AES67 Standard and Ravenna Specifications

[Gabriel Bassinello]

Hello,

I'm a systems engineer and music producer just starting to explore the AOIP ecosystem.

Currently, I'm working on prototyping a few applications that involve sending AES-67 audio streams over a local area network (LAN). However, I've noticed that the available documentation on the internet regarding this standard is quite sparse and inconclusive.

Unfortunately, the price to download the specification document as a non-member of the AES is currently beyond my means.

I reached the company behind RAVENNA in hopes of accessing more technical specifications of their implementations but got the following response:

"RAVENNA is available as an open, license-free technology for interested implementers (manufacturers). General information and material (specifications, White Papers, manuals, a virtual sound card etc.) can be downloaded from the resources section of the RAVENNA web site. Except for a free Virtual Sound Card, all RAVENNA implementations / devices are offered by RAVENNA partners (manufacturers). "

Their partnership options are €1500 and €3500. Not exactly what I call open.

I would like to ask if anyone who has already begun building something using these protocols and specifications would be willing to share a copy of these documents with me.

Of course once I have something concrete, I will be more than happy to contribute it back to the community. free and open-source.

Much thanks!

[Philip Tschiemer]

Hi there

I know that 100$ for the latest AES67 revision can be taxing depending on personal circumstances, especially just for that single doc. I still mention, if you can afford so, I'd recommend becoming an AES member which - if I recall correctly - is something like 220$ and gives you access to a lot more documents.

I think I once found an older revision published with a request for comments or so, either way, I think this is it:

https://www.aes.org/standards/comments/drafts/aes67-r-171107-draft-rev-cfc.pdf

Either way, Ravenna sort of is based on AES67 but extends upon it and adds a bit, most noticably on the discovery and management side of things.

Also see this public document: https://ravenna-network.com/wp-content/uploads/2020/02/RAVENNA_Operating_Principles_-_Draft_1.0_final.pdf

If you're looking for some utilities, also see: https://github.com/tschiemer/aes67

at its core, according to standard, the audio stream uses RTP with L16 or L24 encoding (also see RTP RFCs/docs), SDP, practically relevant are SAP and possibly mdns (if you wanna do ravenna style).

PTP (ie IEEE 1588-2008) is used for clocking/sync'ing: https://standards.ieee.org/ieee/1588/6825/

Personally, I think the ravenna approach is quite nice, but I hear NMOS (for discovery and management) will be a thing, especially in broadcast.

https://github.com/AMWA-TV/nmos

Also personally, I'd recommend having a look at the relevant smtpe st2110 specs because I also consider it a meaningful and pragmatic adaptation and will likely find wider use (was it 2110-30/31 or so and something for clock?); think they cost also, but you can find some presentations showing differences/particulars. Amongst others: no RTPC, only multicast, some clock-option = 0

I started out on a framework but have been a bit lacking capacity; somewhat at the point where a PTP service would have to be implemented (or integrated), the actual audio/RTP aspects respectively. Sort of trying to make the core-codebase low-level and as usable on embedded devices as possible but also to provide some generic tools/functionality around AES67/RTP/PTP/etc (ie without having to rely on some fancy xy-systems-library). - > https://github.com/tschiemer/aes67

Otherwise: Phil Hartungs list of resources is also helpful: https://hartung.io/2020/07/aes67-resources/

Hope this helps, cheers

Philip

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[Elliott Balsley]

Unfortunately I don't have much to add to help Gabriel.  Sharing these documents would be a copyright violation, and therefore illegal.

I just want to point out a small correction.  Philip, the ST 2110 spec says that senders and receivers shall support both multicast and unicast.  One example of the latter is AWS MediaConnect.