[mythtv-users] Stutter playback 720 60fps

[R. G. Newbury]

On 11/14/2016 02:37 PM, Kevin Johnson wrote:
>
>
> On Mon, Nov 14, 2016 at 9:53 AM, Peter Bennett <cats22 at comcast.net
> <mailto:cats22 at comcast.net>> wrote:
>
>     On 11/14/2016 12:25 PM, R. G. Newbury wrote:
>     > On 11/12/2016 04:11 PM, Kevin Johnson wrote:
>     >
>     >> This may only be happening on channels that are 720p and h.264 encoding.
>     >> Maybe it is just me, but when it does happen, it seems like livetv
>     >> starts faster than normal.  Meaning that when I start livetv, it is up
>     >> and going in like one second.  When it does not happen, live tv takes
>     >> 2-3 seconds to start.
>     >> And, when it is happening, (the stutter) the progress bar shows about a
>     >> 2 second delay.  When it starts without stuttering, the progress bar
>     >> shows about a 5 second delay.
>     >> So I think this is all about livetv starting to fast.
>     >> Is there anything I can do to delay the live tv start time?  (Add some
>     >> sort of buffer)

> Thank you for the help.
>
> I changed the backend setting from always to none.  Did not change
> anything.  Still stutters.
>
> So i then went  and watched some live tv with the stutter.  Went to the
> live tv recodings, watched the same exact show.
> The recording under the Live Tv group played without issue.
>
> One interesting thing I did see.
> There were two of the same recordings.  Same time and title of the live
> tv show I just watched.
> One was yellow and played back fine.
> The other was blue, and when I tried to play that one, I got a message
> saying that it could not be played, recording empty.
>
> I was able to repeat the above scenario several times.
>
> Strange.
>
> Just so its clear.  This only happens on LiveTv.  720P at 60fps,

Another question: Is the problem channel on a different tuner than the 
non-stuttering channels?
You noted that tuning seemed really fast when you got a stuttering 
channel, That's what prompted my reply about the tuning setting.

But if the recorded 'LiveTV' video plays fine there has to be something 
else going on. NOT the tuner.

If it is not the tuner (check with same tuner and input against 720i or 
1080i channels if possible) then that leaves how the video is being 
processed. If you are using VDPAU Normal, then try VDPAU Slim etc. (TV 
-> Settings -> Playback iirc, but I always have to hunt).

It just may be that recording the video stream *AND* processing it for 
display is a bottleneck. The bottleneck could be almost anywhere in the 
chain, including a slow hard drive (some hard drive or partition almost 
full ->  'df -h' ) or slow processing.

I had a problem a few weeks ago with audio stuttering, which turned out 
to be a mis-setting to a software display process instead of VDPAU in 
the video display section... THe video had the same stutter, but it 
still took a while before the facepalm...

Geoff













-- 
              R. Geoffrey Newbury			
            Barrister and Solicitor
              954 Owenwood Drive
          Mississauga, Ontario, L5H 3J2

           t905-271-9600 f905-271-1638
              newbury at mandamus.org