Buffer Basics

When DirectSound is initialized, it automatically creates and manages a primary buffer for mixing sounds and sending them to the output device.

Your application must create at least one secondary sound buffer for storing and playing individual sounds. For more information on how to do this, see Creating Secondary Buffers.

A secondary buffer can exist throughout the life of an application or it can be destroyed when no longer needed. It can contain a single sound that is to be played repeatedly, such as a sound effect in a game, or it can be filled with new data from time to time. The application can play a sound stored in a secondary buffer as a single event or as a looping sound that plays continuously. Secondary buffers can also be used to stream data, in cases where a sound file contains more data than can conveniently be stored in memory.

Buffers can be located either in hardware or in software. Hardware buffers are mixed by the sound card processor, and software buffers are mixed by the CPU. Software buffer data is always in system memory; hardware buffer data can be in system memory or, if the application requests it and resources are available, in on-board memory. For more information, see Dynamic Voice Management and Hardware Acceleration on ISA and PCI Cards.

You mix sounds from different secondary buffers simply by playing them at the same time. Any number of secondary buffers can be played at one time, up to the limits of available processing power.