[mythtv-users] LiveTV Stutters - Recordings are Perfect

[David Hofstra]

On Mon, Jun 11, 2012 at 4:50 PM, Karl Newman <siliconfiend at gmail.com> wrote:

> On Mon, Jun 11, 2012 at 12:54 PM, David Hofstra <dave at dhofstra.com> wrote:
> > I'm a long-time MythTV user, but I've only ever used Myth to watch
> > recordings (not to watch live-tv).  I've always used my DirecTV box for
> > LiveTV as it was easier for the WAF.
> >
> > I recently purchased a HDHomerun Prime, and switched from DirecTV to
> > Xfinity.   I found that the Xfinity box on-screen guide is unbearable to
> > watch LiveTV... ughh  So, I'm trying to use MythTV to watch LiveTV and
> ditch
> > the Xfinity box altogether.
> >
> > Problem:   Recordings playback wonderfully 100% on my frontend (and have
> for
> > years).  LiveTV stutters about 10 times per hour, and about once per day
> it
> > fails.   It almost always stutters a few seconds after the channel
> change,
> > which I hear is to be expected, but then it continues to stutter every so
> > many minutes.
> >
> > A)  When LiveTV fails, it fails with 'video buffering failed too many
> times'
> > B)  When LiveTV stutters, I see a bunch of the following in the frontend
> > terminal (infact, I see this when it doesn't stutter also)
> >      -RingBuf(<filename>): Waited 0.2 seconds for data to become
> > available... 15720 < 32768
> >      -RingBuf(<filename>): Taking too long to be allowed to read..
> >
> > I have a Geforce 210 @1024MB running 295.40 and it is using VDPAU normal
> > settings on mythbuntu (OS 12.04)
> >
> > Here's what I have tried so far:
> >
> > 1)  Replaced network cables to HDHomerun Prime as well as to the
> frontend.
> > 2)  Replaced the hard-drive in the frontend.
> > 3)  Moved the LiveTV recording group directory to a faster RAID5 drive
> set
> > on the backend (previously on home directory)
> > 4)  Stopped upmixing stereo to 5.1
> > 5)  I tried both streaming using the myth:// protocol, and also having
> the
> > liveTV directory on the NFS share directly.
> > 6)  I tried using every window manager known to man
> > 7)  Upgraded to the newest 0.25 mythtv-fixes, which updates to a new
> version
> > virtually every day
> > 8)  I have one other frontend with a Geforce 6150, and while it doesn't
> seem
> > to stutter, the HDTV tearing is so horrible, I cannot really tell if this
> > box has the same problem or not.
> > 9)  I've increased the HD ringbuffer size in the backend-setup
> > 10)  Some folks note that if you pause LiveTV for a few seconds, then the
> > stuttering stops.   This also seems to work for me, but I hate to have to
> > pause LiveTV every time I change the channel.
> >
> > Does anyone have any other thoughts, or notice something I have not tried
> > after looking the above over?  Why/How could Recordings be so perfect,
> and
> > LiveTV be so horrible????  Any suggestions appreciated.
> >
>
> What about Playback -> Extra Audio Buffering? I had similar symptoms
> (although much more frequent than 10 times per hour) and this setting
> smoothed out Live TV for me with VAAPI on Intel.
>
> Karl
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>


I did check, and extra audio buffering is on.   Thanks for the suggestion.
  I've also fiddled with realtime priority threads, neither of which seem
to really help anything.

I'm perplexed as to why pausing for a brief second seems to fix the LiveTV
problem.   I keep wondering what the "HD Ringbuffer size" in the backend
is... is that a way to set a large enough buffer for LiveTV?

If a recording is going on, and I watch another recording at the same time,
it is perfect, why would LiveTV be any different than this scenario?
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