关于重采样的问题，麻烦大神帮忙看看

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自己在matlab里面编的一个重采样程序，但是效果很差，而且输出前一段数据有错，麻烦路过的大神帮我看看？

%input data
  \( d1 _# D8 J" `0 zfa = 8000; %%signal frequency
fs = 44100; %%44.1kHz sampling frequency
n = 1:64;
x = sin(2*pi*fa*n/fs);
lengthx = length(x);
  m- O% X; r* n) ?% ?: At = n*1000/128/fs;
, ~! |2 E6 M: B# Y6 i( @%plot(t,x);xlabel('time in ms');

% [y fs nbits] = wavread('acoustic.wav');
* H- t% ^% k* D/ ?+ b% x = y';
% lx = length(x);
! B- b( V: e, u0 a) a( O% k%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
& M9 y: I0 U" N) G- d- O' |3 I%Resample parameters
" y: I0 T3 s: zL1 = 8;
M1 = 7;
# i# ?# `, g+ x5 d$ I% Y. _* K% lL2 = 4;
: O$ A" O! O4 \% j- eM2 = 3;
! Z7 \" A5 i5 E; W$ ?: i, T0 OL3 = 10;
M3 = 7;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
6 h/ ]2 L. Z+ \+ S; {0 ]% \3 Q$ p+ b% e%%filters
load filter.mat
filter1 = b1;
$ ?6 k% W* M0 d/ G1 I) W) afilter2 = b2;
2 e' e( b. C# P/ a; \& |filter3 = b3;
1 F$ \; z! L4 d% j  K8 u%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1 x1 Q9 m1 ^' R* U%Initialize the subfilters

%First Filter
upFilter1 = decompose(filter1,L1);
+ R" v" [/ V% s' [5 o8 x1 TdownFilter1 = decompose(filter1,M1);

%Second Filter
upFilter2 = decompose(filter2,L2);
0 [; p4 E+ H6 ^2 t2 O! pdownFilter2 = decompose(filter2,M2);

%Second Filter
: ~$ B/ A% I1 E4 R& r" F) DupFilter3 = decompose(filter3,L3);
. x8 a- l% T  |/ [% c0 x% KdownFilter3 = decompose(filter3,M3);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Polyphase Filtering

%First Filter
%
" ?( N, H0 Y: W+ z8 \# e0 q( u2 i  t%%upsampling
, Y1 S& B8 i: }: w9 B( m& Hintermediatex1 = zeros(L1,length(x));
& c& e6 [5 D6 R' Yx11 = zeros(L1,length(x)*L1);
for i = 11
intermediatex1(i, = filter(upFilter1(i,,1,x); %%do the filtering before upsampling
7 O. z* o2 a% J. e  W0 _0 Tx11(i, = upsample(intermediatex1(i,:),L1); %%upsample by L, inserting L-1 zeros.
end

X1 = zeros(1,length(x)*L1);
for i = 1:length(x)
, v5 F7 K0 r7 L+ Y) {" o  qX1(L1*(i-1)+11*(i-1)+L1) = x11(:,(i-1)*L1+1)';
. H" M! k( T3 L, _$ wend
%%downsampling
4 y- P! }; V. ?0 E$ o' K: G3 @X1_down = [X1 zeros(1,M1-mod(length(X1),M1))];
, Z9 X8 W( ~# r" H; soutput1 = zeros(1,length(X1_down)/M1);
2 ]9 R& q9 a/ f4 ]7 e# X3 Ox1down = zeros(M1,length(X1_down)/M1);
  g) `7 S8 r$ c1 N$ h/ s: U0 Bx11down = x1down;
for i = 1:M1
for k = 1:length(X1_down)/M1
& Z: n1 [1 p, ?% ]" Jx1down(i,k) = X1_down(M1*(k-1)+i);
8 R5 y: |9 B+ i) vend
" h- I& }0 J: cx11down(i,:) = filter(downFilter1(1,:),1,x1down(i,:));
output1 = output1 + x11down(i,:);
end

%Second Filter
1 o% U3 T, C5 ]% f8 g0 `%
%%upsampling
intermediatex2 = zeros(L2,length(output1));
x22 = zeros(L2,length(output1)*L2);
for i = 12
intermediatex2(i,:) = filter(upFilter2(i,:),1,output1); %%do the filtering before upsampling
3 ^# b3 h/ I: y/ Dx22(i,:) = upsample(intermediatex2(i,:),L2); %%upsample by L, inserting L-1 zeros.
end

X2 = zeros(1,length(output1)*L2);
8 {  w7 O" i/ @for i = 1:length(output1)
X2(L2*(i-1)+1:L2*(i-1)+L2) = x22(:,(i-1)*L2+1)';
end
%%downsampling
X2_down = [X2 zeros(1,M2-mod(length(X2),M2))];
output2 = zeros(1,length(X2_down)/M2);
- `7 h) ~# r' e9 h4 Rx2down = zeros(M2,length(X2_down)/M2);
3 z, X9 V( D% z0 Y* Qx22down = x2down;
$ l8 q. D; }- f+ q7 I4 \for i = 1:M2
for k = 1:length(X2_down)/M2
x2down(i,k) = X2_down(M2*(k-1)+i);
end
% m( S. W* h- j! w4 J9 u1 `5 {8 ~x22down(i,:) = filter(downFilter2(1,:),1,x2down(i,:));
output2 = output2 + x22down(i,:);
( R* U! Z1 ~& [& n9 {1 [end

