Tips and tricks

This page lists features, hacks and nuances, which might be handy, or non-obvious, or both.

Piano roll


While playback, Helio may sometimes draw red or yellow vertical warning lines:


These are the clipping and oversaturation warning markers:

  • red lines indicate problematic regions with clipping sound,

  • yellow warning lines will appear in the areas where the perceived loudness (a.k.a. the root mean square loudness) is way lower than the peak loudness, which is considered harmful unhealthy: in my setup it typically means that I have some redundant duplicate notes at the same place.

Spacebar panning

One quick way to switch between the current editing mode and the canvas panning mode is holding the Space key:


Dragging with the right mouse button does a similar thing, but it will also switch to another track, if clicked on any semi-transparent note.

Time measure tool

Hold the Space key, then click-and-drag over the timeline to measure time between two points at the timeline:


Sound probe tool

Finally, holding Space and clicking at the timeline is something I call “sound probe”, which is supposed to give an idea of what notes are playing at the given point:


Range selection

Click-and-drag at the timeline while holding any modifier key (Control/Alt/Shift) to select all notes or clips in some time range:


Velocity map fine-tuning

It’s possible to use the mouse wheel when dragging the velocity ramping tool to control how it blends with the original notes’ velocities. The main use case for that is fine-tuning the dynamics:


Resizing a group

Resize a group of notes proportionally by holding Shift:



Hold Shift to drag-and-copy notes in the piano roll, clips in the pattern roll, key/time signatures and annotations at the timeline:


Pen tool

Also hold Shift or any modifier key to change the behavior of the pen tool when adding notes. By default, the newly added note is edited in the transpose-and-resize mode. Alternatively, it’s the drag mode, more familiar:


Transposition and inversion

Shift + Up and Shift + Down hotkeys transpose the selected notes one octave up or down. Alt + Shift + Up and Alt + Shift + Down are used for the less common transposition to the next or previous key in the circle of fifths (simply put, it’s a transposition by +7 or -7 semitones in the 12-tone temperament, or by the closest equivalent of a perfect fifth in other temperaments, e.g. +18 or -18 for 31-edo, etc).

Use Control + Up and Control + Down for chord inversion (don’t confuse it with melodic inversion, which is triggered by Alt + I hotkey). Chord inversion treats selected notes as chord(s); the lowest note in each chord moves one octave up (or the highest note moves one octave down), all others stay in place.

In-scale transposition

Use Alt + Up and Alt + Down hotkeys to transpose the selected notes using in-scale keys only:


The notes which are out of scale will be aligned up or down to the nearest in-scale keys.

UI flags

A couple of display options are available to provide a visual cue. They are toggled either in the navigation panel, or via hotkeys (G and H by default).

The first one is for displaying the note name guides:


Another one highlights the in-scale keys of the key signatures that are added to the timeline. If you prefer C Major coloring in the piano roll, just turn it off:


More UI flags

The audio monitor view can be toggled between two modes on click or tap, switching between the simple spectrogram mode and the waveform mode:


The mini-map mode can be toggled with B hotkey, or by clicking at any area except the screen range rectangle.

When in compact mode, it is stretched to fit all project:


Tip: when in full mode, the mini-map allows to draw a region to zoom at:


Chord tool

By double-clicking on a row in the piano roll, you invoke the chord tool:


It picks the current key signature from the timeline to determine what scale and root key to use to generate chords. Hence the main limitation of this tool: it can only generate chords that are easy to define with in-scale keys.

It can be dragged around by the center node — kinda helpful if you clicked the wrong row or position.

Since it depends on the harmonic context, it will do nothing when placed on the out-of-scale note (the grey row). It might be a good idea to make sure the scales highlighting is enabled to avoid confusion.

Quick rescale tool

Another tool for experiments and prototyping is the quick rescale menu: once you right-click on any key signature at the timeline, you can choose another scale, into which all the tracks will be translated. This affects all notes of all tracks up to the next key signature (or the very end of the project).

This example shows rescaling, along with some undo/redo to see the difference:


As well as the chord tool, this tool assumes that the harmonic context is specified correctly. In this example, the first section is marked as D Dorian, and all the notes in that section are in the key. Any out-of-scale notes will be left in their places.

See also: piano roll hotkeys

Pattern roll

Knife tool

In my workflow, I’m often adding new tracks with a knife tool: even though there’s a normal way to add an empty track via project menu, or duplicate a track, I often end up having added some sketches in different places of a single sequence, and then, after switching to the pattern mode I see that they represent different parts, and can be cut into different tracks:


Clips and track grouping

In the example above, two split tracks remain on the same row because the tracks are grouped by name, and the knife tool keeps the track name the same. Pattern roll can also group tracks by color, or by instrument, or by track id — yet grouping by name works better for me.

So, the segments on one row might be either different tracks, or they also might be several instances (or “clips”) of the same track. Instances always share the same notes, and have the same name and color, but they can be slightly modified: have different position, key shift or volume multiplier, which is mainly meant for prototyping:


Note that when you select an item in the pattern roll, all its instances are highlighted with a dashed header: this helps to tell where are the “instances”, and where are other tracks of the same name or color on the same row.

Track grouping also affects MIDI export: all segments on one row will be exported as one track in the resulting MIDI file.

See also: pattern roll hotkeys

Command palette

This command palette control is inspired by ‘Goto Anywhere’ in Sublime Text or ‘Locator’ in QT Creator, and is meant for quick access to the commands available for the current context, and things like projects and timeline events.

Toggled by ~ or Control + P hotkeys by default:


Besides just commands, it supports several modes, which are triggered by typing a certain symbol. This symbol also acts as a hotkey to show the command palette in that mode:

  • / is for the project list,
  • @ is for the timeline events list + tracks list,
  • ! is for the chord compiler, which deserves a separate description:

Chord compiler

One of the modes of that command palette allows to generate chords based on the chord name decoding rules. This tool is not aware of any of the key signatures present at the timeline, all the chord’s notes are inferred from the given description.

Just hit ! and start typing a chord description, or pick some of the suggestions it provides: