[LAD] How can a LV2 plugin know on what host's MIDI Channel it's on?

David Robillard d at drobilla.net
Sat Nov 15 05:55:32 UTC 2014

On 2014-10-16 11:42, Phil CM wrote:
> Is there a way to retrieve this info (and others, ideally) from the
> host, thus removing the need for a "midi channel" control port?

It would be simple for the host to send a message describing this or
whatever other information, but I don't really see the point.

If the host is doing specific channel filtering and such anyway, what's
won by telling the plugin about it?

Just play all channels, i.e. ignore the channel entirely (omni).

> Also, is there a way to tie the "volume" controller of the host (in
> Qtractor's case, the volume fader of the mixer strip) to one "volume"
> control port of the plugin, thus removing the need for the "control
> mode" control port ?

You can designate a port as volume in the metadata, but AFAIK no hosts
actually do anything with such information.  Particularly since...

> Yes because you see, here in my Qtractor (latest SVN - but it has always
> been that way) I can either edit the plugin (about 50% of my plugins
> behave that way) controls but then the mixer's volume is inoperant, or
> control the volume w/ said mixer but NOT the plugins controls. How can I
> have my cake and eat it?

... the fader in a DAW typically does its own thing with the signal at
that point, and wouldn't be mapped to a plugin volume anyway.  Since
there can be many plugins in a strip, this doesn't really make sense.

It sounds like your plugins are post-fader, which is not what you want,
but I don't know Qtractor.


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