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Fix Corrupted MP4 File Online

Repair broken MP4 videos in 60 seconds. Fix missing moov atom, header corruption, and playback errors. Works with GoPro, DJI drones, iPhones, DSLR cameras, and screen recordings. Free for files under 25MB.

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No signup required • Works in your browser • 100% money-back guarantee

Why Do MP4 Files Get Corrupted?

MP4 is the most widely used video format in the world, powering everything from iPhone recordings to professional cinema cameras. But this popularity comes with a vulnerability: MP4 files can become corrupted when the recording or saving process is interrupted.

Unlike older formats like AVI, MP4 files store critical metadata called the "moov atom" that tells video players how to decode the content. If this metadata is missing or damaged, your entire video becomes unplayable - even if 99% of the actual video data is perfectly intact.

The Most Common Causes of MP4 Corruption

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Battery Death During Recording

Your camera or phone died while recording. The video data was written, but the moov atom at the end was never completed.

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SD Card Removed Too Early

You ejected the memory card before the camera finished writing. Common with GoPros, drones, and DSLRs.

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Software Crash

OBS, screen recorders, or video editors crashed during export. The file exists but can't be opened.

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Transfer Interrupted

File copy failed partway through. The destination file is incomplete and unplayable.

⚠ Important: If your MP4 file shows as 0 bytes or only a few KB, the data is completely lost. We can only repair files that contain actual video data but have corrupted headers or missing metadata.

Signs Your MP4 File Is Corrupted

Not sure if your MP4 is actually corrupted? Here are the telltale signs:

If you're experiencing any of these symptoms, your MP4 file's container structure or metadata is damaged. The good news? In most cases, the actual video and audio data is still there - it just needs the container rebuilt.

How to Fix Your Corrupted MP4 File

Our repair tool automatically detects and fixes the most common types of MP4 corruption. Here's exactly what happens when you upload your file:

1

Upload Your Corrupted MP4

Drag and drop your file or click to browse. We accept MP4, M4V, and M4A files up to 4GB. Your file is encrypted during upload and automatically deleted within 24 hours.

2

Automatic Corruption Detection

Our system scans your file to identify the specific corruption type: missing moov atom, damaged headers, broken timestamps, or container structure issues. Different problems require different repair strategies.

3

Intelligent Repair

We reconstruct the damaged portions using FFmpeg and custom algorithms. For missing moov atoms, we analyze the raw H.264/H.265 video stream and rebuild the metadata from scratch.

4

Download Your Working File

Once repair completes (usually 30-90 seconds), download your fully playable MP4. The original quality is preserved - we don't re-encode your video.

✅ Our Success Rate: We successfully repair approximately 85-90% of corrupted MP4 files. The remaining 10-15% typically have severe data corruption where significant portions of the actual video data are missing or destroyed.

Understanding MP4 File Structure

To understand why MP4 files corrupt and how we fix them, it helps to know how the format actually works.

🛠 Technical Deep Dive: The ISOBMFF Container

MP4 is based on the ISO Base Media File Format (ISOBMFF), which organizes data into nested "boxes" (also called atoms). The most important boxes are:

  • ftyp - File type declaration (identifies this as MP4)
  • mdat - Media data (the actual video and audio bytes)
  • moov - Movie metadata (timing, codec info, sample tables)

The moov box is crucial. It contains sample tables that map timestamps to byte positions in the mdat box. Without it, players have no idea how to decode your video.

Why the moov Atom Matters

Most cameras and recording software write the moov atom at the end of the file, after recording finishes. This is efficient for writing but creates a vulnerability: if recording is interrupted, the moov atom never gets written.

The result? You have a file with all your video data (the mdat box) but no index to read it (the moov box). Players see this and report the file as corrupted or unplayable.

How We Rebuild Missing Metadata

Our repair process analyzes the raw video stream to reconstruct the missing metadata:

  1. We scan the mdat box to find H.264/H.265 NAL units (the building blocks of video frames)
  2. We detect frame boundaries, I-frames, P-frames, and B-frames
  3. We reconstruct timing information based on frame patterns and common encoding settings
  4. We identify audio stream parameters (AAC/PCM, sample rate, channels)
  5. We generate a new moov box with complete sample tables
  6. We output a properly structured MP4 that any player can read

Comparing Free MP4 Repair Options

There are several tools that claim to repair MP4 files. Here's an honest comparison:

Tool Works For Limitations Price
FixMyFile.ai Missing moov, headers, container damage Files must have video data intact Free under 25MB, $4.99-$7.99 larger
VLC "Repair AVI" AVI index only Does NOT work for MP4/MOV at all Free
Untrunc (GitHub) Missing moov atom Requires working reference file from same camera, command line only Free
Stellar Video Repair Various corruption types Desktop software, can be slow $49.99/year
Wondershare Repairit Various corruption types Free version has watermark/limits $69.99/year

Why VLC Can't Fix Your MP4

VLC Media Player has a "Repair AVI" feature that many people try to use for MP4 files. Unfortunately, it simply doesn't work. VLC's repair function is specifically designed for AVI index corruption and has no understanding of the ISOBMFF container format used by MP4.

If VLC gives you a "moov atom not found" error, you need a specialized MP4 repair tool, not VLC's built-in repair.

How to Prevent MP4 Corruption

The best fix is preventing corruption in the first place. Here's how to protect your recordings:

For Camera/Phone Recordings

For Screen Recordings & Streaming

For File Transfers

Frequently Asked Questions

Why does my MP4 file say "moov atom not found"?

The moov atom is metadata that tells video players how to read your MP4 file. It's normally written at the end of recording. If your camera lost power, crashed, or the SD card was removed during recording, the moov atom never got written. Our tool reconstructs this metadata by analyzing the raw video data.

Can I repair a corrupted MP4 file for free?

Yes! FixMyFile.ai repairs MP4 files under 25MB completely free with no signup required. For larger files (which most videos are), we charge $4.99 for files up to 500MB or $7.99 for files up to 2GB. You only pay if the repair actually succeeds.

How long does MP4 repair take?

Most MP4 files are analyzed and repaired in 30-90 seconds. Very large files (1GB+) may take 2-5 minutes. The process happens in your browser and on our secure servers - no software download required.

Will repairing my MP4 reduce video quality?

No. Our repair process uses stream-copy techniques that preserve your original quality. We're rebuilding the container structure and metadata, not re-encoding your actual video and audio data. What goes in comes out at exactly the same quality.

Why can't VLC repair my corrupted MP4?

VLC's "Repair" feature only works for AVI index issues. It has no capability to fix MP4/MOV container corruption, missing moov atoms, or header damage. MP4 files use a completely different container format (ISOBMFF) that requires specialized repair tools to fix.

What if my repair doesn't work?

You don't pay unless the repair succeeds. If we can't fix your file (usually because the underlying video data itself is corrupted or missing), you won't be charged anything. For paid repairs that don't meet your expectations, we offer a 100% money-back guarantee.

Can you repair MP4 files from any camera?

Yes. We successfully repair MP4 files from GoPro (all Hero models), DJI drones (Mavic, Mini, Air, Phantom), iPhones, Android phones, Canon DSLRs and mirrorless, Sony cameras, Nikon, Panasonic, Fujifilm, dashcams, security cameras, screen recorders like OBS, and more. The repair process works with any standard MP4 file regardless of source.

Is my file kept private?

Absolutely. Your files are encrypted during upload (TLS 1.3), processed in an isolated environment, and automatically deleted from our servers within 24 hours. We never view, share, or store your content beyond what's needed for repair. See our Privacy Policy for details.

Ready to Fix Your Corrupted MP4?

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