echo watermark (#1)

* add: echo watermark for wav

example/example_echo_watermark.py

@@ -2,33 +2,34 @@
 from hide_info.echo_watermark import EchoWatermark, get_error_rate, get_snr
 from hide_info import utils
 
-ori_file = "音乐.wav"
-embedded_file = "打入水印_音乐.wav"  # 嵌入了水印的文件
-wm_str = "回声水印算法测试用水印"
+ori_file = "sounds.wav"
+embedded_file = "sounds_with_watermark.wav"
+wm_str = "回声水印算法，欢迎 star!"
 
-wm_bits = [int(i) for i in utils.bytes2bin(wm_str.encode('utf-8'))]
+wm_bits = utils.bytes2bin(wm_str.encode('utf-8'))
 
 len_wm_bits = len(wm_bits)
 
 # embed:
-echo_wm = EchoWatermark(pwd=111001, algo_type=2)
+echo_wm = EchoWatermark(pwd=111001)
 echo_wm.embed(origin_filename=ori_file, wm_bits=wm_bits, embed_filename=embedded_file)
 
 # extract：
-echo_wm = EchoWatermark(pwd=111001, algo_type=2)
+echo_wm = EchoWatermark(pwd=111001)
 wm_extract = echo_wm.extract(embed_filename=embedded_file, len_wm_bits=len_wm_bits)
 
-wm_str_extract = utils.bin2bytes(''.join([str(int(i)) for i in wm_extract])).decode('utf-8')
+wm_str_extract = utils.bin2bytes(wm_extract).decode('utf-8', errors='replace')
 print("解出水印：", wm_str_extract)
 get_error_rate(wm_extract, wm_bits)
 
-# %%
+# %% There are 3 algorithms：
 wm_bits = np.random.randint(2, size=200).tolist()
 len_wm_bits = len(wm_bits)
 
 for algo_type in [1, 2, 3]:
     echo_wm = EchoWatermark(pwd=111001, algo_type=algo_type)
     echo_wm.embed(origin_filename=ori_file, wm_bits=wm_bits, embed_filename=embedded_file)
     wm_extract = echo_wm.extract(embed_filename=embedded_file, len_wm_bits=len_wm_bits)
-    get_error_rate(wm_extract, wm_bits)
+    error_rate = get_error_rate(wm_extract, wm_bits)
     get_snr(embedded_file, ori_file)
+    assert error_rate <= 0.03

example/example_hide_in_music.py

@@ -2,15 +2,15 @@
 
 text = "待嵌入到音乐文件的文本，下面的代码中，会把这段文本以二进制形式隐藏到一个音乐文件中"
 
-hide_in_music.encode(text.encode('utf-8'), music_filename="音乐.wav", music_filename_new="藏文于音.wav")
+hide_in_music.encode(text.encode('utf-8'), music_filename="sounds.wav", music_filename_new="藏文于音.wav")
 
 text_encode = hide_in_music.decode(music_filename="藏文于音.wav")
 
 print(text_encode.decode('utf-8'))
 
 # %%
 # 把文件隐藏到某个音乐中
-hide_in_music.file_encode(filename='要隐藏的文件.zip', music_filename="音乐.wav", music_filename_new="藏物于音.wav")
+hide_in_music.file_encode(filename='要隐藏的文件.zip', music_filename="sounds.wav", music_filename_new="藏物于音.wav")
 # 从音乐中提取文件
 hide_in_music.file_decode(filename="藏物于音-解出的文件.zip", music_filename="藏物于音.wav")
 

hide_info/echo_watermark.py

@@ -1,45 +1,43 @@
 # 回声音频水印
 import numpy as np
 from scipy.io import wavfile
-from scipy.signal import windows
+from scipy.signal.windows import hann
+from numpy.fft import ifft, fft
 
 
 class EchoWatermark:
-    def __init__(self, pwd, algo_type=2, verbose=False):
+    def __init__(self, pwd, algo_type=3, verbose=False):
         self.pwd = pwd
         self.algo_type = algo_type
         self.verbose = verbose
 
-        self.FRAME_LENGTH = 2048  # 帧长度
-        self.CONTROL_STRENGTH = 0.2  # 嵌入强度
-        self.OVERLAP = 0.5  # 帧分析的重叠率
-        self.NEGATIVE_DELAY = 4  # negative delay, for negative echo
-        self.LOG_FLOOR = 0.00001
+        self.frame_len = 2048  # 帧长度
+        self.echo_amplitude = 0.2  # 回声幅度
+        self.overlap = 0.5  # 帧分析的重叠率
+        self.neg_delay = 4  # negative delay, for negative echo
 
