[mythtv-users] Livetv stutter

[Tim Draper]

 ---- On Wed, 18 Oct 2017 13:30:42 +0100 David Birch <david.birch at gmail.com> wrote ---- 
 > Thanks Nick, yeah should have ssid i'm using dvb-t, and get same behaviour with a hauppage nova t 500 & winfast 1000, so i didn't think tuner is the culprit in my case.
 > ThanksDave
 > On Wed, 18 Oct 2017 at 11:17 pm, Nick Morrott <knowledgejunkie at gmail.com> wrote:
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 > On 18 October 2017 at 12:45, David Birch <david.birch at gmail.com> wrote:
 >  > Hi, i'm running myth 0.28 on ubuntu 16.04 and am having trouble with pal
 >  > 1080i live tv streams stutter. If i pause for just a second the stream then
 >  > plays stutter free, prev recordings play fine too. I've tried adjusting
 >  > decoders & deinterlace, ssd for live recordings & ringbuffer sizes but they
 >  > don't seem to help, it also happens with vdpau on one frontend and vaapi on
 >  > another. When i watch the playback data i see the a/v sync going wild
 >  > between 0 to -1.5, after the pause & resume it then sits pretty much rock
 >  > steady on -0.25. Any other settings to try??
 >  >
 >  > Thanks in advance, i've had many happy years from myth, i just can't seem to
 >  > get this sorted & its more prevalent on a new bigger tv.
 >  
 >  FWIW I see this on an old 0.27 system when watching LiveTV from my
 >  PVR-150 backend which is recording PAL 576i content. Playback is via
 >  XVideo.
 >  
 >  Even pausing for just a second as soon as LiveTV starts produces
 >  perfectly normal playback. If I don't pause immediately the picture
 >  breaks up with stream corruption before the session eventually fails.
 >  Programme transitions also fail on this recorder. I have no issues at
 >  all with my DVB-T sources.
 >  
 >  I poked around in the source changing various playback settings/delays
 >  to no avail. Not being au fait with the playback source clearly didn't
 >  help, but it would be nice for the FAF to resolve this issue. Still
 >  need to get this particular system upgraded to 0.28/0.29 and see if
 >  the issue persists.
 >  
 >  Nick
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 >  

this one has been lurking around for ages and doesnt seem to get much attention.
in the playback data, there's something about dropped frames in a 19/1 type format about 2/3rds the way across on the bottom row. When the stutter happens, the second number goes high (dropped frames). is this what you experience? you'll also notice that the buffer bounces off 0% filled. i cant remember what my a/v sync values do, as these are the two i focus on.
Only happens on HD content; SD is fine.

i swear theres a bug trac report for it, but cant find it right now. i think it first occured part way through 0.27 release and it's stuck like this ever since.

i too have spend a while looking into settings in both the FE and mythtv-setup but to no avail. i've even tried to look at git to provide a fix myself, but it's all double-dutch to me. From a user perspective, it seems such a trivial tweak to +1sec extra on the buffer for livetv source, which would fix it.