[mythtv-users] Live TV Pauses

Kevin Stussman kevins at solium.com
Wed Jun 30 12:41:25 EDT 2004

Followed the instructions here http://wopr.yi.org/mythtv.html and so far
everything has worked except for two items:

1. I could not get the OSS audio to work properly, but ALSA worked fine.
So I changed the MythTV audio device to "ASLA:Default" and the sound now
works fine.

but the part that is driving me crazy is:

2. The live video pauses/jitters/slows down approx every 10 to 20
seconds. My gut feeling is that either the decoder is somehow not
keeping up with the video stream or the process of putting the images
onto the TV is somehow too slow. Here's what I have tried but have had
no success so far:

- I am using XFS for the main partition and get 56.62 MB/sec with hdparm
- Updated the Hauppauge firmware drivers for ivtv to the latest I could
find. (the drivers on the HOWTO are a bit outdated)
- Tried to update the nvidia-kernel drivers to the latest gentoo build.
Also tried to use the latest from nvidia.
- Nice'd mythfrontend to 15 (as per a suggestion to help someone with a
similar problem)
- I have audio buffers and interlace set to on and XvMC off (also per
the guide)
- Tried setting the mythtv video device to /dev/video16 and /dev/video32
- The load average is between 1 and 3 when watching live tv, with X
leading the pack in CPU usage, but the cpu is only at 20-40% used.
- I tried to increase the buffers for the ivtv module, but i'm not sure
it did anything: options ivtv ivtv-debug=0 mpg_buffers=100
dec_mpg_buffers=100 yuv_buffers=100 dec_mpg_qlen=100

A couple of observations/suggestions:
- I am using the svideo out on the nvidia card, but am not sure if my
settings are correct...could that have an effect in something like this?
- When I switch channels, there is a noticeable pause, then the first
few seconds are jittery/slow, then smooth sections and the 10-20 second
pause/jitter/slowdown start. But recorded shows seem to play back
without the pauses (still verifying this).

I am so close to having a complete system, it is driving me crazy :-)



System Details
Board : ASUS A7V8X
CPU: AMD AthlonXP 2800+
Video: Asus V9250 (nVidia Corporation NV34 [GeForce FX 5200])
Sound: Onboard nVidia Corporation nForce2 AC97 Audio Controler (MCP)
(rev a1)
Tuner Card: Hauppauge computer works Inc. WinTV PVR 250 (Internext
Compression Inc iTVC16 (CX23416) MPEG-2 Encoder (rev 01))
OS: Linux 2.6.5-gentoo-r1
ivtv : 0.1.9

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