Function exportAudio

packages/playground/src/components/AudioExporter.ts:33–103

(api: alphaTab.AlphaTabApi, trackItems: readonly TrackItem[] = [])

}

export async function exportAudio(api: alphaTab.AlphaTabApi, trackItems: readonly TrackItem[] = []): Promise<void> {
    if (!api.score) {
        return;
    }
    const options = new alphaTab.synth.AudioExportOptions();
    options.sampleRate = 44100;
    options.masterVolume = api.masterVolume;
    options.metronomeVolume = api.metronomeVolume;
    if (api.playbackRange) {
        options.playbackRange = api.playbackRange;
    }

    const soloed = new Set<number>();
    for (const item of trackItems) {
        const idx = item.track.index;
        const ratio = item.getVolume() / Math.max(1, item.track.playbackInfo.volume);
        options.trackVolume.set(idx, item.isMuted() ? 0 : ratio);
        if (item.isSoloed()) {
            soloed.add(idx);
        }
    }
    if (soloed.size > 0) {
        for (const t of api.score.tracks) {
            if (!soloed.has(t.index)) {
                options.trackVolume.set(t.index, 0);
            }
        }
    }

    options.soundFonts = [await fetchSoundFont(Paths.soundFont)];

    const exporter = await api.exportAudio(options);
    let generated: Float32Array | undefined;
    let totalSamples = 0;
    try {
        while (true) {
            const chunk = await exporter.render(500);
            if (!chunk) {
                break;
            }
            if (!generated) {
                generated = new Float32Array(options.sampleRate * (chunk.endTime / 1000) * 2);
            }
            const needed = totalSamples + chunk.samples.length;
            if (generated.length < needed) {
                const grown = new Float32Array(needed);
                grown.set(generated, 0);
                generated = grown;
            }
            generated.set(chunk.samples, totalSamples);
            totalSamples += chunk.samples.length;
        }
    } finally {
        exporter.destroy();
    }

    if (!generated) {
        return;