Store the repaired file alongside the original broken file and the reference clip you used. If a better repair method appears later, or you need to redo the work with different settings, you will have everything you need.

Follow the 3-2-1 approach: three copies, on two kinds of storage, one off site. For video, that might be a working drive, a backup drive, and a cloud copy.

Note what caused the corruption, if you know. A pattern of the same camera, card, or reader causing problems points to failing hardware. Replace the card or reader before the next shoot rather than after.

Handling many corrupted files from one shoot

When a whole card is affected, prioritise. Sort clips by importance, repair the critical ones first, and batch the rest. Files from the same camera and settings can share one reference clip, so rebuilds can run unattended in a loop.

Keep a simple spreadsheet: filename, size, symptom, method tried, result. On a big job it prevents repeated work and gives clients a clear account of what was recovered.

For deeper background on the most common cause, see what the moov atom is. For a quick single-file version of this process, see how to fix corrupted MP4 files.

Choosing a reference clip that actually helps

Reference-based rebuilding is the most powerful repair technique for files with a missing index, and also the one most often done badly. The reference teaches the repair tool how your camera writes files, so it must match the broken file as closely as possible.

Same device, ideally the same physical camera or phone. Different models from the same brand often use different encoder settings and audio layouts.

Same resolution and frame rate. A 4K 24 fps reference won’t describe a 1080p 60 fps recording correctly.

Same codec and bit depth. Many cameras offer H.264 and HEVC, 8-bit and 10-bit. Check the broken file’s settings in the camera menu history or by elimination.

Same picture profile and HDR mode. Log and HLG profiles change the codec setup data, and a mismatch produces wrong colours or a green picture.

Same audio settings. External microphones, wind filters, and stereo versus mono change the audio layout.

Long enough to include several keyframes and audio chunks: ten seconds is plenty. Record a fresh reference if you can; if you can’t, choose any clip from the same day.

Variable frame rate and why it trips up repairs

Phones record at variable frame rate (VFR) to save power and cope with low light. A clip labelled 30 fps may actually contain frames at irregular intervals, from 24 to 30 per second. The original index records each frame’s exact time.

When the index is lost, those exact times go with it. A rebuild has to estimate them, usually by assuming a constant rate, which makes video and audio drift apart slowly over long clips. Good repair tools correct this by using the audio, which is always constant rate, as a clock and spacing the video frames to match.

If a repaired phone clip drifts out of sync, that is the cause. Re-run the repair with a tool that does audio-anchored timing, or convert the result to constant frame rate in an editor and nudge the audio once at the start.

Common repair errors and what they mean

“No moov found in reference”: the reference file is itself damaged or not an MP4. Pick another.

“Unknown codec” or “unsupported track”: the camera uses a format the tool doesn’t understand, such as PCM audio, a timecode track, or proprietary metadata. Try removing extra tracks from the reference with ffmpeg -i ref.mp4 -map 0:v -map 0:a -c copy ref-clean.mp4.

Output is a few seconds long: the tool stopped at the first damaged region. Look for options to skip errors and continue scanning.

Output has video but garbled audio: audio packet boundaries were guessed wrongly. A better-matched reference usually fixes it.

When the free tools give up, our repair page applies several strategies in turn and shows a free 15-second preview, with full unlocks at $9/month or $29/year.

Repair checklist to keep handy

Preserve: stop using the device; image the card or drive; work on copies only.

Recover: check backups and cloud versions; carve the image with PhotoRec if files are missing.

Repair: remux first; rebuild the index if missing; use a matched reference clip; cut or re-encode around damaged frames.

Verify: play in two players; run an FFmpeg decode check; test in your editor; listen to the audio on headphones.

Archive: keep originals, references, and repairs together; back up three copies; replace suspect media.

When you want the repair stage handled for you, open the repair page for a free 15-second preview, with full files at $9/month or $29/year.

Matching the repair method to the cause

Most corrupted video files fall into one of four groups. Interrupted recordings are missing their index and respond well to a rebuild. Badly transferred files have gaps or truncated endings and are best re-copied from the source if it still exists. Files damaged by failing storage often have scattered unreadable blocks, so they need to be imaged first and repaired from the image. Finally, files that were partly overwritten can only be salvaged in part.

Identifying which group your file belongs to saves time. Look at where the file came from, whether the device reported any error, and whether other files from the same card or drive also misbehave. Patterns across several files usually point to the storage, while a single bad clip usually points to an interrupted recording.