Lesson 6: Automated Playback

Goals for This Lesson

Learn how to create automated music playback using text data and GUI tools.

Specifically, this lesson covers:

• Automated output using text data
• Automated audio file playback driven by text sequences
• Beat programming with a GUI (rhythm machine)
• Overview of DAW integration via MIDI

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Automated Output with Text Data

In Pd, you can use text data to output messages at specified timings in sequence. This makes it possible to play sounds automatically based on pre-written data.

Objects Used

Object	Function
text define	Define and store text data
text sequence	Output text data line by line in order

Text Data Format

Text data is written in the following format. Each line corresponds to one event, ending with a semicolon (;).

data c;
data d;
data e;
data f;

Writing Text Data

• Write one piece of data per line
• Each line must end with a semicolon (;)
• Write the value after data followed by a space
• You can include multiple values on one line separated by spaces (e.g., data c 500;)

Patch Example

Write text data inside the text define object, and text sequence outputs it line by line.

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Automated Audio File Playback via Text

By connecting the output of text sequence to else/play.file~, you can automatically play audio files in the order specified by the text data.

Key Messages

Message	Action
auto	Enable auto-play mode (automatically outputs the next line based on timing in the text data)
bang	Output the next line manually (manual mode)
line 0	Return to the beginning

Steps

1. Write text data (file names, note data, etc.) inside text define
2. Create a text sequence and specify the name of the text define as its argument
3. Send auto to automatically output each line in order
4. Send bang to output one line at a time manually
5. Send line 0 to return to the first line

Choosing Between auto and bang

• auto: Advances automatically at time intervals specified in the text data. Best for BGM and automated playback.
• bang: Advances one step at a time with user interaction (e.g., pressing a button). Best for interactive performance.

Patch Example

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Beat Programming with a GUI

The else/drum.seq object provides a graphical interface for programming rhythm patterns. You can click with the mouse to intuitively build beats.

Objects Used

Object	Function
else/drum.seq	Rhythm pattern GUI editor
else/tempo	Set the tempo (BPM)
route	Route output data to different instruments

Setting the BPM

Use the else/tempo object to set the BPM (Beats Per Minute).

• Specify the BPM value as an argument (e.g., else/tempo 120)
• You can also change the BPM dynamically by sending a number message

BPM Reference

BPM	Feel
60--80	Slow (ballad)
100--120	Medium (pop)
120--140	Somewhat fast (dance music)
140--180	Fast (drum and bass)

Building a Rhythm Machine

1. Create an else/drum.seq and program rhythm patterns in the GUI
2. Set the BPM with else/tempo
3. Use route to distribute each track's output (kick, snare, hi-hat, etc.)
4. Connect audio sources (else/play.file~ or synthesizers) to each track

Patch Example

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Automated Playback via MIDI with a DAW

Reference Information

Pd can also connect to DAW (Digital Audio Workstation) software using MIDI (Musical Instrument Digital Interface).

Overview

MIDI is a standard protocol for exchanging performance data between electronic instruments and computers. Pd can send MIDI messages to or receive them from external DAWs such as Ableton Live and GarageBand.

Using MIDI in Pd

• MIDI output: Use the noteout object to send MIDI notes
• MIDI input: Use the notein object to receive MIDI notes from external sources
• Virtual MIDI bus: On macOS, you can create a virtual MIDI bus in "Audio MIDI Setup" to connect Pd and a DAW

Scope in This Course

MIDI integration is an advanced topic. We will only cover the overview in this course, but feel free to consult the instructor if you want to use it in your project.

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Practice Exercises

Exercise 1: Play "Frog Song" One Note at a Time with the A Button

Use text define and text sequence to prepare the melody of "Frog Song" (Kaeru no Uta), and create a patch that plays one note each time the micro:bit's A button is pressed.

Hint

• Write the note data in text define (e.g., data c; data d; data e; data f; ...)
• Use the bang message on text sequence to output one note at a time
• Send bang when the A button is pressed
• Connect the output note data to osc~ or an audio file player
• Consider using line 0 to return to the beginning when the song ends

Exercise 2: Rhythm Machine with Tilt-Controlled Tempo

Create a rhythm machine using else/drum.seq, and make the BPM (tempo) change based on the micro:bit's tilt.

Hint

• Create rhythm patterns with else/drum.seq
• Control the BPM with else/tempo
• Get the micro:bit's tilt (accelerometer) value
• Map the tilt value to a BPM range (e.g., 60--180)
• Use the scale object to convert the value range
• If the value changes too rapidly, use else/lowpass to smooth it out