[mythtv] Is there a magic resolution for recording ?
Fri, 13 Dec 2002 18:46:56 -0800
On Friday 13 December 2002 17:25, Christopher Mind spake thus:
> I am trying to tweak mythtv for my P3 1 Ghz machine. I am using MPEG4 as
> RTjpeg quality was poor on my system. I have 700 plus MB memory, an ATI
> TV wonder PCI card, Turtle Beach Santa Cruz, 100 Gig Hd, Nvidia Geforce
> Ti200 with TV out running Linux Mandrake 9 via TV out with a resolution
> of 640x480. Also using WindowMaker (which seems to work best the irxevent
> which gets confused with KDE) and Creative Infra Remote.
> So far I found that 640 x 480 is very very choppy at 1800 data rate or
> 400 x 300 with 2000 data rate seems to be ok for recording only. When I
> attempt to playback a recording at the same time that the machine is
> encoding, the program that is being encoded gets a little choppy. 352 x
> 300 seems to be fine but is a tad blurry at 2000 data rate. Does the cpu
> utilization scale with the resolution or data rate or are there optimal
> resolutions which will always result in less cpu utilization. I am not
> even aware of what other resolutions are possible. Also does lowering
> the mp3 quality reduce cpu utilization? I am using Maxquality 2,
> Minquality 15 and 3 for quality difference. Thanks
Similar situation (P3 1GHz, 764MB RAM), except that I can't capture at any
but an integer multiple of 240 for the y resolution (i.e. 240 or 480). The
resolution makes the biggest different to performance, and the codec is far
behind; I use 480x240 for my capture resolution, and speedwise it's just
fine. Plenty of leftover cycles. I'm using rtjpeg, and it's using an
NFS-mounted filesystem over a switched 100Mbps network for storage. No
problems there, either. I'm not currently using any audio compression,
mainly because I just haven't changed the settings from when I was trying
to get 640x(anything) working fast enough. 480x240 with a good quality
input signal looks just fine on my 32" flat-screen Sony TV.
I have recently acquired a Matrox Marvel G200TV, which does hardware MJPEG,
so we'll see how much of a performance hit is imposed by the network once I
get that installed and working.