After it finishes playing the first buffer, the Sound Manager switches buffers, and plays data in the second while refilling the first. This double buffering technique minimizes RAM usage at the expense of additional disk overhead. As a result, SndStartFilePlay is ideal for playing very large sounds. The disk overhead incurred when using SndStartFilePlay is relatively light, and most mass-storage devices currently available for Macintosh computers have response times that are good enough that SndStartFilePlay can retrieve audio data from disk and play a sound without audible gaps. On machines with sufficient CPU resources, several continuous playbacks can occur at once.
Disk fragmentation can affect the performance of playing sampled-sound files from disk.
In addition, playing multiple sounds from the same hard disk may degrade overall performance. The Sound Manager currently supports continuous play from disk only on certain Macintosh computers. You should use the Gestalt function to determine whether a specific machine supports play from disk. Also, if a sound channel is being used for continuous play from disk, then no other sound commands can be sent to that channel. Inc. All rights reserved.