You
can embed cue points in an Adobe F4V or FLV video file during encoding. Historically,
cue points were embedded in movies to give the projectionist a visual
signal that indicated the reel of film was nearing the end. In Adobe
F4V and FLV video formats, a cue point allows you to trigger one
or more other actions in your application at the time that it occurs
in the video stream.
You can use several different kinds of cue points with Flash
video. You can use ActionScript to interact with cue points that
you embed in a video file when you create it.
-
Navigation cue points: You embed navigation cue points
in the video stream and metadata packet when you encode the video
file. You use navigation cue points to let users seek to a specified
part of a file.
-
Event cue points: You embed event cue points in the video
stream and metadata packet when you encode the video file. You can
write code to handle the events that are triggered at specified
points during video playback.
-
ActionScript
cue points: ActionScript cue points are available only to the Flash FLVPlayback
component. ActionScript cue points are external cue points that you
create and access with ActionScript code. You can write code to
trigger these cue points in relation to the video's playback. These
cue points are less accurate than embedded cue points (up to a tenth
of a second), because the video player tracks them separately. If
you plan to create an application in which you want users to navigate
to a cue point, you should create and embed cue points when you
encode the file instead of using ActionScript cue points. You should
embed the cue points in the FLV file, because they are more accurate.
Navigation cue points create a keyframe at the specified cue
point location, so you can use code to move a video player's playhead
to that location. You can set particular points in a video file
where you might want users to seek. For example, your video might
have multiple chapters or segments, and you can control the video
by embedding navigation cue points in the video file.
For more information on encoding Adobe video files with cue
points, see “Embed cue points” in
Using Flash
.
You can access cue point parameters by writing ActionScript.
Cue point parameters are a part of the event object received by
the callback handler.
To trigger certain actions in your code when an FLV file reaches
a specific cue point, use the
NetStream.onCuePoint
event
handler.
To synchronize an action for a cue point in an F4V video file,
you must retrieve the cue point data from either the
onMetaData()
or
the
onXMPData()
callback functions and trigger
the cue point using the Timer class in ActionScript 3.0. For more
information on F4V cue points, see
Using onXMPData()
.
For more information on handling cue points and metadata, see
Writing callback methods for metadata and cue points
.
