1 files changed, 74 insertions, 0 deletions
diff --git a/tools/pcm2pdm.py b/tools/pcm2pdm.py
new file mode 100644
index 0000000..7cf05fb
--- /dev/null
+++ b/tools/pcm2pdm.py
@@ -0,0 +1,74 @@
+import numpy as np
+import soundfile
+
+def second_order_delta_sigma(pcm):
+    # Normalize input XXX: remove normalization
+    pcm = pcm / np.max(np.abs(pcm))
+
+    n = len(pcm)
+    pdm = np.zeros(n, dtype=np.uint8)
+
+    integrator1 = 0.0
+    integrator2 = 0.0
+    quantized = 0.0
+
+    for i in range(n):
+        integrator1 += pcm[i] - quantized
+        integrator2 += integrator1 - quantized
+
+        if integrator2 >= 0:
+            quantized = 1.0
+            pdm[i] = 1
+        else:
+            quantized = -1.0
+            pdm[i] = 0
+
+    return pdm
+
+def save_pdm_bin(pdm_data, file):
+    packed = np.packbits(pdm_data)
+    file.write(packed)
+
+def convert(pcm_data, oversample = 64):
+    # Oversample
+    pcm_upsampled = np.repeat(pcm_data, oversample)
+
+    # --- Convert to PDM ---
+    pdm_data = second_order_delta_sigma(pcm_upsampled)
+
+    return pdm_data
+
+def convert_file(input_file, **kwargs):
+    # --- Load audio ---
+    pcm_data, samplerate = soundfile.read(input_file)
+
+    # If stereo, use one channel
+    if pcm_data.ndim > 1:
+        pcm_data = pcm_data[:, 0]
+
+    pdm_data = convert(pcm_data, **kwargs)
+    return pdm_data
+
+
+def parse():
+    import argparse
+
+    parser = argparse.ArgumentParser(description='Process an input file and write to an output file.')
+    parser.add_argument('-i', '--input', type=str, required=True, help='Path to the input file')
+    parser.add_argument('-o', '--output', type=str, required=True, help='Path to the output file')
+    
+    args = parser.parse_args()
+    return args
+
+def main():
+    args = parse()
+
+    out_path = args.output
+
+    pdm_data = convert_file(args.input, oversample=64)
+    with open(out_path, 'wb') as f:
+        save_pdm_bin(pdm_data, f)
+
+
+if __name__ == '__main__':
+    main()