>>> The only difference non-jack would make is you need some function to
>>> tell you roughly what audio time it is you can call from another thread.
>>
>> Does one use the system clock for that?
> I think frame time (a frame of samples) is meant here ? That time is
> delivered in the jackd process callback.
>
>> Is it accurate enough?
> Depends on the system clock used, I presume.
> For best accuracy, you have to configure your kernel to support HPET
> (high precision event) timers
> and make ALSA use it as default.

the clock used for the system clock is less important than using a DLL
to "link" the audio clock and the system clock. this enables you to
answer the question "if its time T on clock1, what time is it on
clock2?"

fons wrote the canonical paper on this for a Linux Audio conference a
few years ago, and JACK contains a DLL for this purpose
(jack_get_microseconds() will return a prediction of the current time
according to the audio clock, based on the system clock and the DLL.

thanks, it's sounding increasing like I should be using jack for the time being.

Iain