[MPlayer-dev-eng] enhancement for yuv4mpeg output driver

Michael Niedermayer michaelni at gmx.at
Fri Jan 21 00:26:53 CET 2005


On Friday 21 January 2005 00:12, D Richard Felker III wrote:
> On Thu, Jan 20, 2005 at 01:18:50PM -0800, Trent Piepho wrote:
> > On Thu, 20 Jan 2005, D Richard Felker III wrote:
> > > > any fraction that was converted to a floating point number back into
> > > > a fraction, that is theoretically impossible.
> > >
> > > of course. but if you know a bound on the denominator, and the bound
> > > is small enough, it IS possible to losslessly reverse the conversion
> > > to float.
> >
> > Only if the number of bits in the mantissa is smaller than the number of
> > bits in the original denominator.  Secondly, you don't know the original
> > bound on the denominator.
> Smaller?? Nonsense, you have things totally backwards. I'm a
> mathematician so I think there might just be a chance I understand
> these things... And I can assure you that it works fine in practice,
> at least if fps is given as a double. Perhaps with float it's
> problematic?

yes with floats its problematic, though IIRC the standard framerates worked 
except 60000/1001

we definitly should switch all float fps in mplayer/mencoder to doubles, not 
only because of av_d2q() but also because it could lead to av desync after a 
few days


"nothing is evil in the beginning. Even Sauron was not so." -- Elrond

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