[Ffmpeg-devel] [BUG] H.264 + AltiVec == heavy artefacts

Romain Dolbeau romain
Fri Oct 7 17:33:13 CEST 2005

Diego Biurrun wrote:

>>So now let's try the usual suspects: what compiler, what OS, what CPU(s),
>>what extra compiler option(s) are you using ?

> Debian unstable
> PowerBook G4 7447A processor running at 1500MHz
> gcc (GCC) 4.0.2 (Debian 4.0.2-2)
> I get the same results with
> gcc-3.3 (GCC) 3.3.6 (Debian 1:3.3.6-10)
> gcc-3.4 (GCC) 3.4.5 20050821 (prerelease) (Debian 3.4.4-8)

> http://mplayerhq.hu/~diego/bbc-africa_m720p.mov

This sample works fine for me in OSX. It's completely broken
under my Debian/ppc stable. Apparently even in linux,
pointer are aligned on a 16 bytes boundary and strides
are multiple of 16, but I didn't have the time to check
in details, so I may have missed a vector.

This starts looking like a broken compiler to me ; the hadamard
functions were known to be broken with some fsf-gcc and are
disabled in non-darwin OSes already :-(

Romain Dolbeau
<romain at dolbeau.org>

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