Duplicating an AudioPluginInstance

Audio Plugins
1

I wrote a function duplicatePlugin() that is supposed to make a 1:1 copy of a plugin (without the editor, but including its state):

[code]AudioPluginInstance* duplicatePlugin(AudioPluginInstance *plugin)
{
if (plugin==0) return 0;

PluginDescription description;
plugin->fillInPluginDescription(description);
AudioPluginInstance* instance=AudioPluginFormatManager::getInstance()->createPluginInstance(description,String("Could not create plugin instance!"));
if (instance!=0)
{
	MemoryBlock memBlock;
	plugin->getStateInformation(memBlock);
	instance->setStateInformation(memBlock.getData(), memBlock.getSize());
}

return instance;

}[/code]

I must have forgotten something, because when I call the process() method of the duplicated plugin (VSTi), no sound is coming out, whereas the first one (the original) produces sound.
Oh, and just to say, I did not forget to call prepareToPlay() on the second plugin, so that’s not the problem.

2

Did you call setPlayConfigDetails()?

3

That function is called anyway in prepareToPlay() (in the first line of code) !? Shouldn’t really need to call it?

4

Ok, I found out that:

  • my function was not the problem.
  • one has to call AudioPluginInstance::process() at least 2 times with an empty MIDIBuffer before passing the MIDIBuffer with the actual MIDI Notes, otherwise there will be no sound output.

So this seems to be a bug!? Have you got any idea why one has to call process() twice before calling it a third time with the actual MIDI data?

5

There’s nothing I’ve written that would do anything like that - midi buffers just get passed straight through. What kind of plugin is it? Have you traced into these process calls to see what happens?

6

Alright, this seems to happen only with one precise VSTi (ofcourse I just had to pick that one, bad luck for me), so it’s for sure not a JUCE bug…