Skitter - Chapter 6 - MIDI Sound Editing

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Table of Contents:
    1.0 Introduction
    2.0 Install Skitter
    3.0 Performance Files
    4.0 Motion Editing
    5.0 LED Editing
    6.0 MIDI Sound Editing
         6.1 Musical Terms & Notation
         6.2 Navigating MIDI Files
         6.3 Editing MIDI Notes
         6.4 MIDI Note Overlaps
         6.5 MIDI Special Effects
         6.6 Convert MIDI into Wave
         6.7 Sound Start Time
         6.8 Undo/Redo Changes
         6.9 The Splitter Bar
    7.0 Wave Sound Editing
    8.0 The Reference Library
    9.0 The AIBO Window
    10.0 Test Actions on AIBO
    11.0 Upload Actions to AIBO
    12.0 Specify Preferences


6.0 MIDI Sound Editing

MIDI files are the compact way to generate sound on AIBO.   MIDI is a standard music format, with a wide variety of music sources available on the web.   However, AIBO only supports single-track mono-tone MIDI files.  In other words, AIBO can only play one note at a time.  Skitter verifies MIDI files are compatible with AIBO, and can usually convert those which aren't.

The MIDI tempo (beats per minute) & time (beats per measure) are changed in the upper-left corner.   The ruler bar along the top shows keyframes tabs from the motion editor, so aligning sound events to motions is easier.    The velocity/volume bar (between ruler & score-sheet) also shows the loudness of  individual notes.  

The vertical toolbar is for choosing note lengths.  The piano bar previews pitch, and adds notes to the score-sheet using the selected note length.

MIDI Editor

6.1  Musical Terms & Notation

There are a number of terms associated with music.   Tempo, time, measures, beats, etc...   Don't worry if you lack a music background.   Just remember tempo controls how fast AIBO plays your music.   Trial & error works fine for everything else.  Try something, preview it, and edit until it sounds good.   If you want more details, read on...

Sheet music is drawn in measures, to help those reading the music keep track.  A measure is a collection of beats -- commonly 3 or 4 per measure.   Tempo is the number of beats per minute.   Velocity simply means volume or loudness.

A tempo of 120 means there are 120 beats per minute.    A music time of 3/4 means there are 3 beats per measure, and 4/4 means 4 beats per measure.

Note lengths are in terms of 4-beat measures.  A whole note is 4 beats (ie: a whole measure), and quarter-note is one beat.  See table to right.

There are variations in note length.   Notes can be "dotted" which increases their duration by 50%, and a triplet note is 2/3 normal length.    ie:  A half-note is 2 beats.  A dotted half note is 3 beats.    A triplet quarter-note is 2/3's of a beat.

Whole Note
Full measure
Half Note
Half a measure
Quarter Note
1/4 of  measure
8th Note
1/8 of measure
16th Note
1/16 of measure
32nd Note
1/32 of measure

6.2  Navigating MIDI Files
An orange marker bar shows the current time position.   Left-clicking in the ruler, velocity, or score sheet panes, moves the marker. Current Position Marker

Click-n-drag in the ruler bar (above the data pane), and a green selection marker appears at the starting point.  Skitter highlights between the markers & changes any included keyframe tabs green.   All LED's are selected.
Range Selection

Click-n-drag in the score sheet pane (below the ruler & velocity bars), to select one or more notes.   Once you unclick, the green marker disappears and selected notes are highlighted orange.   You can extend a selection by pressing SHIFT, while selecting additional notes.
LED Selection

6.3 Edit MIDI Notes

6.3.1 Set MIDI Velocity (Volume)

You select loudness from the velocity slider, or by clicking-n-dragging a line over the  over the or brightness with the left-most toolbar.   Choose a value from 0% to100%.  


6.3.2 Adding MIDI notes

Adding notes is easy.  First select a MIDI note length, then click in the score sheet where you want the note.  Alternatively, use the piano bar to preview & add notes.

Note Length

6.3.3 Changing MIDI Notes Length

Click on an MIDI note to highlight it.  The note turns orange with a black border.  You can move the highlighted note using keyboard, or click-n-drag the orange highlighted note with the mouse.

To stretch the note, position mouse on its right-most edge.   A resizing cursor appears.  Click-n-drag to stretch or shrink the note.   Note: If you select multiple notes, the resize cursor won't appear -- only one note can be resized at a time.

LED note resizing

6.3.4 Changing MIDI Note Velocity

There are two ways to change the volume.   You can click-n-drag over the velocity/volume bar (shown left), or alternatively select & highlight notes then use the volume slider.

6.4 MIDI Note Overlaps

AIBO doesn't support playing multiple MIDI notes at once.   Skitter highlights such problems in red, and will prompt you to correct them whenever you save.   You can also clean up overlaps by selecting:
   Sound Menu -> Remove MIDI Overlaps

Skitter can fix these problems automatically, by adjusting the MIDI score.   Notes are truncated whenever a new note begins.  The truncated notes don't necessarily sound bad (something like a staccato effect).

6.5 MIDI Special Effects
  • Insert Silence.    Convenient for shifting MIDI note's an exact number of seconds or frames.
  • Scaling MIDI Note Lengths.   Stretch/shrink note durations to exactly match motion or LED's.

6.6 Convert MIDI into Wave

Skitter can convert/render MIDI into Wave files.   You normally shouldn't do this, since the sound file size grows many fold.  However, for certain limited special effects (such as overlaying notes on other wave files) it can be very useful.   

Conversion cannot be undone so save your MIDI file beforehand.

6.7 Sound Start Time

AIBO supports starting sound playback at specific times.   This is useful for aligning sound to motions.   The start time can be specified as either motion frames, or in time (seconds).

AIBO waits the specified interval, relative to the start of motion & LED's, then begins the sound playback.

6.8 Undo/Redo Changes

If you make a change that doesn't work out, simply undo it (Edit Menu->Undo).   Skitter supports unlimited undo (ie: all edits since the MIDI file was loaded, or last platform conversion).  If you undo too much, you can reapply changes (Edit Menu->Redo).

Keyboard shortcuts of Ctrl+Z (Undo) and Ctrl+Y (Redo) are available.

6.9 The Splitter Bar

The vertical splitter bar allows two views of the MIDI file at once.   To adjust the position of the splitter bar, select:
   "Window Menu -> Split Window". 

You can move the splitter at any time.   To dock the splitter bar (hide it), simply drag the splitter to its left-most position. 

Splitter Bar

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"AIBO" is a registered trademark of Sony Corporation.  "AIBO Master Studio", "R-Code", and "Memory Stick" are trademarks of Sony Corporation.