RapidComposer is also usable as a VST plug-in in DAWs that support VST 2.x plug-ins. The plug-in comes in 32-bit and 64-bit versions on Windows and OS X.

Starting from v2.9 the RapidComposer VST plug-in is a small, reliable plug-in which does not include the whole RapidComposer application as in previous versions, but it communicates with the standalone application through shared memory, also known as 'bridge'. This results greater stability and flexibility.

When the RapidComposer plug-in is loaded by the host (DAW), the plug-in locates the RapidComposer application, starts it, and connects to the application. If RapidComposer was already running, it will switch to “VST Mode” which means the user interface and some internals will be changed.


After installing RapidComposer, you need to move the VST plug-in (.dll/.vst) into the VST folder manually.

On 64-bit Windows, the default VST folder locations are:

  • C:\Program Files\VstPlugins (for 64-bit plugins)
  • C:\Program Files\Steinberg\VstPlugins (for 64-bit plugins)
  • C:\Program Files (x86)\VstPlugins (for 32-bit plugins)
  • C:\Program Files (x86)\Steinberg\VstPlugins (for 32-bit plugins)

On OS X you need to copy the plug-in (RapidComposer.vst) to one of these folders:

  • /Library/Audio/Plug-Ins/VST
  • /Users/Username/Library/Audio/Plug-Ins/VST

Application path used by the plug-in

The VST plug-in needs to know where the standalone executable resides. You can set the application path used by the VST plug-in under Settings/Locations.

When the standalone application runs, it creates a file in the settings folder called VSTLastAppPath.txt that contains the application path. The VST plug-in will look for that file and read the application path from it.

It is possible to tell the plug-in to use a different executable than the last used executable. When a file named as VSTAppPath.txt exists, the plug-in will use that path and will ignore the one in VSTLastAppPath.txt.

Multiple plug-in instances

When you load an instance of the RapidComposer plug-in, it will be referenced as “Plug-in #<Sequence> in <Hostname>” in the RapidComposer standalone version. For example the first plug-in is called “Plug-in #1 in REAPER”, but if you load another plug-in instance in REAPER for another 16 channels in RapidComposer, it will be called “Plug-in #2 in REAPER”.

Saving and loading compositions

Unlike in the standalone version, it is not necessary to save and re-load the composition in VST mode. It is the responsibility of the VST host (DAW) which saves and restores the internal state of RapidComposer.

Using preview instruments

The new VST plug-in does not produce audio, so soundfonts cannot be used, which means preview instruments must be set up in each project. Instead of being a global setting, you need to send each chord/scale/… preview to one of the VST host channels. The preview settings are stored by the VST host and restored when the project is loaded.

RC as VST inside Reaper 4

Tutorial Videos mentioned in this Chapter: Part 12 - VST Use & Configuration

RapidComposer is great in standalone mode, but you can get a great deal more functionality out of it when used as a VST/plugin inside your favorite DAW. For this chapter (and our Part 12 Tutorial Video which we highly recommend you watch), we will be using Reaper 4 as our VST host/DAW. The reason we chose Reaper is its increasing popularity among home studio users, songwriters, and electronic music producers. It loads fast, is incredibly stable, and you can download a fully-functioning trial version that doesn’t expire (though it will bug you to purchase a license… it doesn’t “die” or disallow you to get into the program after 30 days like typical demos do.

Here are a few a step-by-step procedures on how we set up RC from scratch, as a VST in Reaper.

SCENARIO 1 (having RC control two separate VSTi instruments)

In this first scenario, let’s say we want RC to control the sound of two of our favorite VST instruments, hosted inside Reaper. RC’s Track 1 will have Chord Generators on it, and RC Track 2 will have Melody Generators on it. We want these Phrases to control the following freeware VST instruments on Reaper tracks: LazySnake (for the Chords), and Organized Trio (for the Melody). You may want to use your own VST instruments, and that’s fine!

1. First, make sure the RapidComposer.dll file is copied to your favorite VST folder, so Reaper knows where to find it, and so that it will show up in the available VSTis in Reaper.

2. Second, start a completely blank Reaper project. Insert one single track (CTRL+T is the Reaper command for adding a track to your project). This will have the RC VST on it.

3. Click the “FX” icon on the track we just inserted, browse to the VSTi section and find “RapidComposer (MusicDevelopments).” Double-click to insert RC on the track.

4. Rename the track to “RC Output” or “RapidComposerOut” or something similar. Open the RC window or GUI, and click “A” to add a second track to the Composition.

