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Inside Macintosh: Sound /


Chapter 2 - Sound Manager

This chapter describes the Sound Manager, the part of the Macintosh system software that controls the production and manipulation of sounds on Macintosh computers. You can use the Sound Manager to create a wide variety of sounds and to manipulate sounds in many ways. The Sound Manager is also used by other parts of the Macintosh system software that produce sounds, such as the Speech Manager and QuickTime.

To use this chapter, you should already be familiar with the information in the chapter "Introduction to Sound on the Macintosh" earlier in this book, especially with the portions of that chapter that describe the Macintosh sound architecture and the routines related to sound output. That chapter shows how your application can play a sound resource or a sound file synchronously (that is, with other processing suspended while the sound plays).

You should read this chapter if you need a greater degree of control over sound output than the routines described in that introductory chapter provide. For example, if you want to play sounds asynchronously or to exercise very fine control over the process of sound production, this chapter contains information you need.

This chapter begins by describing the capabilities of the Sound Manager and the role of sound commands and sound channels in producing sound. Then it explains how you can use the Sound Manager to

You're not likely to use all of these capabilities in a single application. In general, you should read the section "About the Sound Manager" and then turn to the parts of the section "Using the Sound Manager" that describe the features you want to use in your application. The section "Sound Storage Formats" beginning on page 2-73 explains in detail the format of sound resources and sound files. You can find a complete reference to the Sound Manager data structures and routines in the section "Sound Manager Reference" beginning on page 2-89.

IMPORTANT
This chapter describes the capabilities and programming interfaces of version 3.0 of the Sound Manager. See the chapter "Introduction to Sound on the Macintosh" for some information on how version 3.0 differs from earlier versions. The capabilities and performance of version 3.0 are significantly better than those of all previous Sound Manager versions, even though their programming interfaces are largely identical. This chapter occasionally warns you about techniques or routines that cannot be used in versions prior to 3.0, but it does not provide an exhaustive comparison of all available versions.

Chapter Contents
About the Sound Manager
Sound Data
Square-Wave Data
Wave-Table Data
Sampled-Sound Data
Sound Commands
Sound Channels
Sound Compression and Expansion
Using the Sound Manager
Managing Sound Channels
Allocating Sound Channels
Initializing Sound Channels
Releasing Sound Channels
Manipulating a Sound That Is Playing
Stopping Sound Channels
Pausing and Restarting Sound Channels
Synchronizing Sound Channels
Managing Sound Volumes
Obtaining Sound-Related Information
Obtaining Information About Available Sound Features
Obtaining Version Information
Testing for Multichannel Sound and Play-From-Disk Capabilities
Obtaining Information About a Single Sound Channel
Obtaining Information About All Sound Channels
Determining and Changing the Status of the System Alert Sound
Playing Notes
Installing Voices Into Channels
Looping a Sound Indefinitely
Playing Sounds Asynchronously
Using Callback Procedures
Synchronizing Sound With Other Actions
Managing an Asynchronous Play From Disk
Playing Selections
Managing Multiple Sound Channels
Parsing Sound Resources and Sound Files
Obtaining a Pointer to a Sound Header
Playing Sounds Using Low-Level Routines
Finding a Chunk in a Sound File
Compressing and Expanding Sounds
Using Double Buffers
Setting Up Double Buffers
Writing a Doubleback Procedure
Sound Storage Formats
Sound Resources
The Format 1 Sound Resource
The Format 2 Sound Resource
Sound Files
Chunk Organization and Data Types
The Form Chunk
The Format Version Chunk
The Common Chunk
The Sound Data Chunk
Format of Entire Sound Files
Sound Manager Reference
Constants
Gestalt Selector and Response Bits
Channel Initialization Parameters
Sound Command Numbers
Chunk IDs
Data Structures
Sound Command Records
Audio Selection Records
Sound Channel Status Records
Sound Manager Status Records
Sound Channel Records
Sound Header Records
Extended Sound Header Records
Compressed Sound Header Records
Sound Double Buffer Header Records
Sound Double Buffer Records
Chunk Headers
Form Chunks
Format Version Chunks
Common Chunks
Extended Common Chunks
Sound Data Chunks
Version Records
Leftover Blocks
State Blocks
Sound Manager Routines
Playing Sound Resources
Playing From Disk
Allocating and Releasing Sound Channels
Sending Commands to a Sound Channel
Obtaining Information
Controlling Volume Levels
Compressing and Expanding Audio Data
Managing Double Buffers
Performing Unsigned Fixed-Point Arithmetic
Linking Modifiers to Sound Channels
Application-Defined Routines
Completion Routines
Callback Procedures
Doubleback Procedures
Resources
The Sound Resource
Summary of the Sound Manager
Pascal Summary
Constants
Data Types
Sound Manager Routines
Application-Defined Routines
C Summary
Constants
Data Types
Sound Manager Routines
Application-Defined Routines
Assembly-Language Summary
Data Structures
Trap Macros
Result Codes

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© Apple Computer, Inc.
2 JUL 1996




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