feat(Soundfont): add SoundfontInstrumentOptions to BasicAudioPlayer (#14) to set font fetching url etc

src/Playback/BasicAudioPlayer.ts

@@ -19,11 +19,14 @@ export class BasicAudioPlayer implements IAudioPlayer<SoundfontPlayer.Player> {
   protected memoryLoadedSoundFonts: Map<MidiInstrument, SoundfontPlayer.Player> = new Map();
   protected channelToSoundFont: Map<number, number> = new Map();
 
+  public SoundfontInstrumentOptions = {}; // e.g. set { from: 'server.com/soundfonts/' } for soundfont fetching url
+
   public async open(uniqueInstruments: number[], numberOfinstruments: number = 16): Promise<void> {
     if (this.piano === undefined) {
       this.piano = await SoundfontPlayer.instrument(
         this.ac as unknown as AudioContext,
-        midiNames[MidiInstrument.Acoustic_Grand_Piano].toLowerCase() as any
+        midiNames[MidiInstrument.Acoustic_Grand_Piano].toLowerCase() as any,
+        this.SoundfontInstrumentOptions
       );
     }
 
@@ -84,7 +87,8 @@ export class BasicAudioPlayer implements IAudioPlayer<SoundfontPlayer.Player> {
 
     const player: SoundfontPlayer.Player = await SoundfontPlayer.instrument(
       this.ac as unknown as AudioContext,
-      midiNames[soundId].toLowerCase() as any
+      midiNames[soundId].toLowerCase() as any,
+      this.SoundfontInstrumentOptions
     );
     this.memoryLoadedSoundFonts.set(soundId, player);
     return player;