ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with video
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()” on page 497.
For more information on handling cue points and metadata, see “Writing callback methods for metadata and cue
points” on page 486.
Writing callback methods for metadata and cue points
Flash Player 9 and later, Adobe AIR 1.0 and later
You can trigger actions in your application when specific metadata is received by the player or when specific cue points
are reached. When these events occur, you must use specific callback methods as event handlers. The NetStream class
specifies the following metadata events that can occur during playback: onCuePoint (FLV files only), onImageData,
onMetaData, onPlayStatus, onTextData, and onXMPData.
You must write callback methods for these handlers, or the Flash runtime may throw errors. For example, the
following code plays an FLV file named video.flv in the same folder where the SWF file resides:
var nc:NetConnection = new NetConnection();
nc.connect(null);
var ns:NetStream = new NetStream(nc);
ns.addEventListener(AsyncErrorEvent.ASYNC_ERROR, asyncErrorHandler);
ns.play("video.flv");
function asyncErrorHandler(event:AsyncErrorEvent):void
{
trace(event.text);
}
var vid:Video = new Video();
vid.attachNetStream(ns);
addChild(vid);
The previous code loads a local video file named video.flv and listens for the asyncError
(AsyncErrorEvent.ASYNC_ERROR) to be dispatched. This event is dispatched when an exception is thrown from
native asynchronous code. In this case, it is dispatched when the video file contains metadata or cue point information,
and the appropriate listeners have not been defined. The previous code handles the asyncError event and ignores the
error if you are not interested in the video file’s metadata or cue point information. If you had an FLV with metadata
and several cue points, the trace() function would display the following error messages:
Last updated 6/6/2012
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