Easy method for adding automatable master bypass to LV2 plugins?

Community Ideas for Ardour
#1

I’m grateful for the vast array of LV2 plugin options out there, but frustrated that so many of them don’t have an automatable master enable/bypass. This usually makes them useless to me. (I’ve been getting by via L/R crossfading between two plugin chains but that’s a CPU hog and I don’t have the luxury on a raspberry pi for that.)

Is there a quick way to add such a bypass to plugins or is such a thing going to be different from plugin to plugin? (I can code, but have literally zero LV2 or plugin programming experience.)

I see that the .ttl file has to have a block (note I think BYPASS should be opposite, something like ENABLED, but this is what gxAxisFace has):

[
a lv2:InputPort ,
lv2:ControlPort ;
lv2:index 2 ;
lv2:symbol “BYPASS” ;
lv2:name “BYPASS” ;
lv2:default 1.0 ;
lv2:minimum 0.0 ;
lv2:maximum 1.0 ;
lv2:designation lv2:enabled;
lv2:portProperty lv2:toggled;
]

Which I assume points to port handling in the cpp file

// connect the Ports used by the plug-in class
void Gx_AxisFace_::connect_(uint32_t port,void* data)
{
switch ((PortIndex)port)
{
case EFFECTS_OUTPUT:
output = static_cast<float*>(data);
break;
case EFFECTS_INPUT:
input = static_cast<float*>(data);
break;
case BYPASS:
bypass = static_cast<float*>(data); // , 0.0, 0.0, 1.0, 1.0
break;
default:
break;
}
}

but then that bypass variable gets involved with some ramp up/down logic in the code… and now my eyes have glazed over.

I’d kill for a core-ardour ability to automate enable/bypass on any plugin. That way it would be done well and all the plugins wouldn’t need it anymore.

Anyway, what are my options here?

#2

Ardour does not know how to click-free bypass a given plugin. Only the plugin (DSP) itself does know.

e.g. for an EQ the correct way is that the plugin internally ramps all EQ-band gain to zero. A distortion plugin would internally ramp gain to 1.0, a reverb cross-fade (wet -> dry) etc.

So to answer your question: It is different for every plugin.

“Bypass enabled” is confusing. Also LEDs showing “bypass” can be tricky to interpret. Most guitar FX pedals for example show a light when active…

LV2 uses “enabled” and not “bypassed” because it can potentially allow for click-free insertion/removal of latent plugins: insert-plugin (true-bypass), add latency (soft-bypass, ready), activate (process). That also follows C/C++ false = 0; true =1; – http://lv2plug.in/ns/lv2core/lv2core.html#enabled

#3

Ugh. Well that can come later anyway. (read: I won’t be doing it). But thanks for the answer.