quick time overview

[abeetha.m]

Overview




QuickTime is a cross platform
system-level software package for Macintosh, Windows and Java which adds the
capability to play movies, synthesize music, display animations, view virtual
reality worlds and add multimedia capability to the computer desktop.




QuickTime is implemented
as a set of extensions on the Macintosh platform and a dynamic-link library
(DLL) on Windows. It can process video data, still images, animated images
(also known as sprites), vector graphics, multiple sound channels, MIDI music, 3D objects, virtual
reality objects, panoramas and text. The number of data formats QuickTime
recognizes is impressive. Currently, more than 70 different formats can be
imported or exported and as formats are added, applications created today will
work with them automatically.




QuickTime is readily
extensible. It is built in a modular fashion made up of many software
components installed and accessed through the Component Manager. These
built-in components handle the most common multimedia tasks. Developers can
expand on these capabilities by writing custom components to augmented or
completely replace QuickTime's capabilities if desired.




An important concept to
remember is the idea of "time-based media" and how it can be
manipulated. QuickTime is a generalized way to define time lines and organize
information along these time lines.




The QuickTime API is
large to say the least, and attempting to understand it all is a daunting task.
However, QuickTime's modularity allows you to do many things easily and quickly
with as little has a half dozen calls! For example, you can selectively work
with the Movie Toolbox alone or Graphics Importers without
needing to visualize all of the underlying components or API calls. You don't
need to understand it all to start working with it.




Architecture





QuickTime comprises two
main managers - the Movie Toolbox and the Image Compression Manager -
plus a set of built-in components.




Movie Toolbox




Applications gain access
to the capabilities of QuickTime by calling functions in the Movie Toolbox. The
Movie Toolbox lets an application store, retrieve, and manipulate time-based
data and provides functions for editing movies.




Image
Compression Manager




Single image data may
require a large amount of storage space. A sequence of images, like those
contained in a QuickTime movie can demand many times as much space. The Image
Compression Manager provides a device-independent and driver-independent means
of compressing and decompressing images and sequences of images, thereby minimizing
the storage requirements for any application that works with images.




In most cases
applications use the Image Compression Manager indirectly by calling Movie
Toolbox functions or by displaying a compressed picture. However, if an
application compresses images or makes movies with compressed images, it may
call some Image Compression Manager functions directly.




Components




Apple ships a number of
built-in components with QuickTime. These built-in components provide essential
services to applications and to the managers that make up the QuickTime
architecture. The Apple-defined component types include image processors, media
handlers, and miscellaneous utilities.




QuickTime's
built-in data processing components perform these tasks:

• Movie controller components let applications play
  movies through a standard user interface.
• Image compressor components compress and decompress
  image data.
• Image compression dialog components let the user specify the
  parameters for compression operations.
• Image transcoder components convert compressed files
  from one format to another.
• Video digitizer components let applications control
  video digitization by external devices.
• Movie data-exchange components (also known as Movie Import
  and Movie Export components) let applications move various types of data
  into and out of QuickTime movies.
• Video output components convert QuickTime movies
  into video streams.
• Graphics import components let applications work with
  still image files by providing a simple API that works with a wide variety
  of image file formats.
• Graphics export components let applications export
  still image files using a standard easy to use API.
• Music components process and synthesize
  music tracks in QuickTime movies.
• Effects and transitions components implement video synthesis,
  video filters and video transitions, including the 133 standard SMPTE
  transitions. These components are implemented as a subcategory of image
  decompressor components.
• Preview components are used by the Movie
  Toolbox's standard file preview functions to display and create visual
  previews of file contents. [/list]
  
  
  
  QuickTime
  built-in media handling components:
  
  
  
  
  Media handler components
  implement the behavior of different track types. They deal with the specifics
  of how a particular track's media data should be presented to the viewer.
  
  
  
  
  
  • Video media handler Component implements video tracks by
    calling the Image Compression Manager to display video samples.
  • Sound media handler Component implements sound tracks by
    calling the Sound Manager to play sound samples. [/list]
    
    
    
    QuickTime
    built-in utilities perform these tasks:
    
    
    
    
    
    • Clock components provide timing services for
      applications that use QuickTime.
    • Standard Sound component lets an application present
      the user with a dialog for configuring sound settings.
    • Sequence grabber components let applications preview
      and record video and sound data as QuickTime movies.
    • Sequence grabber channel components handle the acquisition of
      individual data streams for sequence grabber components. For example, the
      video sequence grabber channel component acquires video.
    • Text channel components are sequence grabber
      channel components for text.
    • Sequence grabber panel components let sequence grabber
      components obtain configuration information from the user for a particular
      sequence grabber channel component. [/list]