On Sun, Nov 6, 2011 at 2:20 AM, Emanuel Rumpf <[email protected]> wrote: > 2011/11/5 Iain Duncan <[email protected]>: >> On Thu, Nov 3, 2011 at 8:05 PM, David Robillard <[email protected]> wrote: >>> >>> >>> 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. _______________________________________________ Linux-audio-dev mailing list [email protected] http://lists.linuxaudio.org/listinfo/linux-audio-dev
