How does one embed artwork during FLAC → ALAC conversion?
ffmpeg -i track.flac -acodec alac track.m4a
transfers metadata but not artwork.
I think FFmpeg can't do that – M4A files store metadata in a strange way compared to FLAC, or MP3, or OGG. You can, however, use AtomicParsley as detailed in this answer to a very similar question. In summary: