[mythtv-users] Internal DVD player audio capabilities flags

[Rick Hudson]

While experimenting with authoring DVDs that automatically select a DTS 
soundtrack based on the player's capabilities it seems that MythTV's internal 
DVD player VM is not reporting that it is DTS capable.

 From what I can tell about the DVD virtual machine (based on 
http://dvd.sourceforge.net/dvdinfo/sprm.html), SPRM 15 is the audio 
capabilities word and players have bit 11 of this set if they support DTS, bit 
14 for Dolby Digital, etc.

In MythTV's virtual machine (libs/libmythdvdnav/vm.c) it does initialize a 
bunch of SPRM registers as expected but not SPRM 15. When I added the line:

  (vm->state).registers.SPRM[15] = (1<<11) | (1<<12) | (1<<14);

to the VM I did find that my test DVD indeed chose the DTS soundtrack now it 
thought it was available. This is consistent with, say, VLC.

So, is the reason MythTV doesn't report these audio capabilities because it 
doesn't actually know? I would have though that if the AC3 and/or DTS 
passthrough is enabled for SPDIF then it would be reasonable for the DVD VM to 
report those formats as available. Even for locally decoded sound, MythTV can 
decode AC3 and, IIRC, DTS as well.

-- 
Rick Hudson