Explanation of the Concepts

As has been discussed in detail in the previous section, to create audio on a computer is merely to fill a buffer with numbers that represent the displacement of a speaker cone with respect to rest. Actually sending those numbers to the speaker to produce actual audible sound is a separate and complicated issue. A programmer usually does not have direct programatic access to the hardware that controls the speakers. Usually the operating system alone can communicate directly with the speakers, so to get sound out in real-time a programmer must give his precious buffer to the operating system. How this happens, of course, depends on the operating system. Details on how this works for different systems will be given in the appendix. For the most part, however, this book strives to be as platform-independent as possible. For this reason, we will content ourselves to write our sound buffers to disk in the form of Audio-IFF files, and let someone else's software be responsible for sending it to the speakers. While the aiff specification was designed by Apple Computers, the format is popular enough that nearly all computers can play them. Furthermore, the file format has not changed significantly since its creation over 20 years ago, and does not show signs of needing major amendments any time soon.

This file creates a 3 second audio buffer and an empty AIFF file. It then iterates over the contents of the buffer, one frame at a time. As this is just a template, the program does not actually do anything as it iterates over the buffer. An actual program would fill the buffer with valid samples as it iterates. The buffer is then attached to the AIFF file, which is subsequently saved. This is the basic pattern for almost all of the examples in this book, so a clear understanding of this template will facilitate understanding of the more complex examples.