5. Create two new tracks in Reaper, above our RapidComposer track. 5a. Click FX on the first track, and insert the LazySnake VSTi on it, and name the track “1 LazySnake”. 5b. On the second track, click FX and insert Organized Trio on it, and name the track “2 Organ”. 5c. Now, change the input of the 1 Lazysnake track from whatever your soundcard says (probably Input 1 or Input L or something like that), and set the input to “Input: MIDI”, then “All MIDI Inputs”, then “All Channels”. Then, click it again, and after you click “Input: MIDI”, you’ll see a “Map Input To Channel” near the bottom. Change this to 1. 5d. Repeat the same steps from 5c, and change the “2 Organ” track to 2, in the “Map Input To Channel” sec tion. (On all of these steps (including the track names): the numbers represent our MIDI channels)

6. Now, click the “I/O” button on the “1 Lazysnake” track. Go to the “Receive” section and select “RC Output” (or whatever you named the track that has the RapidComposer VSTi on it). Then, below that, you’ll see two buttons that say MIDI: ALL. Change them both to MIDI: 1 (this is important, as it tells RC to play its Track 1/Channel 1 track, to the matching one in Reaper.

7. Similar to Step 6, click the “I/O” button on the “2 Organ” track. Go to the “Receive” section and select “RC Output” (or whatever the name is). You’ll see the same two buttons… MIDI: ALL. Change them both to MIDI: 2 (this is equally important).

Before we go any further, we should save this layout as a Reaper ProjectTemplate. Go to File / Project Templates, and save it whatever filename you like, for example, “RC Scenario 1”

8. Add some chords in the RC VST window… and throw the Generators on the tracks (remember, track 1 is for Chord Generators, and track 2 will be for Melody Generators).

9. Press play in Reaper and you will hear the phrases being sent to the Reaper tracks that have the VSTis on them.

10. With the way we set Reaper up, we’re also able to play the VSTs live (depending on what track we have selected, and whether or not it is armed for recording, and also has record monitoring enabled), and record our own MIDI clips in addition to hearing MIDI being sent from RapidComposer’s VSTi track. This scenario can be worked with further, using Scenario 3 (below). All of this already is pretty involved, and is mainly for people greatly familiar with the MIDI routing capabilities of their favorite DAW. Although Reaper seems complicated, we find its routing pretty easy to grasp.

SCENARIO 2 (having RC control a multitimbral or multichannel VST)

Let’s say we have an awesome multichannel VST such as Native Instruments’ Kontakt, or Sampletank 2 by IK Multimedia. Let’s use Sampletank 2 for our example.

1. Repeat steps 1-4 from Scenario 1.

2. Insert a new track in Reaper, and click “FX”, then insert the Sampletank 2 VST. Name this track “Sampletank Out”. 2a. Choose your sounds for each Sampletank slot, starting with slot 1. For this example, let’s put a Piano on slot 1/channel 1, a Vocal preset on slot 2/channel 2, a Bass guitar sound on slot 3/channel 3, and a Guitar sound on slot 4/channel 4. 2b. Click the “Options” menu item in the FX window in Reaper (the one where you can see Sampletank). Choose “Build 16 channels of MIDI routing to this track” (though, we won’t use all 16 channels, because we only chose 4 sounds in Step 2a.) 2c. Delete the tracks numbered MIDI 5 to MIDI 16 (in Reaper). 2d. Highlight MIDI 1 through MIDI 4 by holding shift and clicking each one, then right-click the record buttons, choose “automatically record-arm when track selected”, and then click the Recording Monitoring button so it shows a green arrow. 2e. Click the “I/O” button on the “Sampletank Out” track, and go to the “Receives” section… and choose “RC Ouput”, or whatever you named it. This will let RC send its MIDI phrases to each Sampletank channel. If you add more tracks in RC, you’ll need to add more Sampletank instruments to each new Sampletank slot, and you’ll also need to add more tracks in Reaper, and send them to the “Sampletank Out” track (MIDI channel routing can get very confusing, so we recommend asking any questions on the Reaper forum, if you get lost).

3. Repeat Step 8 fand Step 9 from Scenario 1, and take a listen to your creation! Remember, you can also play along with whatever RC is playing, by selecting the Reaper track that matches the Sampletank slot… (MIDI 1 is Sampletank slot 1, MIDI 2 is Sampletank slot 2, etc.)

SCENARIO 3 (recording the MIDI output of RC onto MIDI tracks in Reaper)

This is basically the same as Scenario 1, but all you have to do is highlight each MIDI track that has a VST instrument on it, right-click its arm-record button, and choose “Record: Output” and then “Record: Output (MIDI)”. Then, you’ll need to right-click each track’s arm-record button, and de-select “automatically arm when track selected.”

Assuming all channels are routed correctly for as many tracks as you have in RC (and matching tracks, in Reaper), if you hit the main record button in Reaper, you will see the RapidComposer tracks and Phrases being recorded in real-time, on separate Reaper tracks, for further manipulation and editing (if you like). This is a quick way to build patterns, without generating a long Composition inside the RC VST. Certain users may want to generate quick MIDI phrases with RC, and then “bounce” them immediately to Reaper tracks, so they can do whatever they like.

There are so many ways to work with RC (and DAWs) and these are just a few examples of a quick workflow with MIDI and RC Phrases.