Pretty names in Patchage via Jack Metadata

The much-awaited (by me, at least) Jack metadata API has arrived. This will allow us to easily achieve many new things with minimal/nonexistent API friction. One of the simplest and most obvious is pretty names for Jack clients and ports, so I’ve chosen this as the first thing to tackle (as part of a drive to get Patchage polished up for a much overdue release).

Unfortunately, as far as I can tell, there is a chicken & egg scenario here since nothing is setting this metadata yet. So, I’ve made Jalv and Ingen both set pretty names for their ports. In the case of Jalv, the “pretty name” is the label given in the plugin data (distinct from the LV2 “symbol” which is restricted and unique).

Firing up Jalv with the Tal Dub III plugin (LV2 port courtesy KXStudio), we can see the port symbols, which are a bit awkward for end users with their prefixes and underscores. Conflating strong identifiers with human-readable labels is a serious design error I learned of the hard way, but that’s a discussion for another time…

Enable “Human Names” in the view menu, or press C-h, and voil√†, we see the pretty names set in Jack metadata (if present) instead.

Tal Dub III in Jalv as shown by Patchage with human names off.

Tal Dub III in Jalv as shown by Patchage with human names enabled.

The metadata API is very simple to use for ports, though there seems to be a hole in the API which makes it difficult to get the UUID for your client to set metadata (I want a simple jack_client_uuid, like jack_port_uuid, but it seems you have to get a string UUID and parse it to a jack_uuid_t, clunky enough that I just didn’t bother). In any case, I am happy to see a low-friction mechanism in Jack which apps can use to share metadata towards making a better user experience.

It will be interesting to see what sort of information proves useful and becomes established/standard. For those of us of a mad scientist bent who live in a nest of patch cables, a CV tag seems like another obvious simple step, but for everyone, a big step is finally having meaningful port grouping and channel roles. I have always liked to joke that Jack (like LADSPA) doesn’t really even do stereo, but with metadata, we can mark up stereo, 5.1, Ambisonics, etc., and other clients will be able to make sense of the channel assignments without resorting to dirty kludges based on guessing from names. All without changing the ABI one bit. Good stuff.

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Labeled MIDI controller values in Ardour

A while ago, I implemented MIDI patch, controller, and note name support for Ardour.

There was one thing missing from that work: labelled controller values. This is particularly useful for controllers that don’t represent a continuous numeric parameter, but instead have a set of specific values. For example, the Moog Minitaur supports CC #86 to control the LFO sync clock division, but it’s not obvious how a 0-127 number maps to a clock division. From the manual, we can learn that 61-67 is “1/4″, 68-73 is “1/8 Dot”, and so on.

Translate that information into standard MIDINameDocument format, and a few hours of hacking later… voila, Ardour displays something sensible when hovering over an automation point instead of a meaningless number.

Ardour displaying a labelled MIDI controller value when hovering over an automation point.

If you want to add support for your MIDI device or program, my .midnam documents for the Moog Minitaur, MF-104M, and MF-108M, included in the Ardour distribution all contain examples of labelled values. It should be relatively obvious how to copy and modify these for other devices.

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Jalv 1.4.4

Jalv 1.4.4 is out. Jalv is a simple but fully featured LV2 host for Jack. It runs LV2 plugins and exposes their ports as Jack ports, essentially making any LV2 plugin function as a Jack application.

Changes:

  • Add -c option for setting controls from the command line
  • Add –no-menu option for jalv.gtk
  • Don’t expose non-MIDI event ports to Jack
  • Hide controls for ports with notOnGUI property in generic UI (based on patch from Robin Gareus)
  • Support ui:portMap feature to allow UIs to avoid hard-coded port indices (useful for compatibility and separately distributed UIs)
  • Preset menu support for Qt (patch from Timo Westk√§mper)

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Lilv 0.18.0

Lilv 0.18.0 is out. Lilv is a C library to make the use of LV2 plugins as simple as possible for applications.

This release includes several bug fixes and improvements. Upgrading is recommended. A function has been added but the API remains backwards compatible with all previous releases.

Changes:

  • Allow lilv_state_restore() to be used without passing an instance, for restoring port values via a callback only
  • Fix unlikely memory leak in lilv_plugin_instantiate()
  • Support denoting latency ports with lv2:designation lv2:latency
  • Allow passing NULL port_class to lilv_plugin_get_port_by_designation
  • Call GetProcAddress with correct calling convention on Windows
  • Add support for running plugins from Python by Kaspar Emanuel
  • Clean up after test suite so multiple runs are successful
  • Add lilv_port_get_node() for using world query functions with ports
  • lv2info: Don’t display invalid control maxes and defaults (patch from Robin Gareus)
  • lilvmm.hpp: Add wrappers for UI API

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Suil 0.8.0

Suil 0.8.0 is out. Suil is a lightweight C library for loading and wrapping LV2 plugin UIs. Suil transparently presents UIs written in any toolkit as the desired widget type of host programs, so hosts do not have to depend on foreign toolkits.

This releases adds a function, but remains backwards compatible with all previous releases.

Changes:

  • Add suil_instance_get_handle (patch from Rui Nuno Capela)
  • Fix compilation errors on some systems
  • Upgrade to waf 1.7.14

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Interactive force-directed graph layout in Ingen

GraphViz has, unfortunately, broken reverse compatibility of their library API, which has been nagging as a maintenance headache for FlowCanvas and its successor Ganv for a while now. It would be nice to just get rid of that dependency altogether…

Meanwhile, I had to write some force-directed graph layout (FDGL) code for another project…

… You can probably see where this is going. In the spirit of it theoretically being a holiday (there are no holidays in practice in grad school), I spent some time implementing live FDGL in Ganv, and recorded a video of interactive layout in Ingen to show progress.

One nice thing about using live FDGL in a program like Ingen is that the user can customize the layout in an intuitive tactile way, since objects behave physical laws. This video demonstrates some manual rearranging of a patch, and a total reconfiguration by switching the signal flow direction. Manual tweaking of the layout like this was not possible with the previous GraphViz-based layout code.

It took quite a bit of tweaking to get the physics working well, so layouts looked good but the patch didn’t explode if there are disconnected components. It’s still not quite ideal, but usable.

This is implemented at the Ganv level and thus works in Ingen (as shown), Patchage, and Machina. I’m still not confident enough in this implementation to enable it by default and/or drop Graphviz quite yet, but the adventurous who follow svn, ./waf configure --debug --fdgl. If you’re hit by the graphviz breakage (and I still haven’t fixed the check…), add --no-graphviz to work around the problem.

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