Screen recording won't play? Repair the MP4 file

A recording you never stopped has no index

An MP4 file carries an index, the moov atom, that tells a player where each frame and sound packet sits. Screen recorders write that index last, after you press stop. If the recorder crashes or the device shuts down first, the file keeps the footage and the index never arrives. A full disk does the same damage: the recorder runs out of room before it can write the index.

Your gallery and your media player read the index before anything else, so they refuse the file, though the recorded data is still in it.

The tool on this page writes a new index around that data. It re-encodes nothing, so the repaired file holds the recorder's own video and sound, byte for byte. It reads MP4 and MOV files (M4V and 3GP too) with H.264 or H.265 (HEVC) video and AAC sound.

Where screen recorders save their files

Game Bar names each clip after the game or app, plus the date and time, so you can match the broken clip to the session that crashed. Samsung starts its file names with Screen_Recording_ and the date. Third-party Android recorders keep their own folder, and the app's settings show you where. Check the file size before anything else: a size in megabytes means the recorder saved data, and a 0-byte file holds nothing to repair. If the file seems to be missing, turn on hidden files in your file manager.

Two recorders keep unfinished files somewhere else:

• Pixel phones. Android's built-in screen recorder writes to a private temporary file and copies the video to Movies after you stop. If the phone died mid-recording, the unfinished file sits where you can't reach it, and no video appears in Movies.
• Snipping Tool. It keeps recordings in a temporary folder before saving them: %LOCALAPPDATA%\Packages\Microsoft.ScreenSketch_8wekyb3d8bbwe\TempState\Recordings. If a recording never reached Videos\Screen Recordings, look there.

Repair the recording

On Android, the Video Repair app on Google Play repairs the file on the phone. On a computer, use the checker on this page:

1. Copy the broken file somewhere safe and work on the copy. From an Android phone, connect a USB cable, choose file transfer in the phone's USB options and copy the file from its folder.
2. Open the copy in the checker. Your browser reads it from your disk and never uploads it, which matters when your screen showed private chats or account details.
3. Read the result. The checker tells you, for free, whether it can rebuild the index.
4. If it asks for a reference clip, record ten seconds with the same recorder and the same settings, sound included, and give it that file. Some recorders keep the encoder settings only in the index, so the tool borrows them from a healthy clip. The same clip brings the sound back when needed.
5. Watch the free 5-second preview. It plays at reduced quality with a watermark.
6. Download the full video with a paid plan: one video, 3 months or 1 year, cancel anytime. If the repaired video doesn't play, you get a refund.

MKV, WebM and other formats

The checker opens MP4 and MOV files, plus M4V and 3GP. It can't open AVI, MKV, TS or WebM yet. You meet those formats when a recorder lets you pick them: OBS Studio can record MKV, and recorders that run inside a browser tab save WebM in many cases. A broken file with one of those extensions is outside what this tool handles today. If OBS saved an MKV, OBS's own File > Remux Recordings turns it into an MP4 without re-encoding.

Avoid a repeat

• Before a long recording, free up more space than the recording will need. A full disk leaves the recorder no room for the index.
• Stop the recording yourself before you shut the device down or let the battery run out.
• On a PC, pick a recorder with a crash-safe format for long sessions. OBS Studio's Hybrid MP4 survives a crash and still gives you a normal MP4 when you stop.