[Ardour-Users] LV2 plugin state

[Robin Gareus]

On 03/02/2016 06:32 PM, Will Godfrey wrote:
> I was under the impression that state save and retrieve was purely at the behest
> of the host, but someone told me that when he changes parameters in some of his
> plugins, Ardour recognises this and prompts for a session save on exit.
> 
> Is this correct? 

Yes.

Does Ardour recognise some undocumented plugin message?

No.

Ardour simply asks the plugins that have a state interface to save the
state and then compares it against the previously saved state.

http://lv2plug.in/ns/ext/state/ is well documented.

> Or has he thought he was using native GUI controls when actually using the
>  generic ones (which Ardour would know had been changed) ?

Even if you use a custom (plugin provided) GUI, the host always knows
the value of standard float-control ports (which can be automated).
The same is true for Atom Patch messages.

The host cannot know about plugin-specific messages or hidden internal
state, which is why Ardour (actually liblilv) also polls the
state-interface.

best,
robin