[mythtv-users] Tweaks to playback HDTV

Jean Connelly unksme at gmail.com
Sun Jun 12 18:31:03 UTC 2005

Hi Paul et al,

I'm still stuck and would be grateful for any suggestiongs.

First, I picked up a new video card and processor.
Video Card: Nvidia FX5200
Processor: P4 3.06Mhz 533FSB

Regarding your checklist, here's what I've done so far.

> a) Right drivers for card with your kernel

Presently, I've got nvidia drivers version 7174.  I tried the 7664
drivers first, but XvMC didn't seem to work, so I went back to my 7174
drivers after reading more posts on the list that said 7664 didn't
have a great XvMC track record.  However, I still couldn't get any
XvMC stuff to work on 7174 under Myth (thought it does work with

> b) Proper AGP bus speed and AGP interface driver in use

I'm using agpart and I in /proc/drivers/nvidia/agp/status I see

Status : Enabled
Driver : AGPART
AGP Rate : 4x
Fast Writes : Enabled
SBA : Disabled

If I enable SBA, I get no video and can't get back to console when I start X.

> c) Proper user of openGL sync for retrace

I recompiled with --enable-opengl-vsync, but I've still got
Video Timing method: RTC

Where do I change that?

> d) Proper settings for deinterlace and, if used, xvmc 

I'm not even attempting deinterlaced playback yet.
As I mentioned, if I enable XvMC in myth, it segfaults when I try to
play back a capture.

> e) Proper sound settings and handling of 5.1 sound and multiple streams

I'm using ALSA:default and I'm getting sound.  I don't know what else
to check here.

> f) Real time scheduling of playback thread

When I run it sudo'd I get "Using Realtime Priority" but that has no
effect on my playback issues.

> g) Making sure disk or network speed is adequate

I'm working off a local disk.  
hdparm tells me that I've got 51 MB/sec on buffered disk reads.

> h) Nothing else sucking up CPU on the machine 

I'm not running anything else that is CPU intensive.

I'm now scoring like 3600 on glxgears.

Playback of my 1080i test stream is still impossible and I'm seeing
lots of "prebuffering pause" in the related terminal.

Is there a "Turn off annoying pauses" checkbox that I'm missing?


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