MIDI Implementation

This describes what messages SpessaSynth can receive.

Here is a useful resource about the MIDI standard. It's in japanese, but all the PDFs are english.

Supported MIDI Messages

Per-note Pitch Wheel

As of 4.1.0 SpessaSynth supports per-note Pitch Wheel as a part of the MIDI 2.0 specification. Note that this is API-only, there are no MIDI messages that allow for changing it for now. The per-note mode will activate on using the API and deactivate on channel or system reset.

Controllers

Default Supported Controllers

Below is the list of controllers supported by default.

Default controller values

Below are all the controller values which are not zero when the controllers are reset.

Parameter Numbers

Supported Registered Parameters

Below is the list of currently implemented Registered Parameters.

Supported Non-Registered Parameters

Below is the list of currently implemented Non-Registered Parameters. Note that all these are non-standard GM. These only apply for GS

rr: Drum note number.

Custom Vibrato

The NPRN vibrato messages have special behavior. On synth start and reset it is disabled. Any value other than 64 received for any of the states activates it with the default settings:

• depth = 50 cents
• rate = 8 Hz
• delay = 0.6s

After which any changes received through the NRPN (including the one that triggered it) are processed.

Calculation for the specific NPRN parameters are as follows (value is the data entry MSB value from 0 to 127):

• Rate: Hz = (value / 64) * 8
• Depth: cents = value / 2
• Delay: seconds = (64 / value) / 3

This behavior has existed since the beginning of this program as a way to enhance Touhou Project MIDI files, the original target of SpessaSynth.

It is disabled for any channel that has CC#1 (Mod Wheel) set to anything other than 0. This can be useful as setting CC#1 to something like 1 (which is usually imperceptible), will disable the extra vibrato for this channel.

Custom vibrato can be disabled globally as well.

SoundFont2 NRPN

As of 3.26.15, spessasynth supports the standard SF2 NRPN implementation, as defined in Section 9.6 of the SoundFont2.04 specification.

AWE32 NRPN Compatibility Layer

As of 3.26.11, spessasynth supports emulation of the AWE32 NRPN generator modification. The implementation is similar to fluidsynth's emulation, as it has been tested and found relatively accurate to the sound cards. Here are some useful resources about this:

• AWE32 Frequently Asked Questions
• AWE32 Developer's Information Pack
• S. Christian Collins's AWE32 MIDI Conversion Repository
• S. Christian Collins's AWE32 NRPN Filter Tests
• Fluidsynth AWE32 NPRN implementation

There are a few differences from fluidsynth's implementation:

• LSB 16 overrides the fineTune generator instead of emitting a pitch-wheel event.
• Effect generators get overridden directly rather than passing through the modulator.
• Filter cutoff and Q have been tuned slightly differently.

System Exclusives

Supported System Exclusives

Below is the list of currently implemented System Exclusive messages.

Supported Bank systems

See the MIDI Patch system for more information.

GM

General MIDI (Level 1).

Ignores all bank select messages.

GS

Roland GS, default.

Bank MSB processed directly, LSB is ignored. SysEx can be used to turn a channel into a drum channel.

GM2

General MIDI Level 2.

Bank LSB and MSB are processed. MSB can be used to turn a channel into a drum channel. Drums will be selected according to the XG Validity Test

XG

Yamaha XG.

Bank LSB and MSB are processed. MSB can be used to turn a channel into a drum channel. Drums will be selected according to the XG Validity Test

GS Parameters

Below are the supported GS SysEx Parameters.

