AU main type update and backward compatibility

Audio Plugins
1

Hello devs,

we’ve recently updated one of our plug-in in order to support the MIDI input functionality and in order to be able to use a MIDI in Logic, we had to change the plug-in category from kAudioUnitType_Effect to kAudioUnitType_MusicEffect.
Now everything works as expected but this seems to have the side effect of breaking backward compatibility with previously saved sessions, at least in Logic.
Basically, the updated version is being validated and recognized correctly, you can add a new instance of it but if you open a saved session were the previous version was used (the one with kAudioUnitType_Effect type), Logic says the plug-in cannot be found in the system.

I’m probably out of luck here, but it’s worth a try to ask: is it possible to maintain backward compatibility when changing the AU category?

Thanks in advance,
Federico

2

We are exactly in the same spot here… Where you able to solve this? Is there anything one can do about this but warn users?

3

Did a bit of research and it should be possible to provide an aufx and aumf version within the same plugin. This would provide backwards compatibility - has anyone ever done this? Not sure where to start actually…

4

I have recently done a similar thing: I put the instrument, effect, and generator in a single bundle. The key I found was this post:

You may have to look at the id of each variant, but that is all covered in the above thread.

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5

Thanks a lot, I‘ll try that!
This should be documented somewhere…

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