Basic Concept & Functionality

RapidComposer is used to produce compositions quickly using MIDI phrases. It is not meant to, and cannot mix, or master music. Once a composition have been finished, it can be exported as a MIDI, WAV, or AIFF file. These files can then be imported into a DAW for mixing and mastering. RC can also be used as a VST plugin inside your favorite DAW, for synching up audio and virtual instrument tracks (and vocals) with your RapidComposer compositions. Additionally, you can drag-n-drop entire Compositions or separate tracks to your DAW as MIDI files.

Before you start using RC, it is important to understand exactly what a Composition consists of. A Composition is a collection of one or more Tracks, each which contains an Instrument (SoundFont, VSTi, or MIDI) controlled by a Phrase or Phrase Generator. Tracks are common to the whole composition, and, like DAWs, combine to produce a musical arrangement with harmony and melody.

The basic unit of composition is a Phrase, which is a sequence of notes and/or chords (i.e. notes in parallel). Most commonly, phrases are created and extensively manipulated by using a Generator. There are many phrase generators in RC, more in the “Phrase Generators” chapter.

You can also create a phrase manually (in Note Editing Mode or in the Phrase Editor, by entering with mouse or recording from a MIDI keyboard). Furthermore, you are able to save custom phrases with RC. Generators and the Phrase Browser are covered in detail in other chapters. Commonly, you will start with a Generator and tweak it, as this is the fastest way to get ideas going in RC.

There are two types of tracks utilized in RapidComposer:

  • Standard Tracks (MIDI) – Contain notes/chords/phrases for a particular Instrument. These track types are the bread and butter of RapidComposer.
  • Audio Tracks – Audio track implementation is very basic with limited functionality (no pitch-detection or timestretch/tempo-matching). 16-bit/44.1 or 48 WAV and AIFF import only. Useful for sound effect placement, perfectly-chopped drum loops with a known, solid tempo, or for non-harmonic sounds.

Phrases Explained

As mentioned previously, Phrases are the bread-and-butter of RapidComposer. RC uses MIDI phrases intelligently, as no notes are “absolute” unless you want them to be. Since notes in phrases are not “absolute”, you can move phrases up and down after placing them in a Composition and they will automatically (and quickly) be re-shaped by inverting the notes, all the while staying in key, and keeping the same notes of whatever chord you chose!

Common practice with efficient piano playing requires the player to be able to easily “invert” chords as needed, which, in the simplest of terms, means re-ordering the notes of the chord, to move between chords easily, without moving your hands much (the fingers do most of the moving). This is also called “voice leading.”

In “root position”, a C major chord consists of the following notes on a piano (in order from lowest to highest): C E G. The scale notes in that order are named “root, 3rd, 5th.”

In “1st inversion”, a C major chord consists of the following notes (lowest to highest): E G C Tthe “3rd” of the chord is now the lowest note… also known as “3rd in the bass.”

in “2nd inversion”, a C major chord consists of the following notes (lowest to highest): G C E The “5th” of the chord is now the lowest note… also known as “5th in the bass.”

Each of these voicings has a certain type of sound. You can easily move between inversions by left-clicking & dragging a phrase up or down. This is how the voicings look inside a Composition, using the default Chord Generator (quarter notes):

ROOT POSITION C major— C E G (low to high)

1st INVERSION C major— E G C (low to high)

2nd INVERSION C major— G C E (low to high)

Let’s say you have a C chord followed by an F chord in your Composition. The following screenshot shows a Chord Generator in “root position” (over the C bar), and an identical Chord Generator in “2nd inversion” (over the F bar). Notice how the lowest note (C) stays where it is, when “voice-leading” to the F chord. RapidComposer does this automatically, and intelligently, as this is what the program was designed to do!

C (root position), then F (2nd inversion)

New Composition Settings

Now that you understand how phrases work in RC (inversions/moving but keeping the same notes), let’s learn more about composing in RC, and become more familiar with how Compositions are structured in RC (using the Structure Inspector).

