Inside Macintosh: QuickTime Components /

Chapter 8 - Video Digitizer Components

This chapter discusses video digitizer components. Video digitizer components provide an interface for obtaining digitized video from an analog video source. In QuickTime, the typical client of a video digitizer component is a sequence grabber component (sequence grabber components are described in the chapter "Sequence Grabber Components" in this book). Sequence grabber components use the services of video digitizer components and image compressor components to create a simple interface for making and previewing movies. However, video digitizer components can also operate independently, placing video into a window.

IMPORTANT

Most applications never need to communicate directly with a video digitizer component. It is strongly advised that your application use the sequence grabber component instead; it isolates you from the myriad of details associated with video digitization.

This chapter has been divided into the following major sections:

• "About Video Digitizer Components" presents some general information about video digitizer components.
• "Using Video Digitizer Components" gives details on how you tell the digitizer where to put the data and how to control digitization. It describes a technique for improving performance.
• "Creating Video Digitizer Components" discusses how to create a video digitizer component.
• "Video Digitizer Components Reference" describes the constants, data structures, and functions associated with video digitizer components.
• "Summary of Video Digitizer Components" supplies a summary of the constants, data types, and functions associated with video digitizer components in C and in Pascal.

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Chapter Contents

About Video Digitizer Components

Types of Video Digitizer Components

Source Coordinate Systems

Using Video Digitizer Components

Specifying Destinations

Starting and Stopping the Digitizer

Multiple Buffering

Obtaining an Accurate Time of Frame Capture

Creating Video Digitizer Components

Component Type and Subtype Values

Required Functions

Optional Functions

Frame Grabbers Without Playthrough

Frame Grabbers With Hardware Playthrough

Key Color and Alpha Channel Devices

Compressed Source Devices

Video Digitizer Components Reference

Constants

Capability Flags

Current Flags

Data Types

The Digitizer Information Structure

The Buffer List Structure

The Buffer Structure

Video Digitizer Component Functions

Getting Information About Video Digitizer Components

Setting Source Characteristics

Selecting an Input Source

Setting Video Destinations

Controlling Compressed Source Devices

Controlling Digitization

Controlling Color

Controlling Analog Video

Selectively Displaying Video

Clipping

Utility Functions

Application-Defined Function

Summary of Video Digitizer Components

C Summary

Constants

Data Types

Video Digitizer Component Functions

Getting Information About Video Digitizer Components

Setting Source Characteristics

Selecting an Input Source

Setting Video Destinations

Controlling Compressed Source Devices

Controlling Digitization

Controlling Color

Controlling Analog Video

Selectively Displaying Video

Clipping

Utility Functions

Application-Defined Function

Pascal Summary

Constants

Data Types

Video Digitizer Component Routines

Getting Information About Video Digitizer Components

Setting Source Characteristics

Selecting an Input Source

Setting Video Destinations

Controlling Compressed Source Devices

Controlling Digitization

Controlling Color

Controlling Analog Video

Selectively Displaying Video

Clipping

Utility Functions

Application-Defined Routine

Result Codes