QuickTime - A Practical Guide to Video and Audio Compression - page 390

files, and other music formats such as AAC. When you come to burn a CD from iTunes, it
renders these MIDI tracks and loops into AIFF format so that they can be played back on
a normal CD player. You don't have to do anything—it just happens.
Many other audio formats (including the AAC format) are supported in QuickTime
as well. QuickTime also works with surround-sound multi-track audio for movies as well
as the very low bit rates required for mobile audio services.

23.11 Downloadable Extension Components

You can install the Mac OS X version of the Envivio TV plug-in with your other QuickTime
components and play back MPEG-4 BIFS multimedia. You will have to contact Envivio
directly to obtain the plug-in. QuickTime players will automatically download other com-
ponent modules from the Apple web server as the media being played calls for them.
These are listed in Table 23-1 and are supported on both the Mac OS and QuickTime for
Windows:

23.12 QuickTime VR

QuickTime offers VR capabilities as well as navigable movies and wired sprites. These
capabilities lean toward what MPEG-4 has to offer in the systems layer. QTVR elementary
movies come in two varieties, panorama and object. You would 'move around' inside a
panorama, which from your point of view is an environment. You can 'pick up' and turn
over an object to inspect it from all sides. Panoramas are just cleverly constructed sets of
individual frames within a movie with an additional layer of playback control that allows
the movie to be navigated in a totally nonlinear fashion.
They use compression at the frame level, but because the experience is nonlinear,
P and B frames have no meaning in this context.

23.13 Effects

QuickTime contains some special effects for creating additional enhancements to your
content without consuming large amounts of bit rate. These effects are described using
parameters and are then rendered at playback. Examples include ripple, fire, fog, and
clouds. The effects are stored in a separate track that can be enabled or disabled separately
as needed.

23.14 Embedding Videos into Wired QuickTime Movies

QuickTime wired movies come in a variety of different forms. QuickTime VR presenta-
tions can be wired with additional movie panes playing inside the VR environment. This