wip

app/lib/audio.ts

@@ -0,0 +1,134 @@
+export class AudioHandler {
+  private context: AudioContext;
+  private workletNode: AudioWorkletNode | null = null;
+  private stream: MediaStream | null = null;
+  private source: MediaStreamAudioSourceNode | null = null;
+  private readonly sampleRate = 24000;
+
+  private nextPlayTime: number = 0;
+  private isPlaying: boolean = false;
+  private playbackQueue: AudioBufferSourceNode[] = [];
+
+  constructor() {
+    this.context = new AudioContext({ sampleRate: this.sampleRate });
+  }
+
+  async initialize() {
+    await this.context.audioWorklet.addModule("/audio-processor.js");
+  }
+
+  async startRecording(onChunk: (chunk: Uint8Array) => void) {
+    try {
+      if (!this.workletNode) {
+        await this.initialize();
+      }
+
+      this.stream = await navigator.mediaDevices.getUserMedia({
+        audio: {
+          channelCount: 1,
+          sampleRate: this.sampleRate,
+          echoCancellation: true,
+          noiseSuppression: true,
+        },
+      });
+
+      await this.context.resume();
+      this.source = this.context.createMediaStreamSource(this.stream);
+      this.workletNode = new AudioWorkletNode(
+        this.context,
+        "audio-recorder-processor",
+      );
+
+      this.workletNode.port.onmessage = (event) => {
+        if (event.data.eventType === "audio") {
+          const float32Data = event.data.audioData;
+          const int16Data = new Int16Array(float32Data.length);
+
+          for (let i = 0; i < float32Data.length; i++) {
+            const s = Math.max(-1, Math.min(1, float32Data[i]));
+            int16Data[i] = s < 0 ? s * 0x8000 : s * 0x7fff;
+          }
+
+          const uint8Data = new Uint8Array(int16Data.buffer);
+          onChunk(uint8Data);
+        }
+      };
+
+      this.source.connect(this.workletNode);
+      this.workletNode.connect(this.context.destination);
+
+      this.workletNode.port.postMessage({ command: "START_RECORDING" });
+    } catch (error) {
+      console.error("Error starting recording:", error);
+      throw error;
+    }
+  }
+
+  stopRecording() {
+    if (!this.workletNode || !this.source || !this.stream) {
+      throw new Error("Recording not started");
+    }
+
+    this.workletNode.port.postMessage({ command: "STOP_RECORDING" });
+
+    this.workletNode.disconnect();
+    this.source.disconnect();
+    this.stream.getTracks().forEach((track) => track.stop());
+  }
+  startStreamingPlayback() {
+    this.isPlaying = true;
+    this.nextPlayTime = this.context.currentTime;
+  }
+
+  stopStreamingPlayback() {
+    this.isPlaying = false;
+    this.playbackQueue.forEach((source) => source.stop());
+    this.playbackQueue = [];
+  }
+
+  playChunk(chunk: Uint8Array) {
+    if (!this.isPlaying) return;
+
+    const int16Data = new Int16Array(chunk.buffer);
+
+    const float32Data = new Float32Array(int16Data.length);
+    for (let i = 0; i < int16Data.length; i++) {
+      float32Data[i] = int16Data[i] / (int16Data[i] < 0 ? 0x8000 : 0x7fff);
+    }
+
+    const audioBuffer = this.context.createBuffer(
+      1,
+      float32Data.length,
+      this.sampleRate,
+    );
+    audioBuffer.getChannelData(0).set(float32Data);
+
+    const source = this.context.createBufferSource();
+    source.buffer = audioBuffer;
+    source.connect(this.context.destination);
+
+    const chunkDuration = audioBuffer.length / this.sampleRate;
+
+    source.start(this.nextPlayTime);
+
+    this.playbackQueue.push(source);
+    source.onended = () => {
+      const index = this.playbackQueue.indexOf(source);
+      if (index > -1) {
+        this.playbackQueue.splice(index, 1);
+      }
+    };
+
+    this.nextPlayTime += chunkDuration;
+
+    if (this.nextPlayTime < this.context.currentTime) {
+      this.nextPlayTime = this.context.currentTime;
+    }
+  }
+  async close() {
+    this.workletNode?.disconnect();
+    this.source?.disconnect();
+    this.stream?.getTracks().forEach((track) => track.stop());
+    await this.context.close();
+  }
+}