MACROMEDIA Director MX, Руководство пользователя

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Chapter 27 592
If the movie jumps ahead in the Score or uses cast members that are referenced only by Lingo
scripts, the required cast member might not be available when necessary. If cast members are not
available, the movie either ignores them or displays a placeholder, depending on how you set the
streaming options in the Movie Playback Properties dialog box.
A challenge of authoring for Internet streaming is ensuring that all cast members have been
downloaded by the time the movie needs them. To avoid missing cast members, make sure that
all the cast members required for a particular scene have been downloaded before beginning
the scene. You can use the Director behaviors to wait for media in certain frames or for particular
cast members. See “About streaming with the Score and behaviors” on page 594. You can also
write custom Lingo code to do this. See “Checking whether media elements are loaded with
Lingo” on page 595.
Director movies stream unless you turn off streaming. In addition to turning streaming off and
on, you can specify that the media elements for a certain number of frames must finish
downloading before the movie starts playing.
You control streaming movies by arranging sprites in the Score and controlling the movement of
the playhead either with the Director behaviors or with Lingo. You can also use Lingo to specify
when externally linked files are downloaded.
About network operations
Director lets a network operation begin even if a previous network operation isn’t complete. This
capability, often referred to as background loading, lets Director perform multiple operations
while loading files. Because something else is happening while files are loading, the user doesn’t
perceive the wait.
Note: Loading data from a network is different from loading cast members in Director. Loading from a network
loads data to the local disk. Loading cast members in Director means loading cast members into memory.
It’s a good idea to author a Shockwave movie so that it performs other tasks while data is loading
in the background. Because Internet operations require background loading, Lingo for the
Internet behaves differently than Lingo commands that run within one movie. See “Using Lingo
in different Internet environments” on page 598.
Setting movie playback options
To change basic streaming settings for a movie, you use the Movie Playback Properties dialog box.
You can turn streaming off and on, specify a number of frames to download before playing the
movie, and make Director display placeholders if cast members aren’t downloaded yet. The Movie
Playback Properties dialog box also includes options for locking the current tempo and pausing
the movie when the window is deactivated.
Turning off streaming makes sense for some types of movies. For example, a game that requires all
cast members to be available at once might not be suitable for streaming. Other movies work best
if the media for a certain number of frames downloads before the movie begins playing. This
option is especially useful for streaming movies that were not originally designed for streaming.
Placeholders are rectangles that appear in place of media elements for cast members that have
not yet been downloaded. Placeholders are useful when testing to indicate places where media
is missing.