[mythtv-users] judder with SD material

[Frank Schlimbach]

-------- Original-Nachricht --------
> Datum: Fri, 11 Jan 2013 08:40:00 +0000
> Von: mythtv-users-request at mythtv.org
> An: mythtv-users at mythtv.org
> Betreff: mythtv-users Digest, Vol 118, Issue 34

> Message: 4
> Date: Fri, 11 Jan 2013 09:17:18 +1100
> From: Igor Cicimov <icicimov at gmail.com>
> To: Discussion about MythTV <mythtv-users at mythtv.org>
> Subject: Re: [mythtv-users] judder with SD material
> Message-ID:
> 	<CAAKASGxD3gak65s-8pVowYPfiVnqu8YOuomS6qhV6PE8FpfhOQ at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> On 11/01/2013 2:01 AM, "Frank Schlimbach" <galaxy_engine at gmx.de> wrote:
> >
> > > Hi,
> > > I lately switched to using separate backend and frontend machines,
> > > both running current mythbuntu and mythtv 0.26+fixes.  The weird thing
> > > I am experiencing is that watching HD material seems to work fine
> > > while SD liveTV and recordings judder heavily (every 1-2 seconds or
> > > even more frequently). Most discussion on this topic I found are about
> > > the more intuitive reverse case, where HD is the problem. The build-in
> > > SD test works fine and playing the same file locally with vlc also
> > > looks good. CPU (Intel G530, no graphics card) load is low and I am
> > > running gigabit ethernet.
> > >
> > > Any idea?
> >
> > I did some more experiments. My TV can actually play all recordings
> directly through DLNA without any judder (it has other problems, though).
> > I also realized that both HD and SD recordings judder - but HD just not
> as strongly, but maybe more frequently. So I now suspect that this must be
> related with the network connection on the client side. I'll check cables
> tonight, but this experiment doesn't seem very promising.
> >
> > Any thoughts, experience, hints, ideas on how to debug this problem are
> highly welcome.
> >
> Did you read the judder free mythtv wiki page?

I am sorry I didn't mention it: Yes, I did. I followed it as much as I could (I am not using a Nvidia card) but it didn't help. I also used setuid without any effect.  

Last night I made a few more experiments
1. I switched network cables: no change
2. I used VLC on the same frontend machine to get the uPnP streams from the mythtv server: *NO* judder
3. I decreased the ringbuffer size in the backend: Maybe a little effect, but maybe not
4. I used the OpenGL high quality setting in the frontend:
   - higher CPU load
   - less judder, but still visible and annoying

So the current state is that it's probably not the network. Something in the MythTV frontend seems to be responsible for this.

Are there any debug flags I could try?
Any other parameters I could experiment with?