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时间拉伸信号/移植python代码到matlab / octave

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我'm trying to port over paulstretch'的信号延伸到matlab / octave . https://github.com/paulnasca/paulstretch_python

请参阅下面的工作流程
Workflow I'm following

我可以将信号分成频率，幅度和相位，然后使用下面的代码将它们连接起来 . I'm having issues porting over the windowing segments, overlapping, and extending the signals. Any ideas?

Example matlab / octave code:

freq=[0;0.534974;1.06995;1.60492;2.1399]
amp1=[3.94414e-19;1.20523e-05;5.08643e-06;4.22469e-05;3.04322e-05]
phase=[0;0.0546221;-1.11534;-2.4926;-2.55601]

a1=[freq,amp1,phase];
t_rebuilt=linspace(0,2*pi,8000);
sigcomb=zeros(1,length(t_rebuilt));

kk=0
for kk=1:1:length(freq) %rebuild signal from collected freq,amplitudes,and phases
    sigcomb=sigcomb+a1(kk,2)*cos((a1(kk,1))*t_rebuilt+(a1(kk,3)));
end
normalize=(sigcomb/max(abs(sigcomb))*.8);
wavwrite([normalize'] ,8000,16,strcat('/tmp/test.wav'));

PS：这只是测试数据，为了获得音频信号，我将不得不使用更多的数据点，这将使问题变得混乱 .

我的想法是使用for循环来创建新信号的1秒wav文件，无论文件延伸多长时间，因为这将防止更大持续时间文件的阵列大小内存问题 . 然后使用像sox这样的其他程序将它们连接在一起，我已经想到了 .

PS：我正在使用八度音阶3.8.1，假设它与matlab兼容

python matlab signal-processing octave

1 回答

  • 3

    我试图构建一个没有循环的版本，并使用http://hypermammut.sourceforge.net/paulstretch/中的original.ogg . 我认为这是速度和内存大小之间的权衡（如果输入文件很长，下面的版本可能会占用大量内存）

    [d, fs, bps] = wavread ("original.wav");
printf ("Input duration = %.2f s\n", rows (d)/fs);

stretch = 8;
windowsize = round (0.25 * fs);

step = round ((windowsize/2)/stretch);

## original window
fwin = @(x) (1-x.^2).^1.25;
win = fwin (linspace (-1, 1, windowsize));

#win = hanning (windowsize)';

## build index
ind = (bsxfun (@plus, 1:windowsize, (0:step:(rows(d)-windowsize))'))';
cols_ind = columns(ind);

## Only use left channel
left_seg = d(:,1)(ind);
clear d ind;

## Apply window
left_seg = bsxfun (@times, left_seg, win');

## FFT
fft_left_seg = fft (left_seg);
clear left_seg

#keyboard

## overwrite phases with random phases
fft_rand_phase_left = fft_left_seg.*exp(i*2*pi*rand(size(fft_left_seg)));
clear fft_left_seg;

ifft_left = ifft (fft_rand_phase_left);
clear fft_rand_phase_left;

## window again
ifft_left = bsxfun (@times, real(ifft_left), win');

## restore the windowed segments with half windowsize shift
restore_step = floor(windowsize/2);
ind2 = (bsxfun (@plus, 1:windowsize, (0:restore_step:(restore_step*(cols_ind-1)))'))';
left_stretched = sparse (ind2(:), repmat(1:columns (ind2), rows(ind2), 1)(:), real(ifft_left(:)), ind2(end, end), cols_ind);
clear ind2 ifft_left win;

left_stretched = full (sum (left_stretched, 2));

## normalize
left_stretched = 0.8 * left_stretched./max(left_stretched);
printf ("Output duration = %.2f s\n", rows (left_stretched)/fs);
wavwrite (left_stretched, fs, bps, "streched.wav");
system("aplay streched.wav")
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