Synthesizer class

class Synthesizer

Represents a MIDI synthesizer.

A SoundFont file must be loaded into the synthesizer before any synthesis can happen.

The synthesizer can be controlled either via MIDI messages, or directly by calling dedicated methods.

Construction / Destruction

Synthesizer(const SynthesizerSettings &settings)

Constructor.

Parameters:

settings – The settings of the synthetiser

~Synthesizer()

Destructor.

SoundFont file loading methods

bool loadSoundFont(const std::filesystem::path &path)

Load a SoundFont file.

Parameters:

path – Path to the SoundFont file

Returns:

True if the file was loaded successfully, false otherwise

bool loadSoundFont(const char *buffer, size_t size)

Load a SoundFont file from a buffer.

Parameters:

  • buffer – The buffer

  • size – Size of the buffer

Returns:

True if the file was loaded successfully, false otherwise

inline const sf::SoundFont &soundfont() const

Returns the loaded SoundFont file representation.

MIDI & notes

bool processMidiMessage(uint8_t channel, uint8_t command, uint8_t data1, uint8_t data2)

Process a MIDI message.

Parameters:

  • channel – The channel affected by the message

  • command – The command to process

  • data1 – Data associated to the command

  • data2 – Secondary data associated to the command

void noteOn(uint8_t channel, uint8_t key, uint8_t velocity)

Start to press a key.

The key will be pressed until noteOff() is called.

Parameters:

  • channel – The channel

  • key – The key to press

  • velocity – The velocity of the key press

void noteOff(uint8_t channel, uint8_t key)

Release a key.

It is expected that noteOn() has been called on that channel with that key before.

When a key is released, its sound gradually falls off.

Parameters:

  • channel – The channel

  • key – The key to release

void allNotesOff(bool immediate)

Release all the keys.

Parameters:

immediate – If false, the sound of the notes gradually falls off like with noteOff().

void allNotesOff(uint8_t channel, bool immediate)

Release all the keys of a specific channel.

Parameters:

  • channel – The channel

  • immediate – If false, the sound of the notes gradually falls off like with noteOff().

void resetAllControllers()

Reset the value of all the MIDI controllers.

void resetControllers(uint8_t channel)

Reset the value of all the MIDI controllers of a specific channel.

Parameters:

channel – The channel

Audio synthesis

void render(float *left, float *right, size_t size)

Render the audio into stereo buffers (left and right)

It is expected that this method is called with buffers of appropriate size each time a MIDI message is processed by processMidiMessage() or each time a key (or a group of keys) is pressed or released.

Parameters:

  • left – The left buffer (will be filled)

  • right – The right buffer (will be filled)

  • size – Size of the buffers

void render(float *buffer, size_t size)

Render the audio into a mono buffer.

It is expected that this method is called with a buffer of appropriate size each time a MIDI message is processed by processMidiMessage() or each time a key (or a group of keys) is pressed or released.

Parameters:

  • buffer – The buffer (will be filled)

  • size – Size of the buffer

void setMasterVolume(float volume)

Sets the master volume, in dB.

float masterVolume() const

Returns the master volume, in dB.

inline uint32_t nbRenderedSamples() const

Returns the number of samples rendered so far.

uint16_t nbActiveVoices() const

Returns the number of active voices.

Channels

inline size_t nbChannels() const

Returns the number of channels.

bool configureChannel(uint8_t channel, uint8_t bank, uint8_t preset)

Assign a preset from the SoundFont file to a channel.

Parameters:

  • channel – The number of the channel

  • bank – The bank of the preset

  • preset – The number of the preset

inline bool configureChannel(uint8_t channel, sf::preset_id_t id)

Assign a preset from the SoundFont file to a channel.

Parameters:

  • channel – The number of the channel

  • id – The id of the preset

std::map<sf::preset_id_t, std::string> presetNames()

Retrieves a list of the names of all the presets in thr SoundFont file.

inline Channel &getChannel(uint8_t channel)

Returns a channel.

Parameters:

channel – The number of the channel

inline const Channel &getChannel(uint8_t channel) const

Returns a channel.

Parameters:

channel – The number of the channel

Other methods

inline const SynthesizerSettings &settings() const

Returns the settings of the synthesizer.

void reset()

Reset the synthesizer (like if no rendering happened, no key was pressed)