People are sometimes confused about how Ingen works as an LV2 (I need to write proper documentation One of These Days): you don’t load an “Ingen” plugin so much (it wouldn’t do anything), as you save an Ingen graph as an LV2 plugin. The idea is that Ingen is a tool for visually building plugins. Since LV2 does not support dynamically adding ports, it’s easiest to do your building as a Jack app, so the basic work flow is something like:

1. Run Ingen as a Jack app: ingen -eg
2. Build a graph, adding ports, plugins, etc.
3. Save the graph to somewhere in your LV2_PATH, e.g. ~/.lv2 (which happens to be the default directory of the save dialog for this reason).
4. Voila, your graph should now show up in any LV2 host (its URI will simply be its local filesystem path, unless you explicitly set a stable one). You can check with lv2ls.

There is no export or compilation involved, Ingen’s native format is LV2 compatible (graphs are always saved in the same format). If you saved a graph elsewhere you can simply copy it to ~/.lv2 to use it as a plugin, though for now you may have to create or fix the symlink to the engine binary manually to do this.

Note that you can edit the graph while it’s running as an LV2 plugin, including adding new nodes and connections, you just can’t add top-level ports because the host doesn’t know about them. There is still some work to be done polishing this up to be ready for prime-time, but for the brave, it’s more or less good to go.

Changes:

• Send time information to plugin when Jack tempo changes
• Group controls under headings if port group information is available
• Add spinbuttons for precisely setting control values
• Use a more efficient dense layout for controls
• Make URI map thread-safe, fixing occasional crashes for plugins with UIs
• Add menu bar and pass parent widget in Qt version for true UI embedding
• Support state:loadDefaultState
• Update to waf 1.7.8 and autowaf r90

Changes:

• Fix key events for X11 in Gtk without using a troublesome event filter
• Fix crash when a broken UI returns a NULL descriptor
• Fix compilation on BSD

This release fixes many bugs and adds several convenient functions to the API. Upgrading is recommended.

Changes:

• Add lilv_world_ask() for easily checking if a statement exists
• Add lilv_world_get() and lilv_port_get() for easily getting one value
• Add lilv_nodes_merge()
• Make lilv_plugin_get_port_by_designation() return a const pointer
• Require a URI for lilv_state_to_string() and fail gracefully otherwise
• Fail gracefully when lilv_state_new_from_string() is called on NULL
• Make state loading functions fall back to lv2:default for port values, so a plugin description can be loaded as default state
• Ignore state ports with no value instead of printing an error
• Support atom:supports in lilv_port_supports_event()
• Add va_list variant of lilv_plugin_get_num_ports_of_class()
• Fix several plugin functions that failed to load data if called first
• Correctly depend on serd at build time (fix compilation in odd cases)
• Disable timestamps in HTML documentation for reproducible build
• lilvmm.hpp: Support varargs for Plugin::get_num_ports_of_class()
• lilvmm.hpp: Add several missing methods
• Update to waf 1.7.8 and autowaf r90 (install docs to versioned directory)

This releases fixes a few minor bugs and memory leaks, and shrinks the code slightly by making of the new sord_get() function.

Changes:

• Fix serialisation of nested tuples
• Fix memory leaks
• Use new sord API to clean up and shrink code
• Disable timestamps in HTML documentation for reproducible build
• Update to waf 1.7.9 and autowaf r90 (install docs to versioned directory)

Changes:

• Add sord_get() for easily getting single property values
• sord_validate: Pass type check when range is xsd:anyURI and value is a URI
• sord_validate: Support any subClassOf rdf:Property, not just baked-in ones
• sordmm.hpp: Add convenient constructors for decimal and integer literals
• sordmm.hpp: Add Node::to_serd_node()
• sordmm.hpp: Don’t automatically add RDF namespace prefix to world
• Update to waf 1.7.9 and autowaf r90 (install docs to versioned directory)

Other improvements:

• Added a spinbutton to slider controls for precisely setting values numerically
• Much more efficient layout to pack more controls on the screen at once
• Support for named scale points (“ticks”) on non-enumeration ports

Here is the UI generated for Amsynth (after I added the necessary metadata):

Still pretty utilitarian, but much more usable, which is the important thing. Of course, this plugin is quite large, and has a pretty good custom UI, but I happened to be polishing up its metadata anyway and the controls group nicely so I used it as my test case.

