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. 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.

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

Roland GS

Below are the supported Roland GS messages.

System Parameters, Patch Common Parameters

These are global parameters, affecting the entire synthesizer.

System Mode Set (SC-88+ Reset)

Treated like a GS reset.

Master Tune

Precise synth tuning in cents.

Master Volume

Master gain of the synthesizer, treated like GM volume message.

Master Key-Shift

Master transposition of the synthesizer.

Master Pan

Master stereo pan position of the synthesizer.

Mode Set

Resets the synthesizer and switches it to GS mode. (GS reset)

Patch Name

Treated as recognized, decide name is logged to console if output is enabled.

Reverb Parameters

• Macro (all GS macros are supported)
• Character
• Pre-LPF
• Level
• Time
• Delay Feedback
• Predelay Time

These are forwarded to the reverb processor.

Chorus Parameters

• Macro (all GS macros are supported)
• Pre-LPF
• Level
• Feedback
• Delay
• Rate
• Depth
• Send Level To Reverb
• Send Level To Delay

These are forwarded to the chorus processor.

Delay Parameters

• Macro (all GS macros are supported)
• Pre-LPF
• Time Center
• Ratio Left
• Ratio Right
• Level Center
• Level Left
• Level Right
• Level
• Feedback
• Send Level To Reverb

These are forwarded to the delay processor.

EFX Parameters

EFX means Insertion Effect. Both are used interchangeably.

• EFX Type
• EFX parameters 1-20
• Send Level To Reverb
• Send Level To Chorus
• Send Level To Delay

These are forwarded to the insertion processor. See supported insertion effects

Patch Part Parameters

Part (channel) specific parameters.

Tone Number

Bank MSB + Program change in one message.

Rx. Channel

Channel number receive. This allows to combine two instruments on "one" channel.

Mono/Poly Mode

Switches between poly and mono modes. See implementation details.

Assign mode

ASSIGN MODE is the parameter that determines how voice assignment will be handled when sounds overlap on identical note numbers in the same channel (i.e., repeatedly struck notes). This is initialized to a mode suitable for each Part, so for general purposes there is no need to change this. Modes:

• Single: If the same note is played multiple times in succession, the previously-sounding note will be completely silenced, and then the new note will be sounded.
• LimitedMulti: If the same note is played multiple times in succession, the previously-sounding note will be continued to a certain extent even after the new note is sounded. (Default setting)
• FullMulti: If the same note is played multiple times in succession, the previously-sounding note(s) will continue sounding for their natural length even after the new note is sounded.

Note that spessasynth treats LimitedMulti like FullMulti.

Use for Rhythm Part

This message allows to turn any channel into a drum channel. Unlike with sound canvases, there's no limit to drum channels the synthesizer can have. The map number is stored in the channel for drum tuning.

Pitch Key Shift

Channel transposition in semitones (the MIDI notes are shifted)

MIDI Controller aliases

These system exclusives are equivalent to the following MIDI controllers

• Part Level = CC#7.
• Part Pan Position = CC#10, except for -64 which enables random panning for every note.
• Chorus Send Level = CC#93
• Reverb Send Level = CC#91
• Delay Send Level = CC#94
• Vibrato Rate = CC#76
• Vibrato Depth = CC#77
• Vibrato Delay = CC#78
• TVF Cutoff = CC#74
• TVF Resonance = CC#71
• TVA Attack Time = CC#73
• TVA Decay Time = CC#75
• TVA Release Time = CC#72

CC1, CC2 Controller Number

These two controllers can be bound in the controller matrix to control a specific voice parameter.

Pitch Fine Tune

Same as the Fine-Tuning RPN, in cents.

Scale Tuning

Treated like MTS octave tuning, allows to tune an octave in cents. Tuning is repeated for all octaves.

Tone Map Number, Tone Map-0 Number

Treated as Bank LSB controller change.

