[mythtv-users] Stuttering in DVD menus

Richard peper03 at yahoo.com
Sat Nov 10 19:56:21 UTC 2012

On 10/11/12 14:52, Richard wrote:
> I still don't understand why this should only affect playback of DVD
> menus.  What's different about a menu?  The traces seem to indicate that
> video decoding is ahead of audio but is there a some way to determine
> whether it's a video or an audio problem?

Ok, I tried comparing the log messages between ffmpeg and VDPAU 
decoding.  The only difference that appears significant is this when 
VDPAU is selected:

Player(0): Forcing decode extra audio option on (Video method requires it).

I searched through the source code and found this log entry eventually 
causes the 'lowbuffers' variable in avformatdecoder.cpp to be set to 
true.  Looking at where 'lowbuffers' is used, I found this:

else if (lowbuffers && ((decodetype & kDecodeAV) == kDecodeAV) &&
          storedPackets.count() < max_video_queue_size &&
          lastapts < lastvpts + 100 &&
       storevideoframes = true;

That's a lot of conditions, and I don't know what they all relate to but 
the last one looks suspiciously like one that could cause the stuttering 
as it would prevent the assignment if we're in a menu.

Can anyone shed any light onto the purpose of that condition (maybe it 
should only apply to non-animated menus?).


More information about the mythtv-users mailing list