Client-Side Communication ActionScript > NetStream (object)

NetStream (object)

The NetStream object opens a one-way streaming connection between the Flash Player and the Flash Communication Server through a connection made available by a NetConnection object. A NetStream object is like a channel inside a NetConnection object; this channel can either publish audio and/or video data, using NetStream.publish, or subscribe to a published stream and receive data, using NetStream.play. You can publish or play live (real-time) data and play previously recorded data.

You can also use NetStream objects to send text messages to all subscribed clients (see NetStream.send).

The following steps summarize the sequence of actions required for publishing real-time audio and video using Flash Communication Server and the Real-Time Messaging Protocol (RTMP):

Multiple streams can be open simultaneously over one connection, but each stream either publishes or plays. To publish and play over a single connection, open two streams over the connection, as shown in the following example. This example publishes audio and video data in real time on one stream and plays it back on another stream on the same client, through the same connection.

// These lines begin broadcasting
nc = new NetConnection(); // create connection object
nc.connect("rtmp://mySvr.myDomain.com/App"); // connect to server
ns = new NetStream(nc);             // open stream within connection
ns.attachAudio(Microphone.get());   // capture audio
ns.attachVideo(Camera.get());       // capture video
ns.publish("todays_news");          // begin broadcasting

// These lines open a stream to play the video portion of the broadcast
// inside a Video object named myVideoArea.
// The audio is played through the standard output device--you don't
// need to issue a separate command to hear the audio.
ns2 = new NetStream(nc);    // open another stream over the same connection
myVideoArea.attachVideo(ns2); // specify where to display video
ns2.play("todays_news"); // play uses the same name as publish, above

In the previous example, note that both the publisher and subscriber call an attachVideo method. The publisher calls NetStream.attachVideo to connect a video feed to a stream. The subscriber calls Video.attachVideo to connect a video feed to a Video object on the Stage; the incoming video is displayed inside this object.

Note also that although the publisher calls an attachAudio method, the subscriber does not. This is because audio sent through a stream is played through the subscriber's standard audio output device by default; the subscriber doesn't have to attach the incoming audio to an object on the Stage. However, you can use MovieClip.attachAudio to route audio from a NetStream object to a movie clip. If you do this, you can then create a Sound object to control the volume of the sound. For more information, see MovieClip.attachAudio.

 
Method summary for the NetStream object

Method	Description
NetStream.attachAudio	Publisher method; specifies whether audio should be sent over the stream.
NetStream.attachVideo	Publisher method; starts transmitting video or a snapshot from the specified source.
NetStream.close	Stops publishing or playing all data on the stream and makes the stream available for another use.
NetStream.pause	Subscriber method; pauses or resumes playback of a stream.
NetStream.play	Subscriber method; feeds streaming audio, video, and text messages being published on the Flash Communication Server, or a recorded file stored on the server, to the client.
NetStream.publish	Publisher method; sends streaming audio, video, and text messages from the client to the Flash Communication Server, optionally recording the stream during transmission.
NetStream.receiveAudio	Subscriber method; specifies whether incoming audio plays on the stream.
NetStream.receiveVideo	Subscriber method; specifies whether incoming video will play on the stream, or specifies the frame rate of the video.
NetStream.seek	Subscriber method; seeks to a position in the recorded stream currently playing.
NetStream.send	Publisher method; broadcasts a message to all subscribing clients.
NetStream.setBufferTime	Method; for a publishing stream, this number indicates how long the outgoing buffer can grow before Flash starts dropping frames. For a subscribing stream, this number indicates how long to buffer incoming data before starting to display the stream.

 
Property summary for the NetStream object

Property (read-only)	Description
NetStream.bufferLength	The number of seconds of data currently in the buffer.
NetStream.bufferTime	The number of seconds assigned to the buffer by NetStream.setBufferTime.
NetStream.currentFps	The number of frames per second being sent or received on the publishing or subscribing stream.
NetStream.liveDelay	The number of seconds of data in a subscribing stream's buffer in live mode.
NetStream.time	The number of seconds a stream has been playing or publishing.

 
Event handler summary for the NetStream object

Method	Description
NetStream.onStatus	Invoked every time a status change or error is posted for the NetStream object.