view extra/sinemodel.m @ 13:844d341cf643 tip

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function y = sinemodel(x, w, N, t)
% Analysis/synthesis of a sound using the sinusoidal model
% x: input sound, w: analysis window (odd size), N: FFT size,
% t: threshold in negative dB, y: output sound
M = length(w); % analysis window size
Ns= 1024; % FFT size for synthesis (even)
H = 256; % analysis/synthesishop size
N2= N/2+1; % size of positive spectrum
soundlength = length(x); % length of input sound array
hNs = Ns/2; % half synthesis window size
hM = (M-1)/2; % half analysis window size
pin = max(N2,1+hM); % initialize sound pointer to middle of analysis window
pend = soundlength-max(N2,hM); % last sample to start a frame
fftbuffer = zeros(N,1); % initialize buffer for FFT
y = zeros(soundlength,1); % initialize output array
w = w/sum(w); % normalize analysis window
sw = zeros(Ns,1);
ow = triang(2*H-1); % overlapping window (triangular window to avoid too much overlapping)
ovidx = Ns/2+1-H+1:Ns/2+H; % overlap indexes
sw(ovidx) = ow(1:2*H-1);
bh = blackmanharris(Ns); % synthesis window
bh = bh ./ sum(bh); % normalize synthesis window
sw(ovidx) = sw(ovidx) ./ bh(ovidx);
while pin<pend
%-----analysis-----%
xw = x(pin-hM:pin+hM).*w(1:M); % window the input sound
%zero phased window
fftbuffer(:)=0;
fftbuffer(1:(M+1)/2) = xw((M+1)/2:M); % zero-phase window in fftbuffer
fftbuffer(N-(M-1)/2+1:N) = xw(1:(M-1)/2);

X = fft(fftbuffer); % compute the FFT
mX = 20*log10(abs(X(1:N2))); % magnitude spectrum of positive frequencies
pX = unwrap(angle(X(1:N/2+1))); % unwrapped phase spectrum
ploc = 1 + find((mX(2:N2-1)>t) .* (mX(2:N2-1)>mX(3:N2)).* (mX(2:N2-1)>mX(1:N2-2))); % find peaks
[ploc,pmag,pphase] = peakinterp(mX,pX,ploc); % refine peak values
%-----synthesis-----%
plocs = (ploc-1)*Ns/N+1; % adapt peak locations to synthesis FFT
Y = genspecsines(plocs,pmag,pphase,Ns); % generate spec sines
yw = fftshift(real(ifft(Y))); % time domain of sinusoids
y(pin-hNs:pin+hNs-1) = y(pin-hNs:pin+hNs-1) + sw.*yw(1:Ns); % overlap-add
pin = pin+H; % advance the sound pointer
end