[mythtv-users] Major Audio Sync Issues

Thu Nov 19 22:26:42 UTC 2009

On Thu, Nov 19, 2009 at 8:56 AM, Mark Small <msmall at eastlink.ca> wrote:

> On November 18, 2009 21:29:11 Paulin wrote:
> > On Wed, Nov 18, 2009 at 5:24 PM, Paulin <paulin at spextreme.com> wrote:
> > > On Wed, Nov 18, 2009 at 3:13 PM, Mark Greenwood
> <fatgerman at ntlworld.com>wrote:
> > >> On Wednesday 18 Nov 2009 02:08:05 Paulin wrote:
> > >> > I'm been banging my head against the wall on this issue for a couple
> > >> > of
> > >>
> > >> days
> > >>
> > >> > now.  I've search the thread and google for anything I can find on
> > >> > Audio
> > >>
> > >> Out
> > >>
> > >> > Of Sync and I've tried a ton things.   No luck with any of it.
> > >> >
> > >> > I upgrade last week to Mythbuntu 9.10 (myth 0.22).  I'm using VDPAU.
> > >> > Before upgrading I didn't really have this issue.
> > >> >
> > >> > When I say upgraded I basically wiped the disk and started fresh.
> > >> >
> > >> > Anyway now the Myth Recordings that are occurring seem fine.
>  However
> > >>
> > >> when
> > >>
> > >> > playing back the audio and video become out of sync.  I've noticed
> > >> > that
> > >>
> > >> the
> > >>
> > >> > video will attempt to slow down to let the audio catch up but it
> never
> > >>
> > >> stays
> > >>
> > >> > there.  They get out of sync and evenytually get really bad (few
> > >>
> > >> seconds).
> > >>
> > >> > I've tried changing the player to VLC, I also tried the suggestion
> on
> > >> > (
> > >>
> > >>
> http://mythtvbox.blogspot.com/2006/01/fixing-mythvideos-audiovideo-sync.
> > >>html )
> > >>
> > >> > and put oss on the mplayer command string.  I also setup XvMC per
> the
> > >>
> > >> wiki
> > >>
> > >> > page.  Didn't change anything.
> > >> >
> > >> > My first question is, how do I enable extended logging on myth
> > >> > frontend using mythfrontend.real.   I remember something about
> adding
> > >> > the
> > >>
> > >> parameter
> > >>
> > >> > 'playback' but not sure how to do that with mythfrontend.real.
> > >> >
> > >> > Second why is my audio/video so out of sync? How do I track down the
> > >>
> > >> problem
> > >>
> > >> > and fix it.
> > >> >
> > >> > Thanks
> > >> > steve
> > >>
> > >> Have you tried enabling the setting 'Use Video As Timebase', somewhere
> > >> amongst the reams of setup screens, TV playback I think? I did this
> for
> > >> a similar problem, also with VDPAU, and it solved it.
> > >>
> > >> Mark
> > >> _______________________________________________
> > >> mythtv-users mailing list
> > >> mythtv-users at mythtv.org
> > >> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> >
> > OK well here is an updated.
> >
> > Use Video as time base causes the video to slow to a crawl and play
> really
> > weird.  I have Enable RealTime checked, Extra Audio Buffer check ,and
> warn
> > on no audio.  I'm using VDPAU SLIM.
> >
> > It seems to happen mostly with recorded programs but not all. and
> > not consistently.  When the problem occurs, I've seen the video slow down
> > while the audio catches up.  I've also seen where the mouths talking is
> out
> > of sync with audio.  Last night watching Castle and V was the worst.  At
> > some points the video was 3 to 4 seconds out of sync.  Commercial
> skipping
> > causes it to get closer.
> >
> > I did see the problem watching through myth video but that wasn't too bad
> > (half  second off).
> >
> > Also processing power of the node when watching a program is about 8% CPU
> > usage.  Commercial flagging running would spike around 70% (62%
> flagging).
> >  Recording also going on.  So processing wise it should be safe (2.2ghz
> > dual core)
> >
> > So what have I tried,
> > Different players and player options (mplayer, vlc).
> > Playing the video elsewhere (copied mpg to a windows machine played fine)
> > Played with xorg.conf but didn't change anything.
> > Host of other little things here and there as I found online.
> >
> > On a possible related note, I have the following issues occur and I'm not
> > sure if it could be hardware/configuration/or NVidia driver.
> > - While watching a video or recording, the screen just goes blank.
> Audio
> > continues but there is no picture.  Like the TV lost the signal.  I have
> to
> > restart GDM to get it back up.
> > - Sometimes after restarting GDM it comes back up and the entire picture
> is
> > distored.  Like each line (pixel row) is skewed (if that is the best
> > description) so the entire picture is impossible to determine.  At one
> > point I went to the desktop and popped up the NVidia config.  It looked
> > like normal but if I moved it, it became pixellated (like using
> photoshop's
> > noise feature).
> >
> > So any ideas or ways to fix this.  I didn't have these issue in the Myth
> > 0.21 that I built from trunk. So I think everything (hardware) should be
> > fine.
> >
> > I'm desperate and frustrated so I'm willing to try any ideas to fix this.
> >
> > Thanks
> > steve
>
> I've also been seeing audio sync issues.  The weird thing is that it only
> seems to happen on ABC programs (Ugly Betty, Flashforward).  This doesn't
> make sense to me since I'm recording analog on a PVR250.  The station
> shouldn't make a difference, unless its a source issue.
>
> This may be a completely different issue to yours.
> I'm still running 0.21. I'm recording through a Motorola STB on an analog
> channel with Composite output from the box.  I haven't done any
> investigating
> or changed any settings yet.
>
> Mark
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>
>
OK I think I figured it out.  At least one of hte videos that was really bad
I got to play perfectly last night.

By chance I was playing around with Playback Profiles and remember I had to
use a specific deinterlace.  Then I had the problem of not remember what I
did use.  Luckly I dug up this (
http://www.gossamer-threads.com/lists/mythtv/users/365162?search_string=High%20X%20server%20load.%20Why%3F;#365162).
 It talked all about what I had.   Once setting this (and I did some of the
stuff on the VDPUA page - http://www.mythtv.org/wiki/VDPAU#Troubleshooting)
it was playing great.

Thanks for the help.  Now onto the next problem (screwed up video everyone
once in a while).

steve
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mythtv.org/pipermail/mythtv-users/attachments/20091119/f0278ce9/attachment.htm>