Part EFX Assign

Defines if the channel should use the insertion effect or not. If it does, all of its audio gets routed through the insertion effect and therefore all effect sends have no effect on it, as these are determined by the insertion processor, which receives dry voice data.

Patch Part Parameters (Controllers)

All of them are supported! At least, in theory. These define how a controller affects the sound. See page 198 of the SC-88Pro Manual. This is implemented using a dynamic modulator system and additional generators to cover the linear time and hertz range.

Drum Setup Parameters

The following messages allow to tune drum instruments. A drum instrument is defined as a single MIDI key in the drum preset. These search for a matching drum channel with the correct MAP number set.

Drum Map Name

The name is recognized and logged to console.

Pitch Coarse

Relative pitch tuning of the instrument Precision depends on the mode:

• Bank LSB value of 1 indicates an SC-55 preset, the resolution is 100 cents, i.e. a semitone
• Any other value is treated as SC-88 or higher, where the resolution (for whatever reason) is 50 cents.

Level

The drum's loudness. These are normalized against 120 (gain = data / 120).

Assign Group Number

This overrides the exclusiveClass generator, allowing to define custom exclusive notes.

MIDI controllers

Like a regular aliases, except for a specific drum instrument and not the whole channel.

• Pan Position = CC#10, except for -64 which enables random panning for every note.
• Chorus Send Level = CC#93
• Reverb Send Level = CC#91
• Delay Send Level = CC#94

Rx. Note Off

Enabling this (as it is disabled by default) forces the drum instrument to immediately terminate when it receives a Note Off.

Rx. Note On

This allows to disable a specific drum instrument from receiving Note On events.

Yamaha XG

Below are the supported Yamaha XG system exclusive messages.

System parameters

These are global parameters, affecting the entire synthesizer.

Master Tune

14-bit value from MIDI nibbles, centered on 1024. In 1/10th of a cent.

Master Volume

Master output gain, same role as the GM MIDI Master Volume system exclusive (normalized from 0 to 127).

Master Attenuation

Output attenuation; higher values mean quieter output (implemented as master volume from 127 − data).

Master Transpose

Master transposition in semitones, 64 means no shift.

XG Reset

Performs an XG reset and switch the synth into XG mode. The XG mode disables the delay effect.

Reverb, chorus, and variation block

Reverb, chorus, and variation parameter addresses are not supported (yet). They are recognized only for logging; parameters are not applied to the effect engines.

XG Part Setup

Part (channel) parameters set a specific parameter for a specific channel.

XG Drum Setup

The following messages allow to tune drum instruments. A drum instrument is defined as a single MIDI key in the drum preset.

Edits are applied to every drum channel: for each note/key, all drum channels get the same stored parameters, as there isn't a MAP system, like in GS.

Pitch coarse

Relative pitch in cents: (data − 64) * 100, matching XG coarse drum pitch resolution (see also Drum Pitch NRPN).

Pitch fine

Cent tuning for the drum instrument. Send coarse tuning before fine if you rely on a defined baseline; fine is cumulative.

Drum level

Normalizes loudness as gain = data / 120 (same scaling as GS drum level).

Alternate group

Overrides the exclusiveClass generator for that drum instrument.

MIDI controllers

Like regular controllers, except for a specific drum instrument and not the whole channel.

• Pan Position = CC#10, except for -64 which enables random panning for every note.
• Chorus Send Level = CC#93
• Reverb Send Level = CC#91
• Delay Send Level = CC#94

Receive note off

Enabling this (as it is disabled by default) forces the drum instrument to immediately terminate when it receives a Note Off.

Receive note on

This allows to disable a specific drum instrument from receiving Note On events.

MIDI Tuning Standard

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

Poly/Mono implementation

SpessaSynth's poly/mono mode implementation works like GS implementation:

• Poly mode - regular playback, multiple notes are allowed on the channel
• Mono mode - any note on message will immediately force all current voices on this channel to shut down.

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