20 Jul
2010
20 Jul
'10
2:46 p.m.
On 07/20/2010 09:51 PM, Paul Davis wrote:
On Tue, Jul 20, 2010 at 7:48 AM, Patrick Shirkey
<pshirkey(a)boosthardware.com> wrote:
i believe that robin's suggestion is the correct one. you don't
want
to attempt audio timing using the system clock unless you have a
DLL/PLL that relates audio time to system time (and you don't).
decisions about what to do as time progresses need to be made in the
process() callback tree, not in the GUI or some other thread.
so just countdown some number of samples, and then resume playing, as
robin suggested. it won't block anything, anywhere.
I don't have any problem with counting down using the audio clock but
how do I translate that into seconds/milliseconds set in the ui?
At the moment the timer counts in seconds using this function
void *timer_thread(void *arg) {
int how_long = *((int*) arg);
sleep(how_long);
pthread_mutex_unlock(&timer_lock);
return NULL;
}
While it is counting I set the volume for the per track playback buffer
to zero. I also need to stop the playhead from moving but that is a
seperate issue.
Ideally the timer should count in milliseconds which I guess is handled
by changing the call to sleep to select instead?
ex.
void *timer_thread(void *arg) {
int how_long = *((int*) arg);
pause.tv_sec = how_long;
pause.tv_usec = 0;
(void) select(0, 0, 0, 0, &pause);
pthread_mutex_unlock(&timer_lock);
return NULL;
}
I'm not sure how to do that with audio samples instead. Happy to make it
work that way though if it is the best approach.
--
Patrick Shirkey
Boost Hardware Ltd
A simple
approach might be to just set a counter and have the
audio-process count it down (in audio-samples). Once it reaches zero:
play again.
The problem is how to set a counter that doesn't block the rest of the
app
while it is in process.