Nevion ARC-SD-XMUX4 - Manual (Page 18)

ARC-SD-XMUX4 Rev. B
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3.16 AES I/O
The direction of the four AES ports can be selected by the user. This means that the user
has any combinations of inputs and outputs available: 4 inputs and 0 outputs, 3 inputs and 1
output, 2 inputs and 2 outputs, 1 input and 3 outputs or no inputs and 4 outputs.
3.16.1 Audio inputs
When an AES I/O port is set to be input, the sample frequency of the input is monitored to
see if the signal is synchronous with the system clock. If not, the audio input is passed
through a sample-rate converter. After the input block the audio can be delay with individual
delay for each AES port, before it is routed to the audio matrix. The audio delay for AES
inputs are set relative to the AES input port.
If the AES input port is synchronous with the SDI-input, the user can select the AES input
delay to track to the video delay. The card will calculate the relative delay for the audio based
on the delay setting for video and audio. This is useful if the SDI-in and AES has a common
clock source and the sync input has a different clock source
3.16.2 Audio outputs
The AES outputs are routed from the audio matrix via individual audio processing blocks.
The outputs are always 48 kHz and synchronous to the system clock. The AES outputs have
individual fallback options.
3.17 Audio generator
The stereo audio generator is available as an input to the audio cross point matrix, and as a
fallback option. There are therefore three slightly different ways to select the generator:
select it in the matrix directly, select it as the first priority under audio fallback, or to set it as
second priority behind a missing input.
The generator signal is a high purity 1 kHz sine wave with a 250ms interruption on the left
channel every 3 seconds. The audio level may be set to one of two standards. The two
levels are -18 dBFS and -20 dBFS. These two levels correspond to EBU R68 and SMPTE
RP155.
3.18 Audio processing block
The output of each stereo signal from the audio cross point matrix may be processed in the
audio processing block. This is controlled with the Multicon GYDA controller. The processing
includes channel L/R manipulation and audio gain.
Channel L/R manipulation
The stereo signals may be output in one of the following ways:
- LR, Left / Right No change.
- RL, Right/ Left Channels are swapped.
- LL, Left/ Left Left channel is copied into the right channel.
- RR, Right/ Right Right channel is copied into the left channel.
- !LR, ØLeft/ Right The left channel is phase inverted.
- L!R, Left/ ØRight The right channel is phase inverted.
- MM, (Left + Right)/2 The left and right channels are summed.
- MS, MS/AB The left and right channels are converted from AB stereo
to MS stereo.
The sum products (L+R/2 and MS) are reduced in level by 6 dB to avoid any possibility of
clipping.