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By Barb Roeder More Interactivity with Sprites Sprites are an incredibly efficient way to add animation and interactivity to your QT movies. Sprites are vector-based animations, meaning that instead of sending new images for every frame of motion, only one image and then its position and other properties are sent as time progresses in the movie. The viewer's computer performs the task of creating a moving object based on this information. There are many different sprite properties that can be combined to create different effects. You can specify a transformation matrix -- a set of nine numbers describing the sprites position, scale and rotation. You can set its depth, allowing multiple sprites in a track to move in front of or behind each other. The source for the sprite image can be a bitmap, a video track, or any other media that QT can display. For some very cool examples of sprite tracks, check out the links listed at the end of this article. A basic use for a sprite track is to create buttons within your movie. Thus, when HREF tracks are requesting URLs from various places and under various connection speeds, you can pause the movie automatically using a sprite. Users can continue by pressing play when they are ready to move on. Creating Sprites requires specialized authoring tools, some of which are listed at the end of this article. If you are interested in pursuing this type of animation/interactivity for your web movies, your best bet is to invest in one of these tools and learn more from some of the other references listed as well. Removing Buffering Problems with Flash Another important feature of QT is the Flash track. Again, Flash is an excellent way to add new media elements to your movie without significantly increasing its bit rate. A brief description of some examples and a look at those listed in the reference sections may just inspire you to go beyond simple video and audio for your Web site. A Flash animation placed at the beginning of a movie can help ease "buffering" requirements and give the user more immediate gratification when clicking on a movie link. It's also a useful way to add a short commercial to your movie. Flash sprites can also be used in QT movies -- they have somewhat less features then QT sprites. An excellent description of the differences can be found in the Apple Developer Series book, QT for the Web. Images for Backgrounds and Slide Presentations As part of a larger media package, single frame images can be a useful component for keeping data rate requirements down as well. In addition, many corporate communications and distance learning applications can be accomplished with slide shows and voice-overs. QT adds some nice features to such a presentation allowing you to use images in a whole host of ways within your streaming content. If some of your audience can be reached with broadband connections, you can set up QT alternates with transition effects between the slides and video of the speaker to accompany the presentation as well. A basic slide presentation is created using the Open Image Sequence command in the File menu. You will need to create your slides as individual files, numbering them consecutively: Slide1, Slide2, Slide3. You can export a PowerPoint presentation in this manner as well. To add an audio track and effects, follow these steps: 1. Open the Image Sequence in QT, which will create a movie with each slide occupying one second. 2. Open a midi sound track or prerecorded voice-over for the presentation you want to synchronize. 3. Select each slide and copy it. Then select the audio segment you want to play during that slide and choose Add-Scaled in the Edit Menu. The slide becomes one frame, with its duration equal to the audio segment selected. Repeat for all your slides. 4. Again, make sure you save your movie without dependencies. If you want to experiment with effects, you can get a free application from Apple's web site called MakeEffectsMovie Or, if you anticipate creating slide presentations on a regular basis, you should consider a more sophisticated editing tool, some of which are listed at the end of this article. It’s a Wrap By defining media elements such as text, animations and sprites into a delivery architecture, QT movies can reach beyond the boundaries of traditional video and television applications. With all the features touched upon in this article, it's no wonder QT was chosen as the format for the MPEG-4 standard for media production and distribution. Developing streaming media using QT can add new features and interactivity to your content in unique ways, separating your business from the crowded confines of this marketplace.
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