Enables ContextIsolation

ts/WebAudioRecorder.ts

@@ -0,0 +1,161 @@
+// Copyright 2023 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+const DEFAULT_OPTIONS = {
+  bufferSize: undefined, // buffer size (use browser default)
+  encodeAfterRecord: false,
+  mp3: {
+    mimeType: 'audio/mpeg',
+    bitRate: 160, // (CBR only): bit rate = [64 .. 320]
+  },
+  numChannels: 2, // number of channels
+  progressInterval: 1000, // encoding progress report interval (millisec)
+  timeLimit: 300, // recording time limit (sec)
+};
+
+type OptionsType = {
+  bufferSize: number | undefined;
+  numChannels: number;
+  timeLimit?: number;
+};
+
+export class WebAudioRecorder {
+  private buffer: Array<Float32Array>;
+  private options: OptionsType;
+  private context: BaseAudioContext;
+  private input: GainNode;
+  private onComplete: (recorder: WebAudioRecorder, blob: Blob) => unknown;
+  private onError: (recorder: WebAudioRecorder, error: string) => unknown;
+  private processor?: ScriptProcessorNode;
+  public worker?: Worker;
+
+  constructor(
+    sourceNode: GainNode,
+    options: Pick<OptionsType, 'timeLimit'>,
+    callbacks: {
+      onComplete: (recorder: WebAudioRecorder, blob: Blob) => unknown;
+      onError: (recorder: WebAudioRecorder, error: string) => unknown;
+    }
+  ) {
+    this.options = {
+      ...DEFAULT_OPTIONS,
+      ...options,
+    };
+
+    this.context = sourceNode.context;
+    this.input = this.context.createGain();
+    sourceNode.connect(this.input);
+    this.buffer = [];
+    this.initWorker();
+
+    this.onComplete = callbacks.onComplete;
+    this.onError = callbacks.onError;
+  }
+
+  isRecording(): boolean {
+    return this.processor != null;
+  }
+
+  startRecording(): void {
+    if (this.isRecording()) {
+      this.error('startRecording: previous recording is running');
+      return;
+    }
+
+    const { buffer, worker } = this;
+    const { bufferSize, numChannels } = this.options;
+
+    if (!worker) {
+      this.error('startRecording: worker not initialized');
+      return;
+    }
+
+    this.processor = this.context.createScriptProcessor(
+      bufferSize,
+      numChannels,
+      numChannels
+    );
+    this.input.connect(this.processor);
+    this.processor.connect(this.context.destination);
+    this.processor.onaudioprocess = event => {
+      // eslint-disable-next-line no-plusplus
+      for (let ch = 0; ch < numChannels; ++ch) {
+        buffer[ch] = event.inputBuffer.getChannelData(ch);
+      }
+      worker.postMessage({ command: 'record', buffer });
+    };
+    worker.postMessage({
+      command: 'start',
+      bufferSize: this.processor.bufferSize,
+    });
+  }
+
+  cancelRecording(): void {
+    if (!this.isRecording()) {
+      this.error('cancelRecording: no recording is running');
+      return;
+    }
+
+    if (!this.worker || !this.processor) {
+      this.error('startRecording: worker not initialized');
+      return;
+    }
+
+    this.input.disconnect();
+    this.processor.disconnect();
+    delete this.processor;
+    this.worker.postMessage({ command: 'cancel' });
+  }
+
+  finishRecording(): void {
+    if (!this.isRecording()) {
+      this.error('finishRecording: no recording is running');
+      return;
+    }
+
+    if (!this.worker || !this.processor) {
+      this.error('startRecording: worker not initialized');
+      return;
+    }
+
+    this.input.disconnect();
+    this.processor.disconnect();
+    delete this.processor;
+    this.worker.postMessage({ command: 'finish' });
+  }
+
+  private initWorker(): void {
+    if (this.worker != null) {
+      this.worker.terminate();
+    }
+
+    this.worker = new Worker('js/WebAudioRecorderMp3.js');
+    this.worker.onmessage = event => {
+      const { data } = event;
+      switch (data.command) {
+        case 'complete':
+          this.onComplete(this, data.blob);
+          break;
+        case 'error':
+          this.error(data.message);
+          break;
+        default:
+          break;
+      }
+    };
+    this.worker.postMessage({
+      command: 'init',
+      config: {
+        sampleRate: this.context.sampleRate,
+        numChannels: this.options.numChannels,
+      },
+      options: this.options,
+    });
+  }
+
+  error(message: string): void {
+    this.onError(this, `WebAudioRecorder.js: ${message}`);
+  }
+}
+
+window.WebAudioRecorder = WebAudioRecorder;