HTML 如何使用 mediaDevices 以 mp4 格式保存从网络摄像头录制的视频

Question

我正在使用网络摄像头拍摄视频。下面是我的代码。我可以将视频保存为 mp4 文件，但 none 的视频播放器可以播放它。我不断收到不受支持的文件错误。

这可能是什么问题？

错误截图如下

这是HTML源代码

  <!DOCTYPE html>
  <html lang="en">
  <head>
      <meta charset="UTF-8">
      <title>MediaCapture and Streams API</title>
      <meta name="viewport" content="width=device-width">
      <link rel="stylesheet" href="main.css">
  </head>
  <body>
      <header>
          <h1>MediaCapture, MediaRecorder and Streams API</h1>
      </header>
      <main>
          <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Impedit molestiae itaque facere totam saepe tempore esse temporibus, quae reprehenderit aliquid iusto ea laborum, iure eligendi odio exercitationem sapiente illum quos.</p>

          <p><button id="btnStart">START RECORDING</button><br/>
          <button id="btnStop">STOP RECORDING</button></p>

          <video controls></video>

          <video id="vid2" controls></video>

          <!-- could save to canvas and do image manipulation and saving too -->
      </main>
      <script>

          let constraintObj = {
              audio: false,
              video: {
                  facingMode: "user",
                  width: { min: 640, ideal: 1280, max: 1920 },
                  height: { min: 480, ideal: 720, max: 1080 }
              }
          };
          // width: 1280, height: 720  -- preference only
          // facingMode: {exact: "user"}
          // facingMode: "environment"

          //handle older browsers that might implement getUserMedia in some way
          if (navigator.mediaDevices === undefined) {
              navigator.mediaDevices = {};
              navigator.mediaDevices.getUserMedia = function(constraintObj) {
                  let getUserMedia = navigator.webkitGetUserMedia || navigator.mozGetUserMedia;
                  if (!getUserMedia) {
                      return Promise.reject(new Error('getUserMedia is not implemented in this browser'));
                  }
                  return new Promise(function(resolve, reject) {
                      getUserMedia.call(navigator, constraintObj, resolve, reject);
                  });
              }
          }else{
              navigator.mediaDevices.enumerateDevices()
              .then(devices => {
                  devices.forEach(device=>{
                      console.log(device.kind.toUpperCase(), device.label);
                      //, device.deviceId
                  })
              })
              .catch(err=>{
                  console.log(err.name, err.message);
              })
          }

          navigator.mediaDevices.getUserMedia(constraintObj)
          .then(function(mediaStreamObj) {
              //connect the media stream to the first video element
              let video = document.querySelector('video');
              if ("srcObject" in video) {
                  video.srcObject = mediaStreamObj;
              } else {
                  //old version
                  video.src = window.URL.createObjectURL(mediaStreamObj);
              }

              video.onloadedmetadata = function(ev) {
                  //show in the video element what is being captured by the webcam
                  video.play();
              };

              //add listeners for saving video/audio
              let start = document.getElementById('btnStart');
              let stop = document.getElementById('btnStop');
              let vidSave = document.getElementById('vid2');
              let mediaRecorder = new MediaRecorder(mediaStreamObj);
              let chunks = [];

              start.addEventListener('click', (ev)=>{
                  mediaRecorder.start();
                  console.log(mediaRecorder.state);
              })
              stop.addEventListener('click', (ev)=>{
                  mediaRecorder.stop();
                  console.log(mediaRecorder.state);
              });
              mediaRecorder.ondataavailable = function(ev) {
                  chunks.push(ev.data);
              }
              mediaRecorder.onstop = (ev)=>{
                  let blob = new Blob(chunks, { 'type' : 'video/mp4;' });
                  chunks = [];
                  let videoURL = window.URL.createObjectURL(blob);
                  vidSave.src = videoURL;
              }
          })
          .catch(function(err) {
              console.log(err.name, err.message);
          });

          /*********************************
          getUserMedia returns a Promise
          resolve - returns a MediaStream Object
          reject returns one of the following errors
          AbortError - generic unknown cause
          NotAllowedError (SecurityError) - user rejected permissions
          NotFoundError - missing media track
          NotReadableError - user permissions given but hardware/OS error
          OverconstrainedError - constraint video settings preventing
          TypeError - audio: false, video: false
          *********************************/
      </script>
  </body>
  </html>

Answer 1

您的代码没有任何问题。 QuickTime 播放器实际上不支持该格式。

如果您使用 VLC 或 Chrome/Firefox 浏览器播放该文件，它就可以播放。

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