[mythtv] performance

Monty Walls mythtv-dev@snowman.net
Fri, 13 Dec 2002 17:45:28 -0600

On Fri, 13 Dec 2002 15:20:52 -0800
"Chuck Ferring" <chuckf@fullplaymedia.com> wrote:

> I noticed that watching live TV uses 95-100% CPU time using mpeg4
> encoding at 640 X 480.  My system is an Athlon XP 1800 with 256M PC 2100
> ram.  Running hdparm tells me that my hard drive throughput is about 23
> Mb / sec.  Is this performance about what I should expect?  If so, what
> would be the best way to increase performance, more memory, faster
> processor or faster hard drive?

More CPU!!!!!

MythTV when running at 640x480 with mpeg4 is almost totally
compute bound.  About the only time I see any i-o problems
is on ide machine using RTjpeg since the data rates go way up.

As an aside:

640x480*29.97 fps * 24bit = 27mb/s

So tvcard -> memory = 27mbs 
So memory -> agp = 27mbs
So cpu -> disk = .5 mbs
+ system overhead/compression overhead....

Just remember that VIA PCI throughput isn't all that great 
so try to avoid saturating it.

> Thanks.

-Monty Walls (mwalls@castor.oktax.state.ok.us)
-	MIS, Oklahoma Tax Commission
- My opinions are my own, my employer knows nothing about it.