[Ardour-Dev] ardour as audio backend

Robin Gareus robin at gareus.org
Tue Jul 27 01:29:51 PDT 2010

On 07/27/2010 08:39 AM, Evan Laforge wrote:
>>> >> But out of curiosity, is there any reason to suspect that a simple
>>> >> "start now" message scheduled at some time wouldn't suffice for
>>> >> synchronous play?
>> >
>> > Depends what Clock your application uses. JACK is synced to the
>> > audio-interface's oscillator not the system clock. If you use JACK for
>> > timing a sync-start will suffice.
> My app doesn't have a clock at all, since it uses the OS's MIDI
> scheduler.  On OS X this winds up being AudioGetCurrentHostTime(),
> which hopefully is the audio clock too.  Maybe the ALSA midi scheduler
> clock is also the audio clock.  If it's not, it sounds like I can use
> JACK instead of CoreMIDI or ALSA directly then I don't have to worry
> about it.

ALSA can be configured in a variety of ways using different timer
modules. I recommend to use JACK - it's x-platform and easy to use.

> I actually don't need sample accurate-ness, since I don't have any
> samples. 

If it's not sample-accurate and you record (or bounce) the output of the
MIDI sequencer/synth in the DAW it'll produce slightly different results
every time you do so.

> As long as the offset isn't audible it's fine. It would be
> a problem only if it drifted in time.

It's not only drift (which can be considerate) what's worse than drift
is jitter.

Anyway, we're getting OT.

More information about the Ardour-Dev mailing list