[mythtv] DVD playback issues, from revision 22120 onwards

Davin McCall davmac at davmac.org
Sat Oct 31 03:17:17 UTC 2009

Hi all,

I've just joined this mailing list. I've been using MythTV for quite a 
while now, always using subversion trunk and doing regular "svn update". 
A while ago, DVD playback started having issues - basically, on most 
DVDs video started playing too fast and went out of sync with the audio.

When I first noticed I didn't worry too much seeing as I figured it 
would probably be fixed at some point in the future - however, that 
hasn't happened yet, so I did some investigating.

By bisecting commits I discovered the problematic change. It is revision 

    09/30/09 01:35:58 (4 weeks

    Closes #7113 <http://svn.mythtv.org/trac/ticket/7113>. internal dvd
    player: recent dvd code updates in trunk didn't account for dvd
    still frame with audio. made the necessary changes to resolve this.
    tested fix on lord of rings (the two towers) special features dvd.

See the code change:

As you can see various lines have become condition upon whether 
curstream->codec->codec_type == CODEC_TYPE_VIDEO.

Now, on one DVD ("Let it Snow") which has a problem since this change, 
it appears that the menu is implemented as a still frame. There are no 
still frames in the actual chapter, however when it is playing after 
displaying the DVD menu then the video plays too fast (at least for a 
short period) and goes a few seconds out of sync with the audio.

I put in some debug lines and found that during the menu display, 
curstream->codec->codec_type == CODEC_TYPE_AUDIO (not VIDEO).

Has anyone else seen the same problem, or is it just me? Is the change 
in 22120 definitely correct or is it flawed? I don't know enough about 
the code to be able to proceed - presumably the change *was* actually 
fixing a problem so just reverting it might not be the right answer - so 
I'd appreciate any help. (Perhaps A/V sync needs to be reset after 
selecting a DVD menu item? How and where would this be done? etc)

Thanks for any help,


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