Let’s start a new Composition. The easiest way is to click this icon and choose “New Composition” from the menu.

Then, you should open the Structure Inspector .

Once you do that, this Structure Inspector window will appear:

If you then right-click, you’ll see this second Inspector window that appears directly to the right of the main Structure Inspector window. Here, you can set your Composition name, tempo, key/scale, and time signature, as well as chord display (notes or roman numeral notation) and chord rules used for chord suggestions.

You can also click the “C Major 120 BPM 4/X” text items that appear at Bar 1, Beat 1, to set your tempo, key/scale, and time sig:

Pick any tempo you like, and set your key/scale. We can always change these settings later.

Structure Inspector

The Structure Inspector is yet another “rapid” part of RapidComposer. You can use it to build Parts of your Composition, and copy/paste new ones, and rearrange them on the fly. Each Part can have its own key, tempo and time-signature that all override the global Composition settings. On the previous page, we changed some settings in the Structure Inspector window (we picked a key, a tempo, and a time signature). Now let’s go over how RC Compositions are structured, within this very important (and powerful) window.

When you first start RC, you see your “entire” Composition. Within this Composition are “Parts”, and within those “Parts” are “Lines.” When you start a new Composition, you only see one part, and one line, like this:

The key, tempo and signature is displayed for each part or line that changes it! Important: key, tempo and signature are inherited by parts from the composition, and lines inherit these from the parts, so lower levels in the hierarchy inherit higher level settings. However they can also override them!

When you click on a Part or Line a few buttons appear that allows you to add/duplicate/delete a part or line:

Once you’re a little more familiar with RC, you might come up with a Structure that looks like this…

You can easily add new Parts (and rename them to something logical such as “Verse” or “Chorus” or “Pre-Chorus 1” or “Chorus 2” if you want) and you can add new Lines to those Parts (Lines are automatically named Line1, Line2, and are tied to each Part they are made from). You can edit one Part at a time, by double-clicking its name in the Structure Inspector. Right-clicking opens the Master Track Inspector where you can set up the scale, tempo and signature for the selected line or part. Remember, these properties are inherited from higher levels if you don't override them. If you created a line you can change its length by adding bars and beats in the Timeline Inspector. You can also delete a few bars to make it shorter by making a selection on the timeline and pressing Delete.

Let’s take the screenshot above. The 28-bar Composition has five separate Parts. Notice also how there are a total of seven Lines beneath these five Parts. If you’re still confused, please see our Part 7 Tutorial video “Structure Inspector” at

More about Parts/Lines: Say you have a Part with a Line that’s four measures long. If you add another Line to that Part, that Part is now a total of eight measures long (Line 1 is the first half of that Part, and Line 2 is the second half of that Part. Both Lines can be different bar lengths & have different chord progressions, if you want!). Seems complicated at first, but the more you use it, the easier it gets.

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Working With The Master Track

Scale / Tempo / Time Signature are always displayed on the Master Track (added in version 2.7). Left-click the scale and key (in this case, “C Major”, which highlights blue when you hover the mouse over it) to bring up the window below. You can easily pick a root, and common scale set.


Tempo Left-click the tempo (in this case, “120 BPM”, which highlights blue when you hover the mouse over it) to bring up the window below. You can easily pick a new tempo (increments of 5 BPM, or a custom tempo). You can also tap-tempo after you click “Other”.

Time Signature Left-click the time signature (in this case, “4/X”, which highlights blue when you hover the mouse over it) to bring up the window below. You can easily pick a new time signature. For example, clicking “3” would insert a new Time Signature of 3/4 in your Composition.

Want to insert multiple Key Changes, Tempos, and Time Signatures in your Composition? You easily can, at any measure you want. If you right-click on that part of the timeline, elsewhere in the timeline, you can easily change these properties later in your Composition, multiple times if you’d like (and you can change just the Tempo, or all three Composition properties if you like, anywhere you want!)

