[mythtv] XvMC VLD Decoding stuttering problems on some videos

[Terry Barnaby]

Isaac Richards wrote:
> On Thursday 28 September 2006 2:51 am, Terry Barnaby wrote:
>> Ok, I think I have now fixed the problem. The interactive TV OSD was
>> enabled even if "EnableMHEG" was not set to 1.
>> I assume that the interactive TV OSD needs to be displayed all the time
>> when "EnableMHEG" is set to 1 ?
> 
> It wasn't just the ITV OSD set that was always displayed on my machine - one 
> of the other CC sets was always on as well.  I checked in some better 
> detection code for that stuff -- could people test, please (without any 
> additional patches)?
> 
> Isaac
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Hi Isaac,

Yes, your patch basically fixes the OSD issue.

I think it would be worth making the decoder thread a higher priority 
than base system processes as well however, especially using XvMC as 
there are limited output buffers to use and so little leeway in time 
available. If some other system processes get started it is not easy for 
the decoder thread to keep up with the real-time display thread. (Note 
my simple nice(-10) patch will also set the RingBuffer::ReadAheadThread 
and AudioOutputBase::OutputAudioLoop's to -10 when watching liveTv. 
Maybe these should be left alone, if so this would need improving).

After doing the above, my system runs smoothly watching video's but 
still has a few pre-buffering pauses when watching live TV.
So there are still some issues here. The CPU usage of the Video Display 
thread leaps up when the pre-buffering pauses occur so I suspect some 
other issues in the Display thread.

In general it appears that to much is being done in the Display thread, 
especially as it is a real-time process. Maybe it would be worth 
simplifying this to just the GetFrame,MergeOSD,WaitforSync,Display 
functionality and not do so much OSD work ?

Terry