I have used mpv for something like this before. '[' and ']' changes playback speed and 'l' sets the loop-points. Using the --af=rubberband=pitch-scale=<value> c

I have used mpv for something like this before. '[' and ']' changes playback speed and 'l' sets the loop-points. Using the --af=rubberband=pitch-scale=<value> command-line option is also helpful if the melody you want to transcribe is too low or too high for you to decipher easily.