VST3: only 24 channels per bus

[RDan]

Hi there,

I am currently porting my VST2 plug-ins to VST3 and encountered a strange problem:
When I set the bus in Reaper to 64 channels, load the VST2 plug-ins, I get 64 channels (plug-ins support up to 64 channels).

However, when I use the same plug-in with VST3 I only get 24 channels (per bus I define within my plug-in code, using JUCE). I guess that's the 22.2 layout. Other hosts like Plogue Bidule still give me 64 channels.

So my questions: why is Reaper only giving me standard layouts with VST3 plug-ins, and not any bus-configuration like it does with VST2 plug-ins?

Here's the related thread I have posted to the JUCE forum: https://forum.juce.com/t/buseslayout...-to-vst3/30672

[matt_f]

Bumping as I'm facing the same issue whilst developing VST3 plugins. Reaper is never requesting a bus size greater than 24 channels, even though the track channel count is >24 (using 36 for 5th order ambisonics in my test case)

UPDATE: I've been poking around with this and if I set "Request VST3 bus channel count" in "I/O" of the "Plug-in Pin connector" dialog to 64 rather than auto, my VST still seems to be limited to 24 channels (Reaper also shows '24 in 24 out' in the plug-in window). Setting this to 20 also seems to produce strange results; "16 in 16 out".
Worth pointing out that to help debug this, I had set my VST to respond to all supported bus layout queries with true, so it shouldn't be that.

[EvilDragon]

Seems to be a JUCE thing. I remember Modartt (Pianoteq developers) had some issues with proper bus assignment for VST3, in Reaper and I think another VST3 supporting host (don't remember which one). They managed to resolve it somehow, not sure how.

[RDan]

I am not sure if it's really a JUCE thing as other hosts behave differently. Maybe it's related to this one:
https://forum.cockos.com/showthread.php?t=194176

[TBProAudio]

Hmm, have not found a solution: I still have the VST3 24 channel limit in Reaper 5.965. Any chance to extend this to 32 or even 64 channels? Or should the plug-in report a special speaker arrangement to Reaper? Or do i miss something? Thanks

[RDan]

I have opened a issue at Steinbergs VST3SDK repository: https://github.com/steinbergmedia/vst3sdk/issues/28

I think it's a general problem of the VST3 SDK, not allowing discrete layouts. I opened it quite a while ago, and also opened a thread at their forum, but no response so far...

[TBProAudio]

Thank you. But I do not think it is a SDK problem, at least not for my plug, as I have modified the speaker arrangement stuff to support more than 12 channels. In Reaper it seems to work up to 24 channels. More gives strange behaviour...

[jm duchenne]

I don't know if it can help, but the up to 64 channels VST3 made with Synthedit 1.4 work perfectly in Reaper.
Perhaps could you ask Jeff how he uses the SDK ?

http://acousmodules.free.fr/x64.htm

[TBProAudio]

Originally Posted by jm duchenne

I don't know if it can help, but the up to 64 channels VST3 made with Synthedit 1.4 work perfectly in Reaper.
Perhaps could you ask Jeff how he uses the SDK ?

http://acousmodules.free.fr/x64.htm

Great. I wrote an email.

[jm duchenne]

Originally Posted by TBProAudio

Great. I wrote an email.

BTW, does this mean that you intend to do such high channels number plugins ?
It would be great !

[TBProAudio]

Originally Posted by jm duchenne

BTW, does this mean that you intend to do such high channels number plugins ?
It would be great !

Well, we are working on a 32to2CH mixer :-)

[Fiedler Audio]

24 Channels is the VST3 bus size limit (Nuendo and Cubase are not able to do more...). So initialize your plugin with more than 1 bus and voila, more channels available.