audio rate params

[x37v]

if you look in MetasoundCompressorNode.cpp you can see this:

bool bIsSidechainConnected = Inputs.ContainsDataReadReference<FAudioBuffer>(METASOUND_GET_PARAM_NAME(InputSidechain));

and it looks like rnbo looks for nullptr in its inputs and maps those to a zero buffer so we could potentially send nullptr to those param~ inputs if there is nothing connected. the ranges are confusing though and I've captured that in a ticket #18582