LSP Plugins 1.2.24 released!

GenGen · December 5, 2025, 4:35pm

On my system, when I open LSP plugin UI, the time graphs are frozen and sometimes, even the ardour graphics will no longer update. The sound is just fine and keeps running, with processing from LSP. Is this a bug or a configuration issue?
Other plugins, such as ZL EQ (Juce?), work just fine.
Edit: The same LSP VST3 Plugin works just fine in renoise. But renoise seems to be dropping some frames, as the UI in the background begins to stutter. Again, ZLEQ works just fine.

This never worked on my system, I just had no time to look deeper into this, up to now.
LSP 1.2.25 release.

What could I do to get this going?

Any help appreciated.

Some, hopefully helpful, information about my system:

Ardour 8.12.0
$ uname -a
Linux gengen-ThinkPad-P1 6.17.0-7-generic #7-Ubuntu SMP PREEMPT_DYNAMIC Sat Oct 18 10:10:29 UTC 2025 x86_64 GNU/Linux
$ gnome-shell --version
GNOME Shell 49.0

Powermode is set to “Performance”

SadKo · December 5, 2025, 5:18pm

This may be an OpenGL issue on your system.
Please consider looking this topic:

github.com/lsp-plugins/lsp-plugins

Graphical issue when used in Ardour

opened 03:56PM - 25 Sep 25 UTC

audio2000

Linux/Debian based Ardour 8.12 (Official Demo for accurate test results) LSP 1.2….20 LV2 = Does not occur LSP 1.2.21 LV2 = Where this issue begins to occur LSP 1.2.22 LV2 LSP 1.2.23 LV2 Little hard to example but I noticed in Ardour when you open LSP plugin windows, when GUI window pops up if you look inside the window, instead of showing LSP plugins GUI right away, instead you can see a replication of Ardour main edit window inside the plugin window. It flashes and then eventually shows LSP GUI inside the plugin window. Happens each time the GUI window is opened. Can be/look a little distracting and not desired if there is a way that it could possibly be fixed. I made a different post about noticing other graphical issues since this version was released LSP 1.2.21 LV2, this graphical issue I am mentioning in this post seems to start in this version as well. This occurs even if I revert back to the `Cairo` backend, so it does not appear to be `OpenGL` related. ---------------------------------------------------------------------------------------------------------------- ### LSP 1.2.23 LV2 -I tried these plugins mentioned in my other post `Filter Mono` `Graphic EQ x16 Mono` `Limiter Mono` `Parametric EQ x16 Mono` -This occurs each time LSP plugins are opened -Does not happen with other plugins -Again this happens each time the GUI windows are opened, so you can close them and re-open them and can still see this issue. ### LSP 1.2.20 LV2 -When trying the same plugins in this older version `Filter Mono` this plugin very quickly shows it but almost not detectable (maybe because this plugin opens faster then the others?) -With the other LSP plugins this does not occur at all, the plugin GUI windows just open as expected. So there appears to be some kind of a change that occurred in 1.2.21 and up. Again this happens with `Cairo` backend so probably not something with the new `OpenGL` backend update. ---------------------------------------------------------------------------------------------------------------- Not sure if this has to do with the other issue I mentioned but here is the link just in case #550 Thank you to anyone who reads this

You also can try to launch UI using Cairo backend, not OpenGL, to ensure that is is an OpenGL problem.

GenGen · December 7, 2025, 9:18am

Edit2: Forgot my manners! Thanks for the quick reply!!! And thanks for all the hard work going into LSP!

Cairo shows a similar behaviour. I started a new ardour session from a terminal after setting the environment variable you mentioned here:

Created a single track with an audio file from the ardour content clips.
Instantiate LSP Dynamics Processor Stereo VST3
GUI opens, curves are updating but slightly choppy, in an irregular way (no rythm in the drop outs, so does not look like any framerate subdivision).
About dialog shows UI Graphics: Cairo

Closing the ui, ardour still responsible.
Opening ui again. Same LSP behaviour, ardour in the background freezing.
All the time, audio is running just fine.
I was able to close the LSP GUI window. So window stuff seems still responsive?

I then switched window focus a few times, without any change.
Then I switched to firefox, to write this post. Switched back and the Ardour UI is responsible again.

It looks like one of those issues, where a queue of commands needs to finish their thing. Like when you put UI and some other task on the same thread. Not an expert here, but I once tried adding a progressbar somewhere

Edit: Some further observations.

moving the plugin window around, freezes the graphics inside immediately
Opening closing the window will leave ardour in the frozen UI state everytime, after closing it.
Ardour UI will always wake up again after waiting for a while. BUT FASTER, IF PLAYBACK IS STOPPED!
While frozen, Ardour does still respond to commands such as space bar play stop or L for loop playback

SadKo · December 7, 2025, 10:12am

Have you tried to switch Preferences → GUI → Closing a plugin GUI Window to destroys the GUI instance, releasing the resources? This also may be related because LSP plugins may still perform regular window handling (including redraws) even if Ardour hides the plugin window.

GenGen · December 8, 2025, 2:56am

Thanks again, looks like I had this enabled all the time. It did not make a difference for the gl version, but during tonights attempt to reproduce this, the cairo version, while still choppy, did not cause a freeze after closing the window. Maybe I have to stress the system a little bit more to get there again.