System Parameters

• System Mode Set (SC-88 Reset)

Patch Common Parameters

• Master Tune
• Master Volume
• Master Key-Shift
• Master Pan
• Mode Set (GS Reset)
• Patch Name (logs to console)
• Reverb Macro
• Reverb Character
• Reverb Pre-LPF
• Reverb Level
• Reverb Time
• Reverb Delay Feedback
• Reverb Predelay Time
• Chorus Macro
• Chorus Pre-LPF
• Chorus Level
• Chorus Feedback
• Chorus Delay
• Chorus Rate
• Chorus Depth
• Chorus Send Level To Reverb
• Chorus Send Level To Delay
• Delay Macro
• Delay Pre-LPF
• Delay Time Center
• Delay Ratio Left
• Delay Ratio Right
• Delay Level Center
• Delay Level Left
• Delay Level Right
• Delay Level
• Delay Feedback
• Delay Send Level To Reverb
• EFX Type (see supported EFX)
• EFX Parameter 1-20
• EFX Send Level To Reverb
• EFX Send Level To Chorus
• EFX Send Level To Delay

Patch Part Parameters

• Tone Number (Bank + Program change)
• Rx. Channel
• Mono/Poly Mode
• Use for Rhythm Part
• Pitch Key Shift
• Part Level
• Part Pan Position
• CC1 Controller Number
• CC2 Controller Number
• Chorus Send Level
• Reverb Send Level
• Pitch Fine Tune
• Delay Send Level
• Vibrato Rate
• Vibrato Depth
• TVF Cutoff
• TVF Resonance
• TVA Attack Time
• TVA Decay Time
• TVA Release Time
• Vibrato Delay
• Scale Tuning
• Tone Map Number (Bank LSB)
• Tone Map-0 Number (treated as Bank LSB)
• Part EFX Assign

Patch Part Parameters (Controllers)

All of them except for LFO rate as it's in Hz rather than cents.

These define how a controller affects the sound. See page 198 of the SC-88Pro Manual. This is implemented using a dynamic modulator system.

Drum Setup Parameters

• Drum Map Name (logs to console)
• Pitch Coarse
• Level
• Assign Group Number (exclusive class override)
• Pan Position
• Reverb Send Level
• Chorus Send Level
• Rx. Note Off (implemented as forcing instant release)
• Rx. Note On
• Delay Send Level

XG Part Setup

Below are the supported part setup messages for XG.

XG Drum Setup

The following drum setup messages are recognized:

• Pitch Coarse
• Pitch Fine (added to coarse so coarse must be sent first)
• Alternate Group (exclusive class override)
• Pan
• Reverb Send
• Chorus Send
• Rev. Note Off (implemented as forcing instant release)
• Rev. Note On

MIDI Tuning Standard

Below are the supported messages for the MTS. RT means realtime and NRT means non-realtime (both are treated as realtime).

Portamento Implementation

SpessaSynth attempts to recreate the old Sound Canvas/Yamaha XG portamento behavior.

That is:

• Portamento Time is only 7-bit. (only CC#5 is processed)
• Portamento Control gets overridden with the last portamento key.
• For XG, the initial key to glide from is 60, for other systems there's no initial glide.
• Portamento Time depends on the distance of the keys. The final calculation is portamentoSeconds = portaTimeToRate(cc5) * keyDistance
• The details of the portaTimeToRate function can be found here.
• If you know a more accurate algorithm, please let me know!
• Portamento is experimental, although I found it to be accurate to the S-YXG50 and Sound Canvas VA VSTi instruments.

Effects

SpessaSynth's effects are modeled after the Sound Canvas line. There are currently 3 effect processors, below are their built-in implementations.

Reverb

Characters 0-5 use the Dattorro reverb model, based on this processor. Each of the characters has parameters tuned to match the SC-55 effects more closely. The built-in pre-lowpass filter is used for the pre-LPF param.

Character 6 uses a single delay line while character 7 uses a ping-pong delay. A simple 1st order lowpass filter is used for the pre-LPF param.

Chorus

Implemented using 2 delay lines modulated by triangle LFOs. A simple 1st order lowpass filter is used for the pre-LPF param.

Delay

Implemented using 3 delay lines, with the central one having feedback and feeding into the stereo delays. Input is fed to all three.

Disabled in XG mode as CC#94 (used as delay send level) is used for Variation which is not implemented.

Insertion Effects

Spessasynth has an architecture to support SC-88Pro+ insertion effects.

Currently implemented insertion effects

• Stereo-EQ
• Phaser
• Auto Pan
• Auto Wah
• Tremolo
• PH / Auto Wah