         # 回声参数
-        # for key 1
+        # pwd[i] = 1
         self.delay11, self.delay10 = 100, 110
-        # for key 0
+        # pwd[i] = 0
         self.delay01, self.delay00 = 120, 130
 
-    def embed(self, origin_filename,wm_bits, embed_filename):
-        pwd = self.pwd
-        algo_type = self.algo_type
-        FRAME_LENGTH = self.FRAME_LENGTH
-        CONTROL_STRENGTH = self.CONTROL_STRENGTH
-        OVERLAP = self.OVERLAP
-        NEGATIVE_DELAY = self.NEGATIVE_DELAY
-        LOG_FLOOR = self.LOG_FLOOR
-        delay11, delay10, delay01, delay00 = self.delay11, self.delay10, self.delay01, self.delay00
+    def embed(self, origin_filename, wm_bits, embed_filename):
+        frame_len = self.frame_len
+        echo_amplitude = self.echo_amplitude
+        overlap = self.overlap
+        neg_delay = self.neg_delay
+
+        delay_matrix = [[self.delay00, self.delay01], [self.delay10, self.delay11]]
 
-        sr, host_signal = wavfile.read(origin_filename)
-        signal_len = len(host_signal)
+        sr, ori_signal = wavfile.read(origin_filename)
+        signal_len = len(ori_signal)
 
         # 帧的移动量
-        frame_shift = int(FRAME_LENGTH * (1 - OVERLAP))
+        frame_shift = int(frame_len * (1 - overlap))
 
         # 和相邻帧的重叠长度
-        overlap_length = int(FRAME_LENGTH * OVERLAP)
+        overlap_length = int(frame_len * overlap)
 
         # 可嵌入总比特数
         embed_nbit_ = (signal_len - overlap_length) // frame_shift
@@ -57,81 +55,62 @@ def embed(self, origin_filename,wm_bits, embed_filename):
                 f"可以嵌入的总比特数为: {embed_nbit_}，水印长度为{len(wm_bits)},重复嵌入 {n_repeat} 次, 实际嵌入{embed_nbit}")
 
         # 扩展水印信号
-        wmark_extended = np.repeat(wm_bits, n_repeat)
+        wm_repeat = np.repeat(wm_bits, n_repeat)
 
         # 生成密钥
-        np.random.seed(pwd)
+        np.random.seed(self.pwd)
         secret_key = np.random.randint(2, size=int(len_wm_bits))
         secret_key_extended = np.repeat(secret_key, n_repeat)
 
         pointer = 0
-        echoed_signal1 = np.zeros((frame_shift * embed_nbit))
-        prev1 = np.zeros((FRAME_LENGTH))
-        de = NEGATIVE_DELAY  #
+        echoed_signal = np.zeros((frame_shift * embed_nbit))
+        prev1 = np.zeros(frame_len)
+
         for i in range(embed_nbit):
-            frame = host_signal[pointer: (pointer + FRAME_LENGTH)]
+            frame = ori_signal[pointer: (pointer + frame_len)]
 
-            if secret_key_extended[i] == 1:
-                if wmark_extended[i] == 1:
-                    delay = delay11
-                else:
-                    delay = delay10
-            else:
-                if wmark_extended[i] == 1:
-                    delay = delay01
-                else:
-                    delay = delay00
-
-            echo_positive = CONTROL_STRENGTH \
-                            * np.concatenate((np.zeros(delay),
-                                              frame[0:FRAME_LENGTH - delay]))
-
-            echo_negative = - CONTROL_STRENGTH \
-                            * np.concatenate((np.zeros(delay + de),
-                                              frame[0:FRAME_LENGTH - delay - de]))
-
-            echo_forward = CONTROL_STRENGTH \
-                           * np.concatenate((frame[delay:FRAME_LENGTH], np.zeros(delay)))
-
-            if algo_type == 1:
-                echoed_frame1 = frame + echo_positive
-            elif algo_type == 2:
-                echoed_frame1 = frame + echo_positive + echo_negative
-            else:  # algo_type == 3
-                echoed_frame1 = frame + echo_positive + echo_forward
+            delay = delay_matrix[secret_key_extended[i]][wm_repeat[i]]
 
