Generate PCM test files

gen_pcm.py

python3 - <<'PY'
import math
import struct

sample_rates = [8000, 16000, 32000, 44100, 48000]
widths = [8, 16, 24, 32]

freq = 1000
duration_s = 1
steps = 61


def pcm_format_name(width):
    return {
        8: "s8",
        16: "s16le",
        24: "s24le",
        32: "s32le",
    }[width]


def pack_sample(value, width):
    if width == 8:
        return struct.pack("<b", value)

    if width == 16:
        return struct.pack("<h", value)

    if width == 24:
        # Signed 24-bit little-endian PCM
        return int(value).to_bytes(3, byteorder="little", signed=True)

    if width == 32:
        return struct.pack("<i", value)

    raise ValueError(f"Unsupported width: {width}")


for width in widths:
    max_amp = (1 << (width - 1)) - 1

    for sample_rate in sample_rates:
        fmt = pcm_format_name(width)
        out = f"stereo_opposite_levels_{fmt}_{sample_rate}hz.pcm"

        with open(out, "wb") as f:
            print(f"\nGenerating {out}")

            for step in range(steps):
                left_db = -60 + step
                right_db = -step

                left_amp = max_amp * (10 ** (left_db / 20))
                right_amp = max_amp * (10 ** (right_db / 20))

                print(f"{step:02d}: L={left_db:4} dBFS, R={right_db:4} dBFS")

                for n in range(sample_rate * duration_s):
                    s = math.sin(2 * math.pi * freq * n / sample_rate)

                    left = int(round(left_amp * s))
                    right = int(round(right_amp * s))

                    f.write(pack_sample(left, width))
                    f.write(pack_sample(right, width))

        print(f"Wrote {out}")

PY