Converting between various file formats

This guide demonstrates how to convert various file formats using spessasynth_core. Whether you're working with SoundFont files (SF2, SF3), Downloadable Sounds (DLS), or MIDI-related formats (RMI, MIDI), these examples will help you perform conversions.

SF2 To SF3

const sfont = SoundBankLoader.fromArrayBuffer(input);
await sfont.setSampleFormat({
    format: "compressed",
    // Your function that encodes the samples.
    compressionFunction: encodeVorbis
});
const output = sfont.writeSF2();
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SF3 To SF2

const sfont = SoundBankLoader.fromArrayBuffer(input);
await sfont.setSampleFormat({
    format: "pcm"
});
const output = sfont.writeSF2();
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DLS To SF2

const sfont = SoundBankLoader.fromArrayBuffer(input);
const output = sfont.writeSF2();
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SF2 To DLS

Make sure to read about the DLS conversion problem.

const sfont = SoundBankLoader.fromArrayBuffer(input);
const output = sfont.writeDLS();
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RMI To MIDI

const rmid = BasicMIDI.fromArrayBuffer(input);
const output = rmid.writeMIDI();
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RMI To SF2/SF3

const rmid = BasicMIDI.fromArrayBuffer(input);
if (!rmid.embeddedSoundBank) {
    throw new Error("This RMI file does not contain a sound bank!");
}
const sfont = SoundBankLoader.fromArrayBuffer(rmid.embeddedSoundBank);
const output = sfont.writeSF2();
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SF2/DLS + MIDI To RMI

This uses two inputs, input1 for MIDI and input2 for the sound bank.

const mid = BasicMIDI.fromArrayBuffer(input1);
const sfont = SoundBankLoader.fromArrayBuffer(input2);
// Compress this if you want
const sfontBinary = sfont.writeSF2();
const output = mid.writeRMIDI(sfontBinary, {
    soundBank: sfont,
    // Adjust this if necessary
    bankOffset: 0,
    // All the values below are examples, showing how to copy MIDI data to the RMI file
    metadata: {
        name: mid.getName(),
        copyright: mid.getExtraMetadata().join("\n"),
        engineer: sfont.soundBankInfo.engineer
    },
    // Recommended for self-contained files
    correctBankOffset: true
});
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Tracker module (MOD/XM/S3M) To RMI

Tracker modules are loaded as MIDI files with an embedded sound bank.

const mid = BasicMIDI.fromArrayBuffer(input);
const output = mid.writeRMIDI(mid.embeddedSoundBank!, {
    // The presets of the converted sound bank are already in the right banks
    correctBankOffset: false
});
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DLS RMI To SF2 RMI

const dlsRMID = BasicMIDI.fromArrayBuffer(input);
if (!dlsRMID.embeddedSoundBank) {
    throw new Error("This RMI file does not contain a sound bank!");
}
const sfont = SoundBankLoader.fromArrayBuffer(dlsRMID.embeddedSoundBank);
const sfontBinary = sfont.writeSF2();
// The existing RMIDI metadata is kept. Only the provided fields get overwritten
const output = dlsRMID.writeRMIDI(sfontBinary, {
    soundBank: sfont,
    // The bank offset gets detected for DLS RMI files
    bankOffset: dlsRMID.bankOffset,
    metadata: {
        engineer: sfont.soundBankInfo.engineer,
        // Either use the embedded date or today
        creationDate: dlsRMID.getRMIDInfo("creationDate") ?? new Date()
    },
    // Recommended to be disabled for this conversion
    correctBankOffset: false
});
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