From c4892410fd355280b2dc5ef78a3040db7c446266 Mon Sep 17 00:00:00 2001 From: freq-mod <32672779+freq-mod@users.noreply.github.com> Date: Mon, 14 Aug 2023 19:19:13 +0200 Subject: [PATCH] opl instr editor --- doc/4-instrument/fmopl.md | 70 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) create mode 100644 doc/4-instrument/fmopl.md diff --git a/doc/4-instrument/fmopl.md b/doc/4-instrument/fmopl.md new file mode 100644 index 000000000..da03ffc7c --- /dev/null +++ b/doc/4-instrument/fmopl.md @@ -0,0 +1,70 @@ +# OPL FM synthesis instrument editor + +The OPL FM editor is divided into 7 tabs: + +- **FM**: for controlling the basic parameters of FM sound source. +- **Macros (FM)**: for macros controlling algorithm and feedback +- **Macros (OP1)**: for macros controlling FM parameters of operator 1 +- **Macros (OP2)**: for macros controlling FM parameters of operator 2 +- **Macros (OP3)**: for macros controlling FM parameters of operator 3 (Warning: only when 4-op flag is set, only on OPL3!) +- **Macros (OP4)**: for macros controlling FM parameters of operator 4 (Warning: only when 4-op flag is set, only on OPL3!) +- **Macros**: for miscellaneous macros controlling volume, arpeggio, and YMF262 panning. + +## FM + +The OPL synthesizers are nominally two-operator (OPL3 supports limited 4-operator mode), meaning it takes two oscillators to produce a single sound. + +These apply to the instrument as a whole: +- **Feedback (FB)**: Determines how many times operator 1 returns its output to itself. (0-7 range) +- **Algorithm (AL)**: Determines how operators are connected to each other. (0-1 range and OPL1 and OPL2, 0-3 range on OPL3 4op mode) + - Left-click pops up a small "operators changes with volume?" dialog where each operator can be toggled to scale with volume level. + - Right-click to switch to a preview display of the waveform generated on a new note: + - Left-click restarts the preview. + - Middle-click pauses and unpauses the preview. + - Right-click returns to algorithm view. + +- **4-op**: Enables 4-operator FM instrument editor mode (ONLY ON OPL3) +- **Drums**: Enables OPL drum mode editor + +These apply to each operator: +- The crossed-arrows button can be dragged to rearrange operators. +- The **OP1**, **OP2**, **OP3**, and **OP4** buttons enable or disable those operators. +- **Amplitude Modulation (AM)**: Makes the operator affected by LFO tremolo. +- **Sustain flag (SUS)**: When enabled, value of Sustain Level is in effect. +- **Attack Rate (AR)**: determines the rising time for the sound. The bigger the value, the faster the attack. (0-15 range) +- **Decay Rate (DR)**: Determines the diminishing time for the sound. The higher the value, the shorter the decay. It's the initial amplitude decay rate. (0-315 range) +- **Sustain Level (SL)**: Determines the point at which the sound ceases to decay and changes to a sound having a constant level. The sustain level is expressed as a fraction of the maximum level. (0-15 range) +- **Release Rate (RR)**: Determines the rate at which the sound disappears after KEY-OFF. The higher the value, the shorter the release. (0-15 range) +- **Total Level (TL)**: Represents the envelope’s highest amplitude, with 0 being the largest and 63 (decimal) the smallest. A change of one unit is about 0.75 dB. + +![FM ADSR chart](FM-ADSRchart.png) + +- **Envelope Scale (KSR)**: Also known as "Key Scale". Determines the degree to which the envelope execution speed increases according to the pitch. +- **Frequency Multiplier (MULT)**: Determines the operator frequency in relation to the pitch. (0-10, 12, 15 range) +- **Waveform select (WS)**: Changes the waveform generated by oscillator (OPL2 and OPL3 only, 0-7 range) +- **Pitch Modulation (VIB)**: Makes the operator affected by LFO vibrato. + +## macros + +Macros define the sequence of values passed to the given parameter. Via macro, along with the previously mentioned parameters, the following can be controlled: + +## FM Macros + +All parameters are listed above. + +## OP1-OP4 Macros + +All parameters are listed above. + +## Macros + +- **Arpeggio**: Pitch change sequence in semitones. +- **Panning**: toggles output on left and right channels. (OPL3 only!) +- **Pitch**: fine pitch. + - **Relative**: pitch changes are relative to the current pitch, not the note's base pitch. +- **Phase Reset**: Restarts all operators and resets the waveform to its start. Effectively the same as a `0Cxx` retrigger. + + +# links + +[FM instrument tutorial](https://www.youtube.com/watch?v=wS8edjurjDw): A great starting point to learn how create and work with FM sounds. This was made for DefleMask, but all the same principles apply.