Hi Rich,
As Richard said the 1SFT data is ready to go into the IFFT. A different
story is what you need to do afterwards to
get a smooth synthesized sound. I am not sure what *window* you are
talking about because there are two involved in the
process. The analysis window, which by default is a BlackmanHarris92
with a 75% overlap. You need to multiply by the
inverse of this window after the SFFT. And then a completely independent
triangular window with a size equal to twice
the analysis hop and overlap 50%. This is the one in charge of getting a
smooth overlap and add process in place.
Hope it helps.
X
Rich E wrote:
Okay, I didn't think of looking for the overlap size by checking the
timestamps, but that seems obvious now.. thanks! I have found there
are many things preventing the SDIF files from being used in real-time
(such as the 1TRC frames not containing birth and death information).
So I am already buffering the data in a format that can be used in
real-time, so finding the overlap before sysnthesis-time shouldn't be
a problem.
However, I do not see the 1WIN matrix within the SMS-produced files.
I assumed it is a triangle window with an overlap factor of 2 (this is
the default settings in SMSTools), but of course this can be changed,
in which case I would not know how to find the windowing function.
But I tried these settings without success (in comparison to
SMSTools-produced residual sound), so I am still looking for the
correct ones.
cheers,
rich
On Dec 14, 2007 6:30 PM, Richard Dobson
<[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Rich E wrote:
> Okay, sorry for getting into too much pd stuff... I basically just
> need to know what needs to be done to the 1STF data before I can
> synthesize it. Is it ready to go, or is windowing still necessary?
> Should the frames be overlapped?
>
It's plain real/imaginary DFT data. SO in that sense yes it is
ready to
go straight into the IFFT. It will almost certainly require windowing.
If you haven't already done so, you will neded to check the formal
definition of the 1STF format e.g. at:
http://www.cnmat.berkeley.edu/SDIF/FrameTypes.html#1STF
SDIF is famous/notorious for being particularly "loose" about
definitions and content. In short, each frame (matrix) is time-stamped
(from the centre of the window, because they like doing things that
way), and you have to determine the overlap from that (which means you
have to read at least two frames before you can start rendering,
so this
is not a true real-time streaming format; one would assume the
overlap
is constant, but the format does not see the need to mandate it);
there
should be a 1WIN matrix that defines the window to use. Beyond
that, all
I can say is "good luck"!
Richard Dobson
_______________________________________________
CLAM mailing list
[email protected] <mailto:[email protected]>
http://www.iua.upf.es/mtg/clam
------------------------------------------------------------------------
_______________________________________________
CLAM mailing list
[email protected]
http://www.iua.upf.es/mtg/clam
_______________________________________________
CLAM mailing list
[email protected]
http://www.iua.upf.es/mtg/clam
