[mythtv-users] ffmpeg and multiple CPUs. Was: Should I beswitching to 0.21?

[Moasat]

> -----Original Message-----
> From: mythtv-users-bounces at mythtv.org
> [mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Phil Bridges
> Sent: Monday, April 14, 2008 12:43 PM
> To: Discussion about mythtv
> Subject: Re: [mythtv-users] ffmpeg and multiple CPUs. Was:
> Should I beswitching to 0.21?
>
> On Mon, Apr 14, 2008 at 1:26 PM, Brian Wood <beww at beww.org> wrote:
> >
> >  On Apr 14, 2008, at 11:19 AM, Phil Bridges wrote:
> >  >
> >  > That is interesting.  I wonder if the same applies for AMD chips?
> >  > IIRC, the on-screen documentation recommends not using libmpeg2
> > with  > 64-bit processors, but I may be incorrect.
> >
> >  Would this apply to 64-bit CPUs running 32-bit code? Or just to
> > machines running 64-bit code?
> >
> >  I have yet to become aware of any advantage to running
> Myth in 64-bit
> > mode, but the mpeg libs and possible commflag are where I
> would expect
> > to see a difference if it exists.
> >
> >  The theoretical benefits of 64-bits might well be negated by the
> > optimization over the years of the code for 32-bit environments.
> >
>
> Yeah - I meant 64-bit code (x86_64).  Was I not wise to
> install the 64-bit version of Gentoo when I re-installed it
> on one of my frontends yesterday?

If the compiler is doing its job correctly, code compiled for a 64-bit
processor gains the benefits of 8 extra registers and native 64-bit integer
math.  While we may be talking nano-seconds, think of the time it takes to
load a value from memry instead of keeping it in a register.