External Audio Connections
Overview
The Telos Infinity Intercom uses Livewire+™, a self-contained ecosystem that provides automated device discovery and connectivity between Livewire+™ compliant devices such as Telos Infinity panels, Beltpacks, and xNodes.
On occasion, it may be necessary to connect to external systems to receive audio from, and send audio to, devices not using Livewire+™. An example of this is connecting to the communication circuits of a camera using SMPTE’s ST2110-30. This in turn uses AES67.
In the example in Figure 8.29, the microphone output from the camera operator’s headset would be digitized, converted to the ST2110-30 protocol in the CCU, and then sent to the network to be received by a Telos Infinity Panel.
Although AES67 is being used, important parameters such as the sample rate, bit depth and packet size are not fixed or mandated but are left for the engineers configuring the system to decide. This helps them build the most optimal system for their application. Furthermore, AES67 does not provide any headers within its data payload so there is no way a receiving device can know, from the audio stream alone, if the data is two streams or three streams, 16bit, or 24bit etc.
For the Telos Infinity Intercom to receive and decode the microphone signal it must know all these parameters and more. To achieve this, a Session Description Protocol (SDP) file is created by the camera. This is made available via the camera’s user interface. The contents of the SDP file are copied and pasted into the input configuration window for the Telos Infinity Intercom (see below).
Using Dashboards drag-and-drop, an input can be assigned to a device such as the Directors panel listen key. The Telos Infinity Intercom system automatically knows the multicast address and configuration parameters of the camera microphone feed enabling the panel (or any other connected device) to seamlessly decode the audio feed.
When sending audio from the Telos Infinity Intercom to an external device not using Livewire+™, such as the camera headphones in Figure 8.29, an SDP file is created by Dashboard (see below). This is copied and pasted to the camera’s user interface so it can decode the Livewire+™ audio sent by the Telos Infinity Intercom.
Figure 1 below illustrates how interoperability, such as AES67 in ST2110-30, is achieved when interfacing with Livewire+. The SDP is copied from the camera so that the Telos Infinity Intercom can determine the format of the audio stream. Meanwhile, the SDP from the Telos Infinity Intercom is provided to the camera so that it can decode the Livewire+ stream in order for the camera operator to hear the director in their headset.
An example of a typical SDP file might look like this:
v=0
o=- 0 0 IN IP4 127.0.0.1
s=Camera Intercom
t=0 0
a=rtpmap:96 L24/48000/2
a=ptime:1
a=maxptime:5
a=ts-refclk:IEEE1588-2008:00-1D-C1-FF-FE-0B-92-32:0
a=mediaclk:direct=0
a=sync-time:0
m=audio 5004 RTP/AVP 96
Adding an Input
Adding an input is the process of configuring the Telos Infinity Intercom so it knows the multicast IP address of sending device and the associated SDP file should it be needed. If the input is from a Livewire+™ compliant device then there is no need to provide an SDP file.
Select “Input”.
Click “Add” and the configuration window appears.
Enter the name, multicast address and channel number if required.
Copy and paste the SDP file if required.
Click “Create”, the configuration window closes and the associated icon appears in the Input window.
Drag the icon associated with the input to panel keys, IFB’s, Group’s etc.
Adding an Output
A user can create an output stream within Infinity by using the Output-Add button. The stream is generated by entering the Multicast address, or Livewire+™ channel number. SDP data is made available in the configuration window and the SAP can be enabled to allow external 3rd party equipment not using Livewire+™ to decode the audio stream.
A SAP enabled output will appear as a ‘Talker’ within a Dante system that has AES67 activated equipment.
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