Method start

tfjs-data/src/iterators/webcam_iterator.ts:96–146

()

  // Async function to start video stream.
  async start(): Promise<void> {
    if (this.webcamConfig.facingMode) {
      util.assert(
          (this.webcamConfig.facingMode === 'user') ||
              (this.webcamConfig.facingMode === 'environment'),
          () =>
              `Invalid webcam facing mode: ${this.webcamConfig.facingMode}. ` +
              `Please provide 'user' or 'environment'`);
    }

    try {
      this.stream = await navigator.mediaDevices.getUserMedia({
        video: {
          deviceId: this.webcamConfig.deviceId,
          facingMode: this.webcamConfig.facingMode ?
              this.webcamConfig.facingMode :
              'user',
          width: this.webcamVideoElement.width,
          height: this.webcamVideoElement.height
        }
      });
    } catch (e) {
      // Modify the error message but leave the stack trace intact
      e.message = `Error thrown while initializing video stream: ${e.message}`;
      throw e;
    }

    if (!this.stream) {
      throw new Error('Could not obtain video from webcam.');
    }

    // Older browsers may not have srcObject
    try {
      this.webcamVideoElement.srcObject = this.stream;
    } catch (error) {
      console.log(error);
      this.webcamVideoElement.src = window.URL.createObjectURL(
        this.stream as unknown as MediaSource);
    }
    // Start the webcam video stream
    this.webcamVideoElement.play();

    this.isClosed = false;

    return new Promise<void>(resolve => {
      // Add event listener to make sure the webcam has been fully initialized.
      this.webcamVideoElement.onloadedmetadata = () => {
        resolve();
      };
    });
  }

  async next(): Promise<IteratorResult<Tensor3D>> {
    if (this.isClosed) {