On Sat, 15 Jul 2017, Bearcat Şándor wrote:
Ahh, i was misunderstanding. I was under the impression that i could just put an extra 2 ethernet ports into my computer, install the kernel drivers and libraries (when they're available) and have an operational Ravenna input/output. However, if it needs a wordclock then it obviously needs a card. I had thought that the 'wordclock' was part of the data packet.
It is not word clock. but wall clock with high accuracy so word clock can be derived. It is possible to do an end point without by treating packets in the same way as as buffer in an audio card where alsa does not have to be aware of the exact clock rise or fall to deal with it. However, If you wish to send audio from an internal audio card to any aes67 endpoint. Your computer must be able to be provide an ntp server with good enough accuracy to provide wordclock to both your internal audio ai and to act as a master clock on the network... or be able to sync your internal audio card to an external ntp server. This accuracy pretty much requires a HW ntp server. As I said the intel i210 ethernet cards at $60-ish seems to be about the cheapest route.
Depending on how synced you want things... SRC can do a very good job and the broadcast industry uses it a lot. The zita-njbridge does a great job of connecting two computers together and I suspect using the zita src library as part of an aes67 driver would make <whatever> ethernet card workable so long as the computer was never expected to be a master clock. So an aes67 network with only two linux computers may not be usable or at least your network would not be wholely aes67 compliant. An endpoint with no ntp able to follow a masterclock closely doesn't seem fully compliant to me from what I have read. So the windows drivers downloadable from various places would have the same problem of not being fully compliant too. Some of the MacOS hw does have an ethernet chip with builtin ntp server.
So a driver that does what the windows driver does should be possible. -- Len Ovens www.ovenwerks.net
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