[mythtv-users] Playback Video Stutters & Audio Quits on one Frontend

[John Pilkington]

On 16/08/2020 11:15, Craig Huff wrote:
> On Thu, Aug 13, 2020, 3:11 AM John Pilkington <johnpilk222 at gmail.com 
> <mailto:johnpilk222 at gmail.com>> wrote:
> 
>     On 13/08/2020 04:28, Stephen Worthington wrote:
>      > On Wed, 12 Aug 2020 13:47:04 -0500, you wrote:
>      >
>      >> On Mon, Aug 10, 2020 at 4:39 AM John Pilkington
>     <johnpilk222 at gmail.com <mailto:johnpilk222 at gmail.com>>
>      >> wrote:
>      >>
>      >>>
>      >>> That's an intriguing idea, and as you say it could be
>     decoder-dependent.
>      >>>    But it might be worth looking at the audio readahead setting:
>      >>>
>      >>> Frontend setup > Video > Playback > Advanced Playback Settings >
>      >>>     Audio read ahead (ms)
>      >>>
>      >>> "Increase this value if audio cuts out frequently....."
>      >>>
>      >>> Default is 100 ms.  On my GT 710 box it's at 400 ms.  I suppose
>     I did that.
>      >>>
>      >>> John P
>      >>>
>      >>
>      >> Using multiple steps, I tried using HandBrake to transcode the
>     example
>      >> video to h.264,  swapped the original file with the h.264
>     version, rebuilt
>      >> the seek tables for the h.264 doppelganger, ran a full
>     mythcommflag pass on
>      >> it to detect commercial breaks, and changed audio from 5.2 to
>     stereo.  None
>      >> of these worked, but I did notice that the h.264 file was easily
>     1/3 the
>      >> size of the original.  My conclusion is to just watch the
>     troublesome
>      >> recordings on the BE/FE and/or re-record them now that I'm using an
>      >> (external) infiniTV 6 instead of a pair of PVR-500 cards. 
>     Besides, if/when
>      >> I break down and upgrade my MythTV version, things may clear up. ?
>      >>
>      >> In any case, a big thank you to all for the many suggestions. 
>     They were
>      >> all worth a try.
>      >
>      > Running mythcommflag to re-do the commercial breaks does not rebuild
>      > the seek table.  If you want to rebuild the seek table, which is what
>      > works for me, you need to do "mythcommflag --rebuild", and then after
>      > that if you want the commercial flagging, run mythcommflag again
>     to do
>      > that.
> 
>     I don't know if after all that action you still have the original file
>     playable on one of your frontends.  If so, you could try a 'lossless'
>     mythtranscode --mpeg2
> 
>     Do a mythcommflag --rebuild first.  Then you could, if you wish,
>     establish a cutlist.  Or just go ahead and do the cutting later.   I
>     haven't used mythtranscode recently, but it ought to work.
> 
> 
> Other than using a different tool to transcode, I'm not sure why it 
> might make a difference, but anything is worth a try. Hopefully I can 
> test that later today.  I also need to try the audio readahead 
> adjustment, although, IIRC, the playback doesn't just drop/lose the 
> audio, it either freezes up completely or stutters (like going into 
> slow-motion) -- can't recall which at the moment.
> 

The audioreadahead setting should be easy to change and test, and would 
affect only the one frontend.  Setting up 'mythtranscode -m' might need 
more work; but it isn't really a transcode, IIRC it just demuxes and 
remuxes and might apply a better A/V offset.  Another possibility is 
dropping the first few MB of the file, perhaps using dd.  It all depends 
on how much you want to play that file on that frontend...

John