一、离散小波变换的音频信号数字水印技术简介
0 引言
近年来, 数字水印技术的作用越来越重要。数字水印技术是将一些标识信息直接嵌入数字载体当中, 或间接表示在信号载体中, 且不影响原载体的使用价值。通过隐藏在载体中的这些信息, 可以判断信息是否被篡改, 具有防伪溯源、保护信息安全、版权保护等作用。对于广播转播台站而言, 是广播音频的中转站, 在广播信号发送至千家万户之前务必保证信号的安全可靠, 但现在的大部分台站只是利用人耳的判断, 以及不同信源之间的比较, 具有较大的局限性。若利用数字水印的特性, 应用于广播节目中可以有效地防止信号插播, 可靠地保护信号安全, 保障广播的安全播出。
1 音频数字水印技术分类
根据数字水印在音频信号中的处理技术, 可将数字水印分为时域、变换域、压缩域数字水印。
1.1 时域数字水印
在时域数字水印技术中, 直接将水印信息嵌入至音频信号中, 通常会选择隐藏在信号不重要部位, 以保证其嵌入水印不影响原音频信号的监听效果。时域水印技术的实现较为容易且运算量小, 简单直接, 但是鲁棒性差, 容易被破解, 抵抗力较差。
1.2 变换域数字水印
在变换域数字水印中, 音频信号需经过时域至变换域的转换, 通常的变换域有离散余弦变换 (DCT, Discrete Cosine Transform) 、离散傅立叶变换 (DFT, Discrete Fourier transform) 、离散小波变换 (DWT, Discrete Wavelet Transform) 等。在变换域中嵌入水印信息, 通过反变换得到嵌入水印的音频时域信号。变换域水印技术较时域水印技术复杂, 但变换域嵌入的水印信息较时域而言, 不可见性更强, 隐蔽性更好, 鲁棒性更好。本文的研究主要基于DWT的音频信号的水印信息的嵌入与提取。
1.3 压缩域数字水印
在时域和变换域的水印技术, 都是直接将水印信号嵌入未压缩的音频格式中, 但是通常在音频信号的传输或存储中需要对音频信号进行压缩编码 (例如WMA、MP3等) , 因此压缩域数字水印也是水印技术也具有较大的实用价值。压缩域数字水印技术大致可分为三类: (1) 在非压缩域嵌入水印, 将音频信号与水印信息一起压缩; (2) 在压缩域中, 直接将水印信息嵌入压缩的音频信号中; (3) 将压缩后的信号进行解压缩, 然后嵌入水印信息, 最后将水印信息和解压后的音频信号一起压缩。总的来说, 压缩域水印技术的编解码系统过于复杂, 受压缩编码格式限制大, 压缩后的音频信号已经去除了冗余, 因此加入水印的难度大, 压缩域水印技术有待进一步研究。
二、部分源代码
function varargout = main(varargin)% MAIN MATLAB code for main.fig%MAIN, by itself, creates a new MAIN or raises the existing%singleton*.%%H = MAIN returns the handle to a new MAIN or the handle to%the existing singleton*.%%MAIN('CALLBACK',hObject,eventData,handles,...) calls the local%function named CALLBACK in MAIN.M with the given input arguments.%%MAIN('Property','Value',...) creates a new MAIN or raises the%existing singleton*. Starting from the left, property value pairs are%applied to the GUI before main_OpeningFcn gets called. An%unrecognized property name or invalid value makes property application%stop. All inputs are passed to main_OpeningFcn via varargin.%%*See GUI Options on GUIDE's Tools menu. Choose "GUI allows only one%instance to run (singleton)".%% See also: GUIDE, GUIDATA, GUIHANDLES% Edit the above text to modify the response to help main% Last Modified by GUIDE v2.5 15-Apr- 12:58:02% Begin initialization code - DO NOT EDITgui_Singleton = 1;gui_State = struct('gui_Name', mfilename, ...'gui_Singleton', gui_Singleton, ...'gui_OpeningFcn', @main_OpeningFcn, ...'gui_OutputFcn', @main_OutputFcn, ...'gui_LayoutFcn', [] , ...'gui_Callback', []);if nargin && ischar(varargin{1})gui_State.gui_Callback = str2func(varargin{1});endif nargout[varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});elsegui_mainfcn(gui_State, varargin{:});end% End initialization code - DO NOT EDIT% --- Executes just before main is made visible.function main_OpeningFcn(hObject, eventdata, handles, varargin)% This function has no output args, see OutputFcn.% hObject handle to figure% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)% varargin command line arguments to main (see VARARGIN)% Choose default command line output for mainhandles.output = hObject;% Update handles structureguidata(hObject, handles);% UIWAIT makes main wait for user response (see UIRESUME)% uiwait(handles.figure1);% --- Outputs from this function are returned to the command line.function varargout = main_OutputFcn(hObject, eventdata, handles)% varargout cell array for returning output args (see VARARGOUT);% hObject handle to figure% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)% Get default command line output from handles structurevarargout{1} = handles.output;% --- Executes on button press in pushbutton1.function pushbutton1_Callback(hObject, eventdata, handles)% hObject handle to pushbutton1 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)addpath('.