Tiny Python CLI to display the bit depth of a list of WAVs

bitdepth.md

bitdepth

Tiny Python CLI to display the bit depth of a list of WAVs. Pretty bad "by design", I'm only using this to quickly verify promotional files I get from my secret DJing career.

Usage

$ python bitdepth.py file1.wav file2.wav
file1.wav: 16-bit
file2.wav: 24-bit

Pass in a space-delimited list of files. Globs work too. If nothing is specified, bitdepth lists the bit depth of all WAV files in the current working directory.

bitdepth.py

import glob
import io
from itertools import chain
import struct
import sys

def find_bit_depth(file: io.BufferedReader) -> int:
    if file.read(4) != b'RIFF':
        print('Not a RIFF file', file=sys.stderr)
        exit(-2)
    
    file.read(4) # Length of file, minus the 4-byte RIFF marker

    if file.read(4) != b'WAVE':
        print('Not a WAVE file', file=sys.stderr)
        exit(-3)
    
    next_marker = file.read(4)

    # JUNK chunk aligns the chunk offsets to some boundary, but doesn't always exist
    if next_marker == b'JUNK':
        file.read(struct.unpack('<L', file.read(4))[0])
        # Read the format marker after reading the JUNK chunk
        if file.read(4) != b'fmt ':
            print('Misaligned fmt chunk', file=sys.stderr)
            exit(-5)
    # Ensure there's a format marker
    elif next_marker != b'fmt ':
        print('Misaligned fmt chunk', file=sys.stderr)
        exit(-5)
    
    file.read(4) # Chunk size
    file.read(2) # Format code
    file.read(2) # Number of interleaved channels
    file.read(4) # Sampling rate
    file.read(4) # Data rate
    file.read(2) # Data block size

    return struct.unpack('<H', file.read(2))[0]

if __name__ == '__main__':
    # Add default behavior if no argument is specified
    if len(sys.argv) == 1:
        sys.argv.append('*.wav')

    for filename in chain.from_iterable(glob.iglob(filename) for filename in sys.argv[1:]):
        with open(filename, 'rb') as file:
            print('%s: %d-bit' % (filename, find_bit_depth(file)))