Converting FLAC to ALAC losslessly

FLAC stands for Free Lossless Audio Codec, and like the name implies, it is lossless; the original recording of sounds (usually music in practice) is preserved. Thus, it can be used to playback very high quality music.

But on some media library managers, such as iTunes, FLAC is unsupported. We can re-encode FLAC to ALAC, a supported codec, while still preservering the lossless quality. First, install ffmpeg:

sudo apt install ffmpeg

Then, we just need to tell ffmpeg the desired encoding and appropriate filenames. The -acodec option lets us do so:

ffmpeg -i input.flac -acodec alac output.m4a

That’s all.

We can gain some confidence that the conversion was lossless. Use ffprobe to check the sampling rate and bitrate:

ffprobe input.flac

and compare it against

ffprobe output.m4a

If you can see that they both use 44100 Hz sampling rate and output.m4a’s bitrate is greater than or equal to input.flac’s bitrate (e.g. 547 kb/s > 520 kb/s), then we probably didn’t lose any information through the re-encoding.