[mythtv-users] bttv: too high load (esp. on replay)

Petr Stehlik pstehlik at sophics.cz
Sat Dec 17 06:47:59 EST 2005


I've built a BE/FE machine with 64bit Sempron 3100+ running 32-bit
Debian plus nVIDIA FX5200 with accelerated driver (but couldn't get AGP
working so running with NvAGP "0"). Storing data to a fast SATA disk
(ext3 noatime).

Grabbing full PAL from bttv to nuv takes more than 60% of CPU (I think
it's a bit too much but I could live with that eventually). Problem is
that replaying such recording takes another 55% of CPU, so LiveTV is
impossible (60+55 > 100). Worse yet, the bttv quality is very bad so I
need to denoise it a bit. "quickdnr" takes another 20% of CPU. That's
scary (55% -> 75%).

During the replay mythfrontend eats 35% (55% with quickdnr) and another
20% eats the Xorg process. Why the X running in fullscreen (720x576)
consumes that much CPU? Am I missing Xv? It should be running with

BTW, it's not broken completely because DVB-S LiveTV takes just 7% CPU
(13% of CPU running at half of normal frequency thanks to Cool'n'Quiet).

Can someone please tell me if it's normal for MythTV to create that high
load. If not, what to fix? If yes, how to work around it?

On my old Athlon 2200+ I am able to grab D1/2 PAL, crop, denoise,
deinterlace and encode into MPEG4 in realtime with just 50% of CPU
(mencoder). That's why I am surprised that 3100+ is so overloaded.



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