What do I have: 100k+ music files in different formats with various bitrates (mp3 64/128/192/256/320kbps, aac 256kbps, flac, alac). Most of them are mp3 320kbps.
What do I want: mp3 64/128/192kbps
Why: to free some space as I cannot distinguish difference between 192 and 320kbps bitrate on my audio devices
What's the problem?: I know how to convert ALL files to 192kbps bitrate, but how do I leave untouched mp3 64/128/192kbps bitrate to avoid e.g. 128 to 192kbps conversion?
P.S: OS doesn't matter