%Third Filter
%
%%upsampling
4 h- ^$ x! E! e9 i+ dintermediatex3 = zeros(L3,length(output2));
2 q9 A' F' n. V% jx33 = zeros(L3,length(output2)*L3);
+ q% y2 j9 w$ A0 [+ n$ Vfor i = 1:L3
+ F! F$ n5 R# i/ n' r* yintermediatex3(i,:) = filter(upFilter3(i,:),1,output2); %%do the filtering before upsampling
7 C: S- T3 o" E- l# ?8 `# W" T0 ux33(i,:) = upsample(intermediatex3(i,:),L3); %%upsample by L, inserting L-1 zeros.
end

X3 = zeros(1,length(output2)*L3);
for i = 1:length(output2)
X3(L3*(i-1)+1:L3*(i-1)+L3) = x33(:,(i-1)*L3+1)';
end
%%downsampling
; C- N* p' ^7 ^' c  u2 \X3_down = [X3 zeros(1,M3-mod(length(X3),M3))];
output3 = zeros(1,length(X3_down)/M3);
x3down = zeros(M3,length(X3_down)/M3);
+ I3 T5 {* t  a8 i6 X) Kx33down = x3down;
for i = 1:M3
for k = 1:length(X3_down)/M3
- }' m0 j) s: t; i: F) Ux3down(i,k) = X3_down(M3*(k-1)+i);
4 O2 K. w* h4 k. Z/ @end
x33down(i,:) = filter(downFilter3(1,:),1,x3down(i,:));
output3 = output3 + x33down(i,:);
end

output3 = output3/max(output3);
lout = length(output3);

nx = 1:length(output3);
xorigin = sin(2*pi*fa*nx/96000);
( u* {) ]3 [7 k4 @error1 = xorigin - output3;
yin = [0 0 resample(x,320,147)];
error2 = xorigin - yin;

figure(1)
subplot(3,1,1);plot(xorigin);title('True Signal');
subplot(3,1,2);plot(output3);title('Resampled Signal');
subplot(3,1,3);plot(error1);title('Error');

figure(2)
subplot(3,1,1);plot(xorigin);title('True Signal');
subplot(3,1,2);plot(yin);title('Built-in Resampled Signal');
' P6 M" i- F0 Isubplot(3,1,3);plot(error2);title('Error');

---

function x_decompose = decompose(x,factor)
( y& m$ J) L# m* xlx = length(x);

if mod(lx,factor) ~= 0;
0 }+ ?+ M% c3 ?4 z$ w$ N! HX = [x zeros(1,factor-mod(lx,factor))];
; c! S! n- {$ n/ V/ F6 [: selse
. f) S- ^0 q* xX = x;
* j4 K% ]0 h9 s& l6 Yend

x_decompose = zeros(factor,length(X)/factor);
" Z# T% v" k& z9 {0 Ffor i = 1:factor
  a- Z/ m7 ~* D, ofor k = 1:length(X)/factor
x_decompose(i,k) = X(factor*(k-1)+i);
end
; ^$ I( F. a( A- j9 P7 _end

end

%Filter Generation
$ T- k! _  k. Y: cfs = 44100;
L1 = 8;
M1 = 7;
+ a) R9 U: ], W$ ZL2 = 4;
5 ~- l; d; t7 A( j$ VM2 = 3;
- w2 |: {& m+ n+ D) c& CL3 = 10;
M3 = 7;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
, E7 X# f. v; Y! w$ e; d( Z%%First Filter
3 r5 ^) Z: Z2 P0 xf1 = [20000 24000];
' ^" V) u% @# T6 W% Q8 g  Sa1 = [1 0];
dev1 = [0.01 10^-8];
fs1 = fs*L1;
[n1 fo1 ao1 w1] = firpmord(f1,a1,dev1,fs1);
b1 = firpm(n1,fo1,ao1,w1);

%%Second Filter
& G. Z( s; z7 o& G* K& H0 l- l& zf2 = [20160 30240];
+ P  Q2 D8 {9 [4 k1 Y) _: Aa2 = [1 0];
dev2 = [0.01 10^-8];
fs2 = fs1*L2/M1;
[n2 fo2 ao2 w2] = firpmord(f2,a2,dev2,fs2);
  m7 z8 b+ x4 p) }! Nb2 = firpm(n2,fo2,ao2,w2);

%%Third Filter
f3 = [16800 50400];
a3 = [1 0];
dev3 = [0.01 10^-8];
fs3 = fs2*L3/M2;
[n3 fo3 ao3 w3] = firpmord(f3,a3,dev3,fs3);
% m- H' ^3 C5 K$ Ob3 = firpm(n3,fo3,ao3,w3);

* \9 M" K8 C0 M
& g4 j) a; q" U7 O

木棉花_MM

这个……