[MPlayer-users] Playing ultra-high resolution video

[Reimar Döffinger]

Hello,
On Thu, May 17, 2007 at 01:15:05PM -0600, Loren Merritt wrote:
>  On Thu, 17 May 2007, Reimar Döffinger wrote:
> > How do you know the bandwidth is there? The normal way to do this means
> > the OS must copy the data out of the cache into application memory and
> > then from application memory to video memory (if you're unlucky
> > involving yet anotehr copy to memory). Can your memory really handle the
> > 1.5 to 2.2 GB/s needed for that, in addition to the load caused by
> > trashing the cache completely during each copy?
> 
>  Does it trash the cache? Both MPlayer's fast_memcpy and glibc's memcpy use 
>  prefetchnta/movntq for sufficiently large copies.

The 32 bit libcs almost certainly don't use these. My 64 bit one does
though. So in that regard a 64 bit compiled MPlayer might really help.
I don't know how exactly different CPUs handle prefetchnta.
Either way, not having the full frame in cache is likely to hurt even
when copying as directly to video memory as MPlayer is able to.

Greetings,
Reimar Döffinger