AU plugins - problems when muting/unmuting tracks

using the latest build of Ardour2 on OSX 10.68 I am experiencing stuck buffers with my IPlug made audio-units when unmuting tracks containing those plugins.

IPlug is an open source framework (which I am developing/maintaining) for targeting multiple plug-in formats, you can see the project and the issue reported here:

It seems that when un-muting a track with a stereo IPlug audiounit on Ardour2/mixbuss does not reconnect the input buffer for the right hand channel. This issue has not appeared on any other OSX AU host, and I have tested a lot, so I think it might be an issue to do with Ardour’s AU implementation (although other non-IPlug AUs I tried were OK!)

The source code for IPlug’s AU implementation is here:

here is an example “AGain”-style audiounit plugin to demonstrate this bug:

and here is a “Tracer build” which should print lots of debug info about which methods are called to the stdoutput (check

Does anyone have any idea why this might be happening?

thanks very much,



GMT - olil on IRC

@olilarkin: track muting has absolutely no effect on plugins whatsoever in Ardour. Muting a track doesn’t stop the plugin from being executed, or change its “wiring” in any way. I’ll try to take a look at the issue when I can. It will be more productive by far to discuss this on IRC. What timezeon are you in?