NetStream class
83
After attaching the video source, you must call
NetStream.publish()
to actually begin
transmitting. Subscribers who want to display the video must call the
NetStream.play()
and
Video.attachVideo()
methods to display the video on the Stage.
You can use
snapShotMilliseconds
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
snapShotMilliseconds
, 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
snapShotMilliseconds
parameter serves a different purpose from the
fps
parameter
you can set with
Camera.setMode()
. When you specify
snapShotMilliseconds
, you are
controlling how much time elapses
during playback
between recorded frames. When you
specify
fps
using
Camera.setMode()
, 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
Camera.setMode()
command with an
fps
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.
