如何为HTML5音频元素制作加载栏？ [英] How do I make a loading bar for an HTML5 audio element?

问题描述

我正在尝试为HTML5音频元素制作加载栏（显示加载/缓冲的百分比）。

I'm trying to make a loading bar (showing percentage loaded/buffered) for an HTML5 audio element.

对于视频标记，可以使用以下：

For the video tag it's possible to calculate using the following:

video.buffered.end(0) / video.duration

但我无法使用音频标签。它只返回一个修正值。

But I can't get this to work with the audio tag. It just returns a fix value.

任何想法？

谢谢！

推荐答案

在缓冲上调用 end 方法，而不检查是不可靠的。你有可能试图无所事事地调用这个方法。检查这个小提琴：

Calling end method on buffered without checking is unreliable. It's possible you're trying to call the method on nothing. Check this fiddle:

document.querySelector('span').innerHTML = document.querySelector('audio').buffered.length;

<audio src="http://myst729.qiniudn.com/within-temptation_pale.mp3" controls autoplay></audio>
<p>Buffered Length: <span></span></p>

看？在第一个开始时，缓冲长度为0 - 没有加载任何内容。在调用 start 或 end 方法之前，您需要确保缓冲长度不为0.

See? At the very first beginning, buffered length is 0 - nothing has loaded. You need to be sure that buffered length is not 0 before calling start or end method.

每当你读缓冲时，它确实是固定的。因此，要获得视觉上的加载效果，您需要反复阅读它。

Everytime you read buffered, it is fixed indeed. So, to achive a visually "loading" effect, you need to read it again and again and again.

这里我尝试每50毫秒更新一次加载和播放的百分比：

Here I try to update the loaded and played percentage every 50 millisecond:

var audio = document.querySelector('audio');
var percentages = document.querySelectorAll('span');

function loop() {
  var buffered = audio.buffered;
  var loaded;
  var played;

  if (buffered.length) {
    loaded = 100 * buffered.end(0) / audio.duration;
    played = 100 * audio.currentTime / audio.duration;
    percentages[0].innerHTML = loaded.toFixed(2);
    percentages[1].innerHTML = played.toFixed(2);
  }

  setTimeout(loop, 50);
}

loop();

<audio src="http://myst729.qiniudn.com/within-temptation_pale.mp3" controls autoplay></audio>
<p>Loaded: <span></span>%</p>
<p>Played: <span></span>%</p>

注意：您所在的位置可能无法访问MP3文件。如果是这种情况，请尝试另一个对您有利的来源。否则你会听到一个非常好的女声，并且不断看到百分比的变化，最终会达到100％。

NOTE: The MP3 file may not be accessible in your place. If that's the case, just try another source at your favor. Otherwise you will hear a very nice female vocal, and see the percentage changes continously, eventually ends up 100%.

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