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Post by milk » Fri Feb 21, 2020 6:30 pm

Hey folks! I'm cross-posting this post from LinuxMusicians and the lines to spread the word;

The JACK audio system and LV2 plugin format both provide CV port support that allows the patching of audio-rate parameter control signals between clients/plugins, enabling a multi-app modular synthesis environment that can connect with real world hardware to form a hybrid setup.


Ingen (^) was the first LV2 host to support CVPort, then Non-Mixer and Non-Timeline followed with JACK CV support for automation. More recently the JACK metadata mechanism enabling CV ports was added to JACK2, and CV support can be found in JACK clients/LV2 hosts Carla (v), Synthpod, Jalv, mod-host and Zrythm, plus hardware support on the (almost available) MOD Duo X and (eventually) Zynthian.


The LV2 format also allows for metadata relating to the min, max and "unit" values for the CVPort. Carla also passes this metadata on to any exposed JACK CV ports. Carla also allows plug-in parameters to be exposed as CV ports.


In LV2/Ingen:
* http://lv2plug.in/ns/lv2core/#CVPort
* http://lac.linuxaudio.org/2015/papers/24.pdf - see section 2.4

JACK client/LV2 host commits:
* Ingen
* Non-Mixer
* Synthpod
* Carla
* Jalv
* mod-host
* Zrythm
* GStreamer
* Spaghettis - Pure Data fork with metadata support

Plugins and plugin suites with support:
* ams-lv2 - port of the AlsaModularSynth (AMS) internal modules to LV2
* avw.lv2 - same as above (archived older version)
* blop-lv2 - generators, filters, and various utility plugins
* fomp - 1 auto-wah, 1 EQ, 3 chorus, 2 phasers, 5 filters, 3 oscillators, and 2 reverbs
* ZLFO - multi waveform oscillator, comes with Zrythm
* infamousPlugins - envelope follower & stop/start effects
* beatslash-lv2 - beat repeater & beat slicer
* vm.lv2 - programmable stack-based virtual machine
* mod-cv-plugins - handy utility plugins
* cv-lfo-blender-lv2 - 4 synced LFOs with blended output
* arpeggiator_LV2 - an arpeggiator and a MIDI-pattern plugin
* non-zyn-CV - automate zynaddsubfx using non-timeline CV automation via synthpod

* mod-spi2jack - JACK client for converting SPI to a JACK control-voltage stream and vice-versa
* midimsg-lv2 - basic MIDI aftertouch, CC and mod wheel to CV
* MIDIMonster - Multi-protocol translation software (ArtNet, MIDI, OSC, ...)
* mod-fake-control-voltage - A small Jack-internal client to simulate the physical CV-ports
* jm2cv - older, doesn't use JACK port metadata

Plug-in frameworks that support CV:

Sequencing is possible from MIDI (via mod-midi-to-cv-mono, mod-midi-to-cv-poly, midi2cv of Carla, Note of Ingen, or MIDIMonster), or by using Non-Timeline, though an (open source, afaik) program to easily make multitrack CV recordings doesn't exist yet.

More info on the MOD plugins here, here and here, with discussion on the MOD forums, and more on Zynthian here.

Here's a video of a quick drone patch I threw together in Carla a couple of days ago. Spot the bugs!

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