Jerry Rubinow wrote: >On 1/28/06, Kevin Kuphal <[EMAIL PROTECTED]> wrote: > > >>Jerry Rubinow wrote: >> >> >>>On 1/28/06, Kevin Kuphal <[EMAIL PROTECTED]> wrote: >>> >>> >>> >>>>Jerry Rubinow wrote: >>>> >>>> >>>> >>>>>I'm running myth with separate front/back end computers. The frontend >>>>>is a 2.8GHz P4 with 512MB ram, trying to display 720p HD, but I'm >>>>>maxing out the CPU - myth ~65+%, X around 30+%. The video is at times >>>>>choppy when there's a lot of stuff changing in the frame. What can I >>>>>do to reduce CPU usage? >>>>> >>>>>Here's what I've done so far: >>>>>-compiled myth with --enable-proc-opt (using SVN from less than a week ago) >>>>>-using ratpoison for window manager >>>>>-not using any deinterlacing >>>>> >>>>>Note: XvMC is not an option. >>>>> >>>>>I'm running FC4. >>>>> >>>>>mythfrontend -v playback reports that it's using Xvideo, format I420, >>>>>using realtime priority, video timing method: RTC (glx vsync not >>>>>supported in my driver). Then I get a lot of video ahead of audio >>>>>dropping frames messages, and then a lot of audio ahead of video >>>>>messages. >>>>> >>>>>/proc/meminfo says there's 100MB free while running myth, so I guess >>>>>it's not swapping. >>>>> >>>>>What might be causing the high CPU? I've read about people with >>>>>2.4Ghz P4s not having a problem with HD, so it seems like there should >>>>>be something I can do. Would compiling my own kernel help? With what >>>>>options? Anything else I can try first? >>>>> >>>>> >>>>> >>>>> >>>>Try using libmpeg2 for your playback. I'd suggest looking into >>>>hyperthreading support in your kernel to see if it is enabled. I >>>>believe this means using an SMP kernel. I'm not sure if that will make >>>>a difference but it might. And lastly, your video card and drivers do >>>>help alot. I've struggled with my choice of ATI on one of my frontends >>>>and as I'm moving to HD, I'm biting the bullet and spending the $40 on >>>>an Nvidia FX card and it will be one of the best $40 I've spent on my >>>>system as it means HD playback on my 2.4ghz Celeron with XvMC. >>>> >>>>Kevin >>>> >>>> >>>> >>>Sorry, I left out that I'm using libmpeg2. Hyperthreading - hmm, >>>unfortunately I just checked and my CPU doesn't support hyperthreading >>>(it's a 533MHz bus 2.8GHz P4). I tried going the FX 5200 route, only >>>to discover that I I can't achieve the transfer speeds I need over PCI >>>(my motherboard only has two slots, both PCI). 1280x720x(24 or 32) >>>bits, 30 frames a second (or 60, even worse) - PCI's max throughput is >>>600 to 700 Mbits/sec. I tried XvMC on the 5200 but it was always a >>>bit glitchy. The onboard graphics is AGP, but now instead of being >>>limited by bus speed, it's by CPU speed. Very frustrating, since it's >>>soooo close to working properly. >>> >>> >>> >>> >>Hmm. I'm about to buy an FX5500 PCI for use in my frontend. Are you >>saying that you can't drive HD content to the PCI card because it is >>PCI, not AGP? I'm using XvMC on my MX440 AGP and it works great with >>Myth and the 7676 Nvidia drivers on the SVN. You might want to give >>XvMC with that driver version another shot when 0.19 is released on your >>FX5200. I've found it to be very solid. >> >>Kevin >> >> > >When I was trying to do HD over the PCI FX5200, I consistently had >slowness/skipped frames/stuttering. I eventually did some >calculations, and 720p at 24bits and 30 frames per second is 632 >Mbits/sec. I saw in the list archives that PCI's maximum transfer >speed ranges between 600-700 Mbits/sec. However, I think 24 bit video >is actually using 32 bips per pixels (alpha), and isn't HD refreshing >at 60 frames/sec? So I must not be figuring something right, or else > > > Hi Jerry
Video comes to about 30 Mbytes per second - which would be about 240 Mbits per second, as you're almost a multiple of 3 bigger I'm guessing you assumed 24bits per colour channel? Where it is actually 8bits per colour channel (PAL is 3*720*576*25 bytes). This ought to be well inside the speed of PCI - if you think about it, uncompressed PVRs have existed for some years now and the harddrives on these use the PCI bus. So, it's unlikely you've exceeded the bandwidth. 60 frame/sec is interlaced NTSC (720p is progressive) - I wouldn't think this would increase the bandwidth unless you were doing something like bob deinterlace on your CPU (I'm guessing here), as each frame should have half the number of lines. I don't know about XvMC - I don't know how compressed the data is by the time it gets to the card - you'd hope it was a little compressed though! Ta Dan _______________________________________________ mythtv-users mailing list [email protected] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