-            echoed_frame1 = echoed_frame1 * windows.hann(FRAME_LENGTH)
-            echoed_signal1[frame_shift * i: frame_shift * (i + 1)] = \
-                np.concatenate((prev1[frame_shift:FRAME_LENGTH] +
-                                echoed_frame1[0:overlap_length],
-                                echoed_frame1[overlap_length:frame_shift]))
+            echo_positive = np.concatenate((np.zeros(delay), frame[0:frame_len - delay]))
 
-            prev1 = echoed_frame1
-            pointer = pointer + frame_shift
+            echo_negative = - np.concatenate((np.zeros(delay + neg_delay),
+                                              frame[0:frame_len - delay - neg_delay]))
+
+            echo_forward = np.concatenate((frame[delay:frame_len], np.zeros(delay)))
 
-        echoed_signal1 = np.concatenate(
-            (echoed_signal1, host_signal[len(echoed_signal1): signal_len]))
+            if self.algo_type == 1:
+                echoed_frame = frame + echo_amplitude * echo_positive
+            elif self.algo_type == 2:
+                echoed_frame = frame + echo_amplitude * (echo_positive + echo_negative)
+            else:  # algo_type == 3
+                echoed_frame = frame + echo_amplitude * (echo_positive + echo_forward)
+
+            echoed_frame = echoed_frame * hann(frame_len)
+            echoed_signal[frame_shift * i: frame_shift * (i + 1)] = \
+                np.concatenate((prev1[frame_shift:frame_len] +
+                                echoed_frame[0:overlap_length],
+                                echoed_frame[overlap_length:frame_shift]))
 
-        # 将保存为wav格式
-        echoed_signal1 = echoed_signal1.astype(np.int16)
-        wavfile.write(embed_filename, sr, echoed_signal1)
+            prev1 = echoed_frame
+            pointer += frame_shift
+
+        echoed_signal = np.concatenate((echoed_signal, ori_signal[len(echoed_signal):])).astype(np.int16)
+        # 保存为wav格式
+        wavfile.write(embed_filename, sr, echoed_signal)
 
     def extract(self, embed_filename, len_wm_bits):
-        pwd = self.pwd
-        algo_type = self.algo_type
-        FRAME_LENGTH = self.FRAME_LENGTH
-        CONTROL_STRENGTH = self.CONTROL_STRENGTH
-        OVERLAP = self.OVERLAP
-        NEGATIVE_DELAY = self.NEGATIVE_DELAY
-        LOG_FLOOR = self.LOG_FLOOR
+        frame_len = self.frame_len
+        overlap = self.overlap
+        neg_delay = self.neg_delay
         delay11, delay10, delay01, delay00 = self.delay11, self.delay10, self.delay01, self.delay00
+        log_floor = 0.00001  # 取对数时的最小值
 
         # 打开已嵌入水印的音频文件
-        _, eval_signal1 = wavfile.read(embed_filename)
-        signal_len = len(eval_signal1)
+        _, wm_signal = wavfile.read(embed_filename)
+        signal_len = len(wm_signal)
 
-        frame_shift = int(FRAME_LENGTH * (1 - OVERLAP))
-        embed_nbit_ = (signal_len - int(FRAME_LENGTH * OVERLAP)) // frame_shift
+        frame_shift = int(frame_len * (1 - overlap))
+        embed_nbit_ = (signal_len - int(frame_len * overlap)) // frame_shift
 
         # 重复次数
         n_repeat = embed_nbit_ // len_wm_bits
@@ -144,92 +123,67 @@ def extract(self, embed_filename, len_wm_bits):
                 f"可以嵌入的总比特数为: {embed_nbit_}，水印长度为{len_wm_bits},重复嵌入 {n_repeat} 次, 实际嵌入{embed_nbit}")
 
         # 加载密钥
-        np.random.seed(pwd)
+        np.random.seed(self.pwd)
         secret_key = np.random.randint(2, size=int(len_wm_bits))
         secret_key = np.repeat(secret_key, n_repeat)
 
         pointer = 0
         detected_bit1 = np.zeros(embed_nbit)
         for i in range(embed_nbit):
-            wmarked_frame1 = eval_signal1[pointer: pointer + FRAME_LENGTH]
-            ceps1 = np.fft.ifft(
-                np.log(np.square(np.fft.fft(wmarked_frame1)) + LOG_FLOOR)).real
+            wmarked_frame1 = wm_signal[pointer: pointer + frame_len]
+            ceps1 = ifft(
+                np.log(np.square(fft(wmarked_frame1)) + log_floor)).real
 