The Browsers

The eight icons in the top left of the main RC interface are the Browsers or Browser Windows. The three you will use most will likely be the Phrases, Variations and Progressions, and the others you may not use as frequently are Scales, Chords, Instruments, Rhythm, and Tracks. The Browsers are part of why RapidComposer is indeed, so rapid.

For example, you can open up the Progressions Browser and drag in absolute chords (in specific keys) or a “Roman Numeral”-style progression (in your favorite key) to the Timeline in your Composition, and instantly create a song arrangement. After dragging in a progression, you’ll then need some phrases to play over your chord progression. You can drag in a Generator or specific phrase of your choice from the Phrase Browser (or, even faster, select a phrase you want from the Phrase Browser, then if your desired track is selected (it should be, if you only have one track in your Composition), just hit the letter F, which is a keyboard shortcut for Fill Track With Selected Generator). This takes no more than 10 seconds to do. Hit the spacebar and voila… you’re now listening to a rapidly-composed piece of MIDI music.

The Variations Browser gives you exactly that: a bunch of variations for phrases. Any phrase you select can be tweaked with anything in the Variations Browser. For instance, you might choose to apply some swing to a phrase, giving it a shuffle-feel, or you might want to mirror the phrase horizontally, or humanize the phrase. These things and more can be found in the Variations Browser. This Browser is especially useful when combined with the Idea Tool (see Idea Tool section).

The Scales and Chord Browsers are not used often, you can add new scales and chords here, or remove some from the library. The browsers are not used for scale or chord selection during composing, it is much faster and easier to use the Quick Suggestions window, or Chord Selector. Clicking on a scale on the master track lets you change the root note, or replace the scale from the pop-up window, so it is not necessary to open these browsers. In the browsers you can audition the sounds of scales and chords you might not be familiar with. Scales Browser previews all types of scales from lowest note to highest note, and back down. Chords Browser plays a chord type or “color” (such as minor 7th or sus2) so you can hear how it sounds, and if you like it, you can drag that type to a chord already in the Composition (doing so will change the chord type, but retain its root, although this is not the recommended practice).

The Rhythm Browser shows all the custom Rhythms you have created or added to RC, which can be applied to any Phrase or Generator.

The Instruments Browser shows all of the Soundfonts you added for use with RC (as well as their presets), and all of the VST instruments you added (along with their presets).

The Track Templates Browser shows all the custom Track Templates you made, such as a Soundfont's specific settings, with any Variations you applied beforehand.

Working With Phrases / Composing / Chords

So we’re now familiar with the basic functions of RapidComposer. Let’s build an arrangement for real.

1. Start a new Composition.

2. Click the Structure Inspector icon and set your Key (Scale), Tempo, and Time Signature. You can also do this by left-clicking just below Bar 1, Measure 1 in the Composition (“Master Track” - since version 2.7). Remember that any Parts you add to the Composition can have their own Key, Tempo, or Time Signature that all override the global setting. For this example, let’s keep the key of C major, tempo 120, and time signature of 4/4 (default when starting a new Composition).

3. The Composition defaults to the chord progression I - IV - V - I.

Since we’re still in C major, the chords I - IV - V - I are C - F - G - C, respectively. But from here, you can change them to any chords you want. Right-click the chord right below the timeline to change whatever chord you like (Right-clicking brings up the Chord Selector window right after you click).

The Chord Selector window (above) has three “views” (Scale Degrees, List, or Palette). Choose whichever you like most. Scale Degrees View shows only the “Roman Numeral” chord intervals, which is also commonly known in North America as the “Nashville Number System” or simply, the “Number Chords”. List View and Palette View show the note letters (C, D, E, etc), and Palette View also shows the chord interval numbers. RC can intelligently combine “absolute” chords with “Roman Numeral” chords (a progression could show as “C, IV, Am, V” in the Composition, for instance).

You can leave the Chord Selector window open as you change the chords on each bar (the Chord Selector view is a window that stays “always on top”). Simply right-click the chord in the timeline, and change it to whatever you want by clicking a chord in the Chord Selector. Remember that the Composition shows we are editing/working with Part 1, and Line 1 (in the Structure Inspector).


