[sci.electronics] u-Law/A-Law to ADPCM?

brian@ucsd.Edu (Brian Kantor) (06/30/91)

I'm about to embark on a project in digitized speech for telemetry, and
it would be most convenient for me to be able to record and edit the
speech on a sun Sparcstation.

The Sun has an AM79C30 ISDN chip in it, which samples the audio at 8kHz
and produces 8-bit samples using u-law or A-law compression.

The device that will reproduce the sound is one of those nifty OKI
speech chips that also uses samples at 8 kHz, but wants to see 4-bit
ADPCM data in the ROM.

To save me some work, does anyone have a program or handy algorithm to
convert the sparc audio samples to 4-bit ADPCM?
	- Brian