AES67 and Livewire backfeeds (mix-minus) - How?

SCOPE

This document applies to any Axia Console that was/is capable of creating an automatic mix-minus. In case you are wondering, that is every Axia console ever made. AES67 alone lacks the advertisement and subscription mechanism that allows Axia consoles and other Livewire devices to do this. Therefore, you may not be able to get an automatic mix-minus to show up at the input of your AES67 device. This document will show you some clever workarounds using things you may already have in your setup to get this working.

DESCRIPTION

In this technote, we will be discussing ways to create backfeeds (mix minuses) or convert AES67 streams to Livewire streams to facilitate the auto mix-minus features you expect from an Axia console system.

Method 1: Manually Create a Mix-Minus

This is the simplest way to do it:

  • Configure an output for an extra program bus from the console. Program 2 for example.
  • Use the program 2 buttons on the input channels of the console to manually build a mix-minus.
  • Send this output (with program 2 audio) to the input of the device.
Remember that a Mix-Minus is a "Mix" of all the sources you want the user at the other end to hear "Minus" the output of that device. If you're using Program 2 for this, DO NOT route the device's console channel to Program 2. If you do, this will no longer be a mix-minus.

Method 2: Using the Mixer Matrix of an xNode

This is a method for converting AES67 streams to Livewire and vice versa. It requires two available sources and destinations. The back panel of the xNode will not be used, so it shouldn't interfere with any of that. We'll be using a Comrex NX as our example here.

NOTE: The Multicast addresses and LW channels used here will likely be different from yours. The Multicast addresses used will need to match what is configured at the AES67 device.

Enable Mix / Custom Mode

Go to SIMPLE SETUP in your xNode and configure it for MIX / CUSTOM mode

Configure Destinations

  1. Go to the DESTINATIONS page of your xNode
  2. Configure a DST to receive the AES67 output of the Comrex NX, we'll use DST 5 in this example. Set this up as a "From Source." Here, we assume that 239.100.100.100 is the stream coming from the Comrex.
  3. Configure another DST to receive the Livewire backfeed from the console. We'll use Livewire channel 409 at DST 6 here. Set this up as a "To Source."
  4. Apply changes.
There are two different paths for audio available on each and every Livewire channel. The most common is "From source" which is pretty self-explanatory. This is audio that comes from the source. Backfeeds from console engines send audio back to the source from which the "From Source" stream originated. So we call this "To Source."

Configure Sources

  1. Go to the SOURCES page of your xNode
  2. Configure an SRC to send a Livewire stream to the network. This will be the same Livewire channel configured in the Destination, except this time it's a "From Source" (implied). Let's use Standard Stereo for the stream type on SRC 5 in this example.
  3. Configure another SRC to send AES67 audio back to the Comrex. In this example, we'll use SRC 6 and assume that 239.100.100.101 is configured at the input of the device. Set the stream type to "STEREO 1ms (AES67)"
  4. Apply changes

Route streams using the Mixer Matrix

  1. Now, go to your xNode's MIXER page.
  2. Route the DST with the AES67 stream from the Comrex to the new Livewire SRC
  3. Route the DST with the Livewire backfeed from the console to the AES67 SRC that sends audio to the Comrex

We've highlighted the mix-minus in Blue and the signal from the Comrex in Red.

Configure Console Source

Set up a codec source profile in your console engine and use the new Livewire channel you've created in the xNode (409 in this example) for the input source. The engine will create a mix-minus and the xNode will convert this to the AES67 stream the Comrex wants at its input.

Method 3: Using VMode in a Studio Mix Engine, PowerStation or Zephyr iPort

This is another method for converting AES67 streams to Livewire and vice versa. It will require two available VMode channels. If you choose to do it this way, use an engine that is not powered off or rebooted often. This would obviously interfere with the conversion of audio streams.

  1. Navigate to the VMODE page of one of these devices.
  2. Choose an available channel and click CONFIGURE.
First, notice the location of the different APPLY buttons. Don't let this mess you up.
NOTE: The Multicast addresses and LW channels used here will likely be different from yours. The Multicast addresses used will need to match what is configured at the AES67 device.

Configure Input from AES67 device

You can load your device's SDP file here or continue with manual setup:

  1. Under the input section, set INPUT SELECTOR to EXTERNAL
  2. Name the source. "AES From Comrex" is what we're using in this example
  3. Enter the multicast IP address the device is using for output (239.100.100.100 in this example) in the ADDRESS field.
  4. Set STREAM TYPE to L24 2CH (LIVEWIRE FROM SOURCE)
  5. Click the Apply button in the INPUT section
Note: Leave the "Audio Channel Routing" mode set to PASS STEREO for this configuration.

Configure Livewire Output to the Network

You can load your device's SDP file here or continue with manual setup:

  1. Under the OUTPUT section, name the source. "Comrex to Console" is what we're using here.
  2. Enter the Livewire channel you would like to use in the ADDRESS field. We're using channel 409 in this example.
  3. Set STREAM TYPE to "L24 2CH (LIVEWIRE FROM SOURCE)"
  4. Set PACKET TIME to "5ms (LIVEWIRE STANDARD)"
  5. Click the APPLY button in the OUTPUT section.

Configure an Input for the back-feed (auto mix minus)

  1. Go back to the main VMODE page
  2. Choose another available VMode channel and click CONFIGURE
  3. In the INPUT section, set the INPUT SELECTOR to EXTERNAL
  4. Name the source, we're using "To Comrex NX" in this example
  5. Enter the same Livewire channel as before. We're using 409 in this example
  6. Set STREAM TYPE to "L24 2CH (LIVEWIRE TO SOURCE)" this time
  7. Click the APPLY button in the INPUT section
Note: Leave the "Audio Channel Routing" mode set to PASS STEREO for this configuration.

Configure the AES67 Output to the Device

  1. In the OUTPUT section, name the source. We're using "AES67 to Comrex" in this example.
  2. Enter the multicast IP address the device is expecting input audio on. In this example, we're using 239.100.100.101.
  3. Set STREAM TYPE to "L24 2CH (LIVEWIRE FROM SOURCE)
  4. Set packet time to "1ms (AES67 INTEROPERABLE)"
  5. Click the APPLY button in the OUTPUT section.

Configure Console Source

Set up a codec source profile in your console engine and use the new Livewire channel you've created in the xNode (409 in this example) for the input source. The engine will create a mix-minus and the VModes will convert the streams to the appropriate format.

More information

Since we used Comrex as our example here, check out what they have to say about this HERE!

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