On Wed, 11 Nov 2009 23:30:08 +0100 (CET) karl@xxxxxxxxxxx (Karl Hammar) wrote: > Giso Grimm: > > Maybe I am something missing, but what about the clock synchronisation? > > There are works to make ieee1588 (PTP) into linux, [1-4]. > That might help. > > In [5], they seem to get <10us offset from a master within 2minutes > converging time. [6] gives a little different picture. > > > It would be nice to allow synchronisation of several devices via the > > network connection. This transport medium typically has a lot of jitter > > (even an unloaded gigabit system can be above 50µsec), however, the > > jitter of typical AD/DA converters should be in the order of > > nanoseconds. > > Do you (or anyone else) know the maximum allowable jitter useful for > audio? Jitter, as such is a solvable problem. You use a phase locked loop with a long enough time constant (high division factor) to average out the jitter. Where you have semi-permanent connections this time constant can be quite long provided that all the slave oscillators are pretty stable, and the master is rock solid. An entire cycle of 48kHz is about 20 uS so jitter would have to be significantly less than that to avoid 'cogging'. -- Will J Godfrey http://www.musically.me.uk Say you have a poem and I have a tune. Exchange them and we can both have a poem, a tune, and a song. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
