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Corruption in M4A files appears suddenly, sometimes in a form of a voice note that refuses to play and sometimes in a form of a recorded video that plays without sound. Usually this happens when metadata is not written properly during recording, saving, or transferring the video file. Knowing the exact reason why corruption happens helps a lot in choosing the appropriate method to repair M4A file corruption. We’ll cover the best ways to fix corrupted M4A files and help you identify the different symptoms of corruption that damage these files.
What is M4A file format?
M4A is the audio equivalent of the MP4 video file. It is created in Apple smartphones and is compressed with the Apple Lossless Encoder. To get a lossless compression, Apple uses the Apple Lossless Audio Codecs that give you high-quality audio files. The M4A file is playable in all media players including iTunes, Windows Media Player, VLC Player etc. Sometimes, there is a small chance that you will have to face a corrupt M4A file.
How to identify the symptoms of M4A file corruption?
Before moving forward to understand the reasons for corruption in M4A files, you must know how to identify your M4A file is corrupted.
| Symptoms of corruption in M4A files | Why it happens? |
|---|---|
| Video file shows 00:00 duration | M4A header corruption |
| Audio distorts during playback | Corruption in audio stream |
| Recording got interrupted | Essential metadata is missing during recording |
| VLC has issues with playback | Corruption in video container |
Container corruption doesn’t always mean the audio is lost. AAC data can still be recovered from many 00:00 duration M4A files.
Why do M4A files get corrupted?
Here are the circumstances in which you may face the issue of a corrupt M4A file:
- Interrupted recording: If you were taking an audio recording and it stopped in between because of an incoming call, the audio file can get corrupt.
- Interrupted file transfer: You were receiving the M4A file through a sharing application like SHAREit, and the transfer was not complete.
- App crashed mid-recording: If the Voice Memo app of either Android or iOS mobile phones crashes while recording a voice note, the metadata of the container file isn’t saved correctly, and it damages the file.
- Damaged metadata: Since M4A files store audio in the MPEG-4 container format, all the metadata like the moov atom, duration of the recording, and details about how this file is organized are stored in this container only. If the moov atom is missing or the index of the MPEG-4 file is broken, then the audio file will not play.
How to repair M4A file corruption? Best ways explained
There are a few methods available to repair corrupt MFA files. We’ve explained each of these methods in detail.
Fix Corrupted M4A Files Using VLC Player
With the VLC media player, you can easily fix minor corruptions in M4A files. Here are the steps to follow:
- Open VLC Media Player and go to Tools > Preferences.
- Go to the Inputs/Codecs settings.
- Select Always Fix within the Damaged or incomplete AVI file section.
Fix corrupted M4A file using the FFmpeg method
Another free way to repair corrupt M4A videos is with the help of the FFmpeg method. This method is, in some cases, more effective than VLC Media Player as it rebuilds the entire container format instead of recoding the audio file. The repair process is carried out by running a few commands on the command prompt that analyze the damaged file and remux the recording into a new M4A container. This method works best for situations where the audio file is unavailable because of a 0-second duration error or if the moov atom of the audio file is missing.
Fix corrupted M4A file using a healthy reference file
Commonly, an M4A file gets corrupted because the recording was interrupted in between, either because of an incoming phone call, recording app failure, or if the phone’s battery dies in the middle of recording.
In such cases, even though the audio data remains available in the recording file, it still can’t be played because the final metadata information that’s important for playback is missing. Thus, to fix this damage and repair the recorded file, a healthy M4A reference file is needed. The reference file provides the missing metadata that’s essential to build the damaged M4A file again. Some things to note when choosing a healthy reference file:
- Make sure the reference video is recorded from the same phone model so that the format and encoding structures are the same.
- The reference file must have the same bitrate, sample rate, and codecs to improve compatibility.
- Make sure that the reference video is recorded from the same app as the damaged M4A file.
Note: Some M4A files are DRM-protected and use the M4P file extension. If an M4P file gets corrupted, it’s not possible to repair it because its content is encrypted.
What if your M4A file is highly corrupted?
If you’re unable to salvage your M4A file even after using VLC and FFmpeg, then possibly the corruption is in the audio stream structure itself. In such cases, only a dedicated audio and video repair utility can analyze the corrupt MPEG-4 container and repair the M4A file. Kernel Video Repair efficiently repairs the corrupt M4A audio files and recovers them in their original format.
Let’s check the process of repairing an M4A file using Kernel Video Repair:
- Start the software from the Applications menu. After starting the software, click the + button to choose the M4A file.
- Go to the location of the M4A file, choose it, and click Open.
- The tool will check the file and upload it. Then you need to click the Repair Files button.
- Browse the saving location for the recovered file where you want to access the file after repairing it. Click OK.
- The tool has repaired the file and saved it at your desired location. Click Close. Before closing the Software, you can Save report to CSV file.
Ending note
Mostly, M4A files get corrupt if they’re not transferred properly or if the app crashes when these files are being recorded. In case of minor issues like audio or video not playing, then VLC and FFmpeg are perfect for repairing these files and rebuilding the M4A container. But if corruption is in the audio stream structure itself, where users might require advanced help to rebuild their entire M4A audio file, take the help of a reference file and our recommended utility.
People also ask
A. Yes, a 0-second M4A file can be recovered but only if the actual raw audio data is present within the file. Use the VLC Media Player or reliable online repair tools for an efficient recovery.
Q. When is it not possible to repair the M4A file?
A. It is usually not possible to repair an M4A file if the raw audio data is fully overwritten, missing or replaced with zeros (due to failed recovery). Moreover, a repair tool can reconstruct damaged structures, but it cannot recreate audio data that has been permanently overwritten.
A. For preventing M4A corruption in the near future, make sure downloads and transfers are completed fully and there is zero interruption in the file-saving process. Use a reliable power source and always keep secure backups of your original audio files.
