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? > And in the case of several devices, how is it possible to > compensate the absolute delay? All devices should be in phase, with a > deterministic inter-device delay. We have to think about that, I have no answer today. > If it is only a single device it should be possible to use netjack: Then > it behaves as a small host with its own sound card, and running jack > with netjack_client (or whatever it ins called in recent versions). Any > remote PC can run jack with the net backend to connect. Well, with > netjack for jack0.116.2 the connection request is made from the other > direction, in this case the open sound card, but connect requests could > be triggered via OSC. And Netjack2 for jack2 seems to work completely > differently. So, it amount to write an alsa driver then? Regards, /Karl [1] http://www.ixxat.com/evaluation-kit-linux-live-cd_en,24073,5873.html [2] http://ptpd.sourceforge.net/ [3] http://www.estamos.de/blog/2009/07/01/linux-2-6-30-hardware-assisted-time-stamping-of-network-packets/ [4] http://bombadil.infradead.org/pipermail/ptpd/2009-November/000012.html [5] http://ptpd.sourceforge.net/ptpd_2005_1588_conference_paper.pdf [6] http://www.linuxclustersinstitute.org/conferences/archive/2008/PDF/Ohly_92221.pdf ----------------------------------------------------------------------- Karl Hammar Aspö Data karl@xxxxxxxxxxx Lilla Aspö 148 Networks S-742 94 Östhammar +46 173 140 57 Computers Sweden +46 70 511 97 84 Consulting -----------------------------------------------------------------------
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