speechpreprocess.m

matlab编写的一个音频加密的程序

%Name:		Yan Diqun
%Context:	Data Information Hiding
%Project: 	Least Significant Bit 

global bitstream LengthOfBitstream speech
%yandiqun=m_sequence(4,3);

%保密语音G.729A压缩编码
%!coder nbu.pcm nbu.bit

%将保密语音转化为bit流文件
[speechfilename]=uigetfile('*.wav');
[audio,fs,wmode,fidx]=readwav(speechfilename,'r');
speech=audio+128;
%length_of_bitstream=length(speech);
figure(1);
plot(speech);
yLabel('Original Speech');
axis tight;
for i=1:length(speech)
    temp(i,:)=bitget(speech(i),[1:8]);
end;
bitstream=temp';
bitstream=bitstream(:);

%BCH纠错编码
bitstream=encode(bitstream,7,4,'bch');
LengthOfBitstream=floor(length(bitstream));
%index=find(bitstream==0);
%bitstream(index)=-1;