@return the precise time at the start of the current process cycle.
This function may only be used from the process callback, and can
be used to interpret timestamps generated by jack_frame_time() in
other threads with respect to the current process cycle.
This is the only jack time function that returns exact time:
when used during the process callback it always returns the same
value (until the next process callback, where it will return
that value + nframes, etc). The return value is guaranteed to be
monotonic and linear in this fashion unless an xrun occurs.
If an xrun occurs, clients must check this value again, as time
may have advanced in a non-linear way (e.g. cycles may have been skipped).
@return the precise time at the start of the current process cycle. This function may only be used from the process callback, and can be used to interpret timestamps generated by jack_frame_time() in other threads with respect to the current process cycle.
This is the only jack time function that returns exact time: when used during the process callback it always returns the same value (until the next process callback, where it will return that value + nframes, etc). The return value is guaranteed to be monotonic and linear in this fashion unless an xrun occurs. If an xrun occurs, clients must check this value again, as time may have advanced in a non-linear way (e.g. cycles may have been skipped).