检测录音中的静音

Question

Java和iOS也有类似的问题，但我想知道如何通过getUserMedia(). 所以给出：

navigator.mediaDevices.getUserMedia({ audio: true })
  .then(stream => {
    const mediaRecorder = new MediaRecorder(stream);
    mediaRecorder.start();

    const audioChunks = [];
    mediaRecorder.addEventListener("dataavailable", event => {
      audioChunks.push(event.data);
    });

    mediaRecorder.addEventListener("stop", () => {
      const audioBlob = new Blob(audioChunks);
      const audioUrl = URL.createObjectURL(audioBlob);
      const audio = new Audio(audioUrl);
      audio.play();
    });
  });

我想知道如果没有音频，是否可以检查Blob、URL或Audio对象上的任何内容。如果麦克风不好或选择了虚拟设备 - 任何类似的事情。我之前检查了 blob 的大小，但无声音频仍然有文件大小。我可以通过在后端执行此操作，但希望纯 JS 有一种方法可以简化。stopffmpeg

Answer 1

通过此解决方案的灵感来自 Web Audio API 的可视化，您可以设置所需的最小分贝并检测是否录制了任何内容。

const MIN_DECIBELS = -45;

navigator.mediaDevices.getUserMedia({ audio: true })
  .then(stream => {
    const mediaRecorder = new MediaRecorder(stream);
    mediaRecorder.start();

    const audioChunks = [];
    mediaRecorder.addEventListener("dataavailable", event => {
      audioChunks.push(event.data);
    });

    const audioContext = new AudioContext();
    const audioStreamSource = audioContext.createMediaStreamSource(stream);
    const analyser = audioContext.createAnalyser();
    analyser.minDecibels = MIN_DECIBELS;
    audioStreamSource.connect(analyser);

    const bufferLength = analyser.frequencyBinCount;
    const domainData = new Uint8Array(bufferLength);

    let soundDetected = false;

    const detectSound = () => {
      if (soundDetected) {
        return
      }

      analyser.getByteFrequencyData(domainData); 

      for (let i = 0; i < bufferLength; i++) {
        const value = domainData[i];

        if (domainData[i] > 0) {
          soundDetected = true
        }
      }

      window.requestAnimationFrame(detectSound);
    };

    window.requestAnimationFrame(detectSound);

    mediaRecorder.addEventListener("stop", () => {
      const audioBlob = new Blob(audioChunks);
      const audioUrl = URL.createObjectURL(audioBlob);
      const audio = new Audio(audioUrl);
      audio.play();
      
      console.log({ soundDetected });
    });
  });