AGI Sound Tutorial - Introduction
Written by Lance Ewing from the Unofficial AGI Specifications:
Most people who think of AGI games remember that they played their music and sounds over the PC speaker. What they may not know is that all sounds in the MS-DOS, Tandy and Macintosh versions are composed of four parts, one which is the melody, two which are accompaniment, and the final one being noise. The IBM PC can only play one note at a time so all AGI games for the PC play the melody by itself. The Apple IIgs version has much more sophisticated sound: 16 channel wavetable based MIDI songs for the soundtracks, and digitally sampled PCM sound effects.According to Donald B. Trivette, author of The Official Book of King's Quest, a year before the IBM PCjr was announced IBM asked Sierra to create a game that would show off the new computers color graphics capabilities. IBM supplied the company with a prototype Junior, and Roberta set to work designing a new type of adventure game. The game produced was called King's Quest. This is important because the IBM PCjr had a different method of sound generation than the IBM compatibles of today. The sound data was stored to make it easy to send to the Juniors sound generators. This format appears to have remained right through the AGI games up until 1989--90 when SCI took over even though the PCjr had long since been surpassed by the 286, and 386.
Historically, the AGI development community hasn't had much luck with sound. Some of the tools available have been tricky to use and other people have had problems actually trying to get some music to work. Because of this, there have been a lot of people asking questions and being told that no tutorial was available. The reason why there is so many ways to do things is because there's no one correct tool for the job, so hopefully this entire document will be helpful.
The aim here is to try and get a comprehensive document on the use of AGI sound together to answer any question somebody asks on AGI sound.
First the document will mention the limitations of the AGI sound format. For creation of sounds, information on extraction, conversion and editing will follow. After that you'll want to know how to play the sounds or insert them in your game (because if you've made a sound, you'll want to know how to test it). Finally, I'll mention what might be happening with sound in the future.
This document does not go into the Apple IIgs AGI interpreter, which supported MIDI and PCM effects. This mainly documents the sound format used by the PC, Apple and Amiga.
If this is the first document you've read on AGI, it might be helpful to read a few other tutorials explaining what AGI is, how to program in the logic code and basically how to put a quick game together. There are many other links to tutorials on this site if you wish to have a look.
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