Maybe some day this code will get smarter and evolve into a library that can be used by other Gtk hosts. Better group layout is the obvious “next level” advancement, a flat linear list of controls is pretty limited. Unfortunately there’s no stock Gtk container which can do text-like reflow, which would be ideal. Perhaps a simpler scheme based on a maximum reasonable width for a controller would do, where the table will expand to have more columns if the window is wide enough for several.

Most of the metadata required to generate a good UI is also useful for other purposes, for example groups make building a decent menu of many controls feasible (e.g. to add automation lanes in Ardour), and some types of host UIs like a modular patcher inherently need to generate their own “UI” of sorts.

Good metadata is not at odds with custom UIs, they each have their uses, but it is important to remove the burden of custom UIs for simple plugins with just a few controls that really don’t need them. It’s a waste of that most precious of all resources – developer time – to have to code UIs for a few sliders and toggles. Hopefully better host generated UIs and support for more advanced controls like file selectors free up developers to spend more time making useful plugins and less time wrestling with GUI toolkits.

It is, after all, all about the sound.

The note names are mainly useful for doing percussion. Several of the bundled midnam files have note names defined, and I have added one for General MIDI drums, which more or less corresponds to a lot of instruments, including Hydrogen.

Controller names, to my surprise, were not present in any of the existing midnam files at all. I wanted to sequence a hardware synth (the Moog Minitaur) without constantly referring to the manual and trying to remember which CC is which, so I wrote a new midnam file for the device and implemented support in Ardour. I am very disappointed to learn that there is no ability to group controllers, which really is the best way to do things, so I may embrace and extend (in a completely backwards compatible way) the format in the future to provide a better interface.

The quality of midnam files scattered around the ‘net is atrocious. The MMA actually hosts a DTD for it, but most files use the wrong DOCTYPE (usually with a broken link), among other problems. I fixed and cleaned up all the bundled ones in Ardour, validated them against the DTD, and left a README in that directory about how to do so. Hopefully this, along with incentive added by these features, encourages the community to grow a nice set of quality midnam files.

So, MIDI name support in Ardour is now in pretty good shape. Now we just need to add the corresponding LV2 support…

So, I spent the weekend working on turning Machina back into a usable app. It’s come a very long way in two days, from a mess that doesn’t even compile to most functionality working pretty well:

Aside from rewriting a lot of the code, testing, and fixing things that were broken, I’ve changed the conceptual model a bit. There is now always just one start node for a machine. This tends to create more manageable structures, especially when recording several takes into the same machine.

Step recording has also been significantly improved. You can build machines entirely in the UI, but this is pretty tedious. It’s much more effective to record, or step record if you want regular timing and no delays in-between notes. The above pictured machine was created by step recording MIDI, though I have tweaked the edge probabilities with the mouse. You can also import a MIDI file, which is an easy way to get a big machine to work with.

Hopefully I can find the time to turn this into an LV2 plugin and release it, but for now it is an unreleased Jack application. Give it a try if you’re feeling adventurous, I would appreciate any feedback.

Here is ConvoLV2 running in Jalv:

Note this is the built-in UI generated by Jalv and not a custom plugin UI. Unlike traditional LADSPA style controls, the impulse parameter is not a port, but is set by sending a message to an event port. The plugin lists parameters with the new patch:writable property, so the host knows which controls to display (or which parameters it can automatically set). Parameters are described as normal RDF properties, so any existing property can be used, or plugins can define them as needed in their data files (don’t let the “RDF” scare you, the description of a Property is as simple as LV2 ports). One nice advantage of this over ports is that a project can describe a parameter once and use it in many plugins, without having to describe the parameter every time. This really adds up when you have hundreds of plugins with, say, an identical gain parameter.

These conventions will be established in the next LV2 release (1.4.0), and the sampler example will serve as a test case. When host support becomes established, we can also move towards using messages for numeric parameters, which will finally allow for dynamic parameters, control ramps, and so on.