[mythtv-users] widespread reports of (sort of) the same failures

[Dean Vanden Heuvel]

Please help.  I have not yet discovered the trick for enticing enough 
folks to read one of the posts such that I might get a helpful 
response.  I am not indicating that readers are not helpful, but rather 
that I cannot seem to grab their attention.  In any case, I hope this 
subject is more *catchy*...

In any case, I am (and reportedly others are) having a continuing 
problem with "re-entry" into Live TV mode.  In virtually all cases, the 
first time (post reboot)  I try to watch live TV, all is well.  When I 
exit back to the GUI, and attempt to re-enter live TV...failure.  Most 
often this is a segfault, but I have had cases where the on-screen video 
DOES APPEAR, then freezes, never to restart.  Sometimes this happens 
when I attempt to watch an already recorded program, sometimes not.  But 
ALWAYS, it happens on a re-entry to one of the video display modes.  
NEVER on the first pass.

I have seen other very similar errors reported, and I have previously 
posted to this effect on both the users and dev mailing lists.  Other 
similar errors and assorted list postings include include "stuttering 
video" on the frontend upon re-entry, black screen on re-entry, 
stuttering audio on re-entry.  This appears to afflict a variety of 
graphics/system hardware (Pundit, Nvidia,...) and a wide variety of 
system CPU and bus speeds.

I have personally re-created all of the symptoms using kernels from 
2.6.5 thru 2.6.9-r4, ivtv versions from 0.1.100z thru 0.3.1t, using a 
vaiety of ivtv fw modules, using both Xv and XvMC modes.  Others report 
using all sorts of things with strikingly similar issues.  The fact that 
there are various symptoms surrounding this, IMHO, indicates some sort 
of timing/race, or other multi-task coordination issue, which thus 
manifests itself slightly differently on each and every distinct 
combination of HW, SW, settings, and timing.  But, the problem is there 
and appears quite pervasive.  If you have not yet experienced it, I 
think it may be just a matter of time until you hit the *wrong* combination.

BTW, the one and only thing I have been able to use to dramatically 
improve the situation (now failure only 1 in 4 tries) is to use ALSA 
sound as opposed to OSS.  I was initially encouraged, but the problem 
persists, albeit reduced.

There is one common thread.  The errors ALWAYS occur on re-entry to a 
video mode.  Never on the first pass.  Now I ask, "what is different 
upon re-entry vs. initial entry?".  I would be happy to investigate 
further, if I knew where to start.  Any ideas on where the differences 
might lie?

-dvh