Gabriel M. Beddingfield wrote: >> i am wrong if your displayed frames are not the jack transport frames. also >> all usec values differ around +/- 300 usec. > > usecs is supplied by the JACK server.
Here's TMI on jack_position_t.usecs.... usecs is supplied by the jack server for every process cycle. The number you get back from usecs is hardware dependent. On x86 Linux machines, it is the result of the x86 instruction RDTSC... which is a microsecond counting register on x86 processors since the 386. It is a free-rolling timestamp that's set just before the process cycle. RDTSC is considered to be high precision, and it's value reflects the time that it was called -- not the time that the "jack period" frames would be scheduled to sound out of the audio card. Usually, its value represents the number of microseconds since the last reboot. The +/- 300 usec jitter that you noticed probably has to do with the kernel scheduler switching from some other process to jackd. Peace, Gabriel ------------------------------------------------------------------------------ Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H _______________________________________________ Hydrogen-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/hydrogen-devel
