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ProTracker Effects Reference

Paula Tracker now supports all standard ProTracker effects implemented in the paulalib/audio-engine.js module.

Effect List

0xy - Arpeggio

Usage: 0xy where x and y are semitone offsets
Description: Rapidly cycles between the base note, base note + x semitones, and base note + y semitones.
Example: 037 plays the note, then +3 semitones (minor third), then +7 semitones (perfect fifth)

1xx - Slide Up

Usage: 1xx where xx is the slide speed
Description: Slides the pitch up (period decreases) continuously.
Example: 110 slides up at speed 16

2xx - Slide Down

Usage: 2xx where xx is the slide speed
Description: Slides the pitch down (period increases) continuously.
Example: 220 slides down at speed 32

3xx - Tone Portamento (Slide to Note)

Usage: 3xx where xx is the slide speed
Description: Slides smoothly from current note to the specified target note. Does not retrigger the sample.
Example: Play C-2 01 000, then E-2 01 310 to slide from C to E

4xy - Vibrato

Usage: 4xy where x is speed and y is depth
Description: Applies pitch modulation (vibrato effect).
Example: 442 applies vibrato with speed 4 and depth 2

5xy - Tone Portamento + Volume Slide

Usage: 5xy where x is volume up, y is volume down
Description: Combines effect 3 (tone portamento) with effect A (volume slide).
Example: 510 slides to note while increasing volume

6xy - Vibrato + Volume Slide

Usage: 6xy where x is volume up, y is volume down
Description: Combines effect 4 (vibrato) with effect A (volume slide).
Example: 601 applies vibrato while decreasing volume

7xy - Tremolo

Usage: 7xy where x is speed and y is depth
Description: Applies volume modulation (tremolo effect).
Example: 733 applies tremolo with speed 3 and depth 3

9xx - Set Sample Offset

Usage: 9xx where xx is the offset
Description: Starts sample playback at position xx * 256 bytes.
Example: 904 starts playing from byte 1024 (4 * 256)

Axy - Volume Slide

Usage: Axy where x is up speed, y is down speed
Description: Slides volume up or down. Only one parameter should be non-zero.
Examples:

  • A10 slides volume up at speed 1
  • A01 slides volume down at speed 1

Bxx - Position Jump

Usage: Bxx where xx is the position in the song order
Description: Jumps to a specific position in the song sequence immediately.
Example: B00 jumps back to the beginning of the song

Cxx - Set Volume

Usage: Cxx where xx is volume (0-64)
Description: Sets the channel volume immediately.
Example: C40 sets volume to 64 (maximum)

Dxx - Pattern Break

Usage: Dxx where xx is the row number (in decimal BCD format)
Description: Breaks out of the current pattern and jumps to row xx of the next pattern.
Examples:

  • D00 jumps to row 0 of next pattern
  • D16 jumps to row 16 of next pattern
    Note: The parameter is in BCD (Binary Coded Decimal), so D32 means row 32, not row 50

E1x - Fine Slide Up

Usage: E1x where x is the amount
Description: Slides pitch up once at the start of the row (finer control than effect 1).
Example: E12 slides up by 2 units

E2x - Fine Slide Down

Usage: E2x where x is the amount
Description: Slides pitch down once at the start of the row (finer control than effect 2).
Example: E24 slides down by 4 units

E5x - Set Finetune

Usage: E5x where x is finetune value (0-F)
Description: Sets the finetune value for the current channel.
Values: 0-7 = positive, 8-F = negative (-8 to -1)

E9x - Retrigger Note

Usage: E9x where x is the retrigger rate
Description: Retriggers the note every x ticks.
Example: E93 retriggers the note every 3 ticks

EAx - Fine Volume Slide Up

Usage: EAx where x is the amount
Description: Increases volume once at the start of the row.
Example: EA4 increases volume by 4

EBx - Fine Volume Slide Down

Usage: EBx where x is the amount
Description: Decreases volume once at the start of the row.
Example: EB2 decreases volume by 2

ECx - Note Cut

Usage: ECx where x is the tick
Description: Cuts the note (sets volume to 0) at tick x.
Example: EC3 cuts the note at tick 3

EDx - Note Delay

Usage: EDx where x is the delay in ticks
Description: Delays the note trigger by x ticks.
Example: ED2 delays note by 2 ticks

Fxx - Set Speed/Tempo

Usage: Fxx where xx is the value
Description:

  • Values 01-1F (1-31): Set speed (ticks per row)
  • Values 20-FF (32-255): Set BPM (beats per minute)
    Examples:
  • F06 sets speed to 6 (default ProTracker speed)
  • F7D sets BPM to 125

Effect Combinations

Some effects can be combined or chained:

  1. Portamento + Volume: Use effect 5 to slide to a note while adjusting volume
  2. Vibrato + Volume: Use effect 6 to apply vibrato while adjusting volume
  3. Effect Memory: Most effects remember their last parameter if you use 00

Technical Notes

  • All effects are processed on every tick of the tempo clock
  • Period range is limited to 113-856 (approximately C-1 to B-3)
  • Volume range is 0-64 (ProTracker standard)
  • Arpeggio cycles on ticks 0, 1, 2 (repeating)
  • Vibrato and tremolo use sine wave modulation
  • Sample offset is in multiples of 256 bytes

Implementation Status

  • All standard ProTracker effects are fully implemented
  • Effects are processed in paulalib/audio-engine.js
  • Platform-independent (pure JavaScript)
  • Compatible with standard .MOD files

Usage Example

import { PaulaEngine } from './paulalib/audio-engine.js';

const engine = new PaulaEngine(44100);
engine.setSong(mySong);
engine.play(0);

// Effects are automatically processed during playback
const output = engine.mixAudio(4096);

Testing

Load test MOD files from demomods/test/ to hear effects in action:

  • arpeggio.mod - Arpeggio (0xy)
  • vibrato.mod - Vibrato (4xy)
  • tremolo.mod - Tremolo (7xy)
  • slide.mod - Pitch slides (1xx, 2xx)
  • slide_to_note.mod - Tone portamento (3xx)
  • volume_slide.mod - Volume slides (Axy)