Let’s assume you already have writer’s block. It’s the perfect time to introduce a helpful feature in RapidComposer– Chord Suggestions!

Chord Suggestions (added in version 2.7)

As we learned in the previous section, right-clicking a chord in the Composition timeline brings up the Chord Selector window. As of version 2.7, we can left-click the chord instead, and left-clicking brings up the brand new Chord Suggestions window (Chord Suggestions depend heavily on the Chord Rules you specify - see the EDITORS section of this wiki, on how to use the Chord Rules Editor.

You can use the Chord Suggestions feature on any chord in the Composition, at any time! For this example, let’s keep the first chord as Chord I. For the next chord, however, we want to change the IV chord to a vi, instead. Notice how vi is an option for the next chord, when we left-click the IV in the Composition timeline. Notice also how the probability (neon green horizontal bar, underneath the chord degree) is high, for the vi chord, as the next chord in our progression.

You can also click the right-pointing arrow in the Chord Suggestions window to show (and be able to change) the additional chords that are suggested. Furthermore, if you click the Randomize icon (rightmost icon at the top of Chord Suggestions window), you can create a randomized progression that adheres to the Chord Rule set (and also immediately shows up in the Timeline). This is a powerful tool to find interesting chords very quickly!

Before we go any further, let’s look at the four main functions/icons in the Chord Suggestions window:

Chord Preview (default is on) When you click on a suggested chord, you can hear what it sounds like. Right-clicking offers more options for preview (Chord+Bass, Chord only, force root position, etc)

MIDI input (default is on) If you have a MIDI device (keyboard) specified in Settings, you can play the chord and RapidComposer will add it to the Composition on the beat & bar you clicked on. If the chord you play is in the Suggestions section, you will see it highlighted after you input it from your MIDI keyboard. Right-clicking offers “Add octave number to chord”, so you can get a detailed view of the chord you input, on the Composition timeline.

Text input Clicking on this icon allows you to input the chord you want with your computer keyboard. Acceptable formats are the note letter (C for C major), lowercase m for minor, a number for an extended voicing (6, 7, 9, 11, 13), “sus” for suspended chords, etc.

Randomize Clicking on this icon gives you a random chord suggestion, and a random progression, after you click the right-pointing arrows in the Chord Suggestions window, to expand the available chords. You can right-click the icon for even more further (and uncommon) options for randomization!

All of these suggestions can be completely customized in the Chord Rules Editor (Chapter 3). You can use the included Chord Rules or create your own!

Included Rules:

  • Bach Harmonic Minor Scale Rules
  • Bach Major Scale Rules
  • Default Major Scale Rules (default)
  • Default Minor Scale Rules
  • Mozart Harmonic Minor Scale Rules
  • Mozart Major Scale Rules
  • Pop Major Scale Rules
  • Pop Minor Scale Rules
  • New Rule — create your own using your favorite chords, even if they’re out of key!

Judging from the feedback of our customers/users at our forum, this is a very popular new feature in RapidComposer. We definitely find it very helpful, to make your Compositions truly rapid!

Let’s get back to our Composition example… remember, the progression we created so far is I - VIm- V - I. To make something completely different from the default progression, we can change the V chord (on Bar 3) to a IV chord instead, and then the last chord (I on Bar 4) to a V chord. This is a simple pop progression, that was very popular in the 50s.

4. If you are happy with this progression (I - VIm - IV - V), and want to hear how Phrases sound over those chords, let’s choose some. You are more than welcome to change the chords even more, if you’d like. But just to keep things simple, let’s stick with the progression and add some Phrases.

For this example, let’s open the Phrase Browser and go to PianoSample01. Click with the right mouse button to open the preview window:

You can quickly preview the phrase using the chords (you can select any Major, Minor or 7th chord) or if the phrase includes only scale notes only (e.g. a melody phrase) you can expand the preview window to show scale steps. The phrase preview window offers instrument selection, adding tags, inserting the phrase at the playback position, editing it, or removing entirely from the phrase browser.

