Video file corrupted, or won’t play to the end?

An unfinished download or interrupted copy is one possible cause of a video that fails to open or stops early. These checks can help narrow down the cause. No player can put back data that is missing from a file, and AIX Player does not repair files, but it does show you what a file contains.

Get AIX free from Microsoft Store

Windows 11 & 10 · Guide reviewed 28 October 2026

Signs the file is incomplete

• It is much smaller than the original, or than the size the download page gave.
• It stops at the same moment in every player.
• Your browser or download app shows it as paused, failed or still in progress, or its name still ends in a temporary extension such as .part or .crdownload.
• It was copied from a phone, a camera card or an external drive, and the copy was cancelled or the drive was unplugged too early.

Why a cut-short file can refuse to open

A video file is written from start to finish, and many MP4 and MOV files keep their index, the table that tells a player where each frame is, at the very end. If the download stops before the end, that table never arrives, and the file can fail to open at all even though most of the video is there. That is why an interrupted download so often looks “corrupted” rather than merely short.

Fix it step by step

1. Let the download or copy finish. A file that is still downloading is not complete yet, so it may not open, or it may stop where the download has reached. Wait until your browser or download app shows it as finished.
2. Download or copy it again. Get the file again from where it came from, and compare its size with the original. When copying from a phone, camera card or external drive, wait for the copy to finish before unplugging.
3. Play it from the PC’s own drive. Copy the file to your internal drive and play it from there. A slow or failing external drive can make a whole file look broken.
4. Open it in AIX Player and check what it contains. Right-click the file, choose Open with, then AIX Player. The library’s File info lists available video codec, resolution, bitrate and audio-track count. If another app reported a codec error, see the “unsupported codec” guide.
5. If the picture is broken, rule out the graphics path. Open Settings → Video → Hardware decode and switch it off, then update your graphics driver. The green or pink picture guide explains why.

When the file really is damaged

If a complete copy fails at the same point in several players and on another PC, try a fresh copy from the source. Go back to the source: download it again, copy it again from the camera or phone, or restore it from a backup. Keep the original as it is. Renaming it, for example from .mkv to .mp4, changes only the label on the box, not what is inside, and converting it cannot bring back what is missing.

Plays, but the picture or sound is wrong?

• Sound but a black screen: check Hardware decode, the graphics driver and the file.
• Picture but no sound: the audio track, the output device or the downmix.
• Plays but keeps freezing: decoding, storage, or power settings.