Repair MP4 Video Online
Upload a genuine MP4 for a remux-first repair attempt. If remux cannot produce a verified output, the worker may re-encode at the original resolution to H.264/AAC. Corrupt or unreadable media can still fail.
This page is shown in English because its translation has not been reviewed.
A remux-first MP4 repair attempt
MP4 is a container, not one video codec. An MP4 may fail in a player, editor, browser, or upload flow when its container structure or streams are not accepted. This tool first tries a stream-copy remux into a fresh MP4.
If the remux does not produce a verified output, the worker may fall back to full-resolution H.264/AAC encoding. Neither pass can recreate video or audio data that is missing or unreadable, so severely damaged files can still fail.
What this MP4 repair changes
Attempts a stream-copy remux before any re-encode.
If fallback is needed, video uses full-resolution H.264 (CRF 23, medium, yuv420p) and AAC audio at 128 kbps when audio is present.
Requires a genuine MP4 container with a usable video stream.
Offers no codec, quality, bitrate, resolution, trim, or duration controls.
Accepts guest uploads up to 1 GB per file; completed jobs include a signed MP4 download and manual delete action.
- Remux first
- The worker attempts to copy the input streams into a fresh MP4 without re-encoding. It proceeds to fallback only when the remux fails or its output does not pass verification.
- Fixed fallback when needed
- Fallback re-encodes video at the source resolution as H.264 using CRF 23, the medium preset, and yuv420p. Audio, when present, is encoded as AAC at 128 kbps. The page has no controls for codec, quality, bitrate, resolution, trimming, or duration.
- Streams are checked before download
- The worker checks the output container, stream layout, duration, video dimensions, and playback. If a required stream or output check fails, the job fails and no download URL is provided.
- Genuine MP4 only
- The file extension alone is not enough: the worker checks the container and requires a usable video stream. A MOV, WebM, or other file renamed to .mp4 is not accepted as an MP4.
MP4 repair troubleshooting
Use the symptom to decide whether this page is the right tool. The page does not expose codec, quality, bitrate, resolution, trim, or duration settings.
MP4 playback and upload troubleshooting
The repair is best suited to container or compatibility issues; it is not guaranteed to recover damaged media.
- The file was renamed to .mp4 but came from another format
- Choose an actual MP4 container. The worker validates file content and rejects renamed MOV, WebM, and other non-MP4 containers.
- The file is corrupt, unreadable, or missing streams
- A remux or re-encode cannot recover media data that is missing or cannot be decoded. Try a backup or another source copy.
- The repair finishes with an error
- No download is offered unless the MP4 output passes verification. Keep the original and try a different source file if the worker cannot verify the result.
- The upload is larger than 1 GB
- Choose an MP4 file no larger than 1 GB. This page does not provide trim or resolution controls to reduce the source before upload.
How to repair an MP4 video
- Choose one or more genuine .mp4 video files, up to 1 GB each.
- Start the repair. Each file uploads as a separate job with no user-supplied encoding settings.
- Follow upload and repair progress for each file. The worker tries a remux before a fallback encode when needed.
- Download the signed MP4 file only after the worker reports a verified result.
- Use Delete files now when you no longer need the uploaded source or repaired output.
MP4 Repair FAQ
What does this MP4 repair tool do?
It checks that the upload is a genuine MP4 with a usable video stream, then tries to remux the streams into a fresh MP4. If that output fails verification, the worker may try full-resolution H.264/AAC encoding. Corrupt or unreadable input can still fail.
Does the tool re-encode every MP4?
No. It tries a stream-copy remux first and falls back to re-encoding only if the remux fails or its output does not pass verification.
What settings does the fallback use?
When needed, fallback uses full-resolution H.264 video with CRF 23, the medium preset, and yuv420p. Audio, when present, uses AAC at 128 kbps. These settings are fixed; the page has no user controls for codec, quality, bitrate, resolution, trimming, or duration.
Can MP4 repair recover a severely corrupted video?
No repair can recreate media data that is missing or unreadable. The worker validates the source and output and does not provide a download when processing or output verification fails.
Will the repaired MP4 keep the original resolution and other streams?
The remux first attempts to retain all streams. A fallback keeps the original video dimensions and checks the input stream layout; if the required streams or output checks do not pass, the job fails instead of offering a download.
Can I upload a MOV or WebM renamed to .mp4?
No. The worker checks the actual MP4 container and requires a usable video stream; changing a filename extension does not convert a different media format into MP4.
How large can an MP4 upload be?
Each guest upload can be up to 1 GB. Multiple files are handled as separate repair jobs.
Are there quality, resolution, or trimming controls?
No. This page accepts no codec, quality, bitrate, resolution, trim, or duration settings. It remuxes first and uses the fixed H.264/AAC fallback only when needed.