[mythtv-users] More HD stuttering
ctrown at safe-mail.net
Fri Dec 2 12:59:34 EST 2005
Jean Connelly wrote:
> The system is a 3.06 GHz P4 running Fedora Core 3. The video Card
> is a NVidia 5200FX. For capture, all I have is a HD3000. I've checked
> that DMA is working on all the drives. I built mythtv from stable
> source, 0.18.1. I used the following configure options:
> --enable-xvmc --enable-opengl-vsync --enable-dvb
> --dvb-path=/lib/modules/2.6.12- 1.1381_FC3smp/build/include
> --disable-firewire --disable-joystick --disable-ivtv --enable-proc-opt
> --disable-xvmc-vld --enable-opengl-vsync
> I have close to an identical system; and I have what is probably
> equivalent stuttering. HDTV (live or recorded) is totally unplayable in
> myth. I have tried with and without opengl sync. I can't find the xvmc
> option in the gui with this myth version to disable xvmc for testing.
> Recorded 1080i plays badly (with frequent pauses and never with audio
> sync) in mplayer with xvmc and ffmpeg12mc and plays even worse without
> xvmc. I'll try transcoding my latest sample clips to see if they are
> fine when played back at standard resolutions.
> I've got
> 3.06 GHz P4 (which is a 533Mhz FSB chip)
> 512 MB Ram
> BE7-RAID mobo
> Nvidia 5200FX
> Fedora Core 3
> Night before last's myth svn. No deinterlacing requested.
> Prebuffer pauses all over the place.
> I think what we really need is an hdtv playback test suite external to
> myth to get better benchmarks on actual system performance. From
> previous posts to the list ("well I got *my* P4 1.4Ghz system to
> playback hdtv") I think that my system *should* be able to playback hdtv
> without issue, but perhaps there are some motherboard weaknesses or such
> that make it impossible.
After some tinkering, I found out what the problem was. I think.
I was trying to play a 1080i stream on a 720p screen. What I think
was happening was that the 1080i stream could not be rendered using XVMC
to 720p. It had to me done in software, ie: the CPU. When I changed
the display to 1920x1080, XVMC kicked in and the image played nicely, so
long as it was done by root. No, I wasn't using xrandr. I will when I
get everything going under Core 4.
This prompted my to "upgrade" to Core 4 so I can get realtime
priority threads via PAM. I don't really consider it an upgrade. My
experience is that Core 4 has more issues than Core 3. Case in point,
try compiling 18.1 stable with GCC4. But I like the idea of running
mythfrontend as root more distasteful than the problems.
"Those who would give up essential liberty to purchase a little
temporary safety deserve neither liberty nor safety" -- Benjamin
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