語(yǔ)音信號(hào)處理,基于MATLAB的子帶編碼實(shí)現(xiàn)

1、一:子帶編碼1.子帶編碼首先將輸入信號(hào)分割成幾個(gè)不同的頻帶分量,然后再分別進(jìn)行編碼,這類(lèi)編碼方式稱為頻域編碼。2.把語(yǔ)音信號(hào)分成若干子帶進(jìn)行編碼主要有兩個(gè)優(yōu)點(diǎn): (1.如果對(duì)不同的子帶合理分配比特?cái)?shù),可以控制各子帶的量化電平數(shù)目,以及相應(yīng)的重建信號(hào)的量化誤差方差值,以獲得更好的主觀聽(tīng)音質(zhì)量。(2.各子帶的量化噪聲相互獨(dú)立,被束縛在自己的子帶內(nèi),不影響其它子帶的量化噪聲。 3.影響子帶編碼效率的因數(shù)子帶數(shù)目、子帶劃分、編碼參數(shù)、子帶中比特的分配、每樣值編碼比特、帶寬。4.分類(lèi)(1等帶寬子帶編碼各子帶的帶寬是相同的,其優(yōu)點(diǎn)是易于硬件實(shí)現(xiàn),便于理論分析。其中,k= 1, 2, 3 , m為子帶總數(shù),

2、B編碼信號(hào)總帶寬(2變帶寬子帶編碼各子帶帶寬是不同的,常用的子帶劃分是令各子帶寬度隨K 的增加而增加(低頻段子帶帶寬窄,高頻段寬,其優(yōu)點(diǎn)是對(duì)不同的子帶分配的比特?cái)?shù)不同,能獲得很好的質(zhì)量。二:matlab實(shí)現(xiàn)1.主要是使用非對(duì)稱濾波器組來(lái)實(shí)現(xiàn)語(yǔ)音信號(hào)的子帶分解和合并。2.關(guān)鍵:針對(duì)語(yǔ)音信號(hào)的頻譜設(shè)計(jì)與之相適應(yīng)的樹(shù)形濾波器組。3.編碼采用u律pcm編碼。介紹:本編程所設(shè)計(jì)的樹(shù)形結(jié)構(gòu)濾波器組,是由兩通道的正交鏡像濾波器組通過(guò)級(jí)聯(lián)或并聯(lián)組建而成的。采用正交鏡象濾波器(QMF,quandrature mirror filter來(lái)劃分頻帶,混迭效應(yīng)在最后合成時(shí)可以抵消混迭失真:這是由于分析濾波器組和綜合濾

3、波器組的頻帶不能完全分開(kāi)及x(n的抽樣頻率fs不能大于其最高頻率成分的m倍所致。兩通道的濾波器組 兩通道的濾波器組 兩通道的濾波器組的幅頻特性 兩通道的正交鏡像濾波器組的幅頻特性(從頻頻特性可以看出采用正交鏡象濾波器來(lái)劃分頻帶,混迭效應(yīng)在最后合成時(shí)可以抵消 ·整體框圖頻帶分解(主要(下附matlab 源程序語(yǔ)音為wav 格式自己錄音原始語(yǔ)音y提取一通道抗混疊濾波分析濾波器組U 律pcm 編碼重構(gòu)濾波器組U 律pcm 編碼處理后語(yǔ)音y_he%主程序clear all ;close all;clc;N=4096*50;%采集點(diǎn)數(shù)y,fs,bits=wavread('tangshi

4、',N; %讀取音頻信息(雙聲道 Fs=fs ;ts = 1/fs;%僅處理1通道信號(hào)y1=y(:,1' ;%the signal of channel one%y2=y(:,2 ;%the signal of channel twot=0:1/fs:(N-1/fs;%time%原始語(yǔ)音信號(hào)讀取sound(y1,fs;%原始語(yǔ)音信號(hào)畫(huà)圖figure(1 ;subplot(2,1,1 ;plot(t,y1 ;%1通道信號(hào)title('原始信號(hào)y1' ;%預(yù)濾波%語(yǔ)音信號(hào)預(yù)處理人耳可識(shí)別范圍(3003400,因此多于此頻率的信號(hào)可以濾掉而不用傳輸y1_yu,fs_y

