[Csnd] PVS delay explanation?

Hey hey,
working with the fantastic PVS opcodes again, I experimentally worked out the delay to perfectly synchronise the original audio input with the PVS output. Using pvsanal and pvsynth respectively, with an FFT and window size of 1024 and an overlap of 256, I arrived at )1024 + 512) samples delay.

Now why the 512? My intuition was to have the extra 256. Are the other 256 independent of the analysis parameters or linked to either of the three parameters defining the FFT analysis?

I think I asked about this before, but somehow didn't fully appreciate the answer. Though that was probably some years ago. :slight_smile:

Best wishes,

Jeanette

Maybe the simplest way to think of this is:

1) it takes 1 hopsize to start getting the data in
2) it takes 1 fftsize to do the complete transform
3) it takes 1 hopsize to start getting the data out

So it comes out as 2 hopsizes + 1 framesize.

For a more detailed answer, you can read the code in pvsanal.c and work it out.
Maybe Richard, who wrote this, would be able to add to this.

Hi Victor,
thanks a lot. I think this is detailed enough for my purposes.

Best wishes,

Jeanette

Nothing to add, I think that is exactly it. I can't recall now if I ever did the comparison test (such a long time ago - all developed and tested on a Pentium II at 333MHz!), but using pvsaddsyn for the output should reveal the slightly shorter overall delay, as the additive resynthesis has no need for the overlap aspect.

Richard Dobson

Maybe the simplest way to think of this is:

1) it takes 1 hopsize to start getting the data in
2) it takes 1 fftsize to do the complete transform
3) it takes 1 hopsize to start getting the data out

So it comes out as 2 hopsizes + 1 framesize.

For a more detailed answer, you can read the code in pvsanal.c and work it out.
Maybe Richard, who wrote this, would be able to add to this.

Prof. Victor Lazzarini
Maynooth University
Ireland

...

Csound mailing list
Csound@listserv.heanet.ie
https://listserv.heanet.ie/cgi-bin/wa?A0=CSOUND
Send bugs reports to
        Issues · csound/csound · GitHub
Discussions of bugs and features can be posted here