import wave

def extract_lsb(wav_path, output_path, max_bits=None):
    with wave.open(wav_path, 'rb') as audio:
        params = audio.getparams()
        frames = audio.readframes(-1)
        n_channels = params.nchannels
        sampwidth = params.sampwidth  # 通常是 2 (16-bit)
        n_frames = params.nframes

    print(f"[+] 音频参数: {n_channels} 声道, {sampwidth*8}-bit, {n_frames} 个采样")

    if sampwidth != 2:
        raise Exception("此脚本仅支持 16-bit PCM 音频")

    # 将字节流转换为有符号的 16 位整数（每个采样点）
    import struct
    samples = struct.unpack('<' + 'h' * (len(frames) // 2), frames)

    # 提取每个采样点的 LSB（只取最低位）
    bits = []
    for s in samples:
        bits.append(s & 1)  # 只取最低位

    # 如果未指定最大比特数，则使用全部
    if max_bits is None:
        max_bits = len(bits)

    # 将比特流组合成字节
    extracted = bytearray()
    for i in range(0, min(max_bits, len(bits)), 8):
        byte = 0
        for j in range(8):
            if i + j < len(bits):
                byte = (byte << 1) | bits[i + j]
            else:
                byte = (byte << 1)  # 补 0
        extracted.append(byte)

    # 写入输出文件
    with open(output_path, 'wb') as f:
        f.write(extracted)

    print(f"[+] 提取完成，共提取 {len(bits)} 个比特，保存到: {output_path}")

if __name__ == "__main__":
    wav_file = "Minecraft2.wav"
    output_file = "Minecraft2.bin"
    extract_lsb(wav_file, output_file)