Reducing color depth certainly affects picture quality from a technical
standpoint, but it sounds like you are in a position where you may need
choose the lesser of several picture degrading evils. <br>
<br>
720p is 30 frames/s. 1080i is 60 1920x540 fields/s. Consider
trying out your FX5200 with reduced color depth, the bandwidth needs
should be significant;y reduced. <br><br><div><span class="gmail_quote">On 1/28/06, <b class="gmail_sendername">Jerry Rubinow</b> <<a href="mailto:jerrymr@gmail.com">jerrymr@gmail.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
On 1/28/06, Kevin Kuphal <<a href="mailto:kuphal@dls.net">kuphal@dls.net</a>> wrote:<br>> Jerry Rubinow wrote:<br>> > On 1/28/06, Kevin Kuphal <<a href="mailto:kuphal@dls.net">kuphal@dls.net</a>> wrote:
<br>> ><br>> >> Jerry Rubinow wrote:<br>> >><br>> >>> I'm running myth with separate front/back end computers. The frontend<br>> >>> is a 2.8GHz P4 with 512MB ram, trying to display 720p HD, but I'm
<br>> >>> maxing out the CPU - myth ~65+%, X around 30+%. The video is at times<br>> >>> choppy when there's a lot of stuff changing in the frame. What can I<br>> >>> do to reduce CPU usage?
<br>> >>><br>> >>> Here's what I've done so far:<br>> >>> -compiled myth with --enable-proc-opt (using SVN from less than a week ago)<br>> >>> -using ratpoison for window manager
<br>> >>> -not using any deinterlacing<br>> >>><br>> >>> Note: XvMC is not an option.<br>> >>><br>> >>> I'm running FC4.<br>> >>><br>> >>> mythfrontend -v playback reports that it's using Xvideo, format I420,
<br>> >>> using realtime priority, video timing method: RTC (glx vsync not<br>> >>> supported in my driver). Then I get a lot of video ahead of audio<br>> >>> dropping frames messages, and then a lot of audio ahead of video
<br>> >>> messages.<br>> >>><br>> >>> /proc/meminfo says there's 100MB free while running myth, so I guess<br>> >>> it's not swapping.<br>> >>><br>> >>> What might be causing the high CPU? I've read about people with
<br>> >>> 2.4Ghz P4s not having a problem with HD, so it seems like there should<br>> >>> be something I can do. Would compiling my own kernel help? With what<br>> >>> options? Anything else I can try first?
<br>> >>><br>> >>><br>> >> Try using libmpeg2 for your playback. I'd suggest looking into<br>> >> hyperthreading support in your kernel to see if it is enabled. I<br>> >> believe this means using an SMP kernel. I'm not sure if that will make
<br>> >> a difference but it might. And lastly, your video card and drivers do<br>> >> help alot. I've struggled with my choice of ATI on one of my frontends<br>> >> and as I'm moving to HD, I'm biting the bullet and spending the $40 on
<br>> >> an Nvidia FX card and it will be one of the best $40 I've spent on my<br>> >> system as it means HD playback on my 2.4ghz Celeron with XvMC.<br>> >><br>> >> Kevin<br>> >>
<br>> ><br>> > Sorry, I left out that I'm using libmpeg2. Hyperthreading - hmm,<br>> > unfortunately I just checked and my CPU doesn't support hyperthreading<br>> > (it's a 533MHz bus 2.8GHz P4). I tried going the FX 5200 route, only
<br>> > to discover that I I can't achieve the transfer speeds I need over PCI<br>> > (my motherboard only has two slots, both PCI). 1280x720x(24 or 32)<br>> > bits, 30 frames a second (or 60, even worse) - PCI's max throughput is
<br>> > 600 to 700 Mbits/sec. I tried XvMC on the 5200 but it was always a<br>> > bit glitchy. The onboard graphics is AGP, but now instead of being<br>> > limited by bus speed, it's by CPU speed. Very frustrating, since it's
<br>> > soooo close to working properly.<br>> ><br>> ><br>> Hmm. I'm about to buy an FX5500 PCI for use in my frontend. Are you<br>> saying that you can't drive HD content to the PCI card because it is
<br>> PCI, not AGP? I'm using XvMC on my MX440 AGP and it works great with<br>> Myth and the 7676 Nvidia drivers on the SVN. You might want to give<br>> XvMC with that driver version another shot when 0.19 is released on your
<br>> FX5200. I've found it to be very solid.<br>><br>> Kevin<br><br>When I was trying to do HD over the PCI FX5200, I consistently had<br>slowness/skipped frames/stuttering. I eventually did some<br>calculations, and 720p at 24bits and 30 frames per second is 632
<br>Mbits/sec. I saw in the list archives that PCI's maximum transfer<br>speed ranges between 600-700 Mbits/sec. However, I think 24 bit video<br>is actually using 32 bips per pixels (alpha), and isn't HD refreshing<br>
at 60 frames/sec? So I must not be figuring something right, or else<br>I wouldn't be getting anything approaching viewable, but I was<br>actually getting something pretty close, so I'm not entirely sure<br>what's going on. But in any case, it seems like at a minimum, it's
<br>close to PCI's capacity.<br><br>As far as XvMC, I have no idea how the bandwidth of what's being<br>pushed to the card for XvMC compares that of non-XvMC (although I<br>would really like to know). I do know I had various problems with
<br>XvMC displaying correctly. Maybe due to bandwidth issues also, but I<br>don't know. But I will give it another shot at some point before I<br>throw in the towel on this computer and relegate it to an SD frontend<br>
for the tv upstairs.<br><br>-Jerry<br>_______________________________________________<br>mythtv-users mailing list<br><a href="mailto:mythtv-users@mythtv.org">mythtv-users@mythtv.org</a><br><a href="http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users">
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users</a><br></blockquote></div><br>