Talk:TI Extended BASIC

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[edit] Speech

How speech for games like "Parsec" was done was through the creation of LPC data strings. (LPC = Linear Predictive Coding). For "Parsec" a woman recorded the various speech segments as PCM digitized audio. Those audio files were then run through a program that analyzed them and created LPC data.

The LPC data commanded the speech synthesizer to adjust the ADSR or Attack, Delay, Sustain, Release, and other variables such as pitch and volume to synthesize a copy of the original recording.

This method of electronic speech was more complex than the speech used by various videogame consoles contemporary with the TI Home Computer. The Magnavox Odyssey^2 had a speech module with PCM digitized words and phonems on a ROM chip. The games that used speech merely accessed the audio samples in the speech module. The Mattel Intellivision's speech module was only a digital to analog converter which played back digitized audio samples stored in the ROM in the game cartridges. "Intellivoice" speech varied the audio bitrate on every word and often within the same word to save as much data space as possible. (Such extensive hand-optimization is the main reason there were so few games with speech for the Intellivision.)

TI's LPC method with a genuine speech synthesizer was able to create speech on the fly with better sound than the "canned" speech used by their computer and game console competition, while using a lot less memory space.

There's a way for an Extended BASIC program to send LPC data to the Speech Synthesizer, but first you need to have some LPC data... A Windows 3.1 LPC encoding program which was used internally by a company that used to make products using TI speech chips was released a year or two ago. I don't remember what the program was named, but it's been reported that it can be made to run in 32bit versions of Windows.