[mythtv-users] audio video sync errors

Kevin Johnson dabears_rule at yahoo.com
Sat Dec 26 05:39:00 UTC 2009

----- Forwarded Message ----
From: Kevin Johnson <dabears_rule at yahoo.com>
To: mythtv-users at mythtv.org
Sent: Wed, December 23, 2009 5:06:23 PM
Subject: Re: audio video sync errors

> Running Mythbuntu 9.04 with mythtv.22 using the mythbuntu autobuilds. 
> Lately, (last week) I have been getting audio/video sync errors.  The 
> video will play ahead of the audio, then slow down, then speed up 
> again.  It never seems to be in sync.  This happens on recorded 
> programs or live tv.  BUT not all recorded programs or all live tv 
> broadcast.
> The audio sounds normal and stable.
> I have 3 separate front ends and they all exhibit the same issue. I 
> have one main backend. All the front ends use nvida cards, but not vdpau.
> I cannot say for sure but it appears to only happen on channels that 
> broadcast in 1080i or 480i, but I cant be completely sure of that.
> I have tried several different playback profiles and nothing solves it.
> ifconfig shows no network errors.
> The backend uses two ati hdtv wonder cards and a hdhomerun dual tuner.
> One other thing I should mention.  I get all my signal over the air 
> and it is not always stable.  I get alot of errors.
> 2009-12-22 22:24:06.691 [mpeg2video @ 0x7facf5ab1820]ac-tex damaged at 
> 41 9
> 2009-12-22 22:24:06.691 [mpeg2video @ 0x7facf5ab1820]mb incr damaged
> 2009-12-22 22:24:06.691 [mpeg2video @ 0x7facf5ab1820]mb incr damaged
> 2009-12-22 22:24:06.698 [mpeg2video @ 0x7facf5ab1820]Warning MVs not 
> available
> 2009-12-22 22:30:28.262 [ac3 @ 0x7facf5ab1820]frame CRC mismatch
> 2009-12-22 22:30:28.293 [ac3 @ 0x7facf5ab1820]incomplete frame
> 2009-12-22 22:30:28.293 [ac3 @ 0x7facf5ab1820]invalid frame size
> 2009-12-22 22:30:28.945 [mpeg2video @ 0x7facf5ab1820]Warning MVs not 
> available
> 2009-12-22 22:35:43.431 [ac3 @ 0x7facf5ab1820]frame CRC mismatch
> 2009-12-22 22:35:43.461 [ac3 @ 0x7facf5ab1820]incomplete frame
> 2009-12-22 22:35:43.461 [ac3 @ 0x7facf5ab1820]invalid frame size
> 2009-12-22 22:35:43.949 [mpeg2video @ 0x7facf5ab1820]invalid mb type 
> in B Frame$
> Only thing is, I have been using the same setup for over six months, 
> and this sync error just started happening.  That leads me to believe 
> that the poor signal is not the problem.
> Any help as this is very annoying.

Are you using Pluse Audio? When I was using it I had latency problems 
and the audio would go out of sync....If you are using it try removing 
it and see if your sync problems get any better..

No, pulse audio is not installed.
I think this has something to do with the poor signal I get ota.
When I watch live tv, and the signal is poor, sometimes the audio will crack and the picture will get blocky but stays in sync
But then on another channel, I will see slight picture errors (blocky image) but not very bad.  But this channel will have the sync errors but the audio does not crack.  
I wonder if mythtv has changed the handling of video/audio in the last few updates??
I guess I could roll back one system and see????  

This is from mythfrontend -v playback

2009-12-25 21:35:37.148 Set video sync frame interval to 16683
2009-12-25 21:35:37.148 Disabled deinterlacing
2009-12-25 21:35:37.164 Set video sync frame interval to 16683
2009-12-25 21:35:37.164 Disabled deinterlacing
2009-12-25 21:35:37.181 Set video sync frame interval to 16683
2009-12-25 21:35:37.181 Disabled deinterlacing
2009-12-25 21:35:37.198 Set video sync frame interval to 16683
2009-12-25 21:35:37.198 Disabled deinterlacing
2009-12-25 21:35:37.214 Set video sync frame interval to 16683
2009-12-25 21:35:37.214 Disabled deinterlacing
2009-12-25 21:35:37.231 Set video sync frame interval to 16683
2009-12-25 21:35:37.231 Disabled deinterlacing

I could really use some help as my tv watching is currently on hold.
Should I file a bug???

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