             if secret_key[i] == 1:
-                if algo_type == 1:
-                    if ceps1[delay11] > ceps1[delay10]:
-                        detected_bit1[i] = 1
-                    else:
-                        detected_bit1[i] = 0
-                elif algo_type == 2:
-                    if (ceps1[delay11] - ceps1[delay11 + NEGATIVE_DELAY]) > \
-                            (ceps1[delay10] - ceps1[delay10 + NEGATIVE_DELAY]):
-                        detected_bit1[i] = 1
-                    else:
-                        detected_bit1[i] = 0
-                else:  # algo_type == 3
-                    if ceps1[delay11] > ceps1[delay10]:
-                        detected_bit1[i] = 1
-                    else:
-                        detected_bit1[i] = 0
-
+                delay0, delay1 = delay10, delay11
             else:
-                if algo_type == 1:
-                    if ceps1[delay01] > ceps1[delay00]:
-                        detected_bit1[i] = 1
-                    else:
-                        detected_bit1[i] = 0
-                elif algo_type == 2:
-                    if (ceps1[delay01] - ceps1[delay01 + NEGATIVE_DELAY]) > \
-                            (ceps1[delay00] - ceps1[delay00 + NEGATIVE_DELAY]):
-                        detected_bit1[i] = 1
-                    else:
-                        detected_bit1[i] = 0
-                else:
-                    if ceps1[delay01] > ceps1[delay00]:
-                        detected_bit1[i] = 1
-                    else:
-                        detected_bit1[i] = 0
+                delay0, delay1 = delay00, delay01
+
+            if self.algo_type == 1:
+                if ceps1[delay1] > ceps1[delay0]:
+                    detected_bit1[i] = 1
+            elif self.algo_type == 2:
+                if (ceps1[delay1] - ceps1[delay1 + neg_delay]) > \
+                        (ceps1[delay0] - ceps1[delay0 + neg_delay]):
+                    detected_bit1[i] = 1
+            else:  # algo_type == 3
+                if ceps1[delay1] > ceps1[delay0]:
+                    detected_bit1[i] = 1
 
             pointer = pointer + frame_shift
 
         count = 0
-        wmark_recovered1 = np.zeros(len_wm_bits)
-        # wmark_recovered2 = np.zeros(len_wm_bits)
-        # wmark_recovered3 = np.zeros(len_wm_bits)
+        wm_extract = np.zeros(len_wm_bits)
 
         for i in range(len_wm_bits):
-
-            # 汇总比特值（平均值）
-            ave = np.sum(detected_bit1[count:count + n_repeat]) / n_repeat
+            # 汇总比特值（按平均值）
+            ave = np.average(detected_bit1[count:count + n_repeat])
             if ave >= 0.5:
-                wmark_recovered1[i] = 1
+                wm_extract[i] = 1
             else:
-                wmark_recovered1[i] = 0
+                wm_extract[i] = 0
 
             count = count + n_repeat
 
-        return wmark_recovered1
+        return wm_extract
 
 
-def get_error_rate(wmark_recovered, wm_bits):
+def get_error_rate(wm_extract, wm_bits):
     # 计算错误率
     len_wm_bits = len(wm_bits)
-    denom = np.sum(np.abs(wmark_recovered - wm_bits))
-    BER = np.sum(np.abs(wmark_recovered - wm_bits)) / \
-          len_wm_bits * 100
-    print(f'bit error rate = {BER:.2f}% ({denom} / {len_wm_bits})')
-    return BER
+    error_num = np.sum(np.abs(wm_extract - wm_bits))
+    error_rate = error_num / len_wm_bits
+    print(f'bit error rate = {error_rate:.2%} ({error_num} / {len_wm_bits})')
+    return error_rate
 
 
-def get_snr(wav_with_wm, orig_file):
-    sr, host_signal = wavfile.read(orig_file)
-    _, eval_signal1 = wavfile.read(wav_with_wm)
+def get_snr(file_with_wm, orig_file):
+    sr, ori_signal = wavfile.read(orig_file)
+    _, wm_signal = wavfile.read(file_with_wm)
 
     SNR = 10 * np.log10(
-        np.sum(np.square(host_signal.astype(np.float32)))
-        / np.sum(np.square(host_signal.astype(np.float32)
-                           - eval_signal1.astype(np.float32))))
+        np.sum(np.square(ori_signal.astype(np.float32)))
+        / np.sum(np.square(ori_signal.astype(np.float32)
+                           - wm_signal.astype(np.float32))))
     print(f'SNR = {SNR:.2f} dB')
     return SNR
-