import numpy as np
import scipy.signal
import wave

def read_raw_iq_samples(file_path):
    with open(file_path, 'rb') as file:
        raw_data = file.read()
    iq_samples = np.frombuffer(raw_data, dtype=np.int8)
    return iq_samples

def fm_demodulation(iq_samples, sample_rate, fm_deviation=75e3):
    # Hilbert transform for FM demodulation
    analytic_signal = scipy.signal.hilbert(iq_samples)
    instantaneous_phase = np.unwrap(np.angle(analytic_signal))
    demodulated_signal = np.unwrap(np.angle(iq_samples[1:] * np.conj(iq_samples[:-1]))) / (2.0 * np.pi * 1.0/sample_rate * fm_deviation)
    return demodulated_signal

def decimate_audio(signal, decimation_factor):
    return scipy.signal.resample(signal, len(signal)//decimation_factor)

def low_pass_filter(signal, cutoff_frequency, sample_rate):
    nyquist = 0.5 * sample_rate
    normal_cutoff = cutoff_frequency / nyquist
    b, a = scipy.signal.butter(6, normal_cutoff, btype='low', analog=False)
    filtered_signal = scipy.signal.filtfilt(b, a, signal)
    return filtered_signal

def save_wav_file(signal, sample_rate, output_file):
    scaled_signal = np.int16(signal / np.max(np.abs(signal)) * 32767)
    with wave.open(output_file, 'wb') as wav_file:
        wav_file.setnchannels(1)
        wav_file.setsampwidth(2)
        wav_file.setframerate(sample_rate)
        wav_file.writeframes(scaled_signal.tobytes())

def main(input_file, output_file, sample_rate, channel_width, decimation_factor=10, cutoff_frequency=75e3):
    iq_samples = read_raw_iq_samples(input_file)
    demodulated_signal = fm_demodulation(iq_samples, sample_rate)
    decimated_signal = decimate_audio(demodulated_signal, decimation_factor)
    filtered_signal = low_pass_filter(decimated_signal, cutoff_frequency, sample_rate/decimation_factor)
    new_sample_rate = sample_rate / decimation_factor
    save_wav_file(filtered_signal, new_sample_rate, output_file)

if __name__ == "__main__":
    input_file_path = "fm_capture.bin"
    output_wav_path = "output.wav"
    sample_rate = 2e6  # Replace with the actual sample rate of your FM stream
    channel_width = 200e3  # Replace with the channel width of your FM signal

    main(input_file_path, output_wav_path, sample_rate, channel_width)