[mythtv-users] Stutter playback 720 60fps

[Stephen Worthington]

On Wed, 16 Nov 2016 18:53:35 -0800, you wrote:

>Seems I am the only one with this issue.  I will wait a few days to see if
>anyone has any suggestions.
>After that I will try a purge and re install.
>
>On Mon, Nov 14, 2016 at 9:52 PM, Kevin Johnson <iitywygms at gmail.com> wrote:
>
>>
>>
>> On Mon, Nov 14, 2016 at 4:05 PM, Kevin Johnson <iitywygms at gmail.com>
>> wrote:
>>
>>>
>>>
>>> On Mon, Nov 14, 2016 at 3:58 PM, Kevin Johnson <iitywygms at gmail.com>
>>> wrote:
>>>
>>>>
>>>>
>>>> On Mon, Nov 14, 2016 at 2:53 PM, Kevin Johnson <iitywygms at gmail.com>
>>>> wrote:
>>>>
>>>>> On Nov 14, 2016 1:19 PM, "Peter Bennett" <cats22 at comcast.net> wrote:
>>>>> >
>>>>> > On 11/14/2016 03:59 PM, Kevin Johnson wrote:
>>>>> > > I have tried all the tuners.  (HDHR PRIME)  Does not matter which
>>>>> > > tuner I use.
>>>>> > >
>>>>> > > I dont think its a hardware issue since I never see this issue while
>>>>> > > using Kodi for playback.
>>>>> > > This happens on two different frontends using different hardware.
>>>>> > > Albeit they do both use nvidia.  But I have tried slim, as well as
>>>>> > > vappi and other configurations.  Nothing changes the result.
>>>>> > > I would point at the backend or hardware if this occurred on Kodi.
>>>>> > > But it does not.
>>>>> > > I usually find solutions by searching and searching.  But it seems I
>>>>> > > am the only one with this issue.
>>>>> > > Pressing pause for a split second clears everything up.  So I can
>>>>> live
>>>>> > > with it. It just bums me that .27 worked awesome, but since the
>>>>> > > upgrade to .28 its been a bug chasing extravaganza.
>>>>> > >
>>>>> > > Its probably not possible, but can I use .27 frontend with a .28
>>>>> > > backend?  Most likely not but it would be good for testing.
>>>>> > >
>>>>> > Sorry you cannot use a 0.27 frontend with 0.28.
>>>>> >
>>>>> > Note that it is normal for a few seconds of stopping and starting with
>>>>> > live TV as the frontend can start ahead of where the backend is. That
>>>>> > would normally clear up after a few seconds, or if you pause for a
>>>>> > couple of seconds. If you just leave it running for a few minutes does
>>>>> > the stuttering continue unabated? If it does it surely gets behind. If
>>>>> > you press I do you see it getting further behind with time?
>>>>> >
>>>>> > If you are not getting further behind I wonder if you are getting it
>>>>> > into time-stretch mode, speeded up. If you did that it should reset
>>>>> time
>>>>> > stretch as soon as it catches up with the current time, but maybe that
>>>>> > is not happening correctly.
>>>>> >
>>>>> > Peter
>>>>>
>>>>> It continues until I do something. I let it go for 2 mins the other day
>>>>> just to see.  From the playback info window. It is constantly right around
>>>>> -3 behind. It never changes. I see from -v playback info that frames are
>>>>> being dropped to catch up. But it never catches up. Just continuous dropped
>>>>> frames.
>>>>>
>>>>
>>>> After further investigation, I think this delay may be happening on
>>>> 1080i framerate also.  Its just not as obvious.  But looking at the
>>>> playbackdata while watching live tv, I see the the A/V Sync is always
>>>> around -3 when starting.  Once I hit pause, the sync is around .01
>>>> so the a/v sync is not "correct" at startup of live tv.   After hitting
>>>> pause, the 'lips match the sound' sort to speak.
>>>> Not sure if that is relevant or not.
>>>>
>>>> Just some more info.  In the playback info screen.  When the live tv
>>> image is stuttering, Available Buffer is 0% of 16mb.  Once I hit pause that
>>> never goes below 2% even if I try to fast forward to the "closest to live
>>> moment" if that makes any sense.
>>>
>>
>> The frontend is now showing this message in the logs.  Many times.  Did
>> not see them before.
>>
>> Nov 14 21:48:19 g430 mythfrontend.real: mythfrontend[1757]: W Decoder
>> avformatdecoder.cpp:4899 (GetFrame) AFD: Audio 3373 ms behind video but
>> already 220 video frames queued. AV-Sync might be broken.
>>
>>
>Here is a link to what I have.
>It is hard to see but the bottom scroll is jerky, and the av sync is -3.
>Once I hit pause, playback is smooth and the av sync is under 1
>
>https://goo.gl/photos/WQAV755sWhw29YSD8
>

As I explained in my earlier reply, your stutter problem is fully
explained by LiveTV starting to play back before it has filled its
buffers enough.  Just hit pause for a moment, and it is fixed.  If you
want a permanent cure, you will need to open a ticket and ask the devs
to fix it.  Or find the delay they are currently using in the source
code and increase it a bit for yourself.