QuickTime VR - Definition and Overview

QuickTime is a multimedia technology developed by Apple Computer, capable of handling various formats of digital video, sound, text, animation, music, and immersive virtual reality panoramic images.

There are three main components to the QuickTime technology. There is the QuickTime file format itself which is openly documented and available for anyone to use royalty-free. Apple develops a QuickTime media player which they make available for free download on their website, as well as bundle with every one of their computers. Lastly there are software development kits available for the Macintosh and Windows platforms, that allow people to develop their own software to manipulate QuickTime and other media files.

History

The first version of QuickTime, was released on December 2, 1991 as a multimedia add-on for Mac OS 7. The lead developer of QuickTime Bruce Leak ran the first public demonstration at the May 1991 Worldwide Developers Conference, where he played Apple's famous 1984 TV commercial on a Mac, at the time an astounding technological breakthrough. Microsoft's competing technology Video for Windows did not appear until November 1992.

That first version of QuickTime laid down the basic architecture which survives essentially unchanged today, including multiple movie tracks, extensible media type support, an open-ended file format, and a full complement of editing functions. Among the original video codecs were the Apple Video codec (also known as "Road Pizza"), which was suited to normal live-action video; the Animation codec, which used simple run-length compression and was better suited to cartoon-type images with large areas of flat color; and the Graphics codec which was optimized for 8-bit-per-pixel images, including ones which had undergone dithering.

QuickTime 1.5 for Mac OS was released in the latter part of 1992. This added the SuperMac-developed Cinepak vector-quantization video codec (initially known as Compact Video), which managed the unheard-of feat of playing back video at 320*240 resolution at 30 frames per second on a 25MHz 68040 CPU. It also added text tracks, which allowed for things like captioning, lyrics etc at very little addition to the size of the movie.

In an effort to increase the adoption of QuickTime, Apple contracted an outside company San Francisco Canyon Company to port QuickTime to the Windows platform. Version 1.0 of QuickTime for Windows, was only a subset of the full QuickTime API, including only movie-playback functions that were driven through the standard movie controller.

QuickTime 1.6.x came out the following year. 1.6.2 was the first version to incorporate the "QuickTime PowerPlug" which replaced some components with PowerPC-native code when running on PowerPC Macs.

QuickTime 2.0 for Mac OS was released on February 1994. This was the only version that was never released for free. It added support for music tracks, which contained the equivalent of MIDI data and could be used to drive a sound-synthesis engine built into QuickTime itself (using sounds licensed from Roland), or any external MIDI-compatible hardware, thereby producing sounds using only small amounts of movie data.

The next versions, 2.1 and 2.5, reverted to the previous model of giving QuickTime away for free. They improved the music support and added sprite tracks which allowed the creation of complex animations with the addition of little more than the static sprite images to the size of the movie.

QuickTime 2.0 for Windows was released in November 1994.

QuickTime 3.0 for Mac OS was released on March 30 1998. This introduced the now-standard revenue model of releasing the software for free, but with additional features of the Apple-provided QuickTime Player and Picture Viewer applications that could only be unlocked by buying a QuickTime Pro license code.

QuickTime 3.0 added support for graphics importer components that could read images from GIF, JPEG, TIFF and other file formats, and video output components which were primarily a way to export movie data via FireWire. It also added video effects which could be applied in real-time to video tracks. Some of these effects would even respond to mouse clicks by the user, as part of the new movie interaction support.

QuickTime 4.0 for Mac OS was released on June 8 1999. This added graphics exporter components which could write some of the same formats as the previously-introduced importers could read, though interestingly not GIF. It added the first version of the Sorenson video codec, and support for streaming.

QuickTime 4.1, released at the beginning of 2000, added support for movie files larger than 2 gigabytes on Mac OS 9.0 and later and dropped support for 68K Macs. The QuickTime Player could now be controlled via AppleScript.

QuickTime 5.0 for Mac OS was released on April 23 2001. It added "skins" to the QuickTime Player and multiprocessor image compression support.

QuickTime 6.0 for Mac OS was released on July 15 2002. This was the first to include a version for OS X.

Updates to the current version of QuickTime

The following is a list of major updates to QuickTime 6.

QuickTime Architecture

QuickTime consists of two major subsystems: the Movie Toolbox and the Image Compression Manager. The Movie Toolbox is a general API for handling time-based data, while the Image Compression Manager provides services for dealing with compressed raster data as produced by video and photo codecs.

QuickTime Players

Apple QuickTime Player on Mac OS X

Apple releases official media player software for Mac OS and Windows for free under the brand QuickTime Player. (Earlier versions were called simply "MoviePlayer.") The player also comes with a number of media editing and creation features, however these have to be unlocked by purchasing a key from Apple, turning the media player into QuickTime Pro.

A number of companies base their software on QuickTime. Examples being, Apple's own iTunes jukebox audio player (designed for easy manipulation of audio media) which utilizes QuickTime for its playback technology or the copies of the Encyclopædia Britannica that come on DVD which require QuickTime to play movie clips.

Independent players for QuickTime 6 (MPEG-4) exist for many operating systems, and the FFmpeg library even supports the Sorenson video compression format. Apple, however, is the exclusive licensee of Sorenson technology.

QuickTime File Format

A QuickTime file is a multimedia container file that contains one or more tracks that can contain a particular type of data, such as audio, video, effects, or text (e.g., for subtitles). Each track in turn contains track media, either the digitally encoded media stream (using a specific codecs such as Cinepak, Sorenson codec, MP3, JPEG, DivX, or PNG) or a pointer to the media stored in another file or elsewhere on a network. It also has an "edit list" that indicates what parts of the media are to be used.

Internally, this format is maintained as a tree-structure of "atoms," each of which uses a 4-byte OSType identifier to determine its structure. An atom can be a parent to other atoms or it can contain data, but it cannot do both.

The versatility of QuickTime's file format can probably best be illustrated by Apple's plans for HyperCard 3.0, which was originally intended to store an entire HyperCard stack (similar in structure to a complete web site, with graphics, buttons and scripts) as a QuickTime file.

This structure is similar to that supplied by the Microsoft's Advanced Streaming Format or the open source Ogg and Matroska containers. However QuickTime was the first software framework to use this format-independent framing.

QuickTime and MPEG-4

In February 11 1998, the ISO approved the QuickTime file format as the basis of the MPEG-4 standard, with supporters noting that it was a good "life-cycle" format, well-suited to capture, editing, archiving, distribution, and playback (as opposed to the simple file-as-stream approach of MPEG-1 and MPEG-2, which are poorly suited to editing). MPEG-4 compatibility was added to QuickTime 6 in 2002. However, Apple delayed the release of this version for months in a dispute with the MPEG-4 licensing body, claiming that proposed license fees were prohibitive for many users and content providers. A compromise was reached, after which QuickTime 6 was released.

QuickTime Development

Developers can use the QuickTime software development kit to develop multimedia applications for Mac or Windows with the C programming language or the Java programming language.

See also

• Comparison of media players

External links

• Apple - QuickTime (http://www.apple.com/quicktime/): As would be expected of the official site, it contains general information on QuickTime (mainly for the purposes of marketing), and links to download the latest versions of the program.
• Apple's QuickTime developer site (http://developer.apple.com/quicktime/)
• Apple - QuickTime Version Availability (http://www.apple.com/quicktime/download/version.html)
• Apple - QuickTime File Format (http://developer.apple.com/documentation/QuickTime/QTFF/index.html)
• QuickTime Playback Compatibility Chart (http://www.simnet.is/klipklap/quicktime/)
• QuickTime history timeline (http://david.egbert.name/quicktime/history/index.html)