5. With PianoSample01 still selected in the Phrase Browser, go over to the track and click the grey area (right underneath the track name). That makes the current track active/selected.

RIGHT-CLICK: If you right-click this area, it brings up the Track Inspector window, where you can change the Soundfont or VSTi instrument (as well as their respective presets). You can also change the track/phrase color if you like, and other options. Now hit the letter F on your keyboard, and you will see that RC filled that track with the PianoSample01 phrase. Hit the spacebar to hear how PianoSample01 sounds over the chord progression you made.

Keep in mind that RC’s default track (Track 1) uses RCPiano (included Soundfont) as its default Instrument. If you’d like to change it, you can do so by right-clicking where it says Track 1 (you can change it to a different Soundfont, or a VSTi of your choice).

If you don’t like the way the Phrases sound, either delete it (hit DEL) and choose another, or insert a Generator (such as Generic) and right-click the Generator to edit it to your liking, using one of the many Rhythm types (more on this in Chapter 2). If you want to delete all of the Phrases at once and use another Phrase (or Generator), select them all by left-clicking and dragging (doing so will highlight all phrases in that track) and then hit DEL.

6. If you’re happy with PianoSample01 (let’s assume you are, for this example), let’s now change the chord progression to a I - V - VIm - IV progression. Then, let’s add another Track to our Composition. Hit the letter A to quickly add another Track, and then right-click the Track’s grey area The Track Inspector window will open). For this example, we will choose the RCBass Soundfont.

7. Go into the Phrase Browser, and select Bass Generator. Then actively select our new track, then hit the letter F on your keyboard (You can also hit the letter B on your keyboard). RC will fill that track with the default Bass Generator, and every time the bar or chord changes, the Bass Generator will of course follow it and match perfectly.

8. Let’s add another track. Hit the letter A. You’ll see a track right below the Bass Generator track. Let’s leave the instrument as is (default: RCPiano Soundfont), as we will now make this a Melody track (using the Melody Generator - not available in LE version). Go into the Phrase Browser and select the Melody Generator. Select this new (third) track, and hit the letter F. You will see the Melody Generator filled the four measures with a random melody generator on each bar.

9. You may or may not like what was generated. You can easily edit the Melody Generator (or any Phrase Generator) by right-clicking the Phrase, and tweaking it using the many parameters in the Phrase Inspector. Please see Chapter 2 and also see our Part 9 Tutorials on “Generators” at for more details on how to edit (“tweak”) Generators.

In the interest of saving time following this tutorial, let’s assume you are ok with these randomly generated melodies. Let’s now build more sections of our Composition.

10. Go back into the Structure Inspector.

11. Click Part 1 (where we have been working) and you’ll see two “plus sign” icons pop up. Click the bottom plus sign to add a part AFTER Part 1 (most common) or click the top one to add another Part BEFORE Part 1. In this example, we clicked the bottom plus sign and you can see that the Composition has expanded to 8 bars total, and notice how this new Part has kept the same chords in the same place (and has been conveniently named “Part 2”), but RC left the workspace open for new Phrases to be inserted.

You may have also noticed the “x2” button next to the plus sign buttons. x2 is a new function that allows you to duplicate the current Part right after it, but x2 does something special– it retains all the Chords and Phrases from the duplicated Part, thus saving you even more time!

Again, for this example, we used the bottom plus sign, so it added four new measures, keeping the same chords as the previous part, but leaving the workspace open to add different Phrases.

From here, you can change the chords if you’d like, or put some new Phrases in. Notice how easy it is to create new parts and build a Composition filled with Phrases. Again, this is how RapidComposer does its thing. We assume you now have the basics of how Compositions work in RC, and how you can add new Parts and Lines with the Structure Inspector. Again, we recommend watching our Tutorial videos, especially Part 7 (“Structure Inspector”) and Part 8, entitled “Building A Composition Part By Part” at for more details.