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HTML Audio/视频 DOM playbackRate 属性

HTMLMediaElement.playbackRate 属性设置媒体文件播放时的速率。这用于实现让用户控制快放、慢放等。正常播放速率乘以该值表示当前的播放速率，所以1.0表示一个正常的播放速率。将 playbackRate 设为负值可以实现倒播。媒体文件倒着播放时，或者播放速率低于或高于浏览器内核规定的可用范围（比如，Gecko约定范围是0.25～5.0）时，播放过程将静音。任意播放速率下，音频的音调将默认与其匹配。一些浏览器实现了非标准的 preservespitch 属性来进行音调控制。

　HTML Audio/Video DOM Reference Manual

在线示例

将视频设置为慢速播放：

示例

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>HTML 音频/视频 playbackRate 属性使用-基础教程(oldtoolbag.com)</title>
</head>
<body>
<button onclick="getPlaySpeed()" type="button">回放的速度是多少？</button>
<button onclick="setPlaySpeed()" type="button">视频设置为慢速播放</button>
<br>　
<video id="video1" controls="controls">
　　<source src="movie.mp4" type="video/mp4">
　　<source src="movie.ogg" type="video/ogg">
　　您的浏览器不支持	HTML5　video		标签。
</video>
<script>
myVid=document.getElementById("video1");
function getPlaySpeed()
{　
　　alert(myVid.playbackRate);
}　
function setPlaySpeed()
{　
　　myVid.playbackRate=0.5;
}　
</script>　
</body>
</html>

Test and see ‹/›

Definition and usage

playbackRate attribute sets or returns audio/Current playback speed of the video.

Browser compatibility

IEFirefoxOperaChromeSafari

All major browsers support the playbackRate attribute.

Note:Internet Explorer 9 Versions prior to and including do not support the playbackRate attribute.

Syntax

Set playbackRate attribute:

audio|video.playbackRate=playbackspeed

Return playbackRate attribute:

audio|video.playbackRate

Attribute value

Value	Description
playbackspeed	Indicate audio/Current playback speed of the video. Example value: 1.0 Normal speed 0.5 Half speed (slower) 2.0 Speed up (faster) -1.0 Backward, normal speed -0.5 Backward, half speed

Technical details

Return value:	Numeric value, current playback speed
Default value:	1.0

　HTML Audio/Video DOM Reference Manual

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