音频水印算法python

音频水印算法的实现方式有很多，这里介绍一种基于DWT（离散小波变换）的水印算法：
1. 读取音频文件，并将其转换为数字信号。
2. 对数字信号进行DWT小波分解，得到低频信号和高频信号。
3. 将水印信息嵌入到低频信号中，可以使用LSB（最低有效位）嵌入方法。
4. 对修改后的低频信号和高频信号进行IDWT小波重构，得到带有水印的音频信号。
5. 最后将带有水印的音频信号保存到文件中。

下面是一个Python实现示例：

import pywt
import numpy as np
import wave

# 读取音频文件
def read_wave(filename):
    with wave.open(filename, "rb") as f:
        params = f.getparams()
        nchannels, sampwidth, framerate, nframes = params[:4]
        str_data = f.readframes(nframes)
        wave_data = np.fromstring(str_data, dtype=np.short)
        wave_data.shape = -1, nchannels
        wave_data = wave_data.T
        return wave_data, framerate

# 写入音频文件
def write_wave(filename, data, framerate):
    with wave.open(filename, "wb") as f:
        f.setnchannels(1)
        f.setsampwidth(2)
        f.setframerate(framerate)
        f.writeframes(data)

# 小波水印嵌入
def embed_watermark(data, watermark):
    coeffs = pywt.wavedec(data, 'db1')
    cA, cD = coeffs[0], coeffs[1:]
    cA_size = cA.size
    watermark = np.array(list(watermark) + [0]*(cA_size - len(watermark)))
    cA_embed = np.array([cA[i] | watermark[i] for i in range(cA_size)])
    coeffs_embed = [cA_embed] + cD
    data_embed = pywt.waverec(coeffs_embed, 'db1')
    return data_embed.astype(np.short).tostring()

# 小波水印提取
def extract_watermark(data, watermark_size):
    coeffs = pywt.wavedec(data, 'db1')
    cA, cD = coeffs[0], coeffs[1:]
    cA_size = cA.size
    watermark = np.zeros(watermark_size)
    for i in range(watermark_size):
        watermark[i] = cA[i] & 1
    return watermark.astype(int)

# 测试
if __name__ == '__main__':
    # 读取原始音频文件
    data, framerate = read_wave("test.wav")
    # 嵌入水印信息
    watermark = "Hello, world!"
    data_embed = embed_watermark(data[0], bytes(watermark, encoding='utf-8'))
    # 将嵌入水印后的音频文件保存到本地
    write_wave("test_embed.wav", data_embed, framerate)
    # 读取嵌入水印后的音频文件并提取水印信息
    data_embed_read, _ = read_wave("test_embed.wav")
    watermark_extract = extract_watermark(data_embed_read[0], len(watermark)*8)
    watermark_extract = bytes([int(watermark_extract[i:i+8].to01(), 2) for i in range(0, len(watermark_extract), 8)]).decode("utf-8").rstrip('\x00')
    print("Extracted watermark:", watermark_extract)