PSPATTERN

You build a song from patterns of notes and the PSP generates the sound. Nothing is streamed from disk and no sample files are required.

PSPATTERN has eight channels. Each one can play a sampler, a four engine synthesiser, or MIDI notes played on other gear through the PSP-MIDI adapter. It has a drum kit that is generated when a project loads, a delay and a reverb shared by all channels, and a small automation sequencer called a table attached to any step.

It is a fork of LittleGPTracker by Marc Nostromo, released under the GNU General Public License version 3. The interface follows the same idea as LSDJ: a song is a grid of chains, a chain is a list of phrases, and a phrase is sixteen steps of notes and effects.

What you need

• A PSP running custom firmware. Tested on 6.61 PRO-C.
• A memory stick with room for the program, which is a few megabytes.
• A PSP-MIDI adapter, only if you want MIDI. Everything else works without one.

Installing

Copy the PSPATTERN folder to ms0:/PSP/GAME/ on your memory stick, then launch it from the PSP game menu. The folder holds the program and four support files:

Buttons are named as they are printed on the PSP. Almost everything is a modifier held with a direction, and the bottom line of every screen lists the moves available from where you are.

There are seven. Hold R and press a direction to move between them. The song screen is the top level, and the rest open out of whatever the cursor is sitting on.

Song

Each cell holds a chain number in hexadecimal, or two dashes for an empty slot. Hold O and press up or down to place a chain. The tracker plays down the rows.

Chain

Sixteen rows. Each holds a phrase number and a transpose value in semitones, so the same phrase can be reused at a different pitch. Transpose is signed, so FE is two semitones down. The chain plays its rows in order and then returns to the song.

Phrase

This is where the notes are. Seven columns: note, instrument, velocity, then two pairs of effect and parameter.

The velocity column reads 00 to 99 in decimal, not hexadecimal. Two dashes means nothing is written and the step plays at full level, so a phrase made before the column existed sounds exactly as it did. Hold O and press up or down to move by ten, left or right by one. One step below 00 clears it back to two dashes.

Stand on an effect column and the panel at the bottom explains the command and its parameter. Hold O and press up or down to pick one from the list.

Table

A table is sixteen rows of three effect columns that run alongside a note at tick rate, which is faster than the phrase steps. Use one for anything that has to change while a note sounds: a filter sweep, a retrigger, a pitch slide, a volume shape.

Start a table from a phrase step with the TABL command, or set an instrument to run one automatically from its table field. HOP loops a table back on itself, which is how it becomes an envelope rather than a one shot.

Groove

How many ticks each step lasts. The default is six. Uneven values give swing, and the GROV command switches groove mid song.

Project

Tempo, a whole song transpose, a scale, the master level, whether the song repeats, the master drive and clipper, the MIDI device and sample rate, and the file operations.

An instrument is one of three types, chosen on the top row of the instrument screen.

Sample

Plays a wav file or one of the built in drums. It has volume, pan, root note, fine tune, interpolation, loop mode and points, a slice count, a drive and bit crush stage, a filter with cutoff, resonance and type, a feedback stage, an attenuator and an amplitude envelope.

MIDI

Plays notes on something else instead of on the PSP. Channel, volume, note length, pitch bend range and four CC slots that the MCCA command can address. Select the PSPMIDI device on the project screen first. See the MIDI section below for what the adapter carries.

Synth

Generates sound on the PSP. Pick one of four engines on the second row.

The FM algorithm names describe the routing directly. A greater than sign means the operator on the left modulates the one on the right, a space separates independent branches, and any operator not followed by a greater than sign reaches the output. So 4>3>2>1 is one chain and 4 3 2 1 is four sines added together.

Hard sync and ring modulation

Both are on the vax engine and both are off at zero, so patches made before they existed are unaffected.

sync runs a silent master oscillator at the note frequency. The oscillators you hear are lifted to between one and four times that frequency and reset every time the master completes a cycle. The pitch stays on the note while the timbre climbs. Sweeping it from a table is the classic hard sync lead.

ring multiplies the oscillator by a sine running one octave below the note. At zero the oscillator passes through untouched. It adds tones halfway between the normal harmonics, which is what makes it sound metallic. It is applied before the sub oscillator and the noise, so a ring modulated lead keeps a solid bottom end.

