[FFmpeg-devel] [PATCH v1] filter select - avoid 2 times rounding

[Ulf Zibis]

Am 19.07.19 um 22:46 schrieb Hendrik Leppkes:
> This has absolutely nothing to do with "rounding", since there is no
> rounding being performed, but all to do with that floating point
> arithmetic is just always inaccurate.

Floating point representation and arithmetic *is* "aproximating
(=rounding) a real (and here a rational, wich is a subset of real)
value", see 1st paragraph here:
https://en.wikipedia.org/wiki/Floating-point_arithmetic


> What this comes down to is this:
>
> a) 130560 / 12800
> b) 130560 * (1 / 12800)
>
> There is no rounding there, since everything is kept in full double
> precision. But anyone working with doubles should know that they are
> inherently inaccurate.
> Instead of re-ordering the floating point math to somehow give you a
> slightly more favorable result, maybe there should be actual rounding
> to something reasonable when its evaluating the conditions, so that
> such inaccuracies just don't matter in the first place?
$1 The captain is always right.

$2 If the captain fails, see $1.

0 against 327 fails in 2500 frames is a "slightly more favorable
result". See my last post from 22:23 CEST.

-Ulf