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Sound Bank

This module handles parsing and writing SoundFont2 (.sf2, .sf3 and .sfogg) files.

It also contains support for .dls files.

Tip

If you encounter any errors in this documentation, please open an issue!

Specifications

Initialization

const soundFont = loadSoundFont(buffer);
  • buffer - An ArrayBuffer representing the binary file data either DLS level 1/2 or SoundFont2.

The returned value is the parsed BasicSoundBank, described below.

Methods

getPreset

Returns the matching Preset class instance.

const preset = soundBank.getPreset(bankNr, presetNr);
  • bankNr - MIDI bank number, typically set with the Bank Select controller.
  • presetNr - MIDI program number, usually set with the Program Change message.

If the matching preset is not found, the first preset will be returned. If the requested bank is 128, the first preset with bank 128 will be returned (drums).

getPresetByName

Returns the matching Preset class instance.

const preset = soundBank.getPresetByName(presetName);
  • presetName - The name of the preset as a string. If not found, the first preset will be returned.

write

Write out an SF2 or SF3 file. The return value is an Uint8Array - the binary of the file.

const binary = await soundBank.write(options);
  • options - An optional object:
    • writeDefaultModulators - a boolean indicating if the DMOD chunk should be written. Defaults to true.
    • writeExtendedLimits - if the xdta chunk should be written to allow virtually infinite parameters. Defaults to true.
    • compress - A boolean indicating if any uncompressed samples should be compressed using the lossy Ogg Vorbis codec. This significantly reduces file size. Defaults to false.
    • decompress - A boolean indicating if any compressed samples should be decompressed. If false, the compressed samples are preserved which results in faster write time and no quality loss. Defaults to false and not recommended.
    • progressFunction - See this for a detailed explanation
    • compressionFunction - See this for a detailed explanation

Important

This function is asynchronous.

Note

If the sound bank was already compressed, it will not be decompressed to avoid losing quality.

Warning

This method is memory and CPU intensive with large sound banks, especially if compression is enabled.

writeDLS

Writes out a DLS Level 2 sound bank. The returned value is an Uint8Array - the binary of the file.

const dls = await soundBank.writeDLS(options);

Caution

This method is experimental and may produce corrupted files. See this for more info.

Important

This method is asynchronous.

Warning

This method is memory and CPU intensive with large sound banks.

mergeSoundfonts

Merges multiple SoundFonts, adding (not replacing) presets on top of the previous ones, and returns a new soundBank.

BasicSoundBank.mergeSoundBanks(soundfont1, soundfont2, soundfont3, /* more here... */);
  • soundfonts - BasicSoundBank instances, with any number of inputs. The first is used as a base, and the rest are added on top.

The return value is a new BasicSoundBank.

The INFO data is taken from the first sound bank

Note

This method is static.

trimSoundBank

Trims the SoundFont in place to only include samples used in the MIDI sequence, down to the exact key-velocity combinations.

soundBank.trimSoundBank(midi);
  • midi - MIDI - The MIDI file for which to trim the soundBank.

getDummySoundfontFile

Creates a fake soundfont with a single saw wave preset. Useful when a synthesizer initialization is needed but the proper soundfont is not ready yet.

const sfBinary = await BasicSoundBank.getDummySoundfontFile();
  • the returned value is an ArrayBuffer - the binary represenation of a soundfont file.

Note

This method is static and asynchronous

Properties

isSF3DecoderReady

A Promise object indicating if the SF3/SF2Pack decoder is ready. Make sure to await it if you are loading SF3/SF2Pack files. It only needs to be awaited once, globally. Then all banks can be loaded synchronously.

Note

this property is static.

presets

An array of all presets in the bank, ordered by bank and preset number.

console.log(soundBank.presets);

instruments

An array of all instruments in the bank, not ordered.

console.log(soundBank.instruments);

samples

An array of all samples in the bank, not ordered.

An array of all instruments in the bank, not ordered.

console.log(soundBank.instruments);

soundFontInfo

Represents the SoundFont2’s INFO chunk data. Stored as an object like this:

const infoData = {
    chunk: /* the read's 4-letter code, e.g. */ "INAM",
    infoText: /* the read's data as text, e.g. */ "My cool SoundFont"
}

Check out this website for more information.

