[mythtv-users] Why do I sometimes get no video in LiveTV?

Andrew Junev a-j at a-j.ru
Sun May 18 18:09:04 UTC 2008


Hello All,

I have my mythbackend+frontend machine with two DVB-S tuner cards.
I also have a frontend-only machine (Intel Core2Duo, NVIDIA 8600GT).
Both machines are running Fedora 8 and MythTV 0.21. The setup worked
just great for me over the past months. 

Some time ago I made a 'yum update' on both machines. That's not the
first time I do it and it used to work fine before. But after some
time I noticed a strange problem which occurs on my frontend-only
machine.
When watching Live TV, I sometimes get no video at all - I can only
hear the sound. It usually happens like this: I go to Live TV and
watch a channel for some time, then I try to switch to another DVB
input and then I get no video (even no OSD), but I can only hear the
sound. Switching back to DVB_Input_1 does not bring me the video!

It sometimes happens that LiveTV starts with a blank screen at the
very beginning (i.e. on DVB_Input_1). I couldn't figure out how I can
get the picture back. In all cases I can hear the sound, so the tuning
works fine... This problem appears on frontend-only machine, my
backend+frontend works good all the time.

I assume the problem might have appeared when I tried to set 'Sync to
VBlank' option on my frontend. After checking that option I got no
video in Live TV for the first time. I unchecked it, but since then
the no video issue seem to be sporadic.

I don't know how to trace the problem, so I attached the lof of my
mythfrontend. It shows a typical situation when I start Live TV, watch
a channel for a few seconds (the video is there), then I switch the
DVB Input and I get no video (and no OSD too, the TV is blank).

Here's my OS and MythTV version:

# mythfrontend --version
Please include all output in bug reports.
MythTV Version   : 17180M
MythTV Branch    : branches/release-0-21-fixes
Library API      : 0.21.20080304-1
Network Protocol : 40
Options compiled in:
 linux release using_oss using_alsa using_arts using_jack using_backend using_dbox2 using_dvb using_firewire using_frontend using_hdhomerun using_iptv using_ivtv using_joystick_menu using_libfftw3 using_lirc using_opengl_vsync using_opengl_video using_v4l using_x11 using_xrandr using_xv using_xvmc using_xvmcw using_xvmc_vld using_glx_proc_addr_arb using_bindings_perl using_bindings_python using_opengl using_ffmpeg_threads using_libavc_5_3 using_live
# uname -a
Linux frontend1 2.6.24.5-85.fc8 #1 SMP Sat Apr 19 12:39:34 EDT 2008 i686 i686 i386 GNU/Linux

I was using an NVIDIA 169.12 driver and recently updated to 173.08
(beta) driver. But it didn't change the behavior...

I appreciate any ideas on how to trace / fix the problem.

-- 
Best regards,
 Andrew
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