FLAC to ALAC converter. Requires Mac OS X and `flac` binary installed (ie. via Homebrew: `brew install flac`).

flac2alac

#!/usr/bin/env bash
set -e

convert_to_alac() {
  flac="$1"
  aiff="${flac%.*}.aiff"
  alac="${flac%.*}.m4a"

  flac -s -d --force-aiff-format -o "$aiff" "$flac"
  afconvert -f m4af -d alac "$aiff" "$alac"
  rm "$aiff"
}

if [ $# -ne 1 ]; then
  echo "usage: $0 dir"
  echo "requirements: Mac OS and flac installed"
  exit 1
fi

for file in "$1"/*.flac; do
  echo -n "."
  convert_to_alac "$file"
done

echo " done"

I don't think you need Homebrew or to install anything... here's how I do it on Mojave and Catalina:

export IFS=$'\n'
for x in `ls *.flac`; do afconvert -v -f m4af -d alac $x ${x%flac}m4a; done

@alvarow

absolutely perfect. Had no idea afconvert just existed like that! Thank you.

It's very handy, thanks!

For anyone who may need it: I've also made another version based on ffmpeg which also downsamples the audio to 16bit / 44100kHz, otherwise my iPod was stuttering when playing files with 32bit sample size 😬 It's here: https://gist.github.com/pltb/244899d900a1b0305467f50e32133cc3

(I couldn't make flac or afconvert downsample the audio, and was too lazy to dig deeper, so just used ffmpeg 😅 )