Convert an M4A (AAC) file to MP3
M4A files, often coming from iTunes or an iPhone, are AAC and aren't played by every device. Converting them to MP3 guarantees playback on any player, car stereo or software.
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How to use it
- Install ffmpeg if you haven't already.
- Open a terminal in the folder containing your file.
- Copy the generated command, adjust the file names if needed, then run it.
- Open the resulting file to check the result.
Which setting should you choose?
Variable mode (-q:a) gives a smaller file than a constant bitrate at equal quality. Setting 2 (about 190 kbps) is indistinguishable from the original on most equipment; 128 kbps is enough for voice; 320 kbps makes the file larger for a gain that is rarely audible.
Convert a whole library
To process all the m4a files in a folder at once, the script generator prepares the loop suited to your system.
Convert all the files in a folder
Frequently asked questions
Why does a conversion lose quality?
AAC and MP3 are both lossy formats: converting from one to the other adds a second loss. Choose a high enough bitrate (high or maximum quality) so the degradation stays inaudible, and keep the original M4A.
Is the metadata (title, artist, cover art) preserved?
The title, artist and album are, thanks to "-map_metadata 0". Cover art is dropped by "-vn": to keep it, replace that option with "-map 0:a -map 0:v? -c:v copy" or add it afterward with a tag editor.
A purchased M4A won't convert, why?
DRM-protected files (older iTunes purchases) can't be read by ffmpeg. Files from your own library, voice recordings or extracted videos convert without any problem.
How do I convert a whole folder of files?
Use the folder script generator, choosing m4a as the input extension.