Re: More LV2 questions

On Wed, Aug 12, 2026 at 05:30:12PM +0200, Hermann Meyer wrote:
 
> Save way to get it is a atom port, let your dsp part know that the GUI is up
> and running and ask it for all the states you need, for example, the
> SampleRate. Then you didn't relay on any host behave.

Or even just a standard 'float' control port. But then
it will show up in any host generated GUI. 


> > 3. A GUI may want to show an optional second window
> >     (e.g. a frequency response). The only way to get
> >     a meaningful title for such a window seems to be
> >     to go through a lot of X11 magic to get the plugin
> >     window's WM_NAME. Or is there a better way ?
> 
> That is far from any way LV2 related. Use a toolkit to manage multiple
> windows from your plugin.

This is not about window management. The plugin window's title
should inform the user of e.g. wich track of a DAW the plugin
is in. If the host provides the parent window it can set the
title (and Ardour does this). But the same information is not
available in any other way in case it may be needed. All it
would take is a char* to the instantiate call. 

> There are a far couple of them out there,
>...
> and when I remember right, you've written once a X11 toolkit yourself?

Indeed, and that is by now more than 25 years old. It was
used originally on Sun / Solaris machines for some custom
software I developed for ESA. It's still used for all my
software that has a GUI, but will be retired soon.

For the LV2 exeriments I'm using a new one which is even
simpler. Total source code ATM less than is 30 kB.
It only provides the basic functions to create windows,
receive events, and some utilities. Nothing else. Standard
widgets (buttons, rotary knobs, faders,... are no longer
separate X11 windows. Each window's contents are just
provided to X11 as a cairo image surface. Also provides
HDPI support. Some of my Jack apps, e.g. zita-eq1, are
already using it, but I'll wait releasing those until
the dust has settled down a bit.


> If sample rate is such basic is debatable,

You can't even correctly compute the FR of a simple 
digital filter without knowing the sample rate. If
you don't understand why this is, Google 'frequency
warping'.

> important to know the buffer size were others may be more interested in the
> current sample position.

In the extreme case a host could just provide *nothing* 
at all to the DSP and GUI when creating them, not even
the sample rate or the list of audio ports. Need this
info ? just ask for it !

Indeed extreme, but a lot cleaner than an arbitrary choice
apparently decided upon without much consideration or
experience.


Ciao,

-- 
FA