DCT音频水印算法代码

以下是一个基于DCT的音频水印算法的Python代码实现：

import numpy as np
import scipy.fftpack as fp

# 将消息转换为二进制数组
def str2bin(msg):
    return [format(ord(i), '08b') for i in msg]

# 将二进制数组转换为消息
def bin2str(msg):
    return ''.join([chr(int(i, 2)) for i in msg])

# 在音频信号中嵌入水印
def embed_watermark(audio, watermark):
    # 将消息转换为二进制数组
    msg = str2bin(watermark)
    if len(msg) > len(audio):
        return None

    # 对音频信号进行DCT变换
    dct_audio = fp.dct(audio, norm='ortho')

    # 将消息嵌入到DCT系数的最低位中
    for i in range(len(msg)):
        for j in range(8):
            index = i * 8 + j
            if index < len(dct_audio):
                bit = int(msg[i][j])
                if dct_audio[index] % 2 == 0:
                    if bit == 1:
                        dct_audio[index] += 1
                else:
                    if bit == 0:
                        dct_audio[index] -= 1

    # 对DCT系数进行逆变换得到嵌入水印后的音频信号
    watermarked_audio = fp.idct(dct_audio, norm='ortho')
    return watermarked_audio

# 从音频信号中提取水印
def extract_watermark(audio):
    # 对音频信号进行DCT变换
    dct_audio = fp.dct(audio, norm='ortho')

    # 从DCT系数的最低位中提取水印
    bits = []
    for i in range(len(dct_audio)):
        if len(bits) >= 8 * 16:
            break
        bit = dct_audio[i] % 2
        bits.append(str(bit))

    # 将二进制数组转换为消息
    watermark = bin2str([bits[i:i+8] for i in range(0, len(bits), 8)])
    return watermark

使用示例：

# 导入音频文件
import scipy.io.wavfile as wav
rate, audio = wav.read('test.wav')

# 嵌入水印
watermarked_audio = embed_watermark(audio, 'Hello, world!')

# 提取水印
watermark = extract_watermark(watermarked_audio)
print(watermark)

注意：这里的算法只是一个示例，实际使用时需要进行更多的优化和安全性考虑。