webrtc学习——mediaStream和MediaStreamTrack

This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.

The MediaStream interface represents a stream of media content. A stream consists of several tracks, like video or audio tracks.

Attributes

MediaStream.ended Read only

Is a Boolean value with a value of true if the ended event has been fired on the object, meaning that the stream has been completely read, or false if the end of hte stream has not been reached.

MediaStream.id Read only

Is a DOMString containing 36 characters denoting a unique identifier (GUID) for the object.

Event handlers

MediaStream.onaddtrack

Is a EventHandler containing the action to perform when an addtrack event is fired on the object, that is when a new MediaStreamTrack object is added.

MediaStream.onended

Is a EventHandler containing the action to perform when an ended event is fired on the object, that is when the streaming is terminating.

MediaStream.onremovetrack

Is a EventHandler containing the action to perform when an removetrack event is fired on the object, that is when a  MediaStreamTrack object is removed from it.

Methods

MediaStream.addTrack()

Stores a copy of the MediaStreamTrack given as argument. If the track has already been added to the MediaStream object, nothing happens; if the track is in the finished state, that is has already reached its end, the exception INVALID_STATE_RAISE is raised.

MediaStream.clone()

Return a clone of the MediaStream objet. The clone will have a new id value.

Returns the track whose id corresponds to the one given in parameters, trackid. If no parameter is given, or if no track with that id does exists, it returns null. If several tracks have the same id, it returns the first one.

MediaStream.getAudioTracks()

Returns a list of the MediaStreamTrack stored in the MediaStream object that have their kind attribute set to "audio". The order is not defined, and may vary from one browser to an other, but also from one call to the method to another.

MediaStream.getTrackById()

Returns the track whose id corresponds to the one given in parameters, trackid. If no parameter is given, or if no track with that id does exists, it returns null. If several tracks have the same id, it returns the first one.

MediaStream.getVideoTracks()

Returns a list of the MediaStreamTrack stored in the MediaStream object that have their kind attribute set to "video". The order is not defined, and may vary from one browser to an other, but also from one call to the method to another.

MediaStream.removeTrack()

Removes the MediaStreamTrack given as argument. If the track is not part of the MediaStream object, nothing happens; if the track is in the finished state, that is has already reached its end, the exception INVALID_STATE_RAISE is raised.

MediaStreamTrack

Summary

The MediaStream interface represents a stream of media content. A stream consists of several tracks, like video or audio tracks.

Properties

MediaStreamTrack.enabled

Is a Boolean value with a value of true if the track is enabled, that is allowed to render the media source stream; or false if it is disabled, that is not rendering the media source stream but silence and blackness. If the track has been disconnected, this value can be changed but has no more effect.

MediaStreamTrack.id Read only

Returns a DOMString containing a unique identifier (GUID) for the track; it is generated by the browser.

MediaStreamTrack.kind Read only

Returns a DOMString set to "audio" if the track is an audio track and to "video", if it is a video track. It doesn't change if the track is deassociated from its source.

MediaStreamTrack.label Read only

Returns a DOMString containing a user agent-assigned label that identifies the track source, as in"internal microphone". The string may be left empty and is empty as long as no source has been connected. When the track is deassociated from its source, the label is not changed.

MediaStreamTrack.muted Read only

Returns a Boolean value with a value of true if the track is muted, false otherwise.

MediaStreamTrack.readonly Read only

Returns a Boolean value with a value of true if the track is readonly (such a video file source or a camera that settings can't be modified),false otherwise.

MediaStreamTrack.readyState Read only

Returns an enumerated value giving the status of the track.It takes one of the following values:

• "live" which indicates that an input is connected and does its best-effort in providing real-time data. In that case, the output of data can be switched on or off using theMediaStreamTrack.enabled attribute.
• "ended" which indicates that the input is not giving any more data and will never provide new data.

MediaStreamTrack.remote Read only

Returns a boolean value with a value of true if the track is sourced by a RTCPeerConnection, falseotherwise.

Event handlers

MediaStreamTrack.onstarted

Is a EventHandler containing the action to perform when an started event is fired on the object, that is when a new MediaStreamTrack object is added.

MediaStreamTrack.onmute

Is a EventHandler containing the action to perform when an mute event is fired on the object, that is when the streaming is terminating.

MediaStreamTrack.onunmute

Is a EventHandler containing the action to perform when an unmute event is fired on the object, that is when a  MediaStreamTrack object is removed from it.

MediaStreamTrack.onoverconstrained

Is a EventHandler containing the action to perform when an overconstrained event is fired on the object, that is when a  MediaStreamTrack object is removed from it.

MediaStreamTrack.oneended

Is a EventHandler containing the action to perform when an ended event is fired on the object, that is when a  MediaStreamTrack object is removed from it.

Methods

MediaStreamTrack.getConstraints()

 

MediaStreamTrack.applyConstraints()

 

MediaStreamTrack.getSettings()

 

MediaStreamTrack.getCapabilities()

 

MediaStreamTrack.clone()

 

MediaStreamTrack.stop()

Stops playing the source associated to the track, both the source and the track are deassociated. The track state is set to ended.

Specifications

Specification	Status	Comment
Media Capture and Streams The definition of 'MediaStreamTrack' in that specification.	Candidate Recommendation	Initial definition

https://developer.mozilla.org/en-US/docs/Web/API/MediaStreamTrack

https://developer.mozilla.org/en-US/docs/Web/API/MediaStream