Information Wanted on CCITT 32-kb/s ADPCM Algorithm

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2 total messages Started by Tom Scott Wed, 01 Aug 1990 19:22

#893

Author: Tom Scott
Date: Wed, 01 Aug 1990 19:22

12 lines
1051 bytes

I'm interested in an algorithm for converting between PCM (pulse code 
modulation) and ADPCM (adaptive differential pulse code modulation). 
The system I'm using has a commercial chip, that I believe is made by Toshiba,
to digitize and encode voice and I need to know the algorithm so that I can
write software to decode its output for voice analysis.

My guess is that the chip implements CCITT's standards 32-kb/s ADPCM
algorithm but don't know what this algorithm is.  Help is appreciated.

Tom Scott
tscott@westford.ccur.com

Re: Information Wanted on CCITT 32-kb/s ADPCM Algorithm

#895

Author: Chip Rosenthal
Date: Thu, 02 Aug 1990 01:40

15 lines
1203 bytes

In article <36771@masscomp.ccur.com>
	tscott@westford.ccur.com (Tom Scott) writes:
>My guess is that the chip implements CCITT's standards 32-kb/s ADPCM
>algorithm but don't know what this algorithm is.  Help is appreciated.

If the Toshiba chip does indeed implement the standard ADPCM algorithm,
it would be specified in G.721.  (BTW...even if it is G.721, you need to
know which one -- there were two.)  You can get the CCITT fasciles through
a place like Omnicom, but they are expensive.  A good engineering library
should have them as well.

-- 
Chip Rosenthal                            |  You aren't some icon carved out
chip@chinacat.Unicom.COM                  |  of soap, sent down here to clean
Unicom Systems Development, 512-482-8260  |  up my reputation.  -John Hiatt

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