检测录音中的静音

Question

Java and iOS 也有类似的问题，但我想知道如何通过 getUserMedia() 检测 javascript 中的录音静音。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();
    });
  });

我想知道在 stop 事件的 Blob、URL 或 Audio 对象上是否有任何可以检查的东西没有音频。如果麦克风损坏或选择了虚拟设备 - 任何符合这些要求的东西。我之前检查过 blob 的大小，但无声音频仍然有文件大小。我可以通过 ffmpeg 在后端执行此操作，但希望在纯 JS 中有一种方法可以简化。

Answer 1

使用受 Visualizations with Web Audio API 启发的此解决方案，您可以设置所需的最小分贝并检测是否记录了任何内容。

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 });
    });
  });

检测录音中的静音

Detect silence in audio recording

javascript

audio