ohac / drmr

An LV2 sampler plugin that (currently) plays hydrogen drum kits

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DrMr is an LV2 sampler plugin. It's main reason to exist is to give a way for lv2 hosts to have a built in drum synth that can save its entire state (i.e. no need to go out to external tools and no need to save extra state). See the wiki (click the wiki tab above) for some screenshots. DrMr currently supports the following:

  • Control via midi
  • Scan for and load hydrogen drum kits (see note 3)
  • Multi-layer hydrogen kits (will pick layer based on that samples set gain)
  • Kit is set via an LV2 control (see note 1 below)
  • LV2 controls for gain on first 32 samples of kit (see note 2 below)
  • LV2 controls for pan on first 32 samples of kit (see note 2 below)
  • GTK ui that can select a kit and control gain/pan on each sample
  • Custom knob widget for GTK ui based on phatknob that is both functional and awesome looking. (see wiki for screenshot)
  • Sample grid can start in any corner of the window, to match the layout of your controller.

Hopefully coming soon:

  • Creating / Saving custom kits on a per sample basis using the GTK UI
  • ASDR envelope on samples (Will be automatable and controllable in the UI)

DrMr is a new project, so the code should be considered alpha. Bug reports are much appreciated.

The lv2unstable Branch

There is a branch of DrMr that has a number of new features, the most useful being that the kit loaded can be saved properly as a path, and so the issue described in note 1 below is no longer an issue. You can click the branch button near the top of the page and select lv2unstable to see more information.

The lv2unstable requires some new lv2 features not available outside the lv2-svn version at the moment, so it's living in its own branch, but it will be merged as the main branch when the required features stabilize.


Only via git for now, just check out this repo

Compilation and Install

DrMr is built with CMake.

To build it simply do (from this dir):

mkdir build
cd build
cmake ..    (or "cmake -DUSE_NKNOB=OFF .." if you want old style sliders)

Then do:

make install

to install. There are some customizable variables for cmake. To see them do "cmake -L". The important ones are:

USE_NKNOB - Use custom knob widget for controls instead of the default gtk sliders. This defaults to ON. Try turning it off if you are experiencing problems, or just prefer the sliders.

SAMP_ZERO_POS - Controls where sample zero will position itself in the sample table. This is just the default value, and can be changed in the ui when DrMr is running. Valid values are:

0 - Top Left (default)
1 - Bottom Right (This will align with many drum machines and MIDI pads)
2 - Top Right
3 - Bottom Right

Any other value will emit a warning and use 0.

LV2_INSTALL_DIR - The directory to install the DrMr plugin to. To install to your home directory, use "~/.lv2" and clear the CMAKE_INSTALL_PREFIX. This defaults to "lib/lv2" (this is relative to CMAKE_INSTALL_PREFIX, which is usually /usr/local)

You can also use "ccmake .." or "cmake-gui .." for a more interactive configuration process.

A legacy Makefile is included, that will possibly work for you if you don't want to use cmake. To use it just do (from this dir):

make -f Makefile.legacy
make -f Makefile.legacy install

You'll need the following libraries to build and install DrMr:

DrMr scans the following directories for hydrogen drum kits:

  • /usr/share/hydrogen/data/drumkits/
  • /usr/local/share/hydrogen/data/drumkits/
  • /usr/share/drmr/drumkits/
  • ~/.hydrogen/data/drumkits/
  • ~/.drmr/drumkits/

If you want to add others, add them to the default_drumkit_locations array at the top of drmr_hydrogen.c

Note 1

As stated above, a goal of DrMr is to have the host save all the state for you. As such, the current kit needs to be a control. Unfortunately, string controls in LV2 are experimental at the moment, and not supported by many hosts (in particular Ardour doesn't support them). This means the kit needs to be set via a numeric control. DrMr specifies an integer index as a control to select which kit to load. A kits index is the order in which is was found. This means changing, adding, or removing hydrogen kits could mess up your saved index. Sorry.

You can figure out which kit is loaded by looking in the GtkUI at the bottom, or look at the print output from your host, as drmr will print the names of kits as it loads them.

Note 2

DrMr is currently using a static ttl file. This means I have to decide statically how many gain/pan controls to expose. I've settled on 32 for the moment, but that is arbitrary. At some point DrMr will probably move to using the LV2 Dynamic Manifest feature to expose the appropriate number of gain controls for the current sample set, although how force a host update of the manifest when the kit is changed is unclear (if you know how, please let me know)

Note 3

DrMr only currently supports a subset of things that can be specified in a hydrogen drumkit.xml file. Specifically, DrMr will not use gain/pan/pitch/asdr information. DrMr basically only uses the filename and layer min/max information to build it's internal sample representation. Values specified in .xml files will be used as DrMr begins to support the features needed for those values to make sense.


An LV2 sampler plugin that (currently) plays hydrogen drum kits

License:GNU General Public License v3.0


Language:C 95.9%Language:CMake 4.1%