AES67 Audio Networking Quick Start Guide
By: Attero Tech
This guide is intended to provide an outline of the Ethernet network switch requirements and system design guidelines for successfully deploying Attero Tech’s AES67 enabled products in AES67 audio networks, specifically focused on QSC Q-SYS Core based systems and AES67-enabled Dante products.
Attero Tech’s current AES67 solution provides the following capabilities
- 48kHz, 24-bit uncompressed digital audio format
- 1ms end to end latency
- System wide sample synchronization
- Support for PTPv2 master or slave operation
- SAP (Session Announcement Protocol) based stream identification for use with applications supporting SAP Stream Discovery (Dante Controller, Q-SYS Designer, unIFY Control Panel)
- Multicast audio transmission
- Interoperability with QSC Q-SYS Core DSPs and AES67-enabled Dante products
The current AES67 solution used by most manufacturers, including Attero Tech utilizes multicast audio transmission for the distribution of audio streams. While small systems with only a few devices may work correctly with an unmanaged switch, to ensure that the multicast traffic is dealt with efficiently, it is required that Layer-3 managed 1-Gigabit switches be used to ensure robust system performance.
Attero Tech does not currently maintain a comprehensive list of approved switches, however, QSC’s list of qualified and disqualified audio networking switches is a good starting point for identifying suitable switches as the underlying switch requirements features and capabilities meet the basic requirements for Attero Tech’s AES67 products.
When configuring the network using managed switches, the following switch functions need to be applied.
- Turn off EEE / Green Ethernet
- IGMP must be enabled on all switches
- An IGMP querier must be enabled on one switch (recommended query interval is 30 seconds)
- Filtering for unregistered multicast traffic should be turned on, especially on switch ports that interface to PC control/configuration software
Attero Tech AES67 endpoint products support both PTP clock master and slave operation. It is recommended that in systems using a Q-SYS Core DSP that the DSP be manually prioritized as the AES67 network PTP clock master.
For networks that use Attero AES67 devices with a QSC core, it is recommended to make the DSP the master. This setting is configured within Q-SYS Designer under the File->Design Properties menu. The “PTP Priority” must be changed to a value less than 128.
When deploying a system that includes Dante devices supporting AES67, these devices will always win the PTP clock master election due to their intrinsically higher priority settings when compared to Attero Tech’s default PTP priority values. Additionally, when using AES67 enabled Dante devices, QSC Core DSPs and Attero Tech’s AES67 endpoint products in a mixed system, the AES67 enabled Dante devices will continue to win the PTP clock master election even though the QSC Core DSPs have a configurable clock priority due to the two level priority scheme implemented for PTP clock arbitration, where the Dante device is configured by default for a higher (preferred) priority 1 value.
System Design Considerations
As mentioned earlier, Attero Tech, Q-SYS and AES67-enabled Dante devices utilize multicast audio for all AES67 audio transport. This functionality brings both simplicity and challenges to audio network system design. By utilizing multicast, the network is leveraged for its ability to send audio to all devices at the expense of bandwidth. Due to the additional bandwidth requirements however, care should be taken to implement the multicast filtering recommendations presented earlier.
Stream and Channel Count Limits
When designing a system including Attero Tech’s AES67 endpoints and a Q-SYS Core DSP, two limiting factors for the overall number of supported system devices are stream and channel counts. Depending on the Q-SYS DSP selected these stream and channel count limitations will vary. For example, the stream count limitation of the Core110f is 128 x 128 network channels with a stream count limitation of 64x64 streams. Q-SYS AES67 streams can consist of up to 10 audio channels, care should be taken to match the channel count of any stream being received by the Core from an Attero Tech AES67 enabled device, otherwise the stream will not be received.
