[mythtv-users] h.264 playback issues

Greg Woods greg at gregandeva.net
Thu Apr 30 17:43:48 UTC 2009

When my old system bit the dust, and I was going to install a whole new
system anyway, I decided to make the jump to trunk so I could fire up
that shiny new HD-PVR that I bought a year ago, get VDPAU working, etc.
So far mostly good. Once I gave up on the IR blaster, ordered a firewire
card, and got channel changing on the DCH-3200 cable box working via
firewire, the system is almost stable. Eventually I have to investigate
why the HD-PVR recordings sometimes fail. The backend log looks normal
(Started recording "Name of Show") but the recording light doesn't come
on and no recording file is made. But that's for later, I haven't done
all my homework on this one yet (like, for starters, being certain that
I haven't done something obviously wrong).

The major remaining issues concern playing back the h.264 files. These
issues do not occur with SD recordings. I will have to test to see if
the problems occur with HDHomerun recordings. Since those can only get
the major networks, I don't have a lot of stuff recorded on those
outside of (American) football season. I'll make some test recordings to
see, but I have to watch for a fair chunk of time and I haven't had a
chunk of time to devote to this yet. So I don't know if the problems
will happen with all HD recordings or just the ones from the HD-PVR (I
suspect the latter).

A minor problem is, I sometimes get a rolling horizontal band of
distortion. It can appear anywhere on the screen, and slowly rolls down
until it hits the bottom of the screen, then disappears. It kind of
looks like what I used to see on old analog TV's when I was a kid and
the reception wasn't all that great. Is this what is called "tearing"?
This is fairly minor because while it is noticeable, it doesn't make the
recording unwatchable. I suspect this is an nvidia driver issue (I'm
running 180.41), but I hesitate to upgrade the driver due to recent
threads saying the newer driver was causing problems.

The more important problem that makes recordings unwatchable is that it
sometimes jumps back to a previous point in the recording when fast
forwarding. As far as I can tell, the recording is proceeding normally,
I just can't watch it past a certain point because it keeps jumping
back. It turns out that it will jump back when playing as well, but I
always notice it because the first time it happens has always been while
fast forwarding through a commercial, but once a bad spot is found, it
will always jump when it hits that spot, whether I am fast forwarding or
normal playing at the time. Has anyone seen anything like this? What
additional info can I post to help with troubleshooting?


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