Modifying a Backfeed using a VMixer


How to use the VMixer in the Fusion Engine, Powerstation, or Telos iPort to modify the audio sent back to a codec or phone caller from an Axia console.


Most of the time, the standard mix minus from an Axia console engine's backfeed is good enough. Sometimes a programmer will want to mix additional audio with the mix minus that a caller hears. For example, a preview bus or additional talk back. This example uses a Fusion Mix Engine and a Telos VX, but this can apply to many other products.

Intercept the Backfeed

  1. Determine the Livewire channel being used for transmission. The easiest way is to visit the source profile and read the value of the Primary Source field.
  1. In the VMixer, set a channel's Input Selector to EXTERNAL
  2. Enter this channel number into the Input Channel field.
  3. Set the Stream Type to To source.
  4. Set Enable to On
  1. Click the Apply button below the VMixer you are using.

Set up VMixer Output

  1. Go to the Submix section of the VMixer you are using and enter an available Livewire channel into the Channel field.
  2. Label the output in the Out Name field.
  3. Set the Out Stream Type to Live Stereo
  1. Click the Apply button below the VMixer you are using.

Replace the Backfeed

  1. In the codec, hybrid, or VX Studio, disable Automatic Backfeed, enter Expert Mode, or tick the checkbox under Advanced Receive (depending on what you are working with).
  2. Enter the Livewire channel of the new backfeed into the channel/destination field
  3. Set the stream type to From Source.
  1. Click Apply

Modify the Backfeed

At this point, the original backfeed is being sent to the VX from the Fusion engine with a VMixer in the middle.

You can now add more audio sources to the VMixer and modify it how ever the VMixer allows.

Notice: Changing the state of VMix channel ON/OFF, gain, etc. outside of the VMixer UI in the Fusion engine can be done with a LWCP program such as Pathfinder.

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