[Rosegarden-devel] audio_etc branch update

[Chris C. <ca...@al...>]

So, yesterday afternoon I had one of those sessions in which you do 
hours of testing and tweaking and end up changing about three lines 
of code.  The net result is that we now stop the ALSA queue while 
prebuffering MIDI (not audio yet) when called on to play, and that 
works OK.  The finer points, for the record:

 * A stopped queue will still deliver events that are timestamped at 
the exact time the queue's stopped at.  We don't want that when 
prebuffering, so we have to put off draining the alsa-lib buffer into 
the sequencer core (via snd_seq_drain_output) until the queue is 
started again.  I just hope drain_output is fast.

 * We can't stop the queue while we're not playing, not because of 
things like async system events but because of timed NOTE OFF events 
for notes sent from the GUI for previews etc.  So we simply stop the 
queue briefly while buffering at the start of playback or when 
ffwding/rewinding, and leave it running after playback.


Chris