MACROMEDIA FLASH COMMUNICATION SERVER MX-SERVER-SIDE COMMUNICATION ACTIONSCRIPT DICTIONARY Dokumentacja Pobierz pdf (Strona 148)

Chapter 470

Snapshots and thumbnails

This section compares the techniques for grabbing single frames of video as pictures to use within

your application. You can find the sample files for the code in the

flashcom_help\help_collateral\doc_snapshot and \doc_thumbnails directories under the installed

Macromedia Flash MX authoring directories. To see these applications in action, create

directories named doc_snapshot and doc_thumbnails in your flashcom application directory,

then open the corresponding SWF file. See “Creating your working environment” on page 31 if

you want to re-create these samples.

These samples may seem to behave similarly when you run them, but in fact they work very

differently. The doc_snapshot sample records only one frame, which it then displays. The

doc_thumbnails sample records multiple frames (an entire stream), but displays only the first

frame. You might use a snapshot application when you want to “take a picture” rather than record

a stream, while you might use a thumbnail application when you want to let a user choose among

multiple streams to play; you could display thumbnails for each of the streams that would give the

user an idea of what was recorded on each stream.

Snapshots

If you look at the

NetStream.attachVideo entry in the Client-Side Communication ActionScript

Dictionary, you will see the following usage:

myStream.attachVideo(source | null [, snapShotMilliseconds])

The snapShotMilliseconds parameter is used 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. When you specify the

snapShotMilliseconds parameter, you are controlling how much time elapses during playback

between recorded frames.

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MACROMEDIA FLASH COMMUNICATION SERVER MX-SERVER-SIDE COMMUNICATION ACTIONSCRIPT DICTIONARY Dokumentacja Strona 148