How To Configure Comrex Access for WheatNet-IP Using AES67

How To Configure Comrex Access for WheatNet-IP Using AES67


Prerequisites

    
  1. A Precision Timing Protocol (PTP) v2 clock source on your WNIP Local Area Network. Blades do not generate PTP, but they can lock to it. Comrex codecs running version 4.5p2 or higher can be set to generate PTP clock, or you can use an external PTP source. Consult the Access manual if you want to use it to generate the clock.
  2. A license in WheatNet Navigator to enable the PTP clock function. When you go to the Info tab in Navigator and set the external timing source to PTP-AES67 in the Clock Master Info section, you will be prompted to obtain the license key. Send the license seed to activation@wheatstone.com and the support department will send you a key to paste into the box to activate the feature. There is no charge for this license key.
  3. The Comrex device and Wheatnet System must be set to the same sample rate (44.1 or 48k)

Configure The Equipment To Follow PTP


When your WheatNet-IP system has locked to the PTP clock, the PTP Status indicator will turn green:


Info
For most networks, the domain setting should stay at the default of zero. Adjust this as necessary if the PTP clock is on a different domain.

On the Access web page, go to the Network Manager section and change the secondary Ethernet port to static (DHCP is default). Follow the instructions in the Comrex manual to set the address of the secondary port to an address in the range of your WNIP network.


Once your Access is on the WNIP LAN and can lock to the PTP clock, the Comrex and your Clock Master Blade will be locked to the same clock source and the rest of your Blades will be locked to the Clock Master Blade’s metronome, so everything will be time aligned.

So if you have a green light on the PTP section in Navigator’s info page and a “Locked” message on the Access, we are ready to proceed.


Key Concepts

AES67 is at its core a timing protocol – it is a way to ensure that Audio over IP equipment from different manufacturers will send packets at the same rate and in a common format. There is no common discovery protocol, therefore it is necessary to manually enter the following information and enter it on both ends of the wire:

  1. The multicast address of the audio stream
  2. The UDP port of the audio stream
  3. The packet rate
  4. The payload type
You will enter the information of the Comrex outputs into Navigator as sources, and you will enter the information from Navigator for the WheatNet sources that will feed the codec as inputs to the Access.

Wheatnet-IP defaults to a .25ms packet rate, while the Comrex runs at 1ms. So we have to send the Access a stream it can support. The Access defaults to a payload type of 98 and we use payload type 100, so we need to tell the Blade it’s going to receive a payload type 98. We will account for these items in the steps ahead.

Special Setup For Blade 3

If you have a Blade 3 system, you will need to turn off at least one utility mixer on any blade to turn it into an AES67 translation blade. Go to the Blade Admin tab and choose AES67 1ms support. Each blade set for AES67 1ms Support will create up to 8 1ms streams from any 8 sources on the system.


Blade 4 systems are capable of creating 1ms translations without turning off a utility mixer, so if you have at least one Blade 4 on the network, you won't need to do that.

Create The Outputs to the Codec

Usually, you will send mix minus or bus minus feeds to codecs. The Comrex will need a 1ms stream that is stereo, and on many consoles that source is mono. So, we will use a utility mixer to both translate the stream to stereo and to 1ms. This also will give you the flexibility to change the routes to the codec within Navigator either manually or via Salvos, which is handy when different studios share a codec.
  1. Route the mix minus or bus minus you wish to feed to the codec to utility mixer input 1. Turn its B volume slider down and keep the A volume slider up. Turn the input on.
  2. Route another mix minus or bus minus to utility mixer input 2. Turn its A volume slider down and keep the B volume slider up. Turn the input on.
  3. Turn on the Mixer A and Mixer B Master Faders
  4. Rename the outputs of the mixers (they are on the Sources tab of the blade) as desired.
  5. While you are on the same page to edit the name, check the box for 1ms AES67 Support.


Click Finish when you're done.

Now we're back at the Sources tab in Navigator. Put your mouse over the source you want to send to the Comrex and right-click.

Select Show SDP.
A window will appear with two tabs; one will be for .25 ms and the other for 1 ms.

Click the 1ms tab, then click Copy. This will place the text of the SDP file into the clipboard. Everything that the Access needs to know: multicast address, packet rate, packet type, number of channels is in this text and in a format that the Access can understand.

In the Access web UI, go to Global Settings and open up the desired instance.


Click on the SDP line, which will open up the current SDP settings on the right. Delete the text in this window (if any) and paste in the SDP info you copied from Navigator. As it reloads the information it will briefly error out and then show that it is connected to the WNIP stream. Repeat with the other instances

Create The Inputs From The Codec

We just sent the audio from the Blades to the Access. Now we need to get the audio from the Access to the Blades.
Notes

You will need to create a unique multicast IP address for each codec in the Access. Any valid multicast IP address will do as long as it does not conflict with the range that Wheatnet IP dynamically assigns or in the range that the Comrex might have reserved.. The range of addresses Wheatnet uses is defined on the Info tab of Navigator. The default is 239.192.192.0 and above. The valid range of multicast addresses used for local networks is 239.0.0.0 to 239.255.255.255, so you could choose an address between 239.0.0.0 and 239.192.191.254 and not conflict with the WheatNet-IP address pool.

Since different manufacturers will use different portions of that wide range of possible addresses, it is best to plan out your addressing scheme, so as you add more AES67 devices you don’t overlap. Keep a spreadsheet that you can refer to as you add new equipment in the future.

On the Access, when you turn on AES67, it will create an address automatically for each codec. In the Access AES67 settings, go to Outputs and look at the address that the Comrex selected.


If the Access chose an address that’s outside of the Wheatnet-IP address pool, you don’t need to change anything here. If it conflicts with something, find a valid Multicast address that is in the clear, then Apply on the webpage. Disable and re-enable AES67 on the access for it to begin transmitting on the new address. Otherwise, hang on to that address for the next step.

Enter The Multicast Stream Information Into Navigator

The first step is to create an AES67 device in Navigator.
In Navigator, click on the Devices tab, then choose the AES67 Devices up top.


Click Add.

Give it a Name (ie Access) and enter the IP Address.
From the drop-down list, pick a Host Blade.
Notes
The Host Blade can be any Blade within the system. This will determine which Blade the Comrex's sources will be grouped with in the Crosspoint Grid. We're not actually sending any data through the Host Blade, it's just a place to hang the sources. Choose something that's convenient for you. For example, if this device is used with a studio, you might choose a blade in that room. Or if it's in a rack room, you could use a Blade that is near the Access as its host. Pick something that will make it easy to find the sources in the grid,
Remember that multicast address we just created in the Comrex? in Navigator, click on the AES67 Blade you just created for the Access and click on the Sources tab. Click Add.
Name the source; that's what will appear on the console. Then click on the Stream Info tab.



Enter the multicast address from the Access, and UDP port number 5004. Set the packet timing to 1ms. The Payload Type should be set to 98. This will match up with what the Access is transmitting. Click Ok, then click Finish.

You can now route this source to the console and test audio in both directions.

Repeat with any remaining codec channels.

Special thanks to Tom Hartnett at Comrex for his assistance!

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