Sox: Convert the .wav file with required properties in single command

Thanks to Joseph for his answer. Perhaps it worked at the time of his posting but I had to add -o just after spectrogram for sox to accept the command.

for file in *.flac;do
    outfile="${file%.*}.png"
    sox "$file" -n spectrogram -o "$outfile"
done

I'll be whacking them all in their own folder for archiving.

You could even go a bit further by adding the title of the file above the spectrogram within the image, and making it a little wider to see more details. The default image is a bit small for me.

for file in *.flac;do
    outfile="${file%.*}.png"
    title_in_pic="${file%.*}"
    sox "$file" -n spectrogram -t "$title_in_pic" -o "$outfile" -x 2000
done

Install the flac command from the package of the same name and run

#!/bin/bash
find . -name '*.wav' |
while read file # eg stuff/artist/album/title.wav
do      file="$PWD/${file#./}" # make absolute to get more info
        album=${file%/*}    # stuff/artist/album
        artist=${album%/*}  # stuff/artist
        album=${album##*/}  # album
        artist=${artist##*/} # artist
        title=${file##*/}   # title.wav
        title=${title%.wav} # title
        flac -s --best --delete-input-file \
         --tag="TITLE=$title" \
         --tag="ALBUM=$album" \
         --tag="ARTIST=$artist" \
         "$file" # creates .flac removes .wav
done

The title is the basename of the file, minus the .wav suffix, album is the immediate directory above, and artist the directory above that. The --delete-input-file option removes the .wav. See Parameter Expansion in the bash man page for ${var%pattern} which removes the glob pattern (i.e. formed with * ? and [...]) at the end of the variable, or at the start (${var#pattern}); the %% and ## versions remove the longest matches.