This article will discuss the audio functionality of the DGX when using the Audio Switching Boards (ASB).
DGX audio options
The DGX is a video switcher, that by default, carries embedded audio on the video stream, with no independent audio routing.
To achieve this, additional audio boards are required, of which there are 3 options
Audio Insert/Extract boards (AIE) - https://www.amx.com/en-US/products/dgx-aie (see https://support.polar.uk.com/a/solutions/articles/25000024544)
Audio Switching boards (ASB) - https://www.amx.com/en-US/products/dgx800-1600-asb
Dante Audio Switching boards (ASB-DAN) - https://www.amx.com/en-US/products/dgx3200-asb-dan
Audio Switching Boards configuration
Unlike the AIE boards, the ASB boards must be used as a pair, with both input and output boards connected.
Except in the case of the DGX6400, you must also use the included HSSI cable to connect the input board to the output board for them to show online, pass audio, and provide the additional DSP capabilities. This is due to the switcher back-plane not having the bandwidth to carry the additional audio processing. The DGX6400 was designed at a later date, at a similar time as the ASBs, therefore the additional bandwidth was factored into the design.
Once connected, the boards will provide the DGX with 8 additional line level inputs and 8 outputs for the DGX800/1600/3200 and 16 additional inputs and outputs for the DGX6400. You will then see them listed under the switcher Status menu on the Web UI under the Expansion Audio Boards section.
Downmix and DSP
Once installed, in addition to the extra line level inputs and outputs, you will now have DSP capabilities, such as a 10-Band Parametric EQ, level controls, Sync Delay and Test Tone generators.
This also applies to the audio embedded on the video streams.
To see the ASB line level inputs and outputs, you need to ensure the Switch Mode is set to Audio, as by default it is set to A/V and will only display the ports associated to the video input/output boards.
There is also an additional audio input, labelled 'Downmix'. This allows you to map another audio input that is carrying 5.1 audio, for example, to the Downmix channel, and this will downmix the audio to 2 channel PCM for routing to outputs that do not support high bit-rate audio.
By doing this, you are still able to allow your source, such as a Blu-Ray to pass high bit-rate audio to outputs that will support it, and simultaneously to other outputs that do not.
The Downmix input is always the last input number, so for a DGX3200, inputs 1-32 are the Video board ports, inputs 33-40 are the 8 ASB line level ports, therefore the Downmix is input 41.
Switched Audio vs Embedded Audio
The ASB boards now allow full independent audio and video switching, meaning you can route any video source to an output with another audio source.
This can be achieved in Netlinx code, or via the Web UI on the Switching menu, again with Switch Mode set to Audio.
The Outputs will indicate whether the audio routed to them is embedded from the video source, or switched audio from a different source to that of the video.
The speaker symbol denotes embedded audio, and the crossed arrows indicating the audio is switched from a different source.