🎵 Chipamp

A pure-Java ProTracker MOD file player and playback engine.

Chipamp parses and plays classic Amiga (and PC) .mod tracker files with sample-accurate, tick-based emulation of the original ProTracker / OpenMPT playback behavior — arpeggios, portamento, vibrato, the Amiga hardware low-pass filter, and all the other quirks that make old-school chiptunes sound the way they do.

No native dependencies, no external libraries — just Java and javax.sound.sampled.

🧩 Features

• Full ProTracker MOD parser — reads 15-sample and 31-sample module formats, sample headers, pattern data, and the song / pattern sequence table
• Smart tracker & channel detection — recognizes tracker ID signatures (M.K., M!K!, FLT4/8, 6CHN, TDZ4, OCTA/OKTA, and more) to infer channel count (1–16 channels) and sample-count layout
• Cycle-accurate playback engine — tick / row-based sampler that mirrors real ProTracker timing (speed, tempo, CIA tick calculation)
• Every classic effect implemented — see the full effect tables below
• OpenMPT-style sample correction — automatically fixes malformed loop points found in real-world .mod files
• Fast seeking — pre-computed per-row channel / context snapshots let you jump to any sequence position or row instantly, without replaying from the start
• Infinite loop detection — safely detects and breaks out of modules that loop forever
• Runtime control — mute / unmute individual channels, toggle individual effects or extended effects on/off, adjust panning, clock rate (PAL / NTSC), sampling rate, volume, and more — all live
• Flexible audio output — render to a byte buffer, WAV-style PCM, or stream directly through javax.sound.sampled with a built-in async, non-blocking SourceDataLine writer

🎹 Supported Effects

Basic Effects

Code	Effect	Description
0	Arpeggio	Rapidly cycles between the base note and two offset notes
1	Slide Up	Slides the pitch up
2	Slide Down	Slides the pitch down
3	Tone Portamento	Glides smoothly toward a target note
4	Vibrato	Oscillates pitch using a configurable waveform
5	Tone Portamento + Volume Slide	Combines effects 3 and A
6	Vibrato + Volume Slide	Combines effects 4 and A
7	Tremolo	Oscillates volume using a configurable waveform
8	Set Panning Position	Sets fine stereo panning
9	Set Sample Offset	Starts sample playback from an offset
A	Volume Slide	Slides volume up or down
B	Position Jump	Jumps to another position in the song sequence
C	Set Volume	Sets channel volume directly
D	Pattern Break	Jumps to a specific row in the next pattern
E	Extended Effect	Dispatches to one of the extended (Ex) effects below
F	Set Speed / Tempo	Sets ticks-per-row or beats-per-minute

Extended Effects

Code	Effect	Description
E0	Set Filter	Toggles the Amiga hardware low-pass filter
E1	Fine Slide Up	Small one-time pitch slide up
E2	Fine Slide Down	Small one-time pitch slide down
E3	Set Glissando	Snaps tone portamento to the nearest semitone
E4	Set Vibrato Waveform	Sine, sawtooth, or square
E5	Set Fine Tune	Overrides the sample's fine-tune value
E6	Loop Pattern	Loops a range of rows a set number of times
E7	Set Tremolo Waveform	Sine, sawtooth, or square
E8	Rough Panning	Coarse 4-bit stereo panning
E9	Retrigger Sample	Retriggers the sample every n ticks
EA	Fine Volume Slide Up	Small one-time volume increase
EB	Fine Volume Slide Down	Small one-time volume decrease
EC	Cut Sample	Silences the channel after n ticks
ED	Delay Sample	Delays a note trigger by n ticks
EE	Delay Pattern	Repeats the current row n times (pattern delay)
EF	Invert Loop	"Funk repeat" — inverts loop sample data over time

🚀 Usage

Load and play a module

ModLoader loader = new ModLoader();
Mod mod = loader.load(new File("classic_tune.mod"));

Sampler sampler = new Sampler();
sampler.updateMod(mod);

Player player = new Player(sampler);
player.play();                                          // blocks until the module finishes

Render to a byte buffer (e.g. for exporting)

Sampler sampler = new Sampler();
sampler.updateMod(mod);

byte[] pcm = sampler.read();                            // full module rendered as 16-bit PCM

Seek, mute, and tweak playback live

sampler.seekSequence(4, 16);                            // jump to sequence position 4, row 16
sampler.setMuted(2, true);                              // mute channel 3
sampler.setEffectEnabled(EffectType.ARPEGGIO, false);
sampler.setClockHz(Mods.NTSC_CLOCK_HZ);                 // switch PAL -> NTSC pitch
sampler.setVolumeMultiplier(0.75f);

Query module metadata

System.out.println(mod.getTitle());
System.out.println(mod.getChannelCount() + " channels");
System.out.println(Mods.getUniqueEffects(mod));
System.out.println(sampler.getModLength(TimeUnit.SECONDS) + "s");

📦 Resources

https://moddingwiki.shikadi.net/wiki/MOD_Format
https://www.aes.id.au/modformat.html
https://www.fileformat.info/format/mod/corion.htm
https://www.exotica.org.uk/wiki/Protracker
https://cdimage.debian.org/mirror/CRAN/web/packages/ProTrackR/refman/ProTrackR.html
https://en.wikipedia.org/wiki/Protracker