import { Button, List, Navigation, NavigationStack, Path, Script, Text, useState } from "scripting"
const folder = Path.join(FileManager.temporaryDirectory, `audio-engine-export-${Date.now()}-${Math.random().toString(16).slice(2)}`)
let created = false
let engine: AVAudioEngine | null = null
let task: AVAudio.ExportTask | null = null
let pending: Promise<void> | null = null
let cancelled = false
let alive = true
const preview = new AVPlayer()
async function cancel() { cancelled = true; await task?.cancel(); await engine?.stop() }
function Demo() {
const dismiss = Navigation.useDismiss()
const [message, setMessage] = useState("Ready · offline rendering requires no microphone")
const [busy, setBusy] = useState(false)
const [resultPath, setResultPath] = useState<string | null>(null)
const report = (text: string) => { if (alive) setMessage(text) }
async function run(keep: boolean) {
if (pending) return
cancelled = false; setBusy(true); setResultPath(null); preview.dispose()
pending = (async () => {
let player: AVAudioPlayerNode | null = null
let reverb: AVAudioUnitReverb | null = null
let buffer: AVAudioPCMBuffer | null = null
try {
if (!created) { await FileManager.createDirectory(folder, true); created = true }
engine = await AVAudioEngine.create()
if (cancelled) return
const format = new AVAudioFormat({ sampleRate: 48000, channelCount: 1 })
player = await AVAudioPlayerNode.create(); reverb = await AVAudioUnitReverb.create()
await engine.attach(player); await engine.attach(reverb)
await reverb.loadFactoryPreset("mediumHall"); await reverb.configure({ wetDryMix: 30 })
await engine.connect(player, reverb, { format })
await engine.connect(reverb, await engine.getMainMixerNode(), { format })
await engine.enableManualRendering({ mode: "offline", format, maximumFrameCount: 1024 })
const samples = new Float32Array(48000)
for (let n = 0; n < samples.length; n++) samples[n] = Math.sin(2 * Math.PI * 440 * n / 48000) * 0.1 * Math.max(0, 1 - n / 24000)
buffer = await AVAudioPCMBuffer.fromChannels([samples], format)
// Reuse one immutable buffer for 30 finite schedules, keeping copies small.
for (let n = 0; n < 30; n++) { if (cancelled) return; await player.scheduleBuffer(buffer) }
if (cancelled) return
await engine.start(); await player.play()
if (cancelled) return
task = await engine.exportAudio({
filePath: Path.join(folder, `render-${Date.now()}.caf`), settings: format.settings,
frameCount: 48000 * 30, tailFrames: 48000 * 2, chunkFrames: 1024,
partialFile: keep ? "keep" : "remove"
})
let done = false
void task.finished.then(() => { done = true }, () => { done = true })
while (!done && !cancelled) {
const progress = await task.getProgress()
report(`Rendered ${progress.renderedFrames} / ${progress.totalFrames} frames\nWritten ${progress.writtenFrames} frames`)
await new Promise<void>(resolve => setTimeout(resolve, 50))
}
const result = await task.finished
if (alive) setResultPath(result.filePath)
report(`Finished: ${result.frameCount} frames\n${result.filePath}`)
} catch (error) {
const failure = error as AVAudio.Error
if (failure.partialFilePath && alive) setResultPath(failure.partialFilePath)
report(`${failure.code ?? "error"}: ${String(error)}${failure.partialFilePath ? `\nPartial file: ${failure.partialFilePath}` : ""}`)
} finally {
await task?.cancel(); task = null
await engine?.stop(); await engine?.dispose(); engine = null
await player?.dispose(); await reverb?.dispose(); await buffer?.dispose()
}
})().finally(() => { pending = null; if (alive) setBusy(false) })
await pending
}
async function playResult() {
try {
if (!resultPath) return
await SharedAudioSession.setCategory("playback", []); await SharedAudioSession.setActive(true)
preview.onReadyToPlay = () => preview.play()
preview.onEnded = () => report("Preview finished")
if (!preview.setSource(resultPath)) throw new Error("Cannot open the exported audio")
} catch (error) { report(String(error)) }
}
return <NavigationStack><List navigationTitle="Offline Export" toolbar={{ cancellationAction: <Button title="Close" action={dismiss} /> }}>
<Text>{message}</Text>
<Button title="Export 30 seconds: remove partial on cancel" action={() => { void run(false) }} disabled={busy} />
<Button title="Export 30 seconds: keep partial on cancel" action={() => { void run(true) }} disabled={busy} />
<Button title="Cancel export" action={() => { void cancel().catch(error => report(String(error))) }} />
<Button title="Play result or partial" action={() => { void playResult() }} disabled={busy || !resultPath} />
<Button title="Pause preview" action={() => preview.pause()} />
</List></NavigationStack>
}
async function main() {
try { await Navigation.present({ element: <Demo /> }) }
finally { try { alive = false; await cancel(); await pending; preview.dispose(); await SharedAudioSession.setActive(false); if (created) await FileManager.remove(folder); } finally { Script.exit() } }
}
void main()
