[mythtv-users] ECS Liva stuttering on some Channels

[Tim Pletcher]

Here is a long-winded summary of my experience.

I have two ECS Liva units that I am using for dedicated MythTV frontends.
I concur with the others that there are some issues with the use of VAAPI
on integrated Intel hardware.  As a frame of reference, I do have a
high-powered combination frontend / backend computer with Nvidia graphics
hooked to a projector screen.

One of my two Liva units is connected to a 46" 1920x1080 Samsung television
and is used for watching recordings and live TV on an Ubuntu 14.10
installation. I run the desktop and MythTV at the native television
resolution. After experimenting, I found that I had to set up a playback
profile which uses VAAPI/Opengl-Vaapi along with Bob 2X deinterlacing for
1080i content.  For 720p content, I have the deinterlacer set specifically
to none.  This seems to work well for both 1080i content and for 720p
content without frame drops as long as I ensure that VAAPI is in use. Due
to the known bug ( #12319) that causes VAAPI decoding to disable every
other channel change, I have had to convinced the family to re-tune the
same channel if observing performance issues when channel surfing on
liveTV.

My second Liva unit, which was set up by mirroring the drive from the first
unit, brought some different challenges. It is connected to a 24" 1366x768
Samsung TV. I initially tried to run playback in the native TV resolution
but had repeated issues with varying audio / video sync on 720p content.
This was very evident while trying to watch Wimbledon (ESPN) where the
audio cue of the tennis ball being hit would drift way ahead of the video
being displayed.  Despite trying various combinations of video playback
profiles, adjustment to the playback audio delay, and selection of
different audio devices (alsa, pulse etc.), I was unable to reliably
address the audio sync issues until I changed the Liva to always output at
a 1280x720_60 resolution. Unfortunately, this leads to a small amount of
over-scan for the desktop and MythTV user interface but this is much less
distracting than the audio sync problems. My guess is that this is
indicative of some performance issue when doing output scaling to the
native resolution of the television but I am not knowledgeable enough to
diagnose further.

On both Liva setups, I also attempted to use separate video modes to force
MythTV to output at the resolution of the recording in order to let the
television do the resolution scaling.  However, while I would observe the
expected change in output resolution on the television, the video output
from MythTV resulted in the top edge of the displayed video frame shifted
down to start at roughly the horizontal center-line of the television
screen. The top half of the television screen would then be black and you'd
only see half of the image of the video being displayed.

With the exception the aforementioned LiveTV Vaapi bug, I am mostly pleased
with these devices as MythTV frontends. I have been able to turn in my
digital cable boxes and reduce my cable bill by enough to break even on the
cost of the Liva units in just under a year.

Tim
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mythtv.org/pipermail/mythtv-users/attachments/20150729/b88748bb/attachment.html>