Given that the m4a format is merely a container, and can contain music encoded with a lossy (AAC) or lossless (ALAC) codec, is there a simple way to determine which codec was used for a given file?
How to identify codec (AAC vs ALAC) used in an m4a file
apple-losslessm4a
Related Question
- How to replace mp3 files with m4a versions in itunes
- Convert ALAC to aac 128k with all metadata intact
- How to Find/Filter for 24-bit audio files in Finder or iTunes or another software (if needed)? (audio bit depth / sample size)
- Automate Conversion from m4a to mp3
- Do Apple Lossless tracks remain lossless when sent via Airplay to a 4th gen Apple TV
- IPhone – Is 128kbps too low-quality a file size for the iPhone 5
- Make iTunes recognize MP3 audiobooks with ID3 tag
Best Answer
When I use the
file
command on an .m4a file, I get back a generic response of "ISO Media, Apple iTunes ALAC/AAC-LC (.M4A) Audio" for both AAC and ALAC files. I can think of two other approaches off the top of my head that don't require either the heavy hand of iTunes or installing new software :Open the audio file in question with QuickTime Player. Select "Show Movie Inspector" from the 'Window' menu (or press ⌘-i) to see the file's size, data rate, and the codec used in its creation.
Use the
afinfo
(audio file info) command in Terminal.app to get a more information than QuickTime Player provides. Here's some sample output:For any readers unfamiliar with using the terminal, it's quite simple, and you won't break anything. Open Terminal, and type in--or cut and paste from below--the word afinfo followed by a single space:
Next, drag an audio file over to the Terminal window and drop it in. You will see the file's path get appended to the afinfo command. If dragging the icon caused the Finder to become the active process, you'll need to click on the Terminal's window to wake it up before the final step of pressing enter to run the command. If you like, you can get information on more than one file at a time by dragging and dropping multiple icons instead of just one. When you're finished, just quit Terminal.app as you would any other program.