feat: complete bark battle playable demo

src/games/bark-battle/infrastructure/BrowserMicrophoneInput.ts

@@ -22,3 +22,64 @@ export function isMicrophoneApiSupported(windowLike: { isSecureContext?: boolean
 export function stopMediaStreamTracks(stream: MediaStream) {
   stream.getTracks().forEach((track) => track.stop());
 }
+
+export type BrowserMicrophoneSampler = {
+  stop: () => void;
+};
+
+export type BrowserMicrophoneVolumeHandler = (volume: number, atMs: number) => void;
+
+export async function startBrowserMicrophoneSampler(onVolume: BrowserMicrophoneVolumeHandler): Promise<BrowserMicrophoneSampler> {
+  const supported = isMicrophoneApiSupported(window);
+  if (!supported.ok) {
+    throw Object.assign(new Error(supported.reason), { reason: supported.reason });
+  }
+  try {
+    const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
+    const AudioContextCtor = window.AudioContext || window.webkitAudioContext;
+    if (!AudioContextCtor) {
+      stopMediaStreamTracks(stream);
+      throw Object.assign(new Error('audio-context-blocked'), { reason: 'audio-context-blocked' });
+    }
+    const audioContext = new AudioContextCtor();
+    if (audioContext.state === 'suspended') {
+      await audioContext.resume();
+    }
+    const analyser = audioContext.createAnalyser();
+    analyser.fftSize = 512;
+    const source = audioContext.createMediaStreamSource(stream);
+    source.connect(analyser);
+    const data = new Uint8Array(analyser.fftSize);
+    const sampleStartedAtMs = window.performance.now();
+    let rafId = 0;
+    const sample = () => {
+      analyser.getByteTimeDomainData(data);
+      let sum = 0;
+      for (const value of data) {
+        const centered = (value - 128) / 128;
+        sum += centered * centered;
+      }
+      const volume = Math.min(1, Math.sqrt(sum / data.length) * 3.5);
+      onVolume(volume, window.performance.now() - sampleStartedAtMs);
+      rafId = window.requestAnimationFrame(sample);
+    };
+    sample();
+    return {
+      stop: () => {
+        window.cancelAnimationFrame(rafId);
+        source.disconnect();
+        void audioContext.close();
+        stopMediaStreamTracks(stream);
+      },
+    };
+  } catch (error) {
+    const reason = error && typeof error === 'object' && 'reason' in error ? (error as { reason: MicrophoneFailureReason }).reason : mapGetUserMediaError(error);
+    throw Object.assign(new Error(reason), { reason });
+  }
+}
+
+declare global {
+  interface Window {
+    webkitAudioContext?: typeof AudioContext;
+  }
+}