HTML5 Video - File Loading Complete Event?

I need to detect when a video file has completed loading. I'm thinking I should use progress->buffer, but in the back of my mind, I remember reading that this was unreliable. Is there a better way, or is this safe?

Note, I will be keeping a localStorage cache of videos that have been completely downloaded by each user, so I'll know in advance if a video has already loaded, and could probably bypass progress->buffer if that's a sticking point.

Thanks in advance.

标签： javascript html5 video buffer preload

3条回答

萌系小妹纸

2楼-- · 2019-01-31 14:39

Here's a fleshed out implementation with Google's MDC-Web's mdc-linear-progress UI component.

var doc = document;
var bufferLengthDetector;
var linearProgress;
var mdc = window.mdc;
mdc.autoInit();
var video = doc.querySelector('video');

if(doc.getElementById("footer-progress")){
    linearProgress = mdc.linearProgress.MDCLinearProgress.attachTo(doc.getElementById("footer-progress"));
}

if(video){
    
    video.addEventListener('timeupdate', function() {
        var percent = Math.floor((100 / video.duration) * video.currentTime);
        linearProgress.progress = percent/100;
    }, false);
    
    video.addEventListener('progress', function() {
        var duration = video.duration;
        if (duration > 0) {
            bufferLengthDetector = setInterval(readBuffer, 500);
        }
    });
}

function readBuffer(){
    var percent = video.buffered.end(video.buffered.length - 1) / video.duration;
    if (percent >= .9) {
        linearProgress.buffer = 1;
        clearInterval(bufferLengthDetector);
    }
    else {
        linearProgress.buffer = percent;
    }
}

html {
    height:100%;
}
body{
    margin: 0;
}

#footer-progress{
    position: fixed;
    bottom: 0;
    width: 100%;
    visibility: visible;
    opacity: 1;    
}

video {
    position: fixed;
    top: 50%;
    left: 50%;
    min-width: 100%;
    min-height: 100%;
    width: auto;
    height: auto;
    z-index: -100;
    transform: translateX(-50%) translateY(-50%);
    background: #212121;
    background-size: cover;
    transition: visibility 1s, opacity 1s linear;
    visibility: visible;
    opacity: 1;
}

<head>
<link rel="stylesheet" href="https://unpkg.com/material-components-web@latest/dist/material-components-web.min.css">
<script src="https://unpkg.com/material-components-web@latest/dist/material-components-web.min.js"></script>
</head>

<body>

    <video class="bg-video" playsinline autoplay>
        <source src="//rack.pub/media/do-not.webm" type="video/webm">
        <source src="//rack.pub/media/do-not.mp4" type="video/mp4">            
        I'm sorry your browser doesn't support HTML5 video in WebM with VP8/VP9 or MP4 with H.264.
    </video>
    
    <div role="progressbar" class="mdc-linear-progress" data-buffer="true" id="footer-progress">
        <div class="mdc-linear-progress__buffering-dots"></div>
        <div class="mdc-linear-progress__buffer"></div>
        <div class="mdc-linear-progress__bar mdc-linear-progress__primary-bar">
            <span class="mdc-linear-progress__bar-inner"></span>
        </div>
        <div class="mdc-linear-progress__bar mdc-linear-progress__secondary-bar">
            <span class="mdc-linear-progress__bar-inner"></span>
        </div>
    </div>  

</body>

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甜甜的少女心

3楼-- · 2019-01-31 14:40

You can bind the "buffered" event, but (in Chrome at least) this works fine except that it doesn't call the last "buffered" event (i.e. it will detect 90%...94%...98%... but won't call on 100%).

Note: recent versions of jQuery should use .prop() instead of .attr()

To get around this I've used setInterval() to check the buffer every 500ms (where $html5Video is your <video> element:

var videoDuration = $html5Video.attr('duration');

var updateProgressBar = function(){
    if ($html5Video.attr('readyState')) {
        var buffered = $html5Video.attr("buffered").end(0);
        var percent = 100 * buffered / videoDuration;

        //Your code here

        //If finished buffering buffering quit calling it
        if (buffered >= videoDuration) {
                clearInterval(this.watchBuffer);
        }
    }
};
var watchBuffer = setInterval(updateProgressBar, 500);

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走好不送

4楼-- · 2019-01-31 14:40

I've had the same problem and use a timer attached to the progress event. It's a hack but I haven't seen any other ways of doing this. (I've tested this on Chome 10 - Windows).

var video = document.getElementById('#example-video-element');
var timer = 0;
video.addEventListener('progress', function (e) {
    if (this.buffered.length > 0) {

        if (timer != 0) {
            clearTimeout(timer);
        }

        timer = setTimeout(function () {            
            if(parseInt(video.buffered.end() / video.duration * 100) == 100) {
                // video has loaded.... 
            };          
        }, 1500);

    }
}, false);

This looks like the type of approach you were thinking of taking, but figured I would post an example for those anonymous users who might be looking for a quick code sample =p
GJ

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HTML5 Video - File Loading Complete Event?

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