\wavelet\')%添加小波变换工具箱%% 选择音频[file1,pathname]=uigetfile('*.wav','请选择要识别的样本');%跳出对话框fname=fullfile(pathname,file1);%音频文件名[X,fs]=audioread(fname); %读入音频文件s=get(handles.popupmenu1,'Value'); handles.axes1 %选定坐标轴1subplot(2,2,1); %子窗口plot(X);%显示音频文件波形title('原始音频信号');handles.X=X;%保存原始音频信号handles.fs=fs;%保存原始音频信号频率handles.s=s;guidata(hObject, handles);% --- Executes on button press in pushbutton2.function pushbutton2_Callback(hObject, eventdata, handles)% hObject handle to pushbutton2 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)%% 选择水印[file1,pathname]=uigetfile('*.bmp','请选择要识别的样本');%跳出对话框fname=fullfile(pathname,file1);%选择图片key=35;%密钥参数%Arnold置换次数，作为密钥Orignalmark=double(imread(fname)); %读入64*64的水印图片[wrow,wcol]=size(Orignalmark); %图像大小wrow行，wcol列if wrow~=wcolerror('wrow~=wcol error');%如果行列不相等则报错end%--- 测试密钥key是否超出范围---------n=check_arnold(wrow);if (key+1)>nerror('arnold key error');ends=get(handles.popupmenu1,'Value'); subplot(2,2,2); hold onimshow(Orignalmark),title('原始图像');handles.Orignalmark=Orignalmark;%保存原始图像handles.n=n;handles.s=s;guidata(hObject, handles);% --- Executes on button press in pushbutton3.function pushbutton3_Callback(hObject, eventdata, handles)% hObject handle to pushbutton3 (see GCBO)% eventdata reserved - to be defined in a future version of MATLAB% handles structure with handles and user data (see GUIDATA)%% 嵌入水印%水印嵌入--------------------------------------------------X=handles.X;%读取音频Orignalmark=handles.Orignalmark;%读取水印图像fs=handles.fs;%频率s=handles.s;%算法类型[wrow,wcol]=size(Orignalmark);key=35;%密钥if s==2Arnoldw=arnold(Orignalmark,wrow,key); %对水印图像进行Arnold转化[c,l]=wavedec(X,2,'db4'); % ca2=appcoef(c,l,'db4',2); % cd2=detcoef(c,l,2); % cd1=detcoef(c,l,1); % lca=length(ca2); %低频长度blocksize=fix(lca/(wrow*wcol)); %每块的大小water_vector=reshape(Arnoldw,1,wrow*wcol); %将置乱后的水印转化为一维的wlength=wrow*wcol; %水印的长度a=0.25; %量化步长j=1;for i=1:wlengthBlock=ca2(j:j+blocksize-1);[U,S,V]=svd(double(Block));cc=floor(S(1,1)/a);if(Arnoldw(i)==1) %嵌入奇数倍if(mod(cc,2)==0)cc=cc+1;endS(1,1)=a*cc;endif(Arnoldw(i)==0) %嵌入偶数倍if(mod(cc,2)==1)cc=cc+1;endS(1,1)=a*cc;endBlockw=U*S*V';% 还原ca2(j:j+blocksize-1)=Blockw;j=j+blocksize;endc1=[ca2',cd2',cd1']';MarkedX=waverec(c1,l,'db4');%b为量化嵌入水印后的音频数据elseA=X;L = size(A);% 用变量L存储音频A的长度M=Orignalmark;BW = im2bw(M);% 将图像Lena.bmp转化为二值图并存入变量BW% 计算水印矩阵大小[M1,M2] = size(BW);% M12为中间变量，避免每次都计算M1*M2M12 = M1*M2;% 降维，将水印信息得到的一维序列存入序列C中C = reshape(BW,1,M12);n = M12;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 对水印信号进行扩频处理,效果不是很好% 扩频系数为2n = M12*2;M = zeros(n,1);% 产生密钥序列Mfor k = 1 : nif mod(k,4) == 0M(k) = 1;elseM(k) = 0;end% 水印信号序列分别按位与密钥异或l = ceil(k/2);S(k) = bitxor(C(l),M(k));end%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 嵌入一个水印信息需要的音频数据为NN = 10;length1 = n*10;% 将原始音频信号分解为Ae和Ar两部分i = 1 : length1;j = [1];% 取矩阵A的l到length行构建矩阵AeAe = A(i,j);% Ae(i,j)i = length1+1 : L;% 取矩阵A的length到L行第一列构建矩阵ArAr = A(i,j);% 建立元胞B，每个音频数据段Ae(m)是B的一个元素k = 1;% 建立M1 x M2行l列的元胞B = cell(n,1);th = n*N;% 当k小于Ae的长度时，矩阵Ae每10行作为一个音频数据段存入元胞B中while ( k < th )i = k : k+9;m = (k+9)/10;B{m,1} = Ae(i,j);k = k+10;end
三、运行结果
四、matlab版本及参考文献
1 matlab版本
a
2 参考文献
[1]韩纪庆,张磊,郑铁然.语音信号处理（第3版）[M].清华大学出版社，.
[2]柳若边.深度学习:语音识别技术实践[M].清华大学出版社，.
