Technical information

by Forest Key and Chris Hock
7
n
Producing streaming FLV files
Embedding Video within Flash Player Movies
Since the introduction of Flash MX and Flash Player 6, multimedia
developers have been able to embed video within Flash Player movies by
importing video and placing it on the Flash Timeline. A key benefit of this
approach is the ability to see the individual video frames on the Flash
Timeline and create overlays and interactions with the aid of the Flash
design tools.
Flash MX 2004 builds upon this approach by introducing the Video Import
Wizard, which provides fine control over encoding options, scaling and
cropping presets, as well as color and brightness settings.
However, this approach is not without limitations:
n
During authoring, each time you want to preview or test part or all of
your Flash movie, you must publish the entire video file. This can add
significant time to the authoring process.
n
For web delivery, the entire video file must be downloaded from the web
server in order for playback to begin.
n
At runtime, the entire video file must fit into the local memory of the
playback system.
n
After approximately 120 seconds of continuous video playback, users
may experience audio synch problems.
n
File length is limited to a maximum duration of no greater than 16,000
frames.
n
The video frame rate and Flash Timeline frame rate must be the same
(because they share the same time base).
Producing Progressive FLV Files
Flash Player 7 introduces a new technique called progressive download,
which enables developers to use ActionScript commands to feed external
FLV files into a Flash movie and play them back during runtime. More
specifically, you can use the netConnection and netStream commands to set
the FLV file to play back, and to control the Play, Pause, Seek (to a
timecode), Close behaviors and buffertime and size for a given video file.
Flash MX Professional 2004 also includes a set of components called Media
Components that you can use to quickly add a full-featured FLV or MP3
playback control to your Flash project. Media Components provides support
for both progressive download and streaming FLV files (see Figure 4). Flash
MX Professional 2004 also includes a set of behaviors that can be used in
conjunction with Media Components to create automated interactions
between video sequences and slides in a project. (For details on using
ActionScript and Media Components, see the reference guide, which you
can access through the Flash MX 2004 Help panel.)