Repair · MP4 · ISO BMFF
Repair broken MP4 files.
Whether from a GoPro, Sony, drone, iPhone, Android or a screen recording: MP4 is the most common container for damaged video. Haven analyses the ISO-BMFF structure, rebuilds the moov atom and re-syncs the audio stream.
Analysis free · Pay only when it works · No sign-up
Supported
- · H.264
- · HEVC (H.265)
- · AAC
- · AC-3
- · 8-bit · 10-bit
- · Up to 8K
Recognize your problem?
Common damage patterns with MP4
"File corrupt" — VLC, QuickTime, Premiere
Even VLC, the most robust player, refuses to play it. Premiere and Final Cut do not show the file, or show it as a red "Media offline" marker. A classic sign of a missing moov atom.
File has size, plays 0 seconds
In Finder the MP4 looks normal (say 1.2 GB), but every player reports a length of 00:00. The mdat block is there, the container index is not.
Audio plays, picture is missing (or vice versa)
You hear the sound but the picture stays black — or the other way round. One of the two tracks in the moov is damaged, the other works.
File cuts off after a few seconds
The video starts, runs 3–10 seconds, then goes to a black screen or crashes. The first part of the mdat block is intact, the rest is missing or full of junk bytes.
Why does this happen?
The most common causes
01
Recording interrupted — moov never written
The most common damage. MP4 containers write the metadata (moov) only at the end of a recording. When the recording ends abruptly (dead battery, ejected card, app crash), there is no moov.
02
Card or disk error during the write
On storage errors, gaps or junk bytes end up in the mdat. Frame markers (NAL units in H.264/H.265) can no longer be found, and the decoder gets lost.
03
Incomplete download
A cloud download was interrupted, an FTP upload stopped halfway. The file is syntactically incomplete — the container is left open.
04
Codec mismatch after conversion
A tool wrote the wrong codec parameters. The container is intact, but the decoder cannot read the stream. A rarer case, and repairable too.
How to do it
Repair in four steps
- 01
Save the original, work on a copy
Never repair straight from the source (SD card, USB stick, cloud). Copy the file to the Mac or PC — in the worst case, make two copies.
- 02
Find a reference with the same settings
An intact MP4 with identical resolution, frame rate, codec and bitrate class helps Haven rebuild the exact SPS/PPS parameters. Ideally from the same recording device.
- 03
Open Haven, wait for the diagnosis
Drag and drop both files in. Haven lists the atoms it finds (ftyp, moov, mdat) and reports exactly what is missing — e.g. "moov atom missing, mdat 1.4 GB intact".
- 04
Check the preview, export
You see and hear the finished result in preview mode. On clean playback: export as a recovered MP4 — the original stays unchanged.
Engineering detail
What can break inside an MP4 container
An MP4 file (technically ISO BMFF, ISO/IEC 14496-12) is made of nested "boxes" or "atoms". The key top-level atoms are ftyp (the file-type signature), moov (metadata: track info, codec parameters, sample tables, timestamps) and mdat (the actual video and audio bytes). Without moov, the decoder cannot interpret a single frame — even though all the raw data is still in mdat. Haven rebuilds moov from the mdat stream by scanning for NAL-unit start codes, measuring frame sizes and reconstructing the sample tables.
For CLI nerds — fallback without Haven
ffmpeg -err_detect ignore_err -i kaputt.mp4 -c copy -movflags faststart neu.mp4With an intact moov and corrupt frames, ffmpeg with ignore_err can rescue the healthy parts. When the moov is missing, ffmpeg aborts immediately — then you need Haven or untrunc.
FAQ · MP4
Common questions
What is a moov atom and why is it missing so often?
The moov atom holds all of the MP4’s metadata — codec, frame rate, sample index. The encoder only writes it at the end of the recording (except in "faststart" mode, which puts it up front). If the recording ends abruptly, moov is never written — the file then has ftyp + mdat, but no index.
Can Haven repair any MP4?
If the mdat block is intact and a reference with the same settings exists: in almost every case, yes. With a badly fragmented mdat (e.g. after a DiskDrill recovery with a sector mix-up), Haven can often rescue the first 70–90% and cleanly cut off the rest.
Do I need a reference for every MP4?
For simple container damage (only moov missing, generic codec parameters) Haven works without a reference too. For specific codecs (XAVC, 10-bit HEVC, ProRes in MP4) a reference raises the success rate from around 70% to around 94%.
Does this work with M4V or M4A as well?
Yes. M4V (video with possible DRM) and M4A (audio only) are both MP4 containers with a different brand. Haven treats them identically — DRM, however, is not decrypted.
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