117 lines
2.5 KiB
Plaintext
Executable File
117 lines
2.5 KiB
Plaintext
Executable File
function eval_minblep()
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nsin = 4096;
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nharm_max = 1800;
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L = 48000/2;
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fs = 48000;
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fstart = 440;
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fend = 440;
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f2start = 200;
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f2end = 600;
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df = (fend-fstart)/L
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df2 = (f2end-f2start)/L
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saw = 0;
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% Calc blep table
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nharm = min(fix((fs/fstart/2.0)) + 1, nharm_max)
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Hw = kaiser(nsin, 8);
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xx = (0:nsin-1)/nsin - 0.5;
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for mm=1:nharm
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blitm(mm,:) = sin(xx*(mm-1)*pi)./sin(xx*pi).*Hw';
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blitm(mm,(find(isnan(blitm(mm,:))))) = (mm-1);
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end;
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for mm=1:nharm
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blepm(mm, :) = cumsum(blitm(mm, :))/nsin;
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end;
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w = [1; 2*ones(nsin/2-1,1); ones(1 - rem(nsin,2),1); zeros(nsin/2-1,1)]';
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for mm=1:nharm
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x_rc = real(ifft(log(abs(fft(blitm(mm, :))))));
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y = real(ifft(exp(fft(w.*x_rc))));
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minblepm(mm, :) = cumsum(y)/nsin;
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end;
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x = 0;
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x2 = 0;
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z = 0;
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f = fstart;
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f2 = f2start;
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tri = 0;
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NLG = 2;
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h = lagrange(1, 0.35)
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startup = 1;
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blep = 1;
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for n = 1:L,
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if x >= 1 || startup,
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x = 0;
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p = fs/f;
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dx = 1.0/p;
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m = min(fix((p/2.0)) + 1, nharm_max);
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blep_offset = 0;
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blep_gain = 1;
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z = ~z;
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end;
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if x2 >= 1 || startup,
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x2 =0;
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dx2 = f2/fs;
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% blep_offset = -(1-x);
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% blep_gain = x;
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% x = 0;
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% z = ~z;
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end;
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startup = 0;
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nn = (x+0.0)*(nsin-1) + 1;
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ni = fix(nn);
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nf = nn - ni;
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h = lagrange(NLG, nf);
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blep = h(NLG+1)*minblepm(m, max(1, ni));
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j = 1;
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for i = NLG:-1:1
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blep = blep + h(i)*minblepm(m, max(1, ni-j));
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j = j + 1;
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end;
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saw = x - blep_gain*blep + blep_offset;
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if (z == 0)
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sqr = blep;
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else
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sqr = 1-blep;
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end
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tri = tri + 2*(sqr-0.5)*dx;
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vsqr(n) = 0.5*(sqr-0.5);
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vtri(n) = tri;
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vsaw(n,1) = x;
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vsaw(n,2) = saw+0.5;
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vblep(n,1) = x;
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vblep(n,2) = blep;
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x = x + dx;
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f = f + df;
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x2 = x2 + dx2;
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f2 = f2 + df2;
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end;
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close all
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plot(1:nsin, blepm(fix(nharm/2), :), 1:nsin, minblepm(fix(nharm/2), :)); grid;
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wavwrite(0.5*vtri, fs, 'tri.wav');
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wavwrite(0.5*vsqr, fs, 'sqr.wav');
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wavwrite(0.5*vsaw, fs, 'saw.wav');
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wavwrite(0.5*vblep, fs, 'blep.wav');
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function h = lagrange(N, delay)
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%LAGRANGE h=lagrange(N,delay) returns order N FIR
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% filter h which implements given delay
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% (in samples). For best results,
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% delay should be near N/2 +/- 1.
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n = 0:N;
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h = ones(1,N+1);
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for k = 0:N
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index = find(n ~= k);
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h(index) = h(index) * (delay-k)./ (n(index)-k);
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end
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