I tried to calculate the latency of my system summing up all pd-buffers, driver buffers, DACs and ADCs latency (given by the manufactorer) but, compared to the measured latency (analog loop-back) I get a difference of ~1.5ms (@fs=48kHz). Thus, I wonder what do I wrong and how to calculate which latency of a system which predicts the correct measurable latency.
hm ... i've never done the actual calculations ... but one piece of hardware that has to be taken into account is the pci bus / cardbus bridge ... but this should be reported by the driver ...
the additional latency might result from miller's synchronous scheduler ... instead of using the hardware interrupt to run the dsp (the way devel_0_39 can operate), the dsp scheduler independently from the hardware ... in theory, this would result in one blocksize of latency ... about 1.3ms at 48kHz ...
currently the scheduler that's run by a driver callback at interrupt time is only implemented for portaudio, native asio and jack (although jack adds some additional latency)
cheers ... tim