read time information

["Men Muheim" <muheim@gmx.ch>]

For synchronization purpose I need the current time of my sound card
(information on the sample that is currently played out might be
sufficient / ADAT-Synch timecode) I did anticipate that the functions 

      snd_pcm_status_alloca(&status);
	snd_pcm_status_get_tstamp(status, timestamp);

do help me with this, but obviously they only call gettimeofday()
instead of returning a sound card time information (see
http://www.alsa-project.org/alsa-doc/alsa-lib/_2test_2latency_8c-example
.html#example_test_latency). From the API description I have found that 

snd_pcm_hwsynch(...)
snd_pcm_delay(...)

must be used to get the current sample positions of the DAC/ADC. But
these functions do not seem to work on my system (alsa-0.9.0rc5 and an
RME9652 sound card). Besides that I want to read the ADAT-Synch timecode
instead of the buffer relative sample offset.

Therefore I was looking for another solution to get the time. I tried to
use the ALSA timer interface
(http://www.alsa-project.org/alsa-doc/alsa-lib/_2test_2timer_8c-example.
html#example_test_timer). But unfortunately I am getting a "timer time
out!", which means that 

snd_timer_poll_descriptors(...)

did fail. Is the timer interface implemented for the By the RME9652? By
the way I do not understand how the sample number to the read time do
correlate with each other.

I would appreciate any help with this because if I cannot solve this
problem, I have to move to Windows ASIO (what a pitty!) ASIO provides
the functions

ASIOGetSamplePosition(...)
bufferSwitchTimeInfo(...) 

which do exactly what I need.

Regards,

Men



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