[mythtv] Mythmusic & Goom2k4

[Ed W]

>IMHO what needs to be done is to extend the sound buffering in good a
>little bit so that there is more time for analyzing the upcoming sound
>change and the graphics can "get ready" for that. It might be only
>100-200 milliseconds but it would help to improve the experience
>tremendously, I believe.
>
>I once looked into goom but couldn't see any sound buffering there so I
>didn't know what to tune, to delay the sound a bit more to get the video
>chance to "catch up" :)
>  
>


I looked into this a little and different plugins have slightly 
different av offsets I think?  Goom is fractionally delayed on my setup, 
and some of the other plugins are ahead

Basically the music output sends the data to the visualistion plugin as 
a linked list of PCM sample data.  It is a bit crude and it just chucks 
in the first BUFFER_SIZE samples each time it fires and then the 
visualisation reader has a concept of current time when feeding the 
visualisation and scans the list looking for data due "now" and feed the 
visualisation.  So the visualisation never sees the whole PCM stream 
(which may make some of the fancier ones miss some detail), and instead 
of it being downsampled, we just give it the first X bytes in each 
timeslice.

Secondly I think the AV sync problem probably comes from the 
visualisation itself having a random internal delay which is not always 
correct?  Goom seems to be pretty good, but the others may have 
additional internal buffering which is not properly compensated for

So it should be easy to fix each plugin.

I am snowed under with other work (I'm still running CVS from around Feb 
last year) so unfortunately barely have time to skim this list let alone 
fix this

Good luck

Ed W