Can pydub set the maximum/minimum volume?

Question

As title, can I set a value for maximum/minimum volume, that is, there won't be too loud or too quiet in output audio file? (Not normalize, I just want tune the specific volume to normal, as the photo below.)

Answer 1

Loudness is a little complicated - a simple solution is to measure using one of the simpler methods like dBFS and set the gain on all your audio to match.

sounds = [audio_segment1, audio_segment2, audio_segment3, audio_segment4]

def set_loudness(sound, target_dBFS):
    loudness_difference = target_dBFS - sound.dBFS
    return sound.apply_gain(loudness_difference)

# -20dBFS is relatively quiet, but very likely to be enough headroom    
same_loudness_sounds = [
    set_loudness(sound, target_dBFS=-20)
    for sound in sounds
]

One complicating factor is that some of your sounds may have extended portions of silence, or even just very quiet parts. That would pull down the average, and you may have to write a more sophisticated loudness measurement. Again, a simple way, you can slice the sound into shorter pieces and simply use the loudest one assuming your whole sound is 15 minutes long, we can take 1 minute slices:

from pydub.utils import make_chunks

def get_loudness(sound, slice_size=60*1000):
    return max(chunk.dBFS for chunk in make_chunks(sound, slice_size))


# ...and replace set_loudness() in above example with…
def set_loudness(sound, target_dBFS):
    loudness_difference = target_dBFS - get_loudness(sound)
    return sound.apply_gain(loudness_difference)