I hear crackling sound when using 32bit integer numpy arrays to play audio

Code to reproduce the issue:

import numpy as np
import sounddevice as sd

frequency = 1000
sample_rate = 44100
duration  = 2 # seconds
num_frames = int(duration*sample_rate)

t = np.arange(num_frames) / sample_rate
max_amp = 2**31-1 # maximum value of signed int32
signal = max_amp*np.sin(2 * np.pi * frequency * t)
signal = signal.astype(np.int32)
sd.play(signal,samplerate=sample_rate)

Current OS: Windows 10 Things I have tried:

• Running in other high end laptop running windows 10
• Directly using float32 format doesn’t cause crackling sound but I need to work with int32 and int24
• Using raw output stream and writing to audio buffer has same effect for int32 and int24
• int16 and int8 play well using same method
• float32 and float16 work well
• int24 has same issue as int32
• Increasing sampling rate from 44.1k to 96k increased the frequency of noise
• Disable enhancements in windows sound driver does nothing
• Uninstalled sound driver - no difference
• Tried giving stereo output with same results
• increasing block size upto 10 times the sample rate
• playing with latency settings
• Checking status of stream - no warning or error

[mgeier]

If there are multiple host APIs, your physical devices will appear multiple times in the device list. Each entry contains the host API name after the device name.

So by selecting a specific device from the list, you automatically select a host API at the same time.

I couldn’t find anything related to changing host APIs in the documentation

Yeah, I think that’s not mentioned explicitly.

Do you have an idea how and where we could document this? Would you like to make a documentation PR for this?

[HaHeho]

What is the reason for that you say that you need to work with int32 (your original data / processing generates that)?

In any case, you should be able use .astype(np.float32) (and potentially scale the amplitude) to make it work, right?