Attero Tech’s AES67 streams are product dependent and vary with the capabilities of the device. As an example, the unAX2IO+ wall plate product consists of 4 analog input audio channels that are digitized by the device and packed into a single transmit stream. In addition to the physical inputs of the device, all Attero Tech AES67 products feature a built in tone generator for simplifying system diagnostics. This feature utilizes an additional channel in the transmitter stream, bringing the total channel count in our example to 5. Given these capabilities the maximum number of devices that can be used directly with a Core is first limited by streams and then by the total network audio channel count. Note that in a Q-SYS based system this also includes QLAN connections between QLAN devices. The following table presents the device limitations for mixed Attero Tech AES67 and Q-SYS Core110f based system.
|Product||Transmit Channels||Maximum Number of Devices|
In summary, if you are considering projects that may require a large number of endpoints, and particularly systems that will exceed the device/stream/channel limitations outlined previously, it is recommended to give consideration to Attero Tech Dante endpoint products that do support unicast audio transmission. In large systems, unicast support in Dante will provide simpler system setup and more efficient usage of DSP and network resources. This does imply additional hardware support in some target DSP systems, but will significantly simplify the overall system design.
System Connectivity Guide
The following sections describe the necessary network connections and audio routing configuration for various target systems. This step by step guide assumes that the network has been installed and configured prior to addressing the audio routing configuration.
Attero Tech – Q-SYS Core AES67 System
For this example, this basic system consists of Attero Tech AES67 networked audio wall plates, a Q-SYS Core110f DSP and a TSC7-W. The example highlights all of these products connected to the same LAN A connection on the Core DSP with the LAN B reserved for WAN connectivity. The AES67 endpoints could in fact be connected to only the LAN B side while LAN A is used for other connectivity to the DSP (Control / QLAN).
The TSC-7w is shown as a possible real-time control solution for not only the Q-SYS Core DSP but also for the Attero Tech endpoints by leveraging the device plugins for these products. Refer to the Attero Tech website regarding of Q-SYS Designer plugin support for current Attero Tech products.
Basic AES67 Audio System
Step by Step Audio Routing Setup
For each Attero Tech endpoint that will be used to transmit audio...
- Enable transmitter on each device transmitting audio using unIFY Control Panel v3.0.0.
- If the receiving device is a Core DSP, use Q-SYS Designer to add an AES67 receiver object to the core design and configure it to receive the stream from the Attero device.
For each Attero Tech device receiving audio…
- If the audio is being transmitted by a Core DSP, add an AES67 transmitter to Q-SYS Designer project and enable the stream.
- If the audio is being transmitted by an Attero AES-only device, enable the stream transmitter on that device using unIFY Control Panel v3.0.0.
- Use unIFY Control Panel to assign stream/channel to each of the Attero device’s outputs
Mixed Attero Tech, Q-SYS Core and Dante-AES67 System
Many Dante products based on the Brooklyn 2 platform currently support an AES67 interoperability mode. This can be enabled on Dante products that support this functionality using Dante Controller. The following diagram shows a mixed system consisting of Attero Tech endpoints, a Q-SYS Core110f and an Attero Tech Synapse D32i (AES67 enabled Dante product).
Mixed AES67 / Dante System
Step by Step Audio Routing Setup
If using the Attero Tech Synapse D32i to transmit audio…
- Use Dante Controller to enable AES67. Note that the device will require a reboot afterwards.
- Use Dante Controller to create a multicast AES67 flow containing the channels required, be sure to check the AES67 flow checkbox in the multicast flow setup.
- To assign audio to a QSC DSP, within Q-SYS Designer, place an AES67 receiver object in the design and assign the transmit flow from the Synapse D32i to it.
- To assign the audio to an Attero Tech endpoint, use unIFY Control Panel to assign the endpoint with the streams/channels from the Synapse D32i.
If using the Synapse D32i or other AES67 enabled Dante product to receive audio.
- Use Dante Controller to enable AES67. The device will require a reboot afterwards.
- If transmitting from a Core, within Q-SYS Designer, place an AES67 transmitter object in the design and enable it.
- If transmitting from Attero AES-only device, use unIFY to enable the AES67 transmit stream.
- Use Dante Controller to route channels from the appropriate AES67 streams which should now show up.
For further support regarding setting up streams including video guides please visit the Attero Tech website.
*Note: If you are sending audio between two Dante enabled devices that are also operating in AES67 mode, these devices will still use Dante for the audio transmission between devices. AES67 will only be used when sending audio from an AES67-enabled Dante device and a non-Dante AES67 product like the Attero Tech endpoint products or the Q-SYS Core110f.