I have some some audio samples (from SampleSwap) which I am working with in pydub. Most of them have a sample-depth / bits per sample of 16, while others are 24 or 32. Looks something like this:
import pydub
a = pydub.AudioSegment.from_file('16bit_file.wav')
b = pydub.AudioSegment.from_file('24bit_file.wav')
The problem I am running into is when I try to get them to play back:
from pydub.playback import play
play(a)
play(b)
While the 16-bit files play normally, the 24-bit files are all Earth-shatteringly loud, like seriously to the point of potential speaker damage. With my computer set to minimum volume, the 24-bit play back is about as loud as regular music would play back on maximum volume. It's super distorted, sharp, and clipped.
I'm pretty sure I've isolated it to be a problem of bit-depth. The sounds all play normally when played in other software. I can convert the problem sounds to be 16-bit either using sox or using pydub.AudioSegment.set_sample_width(2) and the issue goes away. I have also gone directly through simpleaudio to do the playback (copying the code from pydub, here) and get the same issue.
The main problem is I am writing some code for working with audio which I would like to share, but I do not want users to experience the physical or mental damage from hearing one of these busted sounds. My only idea of a workaround is to immediately convert the bit-depth of any use loaded sounds/lock audio playback to 16-bit files only; this works for the files I am testing, but a) I don't know if it holds true for all sounds/computers, and b) I thought this shouldn't be an issue in pydub anyway. I also thought to somehow check the volume of the sound before playing (using e.g. a.dBFS or a.max), but I haven't found anything that seems to be reliable (either the metric isn't really correlated with the volume, or the value seems to be more of an indication of the dynamic range provided by the extra bits).
So my questions are:
- Why do I get this alarmingly loud, distorted playback in pydub when playing non-16-bit files?
- What can I do to prevent it?
- Am I missing something obvious here about audio playback?
I understand this is (hopefully) not so reproducible; I could try to record it and post if that would be helpful. I can also point out the sounds I am using on SampleSwap, but the problem really seems to be caused by any file that is not 16-bit (i.e. I can convert a sound to be 32-bit and generate the issue).
Here's some version info:
- ffmpeg 4.4
- PyAudio 0.2.11
- pydub 0.25.1
- simpleaudio 1.0.4
And the issue is on a 2019 MacBook Pro, Catalina 10.15.7. I've also tested my Windows 10 Desktop (with similar versions as above), but rather than the issue above, I just get silence.