[mythtv-users] Audio out of sync when playing back from DVD iso

carl-magnus.bjorkell at pp.inet.fi carl-magnus.bjorkell at pp.inet.fi
Thu Jun 12 07:06:59 UTC 2008

>> The setup is:
>> Hardware:
>>   2.8GHz Hyperthreaded w/4GB ram
>>   2 750GB SATA hardrives
>>   nVidia 6200
>>   HDHomeRun tuner
>> Software:
>>   OpenSuse 10.3 i586
>>   mythtv RPMs 0.21 from Packman
>> I have used ddrescue to get an ISO image from a couple of my DVDs on  
>> to
>> my hard drive.  MythDVD recognizes it and presents menus, etc.  I  
>> start
>> playing one of the DVDs from the image and the sound is out of sync.
>> I'm using mythtv to playback the DVD, not mplayer.
>> Frontend and backend are on the same machine.  The machine is not
>> recording when I try to play back a DVD from an iso image so, the
>> machine is idle apart from the playback.  I have an unencrypted DVD
>> which seems to play fine, the encrypted DVD image I have does not.   
>> The
>> video quality on the unencrypted DVD is also lower quality IMO.
>> MythTV plays recorded HD and SD content just find and in sync, the  
>> DVDs
>> are not playing right.  Any suggestions?
>Rumor has it that this is known and has been fixed in the next  
>release.. I haven't seen the fix yet..  I hope it comes soon.
>In the meantime I've switched to xine to play my DVD ISOs.
>Hope this helps.
>- Michael

I also run OpenSUSE 10.3 (x86_64) and have the same problems. It is not 
limited to the internal mythtv player though, as it is also present in mplayer. 
It seems to me to be related to only ac3 sound, which leads me to believe that 
it's a problem with the ac3 decoder. This is just a hunch though, and I have no 
empirical data to back that up :) 

The sound seems to be lagged with about 140ms usually, which is easily 
corrected via the manual audio sync option. It's somewhat of a hassle, but it 
is a work-around at least (and you only have to do it once per movie anyway). 

I guess that this is a problem that will "solve itself" after a couple of 
ffmpeg/mythtv package upgrades.


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