[LAD] SMPTE and jackd

Fons Adriaensen fons at linuxaudio.org
Tue May 8 15:24:45 UTC 2012

On Tue, May 08, 2012 at 03:50:44PM +0200, Robin Gareus wrote:
> @Paul, Fons,..: does it use a PLL or simply return the difference from
> clock_gettime() since the beginning of the cycle?

jack_frame_time() reads the current time from Jack's usecs timer,
subtracts the cycle start time estimated by the PLL, converts the
difference to frames, and adds the frame count at the start of the
current cycle (which is jack_last_frame_time()).

> IIRC Fons reworked some of jack timing functions not too long ago when
> writing zita-a2j, zita-j2a, but don't know if they also affect the
> transport API.

The changes do not modify any part of the API, they add to it.



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