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by Brad Smith

Understanding Components In QuickTime
March 30th, 2001

A QuickTime movie can contain many components. These components, when put together, create the images, sounds, and interactivity that the end user is presented with. In QuickTime, different types of data are stored in components that are called tracks. Tracks are, essentially, a container for different pieces of media of the same type. Within these tracks are items that are called samples. Samples are the individual pieces of media, or, in other words, the individual container for each piece, or group of pieces, within a track. In QuickTime, you can have as many samples as you would like inside of a track. Likewise, you can have many tracks (even more than one of the same type) in the same movie file. To better understand the different kinds of tracks in QuickTime, we must first look at their purposes.

Each different type of track has a different purpose, and different types of media samples it can contain. The track types are: Sprite Tracks, Picture Tracks, Effect Tracks, Instrument Tracks, Tween Tracks, Modifier Tracks, Text Tracks, Movie Tracks, and Color Tracks. Here is an overview of the different tracks:

Sprite Track: A sprite track is a visual track. It stores samples that are displayed on the screen to the user. Sprites can be interactive in many ways. They can be used to play sounds upon a mouse click, they could jump to another point in the movie, they could assign a value to a variable, or start/stop playback of a video. They are also capable of animation. In fact, the things sprites can do are almost infinite.

Picture Track: A picture track stores image samples. These images are static and cannot be animated. The picture track is often used as a background image or for slide shows.

Effect Track: Effect tracks store information on effects (filters and transitions) that QuickTime can perform. Effect samples call on specific effects to be rendered on the end user's machine at certain points in time. The effect track is often used to transition from slide to slide in a slide show.

Instrument Track: The instrument track stores information on audio. Samples in this type of track are references to the instrument sounds included with QuickTime. Content creators use this track for MIDI-like audio.

Tween Track: To state it simply, tween tracks store tween samples. These samples are used to perform interpolations of values of various data types. This information can then be referenced by another track. Tween tracks are part of a more advanced usage of QuickTime that will be covered in a little more detail later in the year.

Modifier Track: Modifier tracks store predefined sequences of values. This track can be referenced by other tracks. Like tween tracks, I will cover modifier tracks more in detail later.

Text Track: A text track stores text samples. These samples include text size, color, font, anti-aliasing, hyperlinks, and more.

Color Track: A color track sample includes a vector image used as a color sample. Like tween tracks and modifier tracks, I will cover modifier tracks more in detail later.

Movie Track: A movie track contains other QuickTime movies that are separate from your movie and independently controlled.

Other Tracks in QT: External tracks, such as Flash files, can also be a part of QuickTime movie files.

This is simply a basis on which to build you're knowledge and understanding of QuickTime and its interactive capabilities. In future columns I will examine different track types in conjunction with tutorials utilizing each. I hope you'll join me.


Welcome, once again, to iResources. This week has been an exciting week for the Macintosh community with the final release of Mac OS X. While not feature complete, it still is very usable and a huge step forward for the Mac OS. Perhaps the most important part of the release this week is that it includes the final version of QuickTime 5. Like Mac OS X, QuickTime 5 is a large step forward, and in the coming months I will delve into the new features that are found in the new version. For this week, however, I have assembled a collection of resources about Mac OS X and QuickTime 5.

QuickTime Pro Key Notes - It appears that in QuickTime 5 not all QuickTime Pro key numbers work to unlock the full pro capabilities of the software. After some investigation and confirmation from various Observers, I have concluded that this happening is based on when you bought your pro key. Those of you who bought you're key in the days of QuickTime 3 will find that QuickTime 5 will refer to it as a QuickTime 3/4 Registration Code and that the full pro features are not unlocked. Those of you who purchased your key during the days of QuickTime 4 will find that QuickTime refers to it as QuickTime 4/5 Registration Code. In other words, each key code only lasts for two major versions, and those who own a QuickTime 3 code will have to pay $30 and purchase a new pro code. This is disappointing, but I suppose that Apple has to earn some money from QuickTime. I am curious to find out what you think, so let me know in the comments.

The Mac Observer - For some of the most complete coverage on the Web, check out our Mac OS X news page.

VersionTracker - VersionTracker is the best source of software updates on the entire Mac Web, and it has been updated with a "Mac OS X" tab specifically for software for OS X. Check it out for updates to your favorite software programs. On a QuickTime-related note, there is no way in Mac OS X to control volume except from the system preferences sound pane. Run a search on VersionTracker for "Volume" to find some useful volume-control applications.

MacFixIt - Once again, an indispensable Mac Web site has become even better with a Mac OS X-specific Late-Breakers page. Check here for solutions to all your problems (or at least some of them).

Apple's QuickTime Site - This page is always useful for QuickTime content and updates, but at the moment they only have QuickTime Preview 3 available for download. Their examples, however, can showcase many of the new features of QuickTime 5.

Apple's Final Cut Pro Site - This one I missed a couple weeks ago, but Final Cut Pro 2 is now out from Apple, and it's better than ever. I would suggest checking it out if you're in the video production field. Oddly Final Cut Pro is not compatible with Mac OS X, even in the classic environment. Hopefully it will get an update this summer, if not sooner.

You are encouraged to send me your comments, or to post them below.

Most Recent iQT Columns

Using Sprite Tracks & LiveStage Pro
April 20th

Understanding Components In QuickTime
March 30th

Enhancing The QuickTime Web Experience
March 23rd

iQT Archives

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Brad Smith is currently attending school in Lincoln, Nebraska, and has used Macintosh computers since 1984. Brad is a member of the National Association of Photoshop Professionals, and an interactive media devotee, by hobby. In middle school, Brad and three other students from Lincoln, NE, were recipients of the ISTE MultiMedia Mania international multi-media contest in the middle school division. You'll typically find Brad going all out on a simple twenty-point school project by making an interactive QuickTime movie in LiveStage Professional. In other words, he has no life!

Brad has three brothers and is a big fan of the Dave Matthews Band. His enjoyment for music is evident in the vast collection of CDs he possesses and the fact that music is required to do any sort of work on the computer. He welcomes your comments at

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