[Ffmpeg-devel] A question about 'dct_unquantize_h263_intra'
Wed Jan 3 00:26:11 CET 2007
On Tuesday 02 January 2007 22:51, Michael Niedermayer wrote:
> > > > 3. Processing extra elements after block[nCoeffs] is safe (up to but
> > > > not including block[(nCoeffs + 7) / 8 * 8])?
> > >
> > > block[0 .. 63] is always safe
> > > nCoeffs <= 64
> > So overwriting values in this buffer with garbage after nCoeffs is ok and
> > they are not used later anyway? Or at least processing them in the same
> > way as the previous elements is ok?
> the elements after nCoeffs should be 0 before and after *unquantize*
Thanks for the explanations, now everything is clear. Such extra constraints
information really helps to optimize code, but it is not quite obvious from
just plain C sources (for somebody not very experienced with video decoding
algorithms like me). I'm sorry for disturbing you with all these questions,
but better safe than sorry :)
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