Bonjour Cedric, On 10/21/2011 10:03 AM, Cedric Roux wrote: > ----- Original Message ----- >> From: "Fons Adriaensen" <fons@xxxxxxxxxxxxxx> >> I don't think that the DSP code is doing what the parameters >> would suggest - the visual results don't match. >> >> Could it be that 'l' sets the window size ? It shouldn't, >> the window size should be the fft size. Then, if you have >> both 'l' and 's', then both together determine the overlap, >> so this can't be a separate parameter. >> >> Also, with just a 1 kHz sine as the input, I'd expect all >> spectra to be identical, but they are not... > > that's a bit unfortunate... > I'll have a look at all this, thanks to report. > > for s, l and overlap: > s is the fft size (let's say 1024 for an example) > l is the sample count, if set at 512 we compute an fft > each 512 samples. Since fft size is 1024, we append with 512 zeros. > Overlap is how much we advance the input to compute the > next fft. In our example: set to 0, at time 0 we compute with input[0..511] > and next iteration we compute with x[512..1023]. > Set to 0.5, next iteration is computed with x[256..767]. > Set to 1, next iteration would compute with x[1..512] (normally it should > not advance at all, so setting to 1 is in fact setting to 1-epsilon with > epsilon such that we advance by 1 sample) > > The window is computed on the l samples. > > I guess all this is not done the standard way... (and I hope > the code does what I say above...) > > For your 1k sine, I'll have a look. If you have some time, > it would be great to have a screenshot just > to be sure I see the same thing than you? You can compare it to http://www.baudline.com/ which can also provide some inspiration on default settings. jaaa and japa may come in handy to verify the math. > And thanks for the testing. The code does not crash on at least > three and half computers! that's great. Many thanks for taking up that task. A FLOSS version of baudline has been on my wishlist for a while. Cheers! robin _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
