[FFmpeg-devel] [PATCH][RFC] variable frame sizes
Michael Niedermayer
michaelni
Thu Jun 4 19:59:16 CEST 2009
On Tue, Jun 02, 2009 at 08:21:38AM -0700, Eric Buehl wrote:
> >
> > > + /* keep bands proportional to the frame size */
> > > + ost->topBand = MAKE_EVEN(ist->st->codec->height *
> > ost->original_topBand / ost->original_height);
> > > + ost->bottomBand = MAKE_EVEN(ist->st->codec->height *
> > ost->original_bottomBand / ost->original_height);
> > > + ost->leftBand = MAKE_EVEN(ist->st->codec->width *
> > ost->original_leftBand / ost->original_width);
> > > + ost->rightBand = MAKE_EVEN(ist->st->codec->width *
> > ost->original_rightBand / ost->original_width);
> >
> > The multiply can overflow
> >
> > also its not guranteed that the new *Band values fit in 32bit, one
> > probably could generate a mallicious stream where this is not the case
> > (this would even affect float code probably)
> >
>
> Would it be acceptable to multiply into a 64 bit int, divide, and then
> truncate back to 32?
i dont think thats sufficient to avoid problems, have you thought about
what happens when the result does not fit in 32bit ?
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
If you really think that XML is the answer, then you definitly missunderstood
the question -- Attila Kinali
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