I want to change the frequency of an audio file. Meaning: the whole file should sound (say) one octave higher or lower. How to do it? Using
ffmpeg or other command line open source tool would be preferable.
If you need a GUI, use Audacity, it's a free, open source, cross platform audio editing tool.
If you want to use the command line, try sox:
Something like that:
where gives the pitch shift as positive or negative ‘cents’ (i.e. 100ths of a semitone). There are 12 semitones to an octave, so that would mean ±