Synchronize video and audio (preferably without JavaScript)

后端未结

关注

 2  1606

If I have HTML5 video and audio elements, is there a clean way to keep them in sync? They should act like a video file that contains an audio track

相关标签:

2条回答

逝去的感伤

2020-12-30 17:59
To my knowledge, this is impossible with pure HTML.

You can use the currentTime property of both <video> and <audio> elements to synchronize the time.
```
var video = document.getElementById("your-video");
var audio = document.getElementByid("your-audio");
audio.currentTime = video.currentTime;
```
If necessary, you could also use the timeupdate event to continuously re-sync the video and audio.
0 讨论(0)
发布评论:

提交评论
- 加载中...

忘掉有多难

2020-12-30 18:23

You can use Promise.all(), fetch() to retrieve media resource as a Blob, URL.createObjectURL() to create a Blob URL of resource; canplaythrough event and Array.prototype.every() to check if each resource can play; call .play() on each resource when both resources can play

I didn't make it clear in the question. I meant that the two tracks should stay in sync as though playing a regular video file with audio.

One approach could be to create a timestamp variable, utilize seeked event to update .currentTime of elements when set variable is greater than a minimum delay to prevent .currentTime being called recursively.

<!DOCTYPE html>
<html>
<head>
</head>
<body>
  <button>load media</button>
  <br>
  <div id="loading" style="display:none;">loading media...</div>
  <script>
    var mediaBlobs = [];
    var mediaTypes = [];
    var mediaLoaded = [];
    var button = document.querySelector("button");
    var loading = document.getElementById("loading");
    var curr = void 0;
    var loadMedia = () => {
      loading.style.display = "block";
      button.setAttribute("disabled", "disabled");
      return Promise.all([
        // `RETURN` by smiling cynic are licensed under a Creative Commons Attribution 3.0 Unported License
        fetch("https://ia600305.us.archive.org/30/items/return_201605/return.mp3")
      , fetch("http://nickdesaulniers.github.io/netfix/demo/frag_bunny.mp4")
        ])
        .then(responses => responses.map(media => ({
          [media.headers.get("Content-Type").split("/")[0]]: media.blob()
        })))
        .then(data => {
          for (var currentMedia = 0; currentMedia < data.length; currentMedia++) {
            (function(i) {
              var type = Object.keys(data[i])[0];
              mediaTypes.push(type);
              console.log(data[i]);
              var mediaElement = document.createElement(type);
              mediaElement.id = type;
              var label = document.createElement("label");
              mediaElement.setAttribute("controls", "controls");
              mediaElement.oncanplaythrough = () => {
                mediaLoaded.push(true);
                if (mediaLoaded.length === data.length 
                   && mediaLoaded.every(Boolean)) {
                    loading.style.display = "none";
                    for (var track = 0; track < mediaTypes.length; track++) {
                      document.getElementById(mediaTypes[track]).play();
                      console.log(document.getElementById(mediaTypes[track]));
                    }
                }
              }
              var seek = (e) => {
                if (!curr || new Date().getTime() - curr > 20) {
                  document.getElementById(
                    mediaTypes.filter(id => id !== e.target.id)[0]
                  ).currentTime = e.target.currentTime;
                  curr = new Date().getTime();
                }
              }
              mediaElement.onseeked = seek;
              mediaElement.onended = () => {
                for (var track = 0; track < mediaTypes.length; track++) {
                  document.getElementById(mediaTypes[track]).pause()
                }
              }
              mediaElement.ontimeupdate = (e) => {
                e.target.previousElementSibling
                .innerHTML = `${mediaTypes[i]} currentTime: ${Math.round(e.target.currentTime)}<br>`;
              }
              data[i][type].then(blob => {
                mediaBlobs.push(URL.createObjectURL(blob));
                mediaElement.src = mediaBlobs[mediaBlobs.length - 1];
                document.body.appendChild(mediaElement);
                document.body.insertBefore(label, mediaElement);
              })
            }(currentMedia));
          }
        })
    };
    button.addEventListener("click", loadMedia);
  </script>
</body>
</html>

plnkr http://plnkr.co/edit/r51oh7KsZv8DEYhpRJlL?p=preview

0 讨论(0)