How to tell whether an audio file is corrupt

Check these first

1. 1

   Play from beginning to end in two independent players.

2. 2

   Compare file size with the expected duration and bitrate.

3. 3

   Inspect duration, codec, and metadata.

4. 4

   Copy the file again from its original source.

Reliable fixes

• Recover from the original source when possible.
• A converter cannot recreate missing bytes.
• Avoid overwriting the only copy during repair attempts.

Change one variable at a time and test with a short known-good file. That separates a damaged source from a browser, codec, or memory limitation.

Signs that an audio file is damaged

• It will not open anywhere, or the size is 0 KB. A 0 KB file, or one still ending in .crdownload, .part or .tmp, is an unfinished download, not a repairable file.
• Playback stops or skips at the same point every time, in every player. That usually means the end of the file is missing or a block in the middle is broken.
• Clicks, bursts of noise or silent gaps appear at fixed positions that are not in the original.
• The duration looks impossible, such as 2 hours for a 3-minute song. This is often a variable-bitrate MP3 without a proper header rather than real damage, and it is easy to fix.
• It plays in VLC but not on your phone or in the car. That points to an unusual codec or a mislabelled extension, not corruption. Check it with the audio metadata viewer.

Three quick checks before you try to repair anything

1. Read the file's details. Open it in the metadata viewer. If the codec, sample rate and duration cannot be read, the header is damaged or the file is not what its extension says.
2. Compare the size with the length. Expected size is bitrate × seconds ÷ 8. A 4-minute MP3 at 320 kbps should be about 9.6 MB; if it is 3 MB, roughly the last two-thirds are missing. The file size calculator does the arithmetic.
3. Look at the waveform. The waveform viewer shows where audio stops, flat sections and sudden spikes, so you can see the damage without listening to the whole file.

What usually causes it

Most broken audio files come from an interrupted transfer: a download that stopped, a phone that went to sleep mid-download, or a USB stick or SD card pulled out while it was still writing. Recording apps are another source. An M4A recording whose app crashed or ran out of storage can be missing the index at the end of the file (the "moov atom"), so nothing can open it even though the audio data is there. Finally, a file renamed to the wrong extension, such as a WebM saved as .mp3, looks broken to strict players while being perfectly fine.

What can be fixed, and what cannot

• Wrong duration or seeking problems: converting the file once, for example with MP3 Compressor or any local converter, writes fresh headers. Keep the original until the new copy checks out.
• Missing end: converting a truncated file keeps everything up to the break. The missing part is gone; only a fresh copy brings it back.
• Glitches in the middle: software cannot rebuild lost audio. Get the file again from its source.
• Crashed M4A recording: specialist recovery tools such as untrunc can sometimes rebuild the index using a healthy recording from the same device and app. Work on a copy.
• Wrong extension: identify the real format in the metadata viewer, then rename it or convert it, for example with WebM to MP3.
• A file from the AudioFetcher converter: converted files expire after a few minutes, so simply convert the video again and let the download finish. If the new file is broken too, email help@audiofetcher.com with the video link.

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