Cross the Bridge When You Come to It

By: Tony Staires

There has been a lot of discussion about which bank of the Ethernet river is better suited for media networks. Some users recommend open standards, such as AES67/RAVENNA and SMPTE ST2110. Others will point you to Dante, because it is the most popular protocol and supported by a long list of vendors.

Until recently, this choice was a no-brainer: Dante rules for live applications and studios; open standards for broadcast. Following the tectonic shift the covid pandemic set in motion, however, workflows are changing: audio and video networking several campuses and sending out live streams at the same time require WAN (wide-area network) data transport, and this is where AES67/RAVENNA and ST2110 shine, because WAN support is expected from broadcast-grade gear.

Without belittling other audio/video-over-Ethernet protocols out there, let’s just assume that sound engineers need to be aware of Dante and likely use it on a daily basis, not least because there seem to be Dante networks everywhere.

The covid pandemic has taught us that live performances and church services may suddenly come to a grinding halt, while audiences still want to consume concerts, plays, conferences and, of course, services.

After solving the delivery challenge, some creative solutions began to focus on how to decentralize the workflow: physically separating the orchestra from the choir and the soloists became an important consideration. Allowing the sound engineer to work from another room or facility, controlling DSP processors from afar without even noticing that the processing takes place in a different part of the world, are only a few invaluable lessons learned from the pandemic – and they endure.

GATEWAY

Distance can be an advantage, provided the technology you use allows for such an approach. This is precisely why the broadcast world uses open-standards protocols.

Does this mean that Dante is hardly ever used in the broadcast world? Of course not, even though it may seem futile to even bring this up for live sound engineers or studio owners who never go beyond their premises. Yet, there are Dante islands in every broadcast facility, simply because it makes sense to use specific devices and software tools that “only” support this popular protocol in an otherwise AES67/RAVENNA-based environment. Plus, it is always a good idea for broadcasters to be open to the devices used by musicians and producers who may come to the broadcast facility to create jingles, recordings, etc.

How do you cross the bridge that links AES67/RAVENNA to the Dante bank, and how do you get back to the other side? You use a gateway that translates one protocol into the other for incoming streams, and back again for outgoing streams. A rock-solid way of doing this is by equipping a Power Core with a Dante card and connecting that to the Dante network.

The Power Core, for its part, can be connected to the RAVENNA network and thus acts as a reliable bridge between the two riverbanks. You probably wonder whether it is really that easy. After all, adaptors and conversion boxes often require extensive configuration sessions and tweaks to ensure that the streams go to the right destinations and behave as expected.

The simple answer is that the card’s behavior is no different from that of any other Dante device. Thanks to DHCP (Dynamic Host Configuration Protocol), the card is automatically assigned a unique IP address, thus avoiding issues arising from duplicate ID addresses on the network and ensuring that a newly connected device becomes immediately visible.

Similar to any other Dante device, you may need to use the Dante Controller software to route the required streams to the right destinations. If your audio console is a Lawo mc2 model, you enjoy the added convenience of being able to control the software from the console’s display, courtesy of the mc2’s Remote Desktop or VNC support.

Each Dante card in a Power Core handles up to 64 input and as many output channels. If that is not enough, simply add more cards. The Power Core has eight slots that can be populated with a variety of I/O connection formats. If necessary, it can even handle MADI signals at the same time.

Sample-rate converters (SRCs) are built-in and automatically solicited if there is a mismatch, and 96kHz is supported for up to 32 input and output channels per card.

Finally, you may have heard that, in a digital audio environment, there needs to be one master clock to which all devices are synchronized. On the bridge that links Dante to AES67/RAVENNA, clocking is not an issue. No harm will be done to the audio signals traveling either way: no nasty distortion, no artefacts, etc.

There is a technical explanation for this: a Dante live environment usually uses a different clocking type than broadcast equipment. A Dante card in a Power Core syncs to the Dante network clock, while its RAVENNA side clocks to the broadcast domain.

THE BEGINNING OF A BEAUTIFUL FRIENDSHIP

If the reason for not choosing the AES67/RAVENNA mixing console you have heard so much about and consider the ideal candidate for your workflow—both from a sound quality and feature-set point of view—is that it does not support Dante, we have news for you! There is a gateway between Dante and AES67/RAVENNA that future-proofs your Dante setup and allows you to keep using amplifiers and speakers that support this protocol, while at the same time enabling you to benefit from all the advantages an mc2-based audio mixing system brings to the table. You effectively get the best of both worlds.

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Tony Staires currently works as Sales Director for the Audio and House-of-Worship sector at Lawo North America. Previously, he was Production Director at Granger Community Church in Indiana. Over the past 20 years, he has also worked in production and AVL integration, with several national broadcast organizations, and as FOH and monitor engineer for Grammy and Dove Award winning artists.