I had problems with several LADSPA plugins. Some seem to work, some don't. I dug a little deeper with the DeepFilterNet plugin: https://github.com/jacksongoode/DeepFilterNet When changing control values in the Kdenlive UI, the DeepFilterNet plugin gets sent the wrong control indexes. The index is always off by 4, which I verified with a log statement in the plugin code. The DeepFilterNet plugin exposes 4 audio ports (stereo in, stereo out; index 0 to 3) and several control ports. The DeepFilterNet plugin works in Audacity. Other plugins, such als Rubber Band Stereo Pitch Shifter, work also in Kdenlive. Rubber Band Stereo Pitch Shifter and other LADSPA plugins export control ports first, then audio ports. Kdenlive seems to confuse the port indexes when plugins expose audio ports before control ports. SOFTWARE/OS VERSIONS Operating System: Debian GNU/Linux 12 KDE Plasma Version: 5.27.5 KDE Frameworks Version: 5.103.0 Qt Version: 5.15.8 Kernel Version: 6.1.0-39-amd64 (64-bit) Graphics Platform: offscreen Processors: 16 × AMD Ryzen 7 3700X 8-Core Processor Memory: 47.0 GiB of RAM Graphics Processor: NVIDIA GeForce RTX 3060/PCIe/SSE2
https://bugs.kde.org/show_bug.cgi?id=442197 seems related. "listplugins" and "analyseplugin" can be used to check the ordering of audio/control ports.
I reordered the ports in the plugin to expose the control ports first, and the problem is gone. So I'm pretty sure the issue lies there. I don't know enough about Kdenlive internals to create a patch.