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• 句法
• 用法注意事项
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

enabled property on the MediaStreamTrack interface is a Boolean value which is true if the track is allowed to render the source stream or false if it is not. This can be used to intentionally mute a track. When enabled, a track's data is output from the source to the destination; otherwise, empty frames are output.

In the case of audio, a disabled track generates frames of silence (that is, frames in which every sample's value is 0). For video tracks, every frame is filled entirely with black pixels.

值 enabled , in essence, represents what a typical user would consider the muting state for a track, whereas the muted property indicates a state in which the track is temporarily unable to output data, such as a scenario in which frames have been lost in transit.

注意： If the track has been disconnected, the value of this property can be changed, but has no effect.

句法

const enabledFlag = track.enabled
track.enabled = [true | false]
					

值

当 true , enabled indicates that the track is permitted to render its actual media to the output. When enabled 被设为 false , the track only generates empty frames.

Empty audio frames have every sample's value set to 0. Empty video frames have every pixel set to black.

注意： When implementing a mute/unmute feature, you should use the enabled 特性。

用法注意事项

若 MediaStreamTrack represents the video input from a camera, disabling the track by setting enabled to false also updates device activity indicators to show that the camera is not currently recording or streaming. For example, the green "in use" light next to the camera in iMac and MacBook computers turns off while the track is muted in this way.

范例

This example demonstrates a click event handler for a pause button.

pauseButton.onclick = function(evt) {
  const newState = !myAudioTrack.enabled;
  pauseButton.innerHTML = newState ? "▶️" : "⏸️";
  myAudioTrack.enabled = newState;
}
					

This creates a variable, newState , which is the opposite of the current value of enabled , then uses that to select either the Emoji character for the "play" icon or the character for the "pause" icon as the new innerHTML of the pause button's element.

Finally, the new value of enabled is saved, making the change take effect.

规范

规范	状态	注释
媒体捕获和流 The definition of 'enabled' in that specification.	候选推荐	最初的规范。

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
enabled	Chrome Yes	Edge 12	Firefox 24	IE No	Opera Yes	Safari Yes	WebView Android Yes	Chrome Android Yes	Firefox Android 24	Opera Android Yes	Safari iOS Yes	Samsung Internet Android Yes

图例

完整支持

完整支持

不支持

不支持

另请参阅

• MediaStream API
• MediaStream
• MediaStreamTrack
• WebRTC

元数据

• 最后修改： Feb 22, 2020

相关话题

1. Media Streams API
2. MediaStreamTrack
3. 特性

   1. enabled
   2. id
   3. kind
   4. label
   5. muted
   6. onended
   7. onmute
   8. onoverconstrained
   9. onunmute
   10. readyState
   11. remote
4. 方法

   1. applyConstraints()
   2. clone()
   3. getCapabilities()
   4. getConstraints()
   5. getSettings()
   6. stop()
5. 事件

   1. ended
   2. mute
   3. unmute
6. Related pages for Media Capture and Streams

   1. AudioStreamTrack
   2. BlobEvent
   3. CanvasCaptureMediaStream
   4. ConstrainBoolean
   5. ConstrainDOMString
   6. ConstrainDouble
   7. ConstrainLong
   8. DoubleRange
   9. HTMLCanvasElement.captureStream()
   10. LongRange
   11. MediaDevices
   12. MediaStream
   13. MediaStreamTrackEvent
   14. MediaTrackCapabilities
   15. MediaTrackConstraints
   16. MediaTrackSettings
   17. MediaTrackSupportedConstraints
   18. Navigator.mediaDevices
   19. NavigatorUserMedia
   20. NavigatorUserMediaError
   21. VideoStreamTrack
   22. navigator.mediaDevices.getUserMedia()