[Jack-Devel] AVB Backend

Fernando Lopez-Lezcano nando at ccrma.Stanford.EDU
Thu Jun 20 20:06:42 CEST 2019

On 4/11/19 1:44 PM, Christoph Kuhr wrote:
> Hi *,
> I wanted to start a discussion of what kind of AVB connectivity makes 
> the most sense for jack.
> But please keep in mind what AVB is and isn't.

For my use case b) would be the only choice. I have been using Motu 
hardware (with all its problems) because of its flexibility in setting 
up complex systems[*] - the biggest has 8 AVB connected audio 
interfaces. I am actively looking at AVB options as I am currently 
restricted to 64 channel max I/O through USB to/from the Linux computers.

One talker/one listener would not be nearly enough. Dynamic stream 
management without having to restart jack would be (almost) a requirement.

> a) Fully functional Backend
> b) Media Clock Backend with AVB jack clients
> pro a)
> - the AVDECC connection management could be done seamlessly in a jack way
> - out of the box avb functionality
> con a)
> - only one talker/listener, single audio interface
> - huge programming effort
> - no dynamic audio mapping
> pro b)
> - multiple talkers/listeners with multiple audio interface using alsa api

So the AVB stuff would be written in ALSA?

> - avoiding huge code addition to the backend, thus much easier to maintain

Hmmm, sure, but the code has to go somewhere, is that ALSA?

> - AVDECC handling per client for dynamic audio mapping
> con b)
> - cpu load... price for multiple talkers/listeners

Not too concerned about this (a single 64 channel USB interface on my 
current computers uses up about 12% of a core)...

-- Fernando

[*] https://ccrma.stanford.edu/~nando/publications/stage_grail_2019.pdf

> I'm excited to hear your opinions!
> Best,
> Ck
> -- 
> Diese Nachricht wurde von meinem Android-Gerät mit K-9 Mail gesendet.

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