Important

ifil and iver are stored as strings like this: major.minor. For example, major 2 minor 1 will be 2.1

defaultModulators

All the default modulators for this bank. A list of Modulator Objects

customDefaultModulators

A boolean, indicating if the bank uses the DMOD chunk.

Sound bank Internal Structure

The following describes the internal structure of the sound bank and includes some methods not mentioned above. Useful for editing the sound bank.

BasicSoundBank structure

  • soundFontInfo (described above)
  • instruments (BasicInstrument[]) -> All instruments.
    • instrumentName (string) -> The name of the instrument.
      • globalZone (BasicGlobalZone) -> The global zone of this instrument.
      • keyRange ({min: number, max: number}) -> Key range of the zone.
      • velRange ({min: number, max: number}) -> Velocity range of the zone.
      • generators (Generator[]) -> Generators of the zone.
      • modulators (Modulator[]) -> Modulators of the zone.
      • linkedPresets (BasicPreset[]) -> All the presets that are using this instrument. Note that there may be duplicates of the same preset if it uses the sample multiple times.
        • instrumentZones (InstrumentZone[]) -> All zones of the instrument.
        • keyRange ({min: number, max: number}) -> Key range of the zone.
        • velRange ({min: number, max: number}) -> Velocity range of the zone.
        • generators (Generator[]) -> Generators of the zone.
        • modulators (Modulator) -> Modulators of the zone.
        • globalZone (BasicZone) -> The global zone of this instrument.
        • sample (BasicSample) -> The sample of the zone. Undefined if global.
        • See Sample class
  • samples (BasicSample[]) -> All samples.
  • presets (BasicPreset[]) -> All presets.
    • presetName (string) -> The name of the preset.
    • program (number) -> The preset’s MIDI program.
    • bank (number) -> The preset’s MIDI bank.
    • library (number) -> Generally unused but preserved.
    • genre (number) -> Generally unused but preserved.
    • morphology (number) -> Generally unused but preserved.
    • globalZone (BasicGlobalZone) -> The global zone of this preset.
      • keyRange ({min: number, max: number}) -> Key range of the zone.
      • velRange ({min: number, max: number}) -> Velocity range of the zone.
      • generators (Generator[]) -> Generators of the zone.
      • modulators (Modulator[]) -> Modulators of the zone.
    • presetZones (PresetZone[]) -> All zones of the preset.
      • keyRange ({min: number, max: number}) -> Key range of the zone.
      • velRange ({min: number, max: number}) -> Velocity range of the zone.
      • generators (Generator[]) -> Generators of the zone.
      • modulators (Modulator[]) -> Modulators of the zone.
      • instrument (BasicInstrument) -> The zone’s instrument. Undefined if global.

progressFunction

This optional function gets called after every sample has been written. It can be useful for displaying progress for long writing operations.

It takes the following arguments:

  • sampleName - string - sample’s name.
  • writtenCount - number - the count of written samples so far.
  • totalSampleCount - number - the total number of samples.

Please note that it’s usually only effective when writing with compression, as raw writing is inlined for speed.

compressionFunction

This function must be provided if compress is enabled.

The function takes the following arguments:

  • audioData: a Float32Array with the sample data.
  • sampleRate: in Hertz.

The function is recommended to be asynchronous. It must return an Uint8Array instance containing the compressed bitstream.

Note

Note that using a custom function allows for using any type of compression for the SF3 soundBank. This is allowed by the RFC describing SF3 spec, but SpessaSynth can only read Ogg Vorbis compression.

Import your function:

import {encodeVorbis} from './libvorbis/encode_vorbis.js'; // adjust the path if necessary

Then pass it to the write method:

const file = await soundBank.write({
    compress: true,
    compressionFunction: encodeVorbis
});

Why is it not bundled?

Importing it into the package would increase the size with the entire 1.1MB encoder, which would be unnecessary if the functionality is not used. This approach ensures that only software that uses this functionality can rely on this large file.