[mythtv-users] tuning two-card systems ?

Maarten mythtv at ultratux.org
Tue Oct 19 11:57:56 UTC 2004


On Monday 18 October 2004 17:28, Adam Felson wrote:
> On Fri, 2004-10-15 at 22:25 +0200, Maarten wrote:
> > Hi,
> >
> > I just managed to build my two-card (bttv cards!) system.  It works fine
> > I guess, when recording two channels it is 0% idle, but still everything
> > appears to get to disk just fine for now.  I've seen no jerking or
> > hiccups or artifacts.  More on that setup below. First my problem...:
>
> Impossible.  I don't think you're not measuring your CPU usage
> correctly.  If you copied raw data to the hard drive (about 15G/hour?)
> you might get it down to 10%.

What are you saying exactly ? "down to" ??  You saying my CPU works too hard, 
or not hard enough ?  Are you aware that recording two bttv streams WILL 
fully peg the cpu on any but the fastest systems ?
(you do realize that saying "0% idle" is equal to "100% busy", at least ?)

> With RT-MPEG2 compression on an Athlon XP 3000, you need 10%/card.

There is no such thing as RT-Mpeg2 compression.  There is hardware mpeg2 
compression or software mpeg4 compression. Not mpeg2.  Let alone that that 
would never take only 10% CPU...

> For mpeg4 compression, you need 30%/card.

I'm doing mpeg4 compression.  And as I said, the fact that 1 card recording 
needs X% CPU load DOES NOT mean that 2 cards recording will need (2*X)% CPU.
It does not scale as you'd expect. 

> Or are you running at ridiculously low resolution like 240x160?

Again, what are you on about, does my cpu have too high a load, or too low ?!?
Cause I'm recording at a normal resolution, 480x480 @3000

Maarten



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