AudioProcessorGraph undesired replacement of connections


In the last days I worked on a simple routing system using AudioProcessorGraph (lets call it mainGraph) to mix together some Midi-driven Stereo-AudioProcessors (lets call them instruments). This works fine. Additionaly, I want to record the sum of my instruments in a seperate AudioProcessor (call it recorder), which is a node in my mainGraph, too. 

My connections:

1.) mainGraph Midi-In node to all instrument nodes

2.) All instrument nodes to mainGraph Audio-Output node (channel 0/1)

Fine up to this point. I get a stereo output signal from my mainGraph.

3.) All instrument nodes to the recorder node (channels 0/1)

After making connections to the recorder node, my mainGraph outputs a mono signal. In the old connections (2.) channel 0 seems to be replaced by channel 1. So only channel 1 is present on both output channels. In turn the recording is fine.

This doesn't happen, if I don't connect the instruments to the recorder node. Also, it doesn't happen, if I connect only channel 0 or 1 to my recorder node.

The issue can easily reproduced with Juce Plug-In Host demo. Unfortunately the forum software doens't allow to attach screenshots at the moment. To reproduce, add 2 stereo instruments, connect them to the Audio Output and to an additional effect (which is not connected to somewhere). You get the same result.

Am I missing something, or is it a bug? I'd be thankful for any advice.  

JUCE v3.2.0, tested with OSX (Yosemite) and iOS


Can't tell from this whether it's a bug or maybe just something you're not doing right in your recorder processor.. A picture would be handy..


​Hi Jules, unfortunately the juce forum software seems to be broken, because it doesn't allow to upload images (I tried several times with different formats). That's why I explain the reproduction steps in words:

  1. Use the Juce Plug-In Host demo.
  2. Add 2 stereo instruments and connect them with the Midi Input
  3. Connect the instruments to the Main Audio Output (channel 0 and 1) --> you get stereo sound from both instruments after this step
  4. Add an additional effect (e.g. Apple Delay) - this effect isn't connected to the output
  5. Connect the instrument outputs to this effect, too. 

-->​After the second channel of an instrument is connected to the additional effect, the first made "instrument to Main Out" connections are somehow altered / replaced and only one channel is going through (to both outputs).

Could you try this? Thank you, Martin