[mythtv-users] upnp pictures of screens

Leigh Jurus jurus001 at umn.edu
Wed Dec 13 06:41:51 UTC 2006

>  While I'm not doubting that you had problems I really don't see how the 
> myth upnp  code could affect audio sync. Stuttering or skipping due to 
> port performance or something maybe, but not av sync. The way the upnp stuff 
> works is that the upnp client connects to the server(via httpu) and does 
> an HTTP request asking basically "GET FILEXYZ,   BYTES 10000-15000".
> the upnp server then responds with that specific data. It has nothing to 
> do with  playback or the audio streams.
>  Now if you mean you are getting stuttering and such and maybe high CPU usage
> on the server side I can think of a few things which might cause that (some I 
> plan to fix soon in SVN) but the actual playback of the requested data is all
> on the client end.
>  I'm curious on the specs of the machine you were serving the content from
> as I'd like to try and replicate it if possible.

The A/V sync issue that I mentioned occurred when I was using a 
DSM-520.  I never tried any alternative upnp software with my DSM-520, 
so the problem might be with the device itself.  Also, I don't have the 
device anymore so I cannot do any further testing with it.

The A/V sync problem seemed to occur most often when you pressed the FF 
and RW buttons quickly in succession.  For example, you press FF to skip 
through the commercials; you realize you skipped ahead too far so you 
hit play, then RW to go back to the end of the commercial break; perhaps 
you go too far again and hit FF to catch up.  This seemed to cause the 
audio and video to get out of sync, although it did not happen every time.

I'm using an Athlon 2600 and I don't think cpu load was an issue.  I 
just tried streaming an hdtv recording and my cpu was 96% idle.

I'm running Gentoo Linux with mythtv-fixes 11626 -- 1GB ram -- 100Mbps 

The audio stuttering that I referenced was a separate glitch that I 
encountered.  I don't think it had anything to do with upnp.  I could 
not playback any program recorded from a channel that did not include a 
sub-channel.  For instance, WCCO in Minneapolis does not include a 
sub-channel; it only broadcasts channel 4-1.  I could not playback any 
recording from this channel on my DSM-520 (HD or otherwise).  However, 
KARE does include a sub-channel; it broadcasts channels 11-1 and 11-2.  
All recordings on channel 11-1, including HD, were okay.  I noticed when 
examining the recordings in mplayer that the recordings from KARE tended 
to have lower bit rates than recordings from WCCO.

I've had better success with hdtv recordings using the Linkplayer2.  
However, as I previously mentioned, FF and RW does not work for me when 
using MythTV's upnp server.  I can reliably use FF and RW on my 
Linkplayer2 when I use other upnp software.

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