On Tue, Oct 13, 2015 at 01:33:07PM +0200, Christophe Gisquet wrote: > Hi, > > 2015-10-13 13:10 GMT+02:00 Michael Niedermayer <mich...@niedermayer.cc>: > > hmm, iam a bit concerned that adding the rounder (which effectively is > > 0.5) causes a overflow, that would if iam not mistaken imlpy that > > things are very close to overflowing already without it > > It's true, but the immediate cause here is the input coeffs > overflowing (ie, once the rounder is added, a positive value is seen > as a negative one to pmaddwd).
have you tried using saturating additions for the rounder ? > > Otherwise, your concern is basically whether 32bits arithmetics is > enough: then simple_idct may also overflows on x86_32. [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I have often repented speaking, but never of holding my tongue. -- Xenocrates
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