[linux-audio-dev] A sequencer example

[Lee Revell]

On Sun, 2006-01-15 at 14:23 +0100, mlang wrote:
> Chris Cannam <cannam at all-day-breakfast.com> writes:
> 
> > On Sunday 15 Jan 2006 11:12, Florian Schmidt wrote:
> >> If you want to use alsa_seq's queues to schedule events for delivery
> >> at a later time, you probably might have a look at rosegarden.
> >
> > There's a file base/test/seq/generator.c in the Rosegarden source tree 
> > that does basically what was described using the sequencer queue.  It 
> > does however schedule in real-time rather than beats (and so does 
> > Rosegarden itself).
> >
> > http://cvs.sourceforge.net/viewcvs.py/rosegarden/base/test/seq/generator.c?view=markup
> 
> Pretty intersting, I just ran this and noticed it (the diff between
> queue and gettimeofday time) drifts about 70 usecs per second.  Is this
> normal expected behaviour, or another reason to hate the day I decided to buy
> a X2 CPU?
> 
> P.S.: ANyone got any hard facts on the TSC SMP issues?  2.6.15
> is definitely worse for me than 2.6.14, things that used to work just dont anymore.
> 

Yes, the TSC is useless on these machines, but the kernel can work
around it.  You need JACK patched to use clock_gettime() for
jack_get_microseconds.

This really should be in JACK CVS by now, if it is not already.

Lee