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70 lines
4 KiB
Markdown
70 lines
4 KiB
Markdown
# OPL FM synthesis instrument editor
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The OPL FM editor is divided into 7 tabs:
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- **FM**: for controlling the basic parameters of FM sound source.
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- **Macros (FM)**: for macros controlling algorithm and feedback
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- **Macros (OP1)**: for macros controlling FM parameters of operator 1
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- **Macros (OP2)**: for macros controlling FM parameters of operator 2
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- **Macros (OP3)**: for macros controlling FM parameters of operator 3 (Warning: only when 4-op flag is set, only on OPL3!)
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- **Macros (OP4)**: for macros controlling FM parameters of operator 4 (Warning: only when 4-op flag is set, only on OPL3!)
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- **Macros**: for miscellaneous macros controlling volume, arpeggio, and YMF262 panning.
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## FM
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The OPL synthesizers are nominally two-operator (OPL3 supports limited 4-operator mode), meaning it takes two oscillators to produce a single sound.
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These apply to the instrument as a whole:
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- **Feedback (FB)**: Determines how many times operator 1 returns its output to itself. (0-7 range)
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- **Algorithm (AL)**: Determines how operators are connected to each other. (0-1 range and OPL1 and OPL2, 0-3 range on OPL3 4op mode)
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- Left-click pops up a small "operators changes with volume?" dialog where each operator can be toggled to scale with volume level.
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- Right-click to switch to a preview display of the waveform generated on a new note:
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- Left-click restarts the preview.
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- Middle-click pauses and unpauses the preview.
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- Right-click returns to algorithm view.
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- **4-op**: Enables 4-operator FM instrument editor mode (ONLY ON OPL3)
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- **Drums**: Enables OPL drum mode editor
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These apply to each operator:
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- The crossed-arrows button can be dragged to rearrange operators.
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- The **OP1**, **OP2**, **OP3**, and **OP4** buttons enable or disable those operators.
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- **Amplitude Modulation (AM)**: Makes the operator affected by LFO tremolo.
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- **Sustain flag (SUS)**: When enabled, value of Sustain Level is in effect.
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- **Attack Rate (AR)**: determines the rising time for the sound. The bigger the value, the faster the attack. (0-15 range)
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- **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)
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- **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)
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- **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)
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- **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.
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- **Envelope Scale (KSR)**: Also known as "Key Scale". Determines the degree to which the envelope execution speed increases according to the pitch.
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- **Frequency Multiplier (MULT)**: Determines the operator frequency in relation to the pitch. (0-10, 12, 15 range)
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- **Waveform select (WS)**: Changes the waveform generated by oscillator (OPL2 and OPL3 only, 0-7 range)
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- **Pitch Modulation (VIB)**: Makes the operator affected by LFO vibrato.
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## macros
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Macros define the sequence of values passed to the given parameter. Via macro, along with the previously mentioned parameters, the following can be controlled:
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## FM Macros
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All parameters are listed above.
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## OP1-OP4 Macros
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All parameters are listed above.
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## Macros
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- **Arpeggio**: Pitch change sequence in semitones.
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- **Panning**: toggles output on left and right channels. (OPL3 only!)
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- **Pitch**: fine pitch.
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- **Relative**: pitch changes are relative to the current pitch, not the note's base pitch.
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- **Phase Reset**: Restarts all operators and resets the waveform to its start. Effectively the same as a `0Cxx` retrigger.
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# links
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[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.
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