javascript - 媒体记录器 : Record from Multiple Microphones

Question

我目前正在使用 MediaRecorder用于在应用程序内录制音频的 API。

有没有办法从多个输入设备(比如两个麦克风)进行录音？

我可以使用 mediaDevices.enumerateDevices() 获取设备列表，如 here 所示.

理想情况下，如果可能的话，我想选择两个或更多的设备进行录制。

这可能吗？

Answer 1

解决方案是请求多个 getUserMedia 并将流与 AudioContext 混合。

这是如何做到这一点。

const VIDEO_ID = "video_id";
const MIC_1_ID = "mic_1_id";
const MIC_2_ID = "mic_2_id";

// Request permission
navigator.mediaDevices.getUserMedia({ video: true, audio: true }).then(() => {
  // Loop over all available video and audio devices (input and output)
  navigator.mediaDevices.enumerateDevices().then((devices) => {
    // Request exact devices
    const requests = [
      navigator.mediaDevices.getUserMedia({
        video: { deviceId: { exact: VIDEO_ID } },
      }),
      navigator.mediaDevices.getUserMedia({
        video: false,
        audio: { deviceId: { exact: MIC_1_ID } },
      }),
      navigator.mediaDevices.getUserMedia({
        video: false,
        audio: { deviceId: { exact: MIC_2_ID } },
      }),
    ];

    // Wait for all device requests to resolve.
    Promise.all(requests).then((streams) => {
      const ctx = new AudioContext();
      const dest = ctx.createMediaStreamDestination();

      // Connect streams to the destination audio stream.
      streams.map((stream) => {
        ctx.createMediaStreamSource(stream).connect(dest);
      });

      const videoTrack = streams[0].getTracks()[0];
      const mixedTracks = dest.stream.getTracks()[0];

      // Combine video and audio tracks into single stream.
      const stream = new MediaStream([videoTrack, mixedTracks]);

      // Start recorder
      const recorder = new MediaRecorder(stream, { mimeType: "video/mp4" });

      // ...
    });
  });
});