5、u=pre_process(y1,fs ;subplot(2,1,2 ;plot(t(1:fs/fs_yu:3*floor(length(t/3,y1_yu ;%濾波后的信號(hào)時(shí)域波形title('預(yù)濾波后的信號(hào)y1_yu' ;%對(duì)上面兩個(gè)信號(hào)進(jìn)行頻譜分析Y1 = fft(y1;Y1_YU = fft(y1_yu;%畫(huà)出圖形figure(2 ;subplot(2,1,1dfs= fs/length(Y1;H1 = abs(Y1(1:length(Y1/2;f1 = 0:dfs:fs-dfs;f1 = f1(1:length(Y1/2;plot(f1,H1axis(0,10000,

6、0,max(abs(fftshift(Y1title('原始信號(hào)頻譜y1'subplot(2,1,2H2 = abs(Y1_YU(1:length(Y1_YU/2;f2=0:dfs:fs_yu-dfs;f2 = f2(1:length(Y1_YU/2;plot(f2,H2axis(0,10000,0,max(abs(fftshift(Y1_YUtitle('抗混疊濾波后y1_yu的信號(hào)頻譜,fl=300Hz,fh=3400Hz' %抗混疊濾波后語(yǔ)音信號(hào)讀取sound(y1_yu,fs_yu;%分解yu1,yu2=fenjie(y1_yu,fs_yu ;%y1%2

7、次分解y1_1,y1_2=fenjie(yu1,fs_yu ;%3次分解y1_11,y1_12=fenjie(y1_1,fs_yu ; y1_21,y1_22=fenjie(y1_2,fs_yu ;%y2%2次分解y2_1,y2_2=fenjie(yu2,fs_yu ;%3次分解y2_11,y2_12=fenjie(y2_1,fs_yu ; y2_21,y2_22=fenjie(y2_2,fs_yu ;%分解圖示figuresubplot(4,1,1plot(f2,H2;title('原始信號(hào)頻譜,fs=',num2str(fs_yusubplot(4,2,3hy1 = abs

8、(fft(yu1;fhy1=0:dfs:fs_yu/2-dfs;fhy1 = fhy1(1:length(hy1/2;plot(fhy1,hy1(1:length(hy1/2title('1次分解,fs=',num2str(fs_yu/2subplot(4,2,4hy2 = abs(fft(yu2;fhy2=0:dfs:fs_yu/2-dfs;fhy2 = fhy2(1:length(hy2/2;plot(fhy2,hy2(1:length(hy2/2subplot(4,4,9hy1_1 = abs(fft(y1_1;fhy1_1=0:dfs:fs_yu/4-dfs;fhy1_

9、1 = fhy1_1(1:length(hy1_1/2;plot(fhy1_1,hy1_1(1:length(hy1_1/2title('2次分解,fs=',num2str(fs_yu/4subplot(4,4,10hy1_2 = abs(fft(y1_2;fhy1_2=0:dfs:fs_yu/4-dfs;fhy1_2 = fhy1_2(1:length(hy1_2/2; plot(fhy1_2,hy1_2(1:length(hy1_2/2subplot(4,4,11hy2_1 = abs(fft(y2_1;fhy2_1=0:dfs:fs_yu/4-dfs;fhy2_1 = f

10、hy2_1(1:length(hy2_1/2; plot(fhy2_1,hy2_1(1:length(hy2_1/2subplot(4,4,12hy2_2 = abs(fft(y2_2;fhy2_2=0:dfs:fs_yu/4-dfs;fhy2_2 = fhy2_2(1:length(hy2_2/2; plot(fhy2_2,hy2_2(1:length(hy2_2/2subplot(4,8,25hy1_11 = abs(fft(y1_11;fhy1_11=0:dfs:fs_yu/8-dfs;fhy1_11 = fhy1_11(1:length(hy1_11/2; plot(fhy1_11,h

