RPi Python Library Has Retro Chiptunes and Speech Covered

RPi Python Library Has Retro Chiptunes and Speech Covered

The classic SP0256-AL2 speech chip has featured a few times on these pages, and if you’ve not seen the actual part before, you almost certainly have heard the resulting audio output. The latest Python library from prolific retrocomputing enthusiast [Nick Bild] brings the joy of the old chip to the Raspberry Pi platform, with an added extra trick; support for the venerable AY-3-8910 sound generator as well.


The SP0256-AL2 chip generates vaguely recognisable speech using the allophone system. Allophones are kind of like small chunks of speech audio which when reproduced sequentially, result in intelligible phonemes that form the basis of speech. The chip requires an external device to feed it the allophones at a regular rate, which is the job of his Gi-Pi library.


This speech synthesis technology is based on Linear-predictive coding, which is used to implement a human vocal tract model. This is the same coding method utilized by the first generation of GSM digital mobile phones, implementing a system known as Full-Rate. Both an LPC encoder and an LPC decoder are present on the handset. The LPC encoder takes audio in from the user, breaks it into the tiny constituent parts of speech, and then simply sends a code representing the audio block, but not the actual audio. Obviously there are a few more parameters sent as we ..

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