Macromedia flash media server 2-client-side actionscript language reference for flash media server 2 Benutzerhandbuch

NetStream class

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After attaching the video source, you must call 

 to actually begin 

transmitting. Subscribers who want to display the video must call the 

 and 

 methods to display the video on the Stage.

You can use 

 to send a single snapshot (by providing a value of 0) or 

a series of snapshots—in effect, time-lapse footage—by providing a positive number that adds 
a trailer of the specified number of milliseconds to the video feed. The trailer extends the 
length of time the video message is displayed. By repeatedly calling 

attachVideo

 with a 

positive value for 

, the snapshot/trailer/snapshot/trailer... sequence 

creates time-lapse footage. For example, you could capture one frame per day and append it to 
a video file. When a subscriber plays back the file, each frame remains onscreen for the 
specified number of milliseconds and then the next frame is displayed.

The 

 parameter serves a different purpose from the 

 parameter 

you can set with 

. When you specify 

, you are 

controlling how much time elapses during playback between recorded frames. When you 
specify 

 using 

, you are controlling how much time elapses during 

recording and playback between recorded frames.

For example, suppose you want to take a snapshot every 5 minutes for a total of 100 
snapshots. You can do this in two different ways:

■

You can issue a 

NetStream.attachVideo(source, 500)

 command 100 times, once 

every 5 minutes. This takes 500 minutes to record, but the resulting file will play back 
in 50 seconds (100 frames with 500 milliseconds between frames).

■

You can issue a 

 command with an 

 value of 1/300 (one per 300 

seconds, or one every 5 minutes), and then issue a 

NetStream.attachVideo(source)

 

command, letting the camera capture continuously for 500 minutes. The resulting file 
will play back in 500 minutes—the same length of time that it took to record—with each 
frame being displayed for 5 minutes. 

Both techniques capture the same 500 frames, and both approaches are useful; which 
approach to use depends primarily on your playback requirements. For example, in the 
second case, you could be recording audio the entire time. Also, both files would be 
approximately the same size.