technical difficulties intro

intro/conv_nsb_resample.py

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+import sys
+
+import numpy as np
+from scipy.io import wavfile
+from scipy import signal
+
+
+
+def resample_audio(audio, original_sr, target_sr):
+    number_of_samples = round(len(audio) * float(target_sr) / original_sr)
+    return signal.resample(audio, number_of_samples)
+
+
+def noise_shape_and_quantize(signal, bits):
+    steps = 2 ** bits
+    step_size = (signal.max() - signal.min()) / steps
+
+    shaped = np.zeros_like(signal)
+    error = np.zeros_like(signal)
+
+    for i in range(len(signal)):
+        shaped[i] = signal[i] - error[i]
+        quantized = np.round(shaped[i] / step_size) * step_size
+        error[i] = quantized - signal[i]
+        if i < len(signal) - 1:
+            error[i + 1] = error[i] * 0.5  # Simple first-order noise shaping
+
+        shaped[i] = quantized
+
+    return np.clip(shaped, signal.min(), signal.max())
+
+
+# Read the WAV file
+original_sr, data = wavfile.read(sys.argv[1])
+data = data.astype(float)
+data = data / np.max(np.abs(data))
+
+# Define target sample rate
+target_sr = 5000  # 6 kHz
+
+# Resample the audio
+resampled_data = resample_audio(data, original_sr, target_sr)
+
+# Apply noise shaping and quantization
+quantized = noise_shape_and_quantize(resampled_data, 4)
+
+# Scale to 0-15 range and round to integers
+scaled = np.round((quantized - quantized.min()) / (quantized.max() - quantized.min()) * 15).astype(int)
+scaled = np.clip(scaled, 0, 15)
+
+print("Min value:", scaled.min())
+print("Max value:", scaled.max())
+print("Unique values:", np.unique(scaled))
+
+# Pack 4-bit values into bytes
+packed = []
+for i in range(0, len(scaled), 2):
+    if i + 1 < len(scaled):
+        byte = (scaled[i] << 4) | scaled[i + 1]
+    else:
+        byte = scaled[i] << 4
+    packed.append(byte)
+
+# Write packed data to binary file
+with open(sys.argv[1]+'.bin', 'wb') as f:
+    f.write(bytes(packed))
+
+print(f"Packed 4-bit data written to output.bin")
+print(f"Original sample rate: {original_sr} Hz")
+print(f"New sample rate: {target_sr} Hz")
+print(f"Number of samples: {len(scaled)}")
+print(f"Duration: {len(scaled) / target_sr:.2f} seconds")
+
+# Print first few bytes in hex
+print("First 10 bytes in hex:")
+print(" ".join(f"{b:02X}" for b in packed[:10]))
+
+# Save the resampled audio as a WAV file for verification
+# Correctly scale back to 16-bit audio range
+wav_output = (scaled.astype(float) - 7.5) / 7.5  # Center around 0
+wav_output = (wav_output * 32767).astype(np.int16)  # Scale to 16-bit range
+#wavfile.write('resampled_output.wav', target_sr, wav_output)