QuickTime Overview

Peter Hoddie
QuickTime Architect
Apple Computer

What is QuickTime?

• File format
• Run time architecture

What is QuickTime?

• File format used by many run times: QuickTime, ActiveMovie, SGI, X-Anim, Scitex
• Run time supports many file formats: QuickTime, AIFF, Wave, MPEG, AVI, MIDI

File format and run time

• Support many data formats
• JPEG/JFIF, GIF, BMP, PNG, Cinepak, MPEG, H.261, H.263
• AU, IMA, G.728, G.722, MPEG
• Has been implemented efficiently on many platforms: Macintosh, Windows 3.1, Windows 95, Windows NT, SGI, OS/2

QuickTime File Format

• Meta container for media data
• Consists of two distinct parts
• Media data
• Video frame, audio, etc.
• Media index (movie resource)
• Number and types of tracks
• Compression format
• Relationships between tracks

File format - Movie

• Temporal properties: Timescale, duration, default rate
• Copyright
• User data
• Application specific data
• Edit history, author, etc.
• One or more tracks

File format - Track

• Generic media streams
• Spatial properties: location, size, layer, compositing information, clipping
• Audio properties: volume, balance, spatial placement
• Edit list to sequence its media
• Language

File format - Track

• Alternates
• Indicates substitute tracks
• Choose one at run time to use
• Language
• Availability of decompressors
• Bandwidth

File format - Media

• Represents the sample data
• Each sample consists of
• Sample description
• Sample duration: Variable frame rate
• Data reference
• Sample offset and size

Media - Video and Sound

picture

Media - MPEG

picture

Media - Sample Descriptions

picture

Media - Data References

picture

Low bit rate media

• Text
• 3D
• Music/MIDI
• Sprite/Animation
• Tween

File format - Extensibility

• Media index is public
• Updates published regularly
• Adding an extension
• Anyone can add custom extensions
• Apple works with developers
• Avoid conflicting extensions
• Define extensions with the broadest possible applicability

Run time

• Create, modify, and play media
• Parallels the file format
• Built on a standard extension mechanism Ð components
• Registry of available services
• Isolates user of services from implementation
• Anyone can create a component

Run time - Media Handlers

• Implements the play back of a specific media type
• May use lower level components as part of the implementation
• Video or sound decompressors
• Music synthesizers

Run time - Data Handlers

• Provide access to media data for Media Handlers
• Data Reference format determined by Data Handler
• File path
• URL

Run time - Importers

• Convert data into QuickTime format
• Duplicate or process the data and create a QuickTime movie file
• Construct run time movie which references the original data (MPEG, Wave, AIFF, AVI)

Interactivity

• Deliver complete interactive experiences in a QuickTime movie
• QuickTime VR is a simple example
• Build on existing QuickTime ideas
• Extensible
• Public data and file formats
• Media structure distinct from media storage

Interactivity - Objects

• Define movie and track as objects
• Media type for interactive objects
• Sample corresponds to a scene
• Controls, text, windows, movies
• Media data stored independent of object definition
• Object accesses media data through data references

Interactivity - Behaviors

• Common behaviors are controlled by properties, not code
• Object dragging and resizing
• Animation
• Windows, sliders

Interactivity - Behaviors

• Object message handlers to customize behaviors
• Language and runtime independent
• Platform independent byte code (Q-code, Java, command stream, custom)
• Platform dependent code (68k, PowerPC, x86)

Interactivity - Video

• Overlay interactivity onto traditional QuickTime movies
• Stop points
• Reactions to clicks on characters in video

Scenario - Netscape Plugin

• Uses pure QuickTime movie
• Simulates streaming
• Movie must be self contained
• Also handles MPEG, Wave, AIFF
• Future version
• External data references
• Track alternates for data rate, media format, and language

Scenario - Multi-format

• Movie can reference data stored in a streaming format
• Backward compatible access
• No need to duplicate media data
• QuickTime movie file itself can be in streaming format
• Allows same file to be used by clients with varying capabilities

Scenario - Server

• Standard media container allows decisions to be made in generic manner
• Data rate
• Searching
• Server performs alternate selection
• Based on stored user profile cookie
• Fast to create media index
• Server could return only segments of movie based on request
• Smaller media index to transmit
• No need to store separate edited version
• spatial vs audio abstraction lets server make smart decisions for new media types
• Post processing

Scenario - Users

• Common data format everywhere
• Tools support
• Fast and easy to post media to server
• Can support streaming and non-streaming clients

Scenario - Packets

• Extension to store packet size of sample data: Done today by QuickTime Conferencing
• Ability to store progressive resolution data in separate tracks: Allow server or router to disregard higher resolution data

Scenario - Components

• QuickTime's extensibility mechanisms will make it possible to download extensions as needed to client
• Media Handlers
• Decompressors
• New interactive objects

Scenario - Beyond browsers

• The internet as a big hard disk
• Part of media local, part remote
• Combine data from several sites
• Very interesting with interactivity
• CD-ROM of base content
• Enhanced by live information from the internet

For more information

• Web Sites
• www.quicktime.apple.com
• www.quicktimefaq.org
• Email: hoddie@apple.com