[FFmpeg-soc] rfc: swscale-example weird output

[Michael Niedermayer]

On Tue, Jun 24, 2008 at 04:32:05PM +0200, Keiji Costantini wrote:
> I pulled out getcoeff() from initFilter(), as a step for simplify the code.
>
> The patch attached is the relevant part.
>
> This patch changes output of swscale-example
>
> for example:
>
> - yuv420p 96x96 -> rgb565   64x  64 flags=32 SSD=   79,  983,  746
> + yuv420p 96x96 -> rgb565   64x  64 flags=32 SSD=   77,  980,  738
>
> only a (relative) small number of lines are affected, but it's nonetheless 
> strange that moving code makes different output.
>
> Does anyone have any idea about how this can happens?

2 ideas
1. float rounding issues (try if using gcc -O0 for both, maybe that
   makes the differences dissapear)
2. uninitialized variables (valgrind should find them, also try disabling
   all mmx/sse/... if the other ideas havnt located the issue yet)

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

It is dangerous to be right in matters on which the established authorities
are wrong. -- Voltaire
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