[Ffmpeg-devel] [RFC] mdct window generation

[Michael Niedermayer]

Hi

On Mon, Jul 10, 2006 at 02:27:39AM +0200, Benjamin Larsson wrote:
> Michael Niedermayer wrote:
> 
> >Hi
> >
> >[...]
> >
> >>> 
> >>>
> >>>      
> >>>
> >>Ok, then we should do the same with the runtime generated fft and mdct
> >>transform twiddle factors. How should it be implemented, is there some
> >>code already that does this ?
> >>    
> >>
> >
> >one possibility is:
> >
> >float window[Y][X];
> >
> >...
> >
> >    if(!window[needed_window][X-1])
> >        init_window(needed_window);
> >  
> >
> So there is no good solution that only allocate the needed memory and
> share that in a safe way ?

the OS will allocate the memory when it is first written to ...
allocating the memory with malloc() would need some locking
or you might end up loosing some memory
and if you are so terribly concerned about the window size, then
why not calculate the windows on the fly, instead of storing them?
the idea here would be to store just a few coefficients and interpolate
with some low order polynomials ...

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
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