I just discovered that the vst wrapper uses JucePlugin_MaxNumInputChannels and JucePlugin_MaxNumOutputChannels while AU and RTAS uses JucePlugin_PreferredChannelConfigurations
How about allowing multiple channels configurations in VST as well?
IIRC one can also have different channel configurations in VST using setSpeakerArrangement():
I think we could agree on the following arrangements found in RTAS and use the corresponding ones in the VST SDK
ePlugIn_StemFormat_Mono
ePlugIn_StemFormat_Stereo
ePlugIn_StemFormat_LCR
ePlugIn_StemFormat_Quad
ePlugIn_StemFormat_5dot0
ePlugIn_StemFormat_5dot1
ePlugIn_StemFormat_6dot1
ePlugIn_StemFormat_7dot1
kSpeakerArrMono
kSpeakerArrStereo
kSpeakerArr30Cine //L R C
kSpeakerArr40Music //L R Ls Rs (Quadro)
kSpeakerArr50 //L R C Ls Rs
kSpeakerArr51 //L R C Lfe Ls Rs
kSpeakerArr61Music //L R Lfe Ls Rs Sl Sr
kSpeakerArr71Music //L R C Lfe Ls Rs Sl Sr
in VST there’s some potential ambiguity between the cine and music variants for the same number of channels though.