[mythtv-users] playback not smooth regardless of source

Mark Kendall mark.kendall at gmail.com
Wed Feb 28 15:03:52 UTC 2007

On 2/28/07, Seth Daniel <mythtv.org at sethdaniel.org> wrote:
> http://sethd.org/myth/frontend.1080i.nobob.log
> http://sethd.org/myth/frontend.720p.bob.log
> http://sethd.org/myth/xorg.conf
> http://sethd.org/myth/nvidia-settings-rc
> A few observations:
> - 1080i w/o deint is awful.  No jitter as far as I can tell but other
>  problems that I don't really know how to describe.
> - surprisingly to me 720p with Bob seems to work w/o issue.  I recall
>  watching a ripped DVD at 720p a few weeks back (before I figured out
>  how to get my TV to 1080i) and it had the same jitter issues I have
>  seen recently.  Now it seems to be fine.  This time I tried a ripped
>  DVD and then watched some HD.  No problems in the short time I watched
>  either of those.
> - all tests were with openglsync enabled in the frontend.

Mmmm  - you might want to check openglvsync again. Both logs show that
it isn't being used - are you sure it's compiled in? Though I wouldn't
expect the setting to appear if it wasn't.

720p result is good. The last section of that log is what I'd expect
to see  (when you're showing 1080i) - the std.dev of the video timing
has dropped to very low levels. This isn't necessarily the greatest
indicator of playback quality but I know that when everything is
working well on my main frontend, I get st.deviations of less than 50.
If the NTSC dvd stream works fine but the pvr150 480x480 doesn't - it
might point to an issue with the pvr150 settings and hence the mpegs
its producing.

Otherwise, some of the other log stuff looks 'interesting'.

Probably irrelevant - but the 720p log at one point shows a PAL
720x576 video stream. Which is odd... You haven't set the frontend to
PAL by default have you?

I'm not familiar with NTSC dvds, but the main streams of that dvd are
showing as 24fps progressive (ie. film). So I'm not surprised that
they look ok when displayed at 720p and bad when displayed at 1080i.
At 1080i the tv will be trying to remove non-existant interlacing
artefacts and it will be struggling with the frame rate as well. Is
24fps film material normal or are you runing an inverse telecine
filter or something similar?

Have you tried displaying 1080i material from your hdhomerun at 1080i
without deinterlacing ( another log here might help).



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