Importance of kMain and kAux for plugin with multiple output buses

Developer VST 3 SDK
1

Hi Arne,

we’re in the process of adding support for multiple output buses in our VST3 adapter. What significance does BusInfo.BusType hold for output buses? In the BusTypes enum, the comment for kAux says “auxiliary bus (sidechain)”, does that mean that this is only relevant for inputs and output buses are always kMain?

For the specific application, our plugin will have a Stereo Main (mix) out and several individual outputs, so at first glance I’d intuitively use kMain for the former and kAux for the latter, but I’m not sure if this a) makes any difference and b) is the correct way?

Best,
Andreas

2

Hi Andreas
For outputs kMain should be assigned to the main outputs which will always generate audio signal.
The kAux is more for optional bus.
In Cubase context we do not make any difference between kAux and kMain outputs, they have always the same meaning.

3

Hi Yvan,

thanks for your reply. In the meantime, we found out that it actually doesn’t work in Studio One, when the outputs are not all kMain, so kMain it is :slight_smile:

Best,
Andreas