11、y1_11(1:length(hy1_11/2 title('3次分解,fs=',num2str(fs_yu/8subplot(4,8,26hy1_12 = abs(fft(y1_12;fhy1_12=0:dfs:fs_yu/8-dfs;fhy1_12 = fhy1_12(1:length(hy1_12/2; plot(fhy1_12,hy1_12(1:length(hy1_12/2subplot(4,8,27hy1_21 = abs(fft(y1_21;fhy1_21=0:dfs:fs_yu/8-dfs;fhy1_21 = fhy1_21(1:length(hy1_21/2;

12、 plot(fhy1_21,hy1_21(1:length(hy1_21/2subplot(4,8,28hy1_22 = abs(fft(y1_22;fhy1_22=0:dfs:fs_yu/8-dfs;fhy1_22 = fhy1_22(1:length(hy1_22/2; plot(fhy1_22,hy1_22(1:length(hy1_22/2subplot(4,8,29hy2_11 = abs(fft(y2_11;fhy2_11=0:dfs:fs_yu/8-dfs;fhy2_11 = fhy2_11(1:length(hy2_11/2; plot(fhy2_11,hy2_11(1:len

13、gth(hy2_11/2subplot(4,8,30hy2_12 = abs(fft(y2_12;fhy2_12=0:dfs:fs_yu/8-dfs;fhy2_12 = fhy2_12(1:length(hy2_12/2; plot(fhy2_12,hy2_12(1:length(hy2_12/2subplot(4,8,31hy2_21 = abs(fft(y2_21;fhy2_21=0:dfs:fs_yu/8-dfs;fhy2_21 = fhy2_21(1:length(hy2_21/2; plot(fhy2_21,hy2_21(1:length(hy2_21/2subplot(4,8,32

14、hy2_22 = abs(fft(y2_22;fhy2_22=0:dfs:fs_yu/8-dfs;fhy2_22 = fhy2_22(1:length(hy2_22/2; plot(fhy2_22,hy2_22(1:length(hy2_22/2%PCM編碼pcm1 = upcm(y1_11;pcm2 = upcm(y1_12;pcm3 = upcm(y1_21;pcm4 = upcm(y1_22;pcm5 = upcm(y2_11;pcm6 = upcm(y2_12;pcm7 = upcm(y2_21;pcm8 = upcm(y2_22;%decode解碼dpcm1 = dupcm(pcm1

15、,8;dpcm2 = dupcm(pcm2,8;dpcm3 = dupcm(pcm3,8;dpcm4 = dupcm(pcm4,8;dpcm5 = dupcm(pcm5,8;dpcm6 = dupcm(pcm6,8;dpcm7 = dupcm(pcm7,8;dpcm8 = dupcm(pcm8,8;%信號(hào)的合成y_he=hebing8(y1_11,y1_12,y1_21,y1_22,y2_11,y2_12,y2_21,y 2_22 ;%低頻信號(hào)8通道合成figure ;subplot(2,1,1 ;plot(y1_yu ;title('預(yù)濾波后的信號(hào)y1_yu' ;subplo

16、t(2,1,2plot(y_he ;%合成后的信號(hào)title('信宿端恢復(fù)信號(hào)y_he' ;wavwrite(y_he,fs_yu,16,'sound.wav'% sound(y,fs% sound(y1,fs% sound(y1_yu,fs_yusound(y_he,fs_yu%抗混迭濾波器function y1,fs_yu = pre_process(y,Fs %降低采樣率,抽取y = y(1:3:3*floor(length(y/3;fs_yu = Fs/3;fl = 300;fh = 3400;wn1 = fl/(fs_yu/2;wn2 = fh/(fs

