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The QuickTime API

The QuickTime API allows you to add a host of multimedia features to your application without needing to master the often arcane details of particular media formats and specifications.

For example, you can use QuickTime to open and display a series of JPEG images, concatenate them into a time-based slideshow with an MP3 sound track, then export the images as TIFF or PNG graphics, or export the slides and music together as a DV stream, without needing to work directly with, or necessarily understand, the compression, stream, or file formats for JPEG, TIFF, PNG, MP3, or DV.

In this section:

Multilevel API
Frameworks

Multilevel API

The QuickTime API includes over 2500 functions, divided into tool sets for particular tasks, with special functions and data types for virtually any task.

This can be a little daunting for programmers new to the API. It is easy to get lost in details and lose sight of the big picture. The most common error among new QuickTime programmers is to attack a problem using a complex, low-level tool set when there is a much simpler high-level command to perform the entire task.

You can interact with the QuickTime API at many different levels:

• You can simply open and play movies, letting QuickTime handle all the file and format conversion, synchronization, data buffering, component loading and unloading, memory management, and even the user interface. Prebuilt controls are available for play/pause, volume control, time scrubbing, and cut-and-paste editing.

• You can control the playback or editing yourself, setting the play rate, scaling the duration of movie or track segments, rearranging the playback order, and so on, creating your own user interface and controls.

• You can work with individual components, loading particular importers or image decompressors, applying them to groups of files or blocks of memory, and disposing of them when you are done.

• You can work with individual data samples—synthesizing graphics and overlaying them on video frames as a movie plays, for example—or performing pattern recognition on groups of samples, or even generating whole movies programatically.

• You can write new QuickTime components to support features such as new compression algorithms, new media types, new media capture devices, output devices, or data sources.

Frameworks

You can work directly with the QuickTime API using C, C++, Objective C, or Java. There are also QuickTime interfaces for JavaScript, and Windows interfaces for Visual Basic, C#, and other COM or .Net frameworks. Other languages, such as BASIC or Pascal, may support indirect calls to the QuickTime API through calls to a directly supported language or framework.

Most developers call the QuickTime API from procedural C programs written in C or C++, and most of the QuickTime documentation describes this use of the API. Nearly all of the procedural C QuickTime API is also part of the Carbon framework for Mac OS X. However, the QuickTime API does include some Windows-only functions and some legacy functions from earlier versions of the Mac OS. The documentation of any function in the QuickTime API Reference tells you whether that particular function is included in Carbon.

The procedural C QuickTime API for Windows is almost identical to the Mac OS version, with a few exceptions and some minor modifications to avoid naming conflicts with the Windows operating system. These exceptions and modifications are documented in QuickTime for Windows Programmers. Some newer parts of the QuickTime API make use of advanced features of Mac OS X that are not available in Windows. In these cases the documentation will note an alternative API to achieve similar functionality in Windows, if this is possible.

There is also a QuickTime API for Objective-C, which corresponds to the Cocoa programming framework for Mac OS X. This rapidly growing part of the API is greatly streamlined and simplified. It is documented in QuickTime for Cocoa Programmers. It is also possible to call the procedural C parts of the QuickTime API from Cocoa programs if lower-level access to QuickTime is needed.

The Java API for QuickTime is documented in QuickTime for Java. You can make calls to the procedural C parts of the QuickTime API from Java.

Documentation of the JavaScript API can be found in the JavaScript Scripting Guide for QuickTime.

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