The drum kit

The drum instruments are generated when a project loads rather than read from sample files. That is what the progress line on the loading screen is doing. They take no space on the memory stick and they can be redistributed freely. Each drum has a soft and a hard variant.

MIDI runs through the PSP-MIDI adapter, which carries USB MIDI for a computer and TRS MIDI for hardware, in both directions. The tracker is fully usable without it. Samples and synths need no extra hardware at all.

Out

A MIDI instrument sends note on and note off, continuous controllers, pitch bend, program change and channel pressure. The commands beginning with MD and MC address those directly from a phrase or a table, so a controller sweep can be sequenced the same way a filter sweep is. MIDI clock follows the song tempo, so gear downstream stays with the tracker.

In

Incoming notes, controllers, pitch bend and program change are routed through mapping.xml, so an external controller can drive the program. Set the device to PSPMIDI on the project screen.

The project screen also has a sync setting with two positions, Off and Follow. On Follow the tracker takes its clock from outside instead of running its own, which is how you put it in time with something else. Following is deliberately opt in: a stray clock byte from a device you happened to leave plugged in should not take the transport away from you.

ARPG takes four hexadecimal digits, each one a number of semitones above the written note, and cycles through them under a held note. Trailing zeros shorten the cycle, so 0370 is a three note figure and 037A is a four note one. A note starting cancels the previous arp, so the command goes on every step that has a note.

Arp speed

The arp advances one position per tick, and a tick is short. At 150 beats per minute with six ticks to a step a tick is under 17 milliseconds, which gives a 220 Hz note fewer than four cycles before the pitch changes again. That is below what the ear needs to hear a pitch at all, so a fast figure stops sounding like notes and starts sounding like roughness.

ARPS sets how many ticks each arp position holds. The default is 1, the classic every tick trill. Raising it to 2 or 3 keeps the shimmer while giving each note in the figure enough cycles to register as a pitch. It is a channel setting and it survives note starts, so once per part is enough.

Every command takes a four digit parameter. The help panel writes it as aabb when the first two digits and the last two are read separately, or as aaaa when all four are one number. For PTCH and VOLM the first pair is a rate, and a rate of 00 jumps straight to the target instead of sliding.

Projects live in ms0:/PSP/GAME/PSPATTERN/lgpt_NAME/. Save song writes to the current project, save song as makes a new one, and the browser on load song lists every project it finds.

The tracker also keeps an automatic backup. If it was interrupted, it offers to recover the unsaved changes the next time you open that project.

Set render to Stereo on the project screen and press START to write mixdown.wav into the project folder while the song plays. Stems writes one file per channel instead, which is the quickest way to hear what a single part is doing. Set it back to Off when you are finished, or every play writes a new file.

Version 0.2.0a. These are the things that are wrong and known about.

• The PAN command on sample instruments is unverified and may not work.
• Sync and ring can only be set on the patch. They cannot yet be sequenced from a command.
• Synth envelope values are shown in hexadecimal while the sliders on the same page are shown as percentages.
• A few stray pixels are drawn on the bottom rule of the oscillator panel underneath the ring slider. It is cosmetic.
• The product name is provisional.

PSPATTERN is free software under the GNU General Public License version 3. You can use it, study it, change it and pass it on, and anything you pass on has to carry the same freedoms and the source that goes with it.

The complete source lives at github.com/HobbyChop/PSPATTERN, where releases will be published as they are made.

It is derived from LittleGPTracker by Marc Nostromo and contributors, with feature work from the djdiskmachine fork. The original authors are not responsible for this version.

usbmidi.prx is a separate work, the kernel driver for the PSP-MIDI adapter. It is not part of this program and talks to it only through the system call interface. It ships alongside for convenience.

The drum kit and the demo songs are original work and may be redistributed.