17、_yu/2;wn=wn1,wn2;a = 1;N=70;b=fir1(N,wn,'bandpass'y1=filter(b,a,y;%信號(hào)插值子程序(完成信號(hào)的零插值和高通濾波 function f=interp1(x%實(shí)現(xiàn)信號(hào)的零插值f=interp(x,2 ;for i=1:length(xf(2*i=0 ;end%設(shè)計(jì)高通濾波器a1=fir1(200,1/2,'high'%完成對(duì)信號(hào)的高通濾波f=filter(a1,1,f;%樹(shù)形結(jié)構(gòu)分解子程序(完成信號(hào)的2通道分解以及降采樣率function y1,y2=fenjie(x,fsa1=fir1(100,1/

18、2; %頻譜的一半濾波a2=qmf(a1 ; %鏡像濾波器w1=filter(a1,1,x; %低通濾波w2=filter(a2,1,x; %高通濾波%抽取% y1=w1;y2=w2;y1=downsample(w1,2; %抽取2y2=downsample(w2,2; %抽取2%信號(hào)的8通道的分解子程序( function f1 f2 f3 f4 f5 f6 f7 f8=fenjie8(x,fs %1次分解y1,y2=fenjie(x,fs ;%y1%2次分解y1_1,y1_2=fenjie(y1,fs ;%3次分解f1,f2=fenjie(y1_1,fs ;f3,f4=fenjie(y1_

19、2,fs ;%y2%2次分解y2_1,y2_2=fenjie(y2,fs ; %3次分解f5,f6=fenjie(y2_1,fs ; f7,f8=fenjie(y2_2,fs ;%律PCM編碼function pcm = upcm(xL=length(x;for i=1:Lx(i=x(i/4;x(i=fix(x(i*4079;s=sign(x(i;if s<0pcm(i-1*8+1=0;elsepcm(i-1*8+1=1;endx(i=abs(x(i;p(i=x(i;if x(i<=15.5pcm(i-1*8+2:(i-1*8+4=0,0,0; else if x(i<=47

20、.5pcm(i-1*8+2:(i-1*8+4=0,0,1;p(i=floor(x(i-15.5/2;else if x(i<=111.5pcm(i-1*8+2:(i-1*8+4=0,1,0;p(i=floor(x(i-47.5/4;else if x(i<=239.5pcm(i-1*8+2:(i-1*8+4=0,1,1;p(i=floor(x(i-111.5/8;else if x(i<=495.5pcm(i-1*8+2:(i-1*8+4=1,0,0;p(i=floor(x(i-239.5/16;else if x(i<=1007.5pcm(i-1*8+2:(i-1*8

21、+4=1,0,1;p(i=floor(x(i-495.5/32;else if x(i<=2031.5pcm(i-1*8+2:(i-1*8+4=1,1,0;p(i=floor(x(i-1007.5/64;else if x(i<=4079.5pcm(i-1*8+2:(i-1*8+4=1,1,1;p(i=floor(x(i-2031.5/128; end;end;end;end; end;end;end;end;y=str2double(dec2bin(p(i;pcm(i-1*8+5=floor(y/1000;pcm(i-1*8+6=floor(mod(y,1000/100; pcm

22、(i-1*8+7=floor(mod(y,100/10; pcm(i-1*8+8=floor(mod(y,10;endend%u律pcm解碼function dpcm = dupcm(pcm,nbitL=length(pcm/nbit;for i=1:Lk(i=pcm(i-1*8+2*4+pcm(i-1*8+3*2+pcm(i-1*8+4;h(i=pcm(i-1*8+5*8+pcm(i-1*8+6*4+pcm(i-1*8+7*2+pc m(i-1*8+8;switch k(icase 0dpcm(i=h(i;case 1dpcm(i=16.5+h(i*2+1;case 2dpcm(i=49.5+h(i*4+2;c