Bit-depth is not detected correctly by pydub

Steps to reproduce

def open_audio(file_path):

    audio = pd.AudioSegment.from_file(file_path)
    return audio

def get_bit_depth(file):

    bit_depth = file.sample_width  # 1-4. 1=8 2=16 3=24 4=32

    if bit_depth is 1:
        bit_depth = 8

    elif bit_depth is 2:
        bit_depth = 16

    elif bit_depth is 3:
        bit_depth = 24

    elif bit_depth is 4:
        bit_depth = 32

    return bit_depth

file = pd.open_audio("PUT FILE PATH HERE")
bit_depth = pd.get_bit_depth(file)

print(bit_depth)

Expected behavior

Should print the actual bit-depth of the file (not the 1-4 value).

Actual behavior

I’ve tested 4 different files with 8 bit, 16 bit, 24 bit, and 32 bit depths.

Files were exported out of Ableton Live 10. Ableton does not support 8 bit exports, so I used an online converter to test that bit-depth instead.

8 bit is detected correctly, but whenever exported with PyDub, audio becomes garbled and in-comprehensive compared to the source file (‘8’). It should stay 1:1, especially if assigned a bit-depth higher than source. 16 bit is detected correctly 24 bit is detected as 32 bit file 32 bit file is detected correctly.

Your System configuration

• Python version: 3.7
• Pydub version: 0.23.1
• ffmpeg or avlib?: ffmpeg
• ffmpeg/avlib version: 4.1.3 win64 static (stable distro, not nightly)

Is there an audio file you can include to help us reproduce?

4 different samples, one of every bit-depth type. Test sample (kick drum).zip

[jiaaro]

Hi, thanks for writing 😃

Pydub uses Python’s stdlib audioop module for most operations, and unfortunately audioop does not have support for 24-bit audio (at least, in many versions of python, CPython added support for 24-bit audio in Python 3.4). So the decision was made to convert 24 bit audio to 32 bit to avoid losing quality.

It may be time to revisit the decision perhaps in favor of an approach that uses 24-bit audio in environments that support it.

We could check for 24-bit support relatively easily I think:

import audioop

def supports_24_bit_audio():
    try:
        audioop.add(b'', b'', 3)
        return True
    except audioop.error:
        return False

[aspen1135]

@jiaaro

It’s been a few months since I made this thread. I wanted to see if an update has been added to support 24 bit conversion.

I’m using another library right now called PyAV which gives me some python bindings to FFmpeg’s framework. And although it supports 24 bit (only when using pcm_s24le encoder), the library still only has some limited support for other features I’d like to implement into my project.

Has there been any update on this?