python - How to change audio playback speed using Pydub?

Question

I am new learner of audio editing libs - Pydub. I want to change some audio files' playback speed using Pydub(say .wav/mp3 format files), but I don't know how to make it. The only module I saw that could possibly deal with this problem is speedup module in effect.py. However, there is no explanation about how I am supposed to call it.

Could anyone kindly explain how to do this task in Pydub? Many thanks!

(A related question: Pydub - How to change frame rate without changing playback speed, but what I want to do is to change the playback speed without changing the audio quality.)

Answer 1

sound.set_frame_rate() does a conversion, it should not cause any "chipmunk effect", but what you can do is change the frame rate (without a conversion) and then convert the audio from there back to a normal frame rate (like 44.1 kHz, "CD quality")

from pydub import AudioSegment
sound = AudioSegment.from_file(…)

def speed_change(sound, speed=1.0):
    # Manually override the frame_rate. This tells the computer how many
    # samples to play per second
    sound_with_altered_frame_rate = sound._spawn(sound.raw_data, overrides={
         "frame_rate": int(sound.frame_rate * speed)
      })
     # convert the sound with altered frame rate to a standard frame rate
     # so that regular playback programs will work right. They often only
     # know how to play audio at standard frame rate (like 44.1k)
    return sound_with_altered_frame_rate.set_frame_rate(sound.frame_rate)


slow_sound = speed_change(sound, 0.75)
fast_sound = speed_change(sound, 2.0)