help with Digital Voice Card

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Article #21369

#21369

From: Thomas Scott
Date: Wed, 10 May 1989 23:10

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I am running the Digital Voice Card (DVC) from Computer Age Ltd on my PC and
need information about how to interpret the audio files it produces.

The DVC is a playback/record system that records audio on hard disk as a bit
stream, using one of the many variants of the Adaptive Delta Modulation (ADM)
technique.  The ADM technique produces very compact audio files but is not
very convenient for audio analysis.   For analysis, Pulse Code Modulated (PCM)
data is much more convenient.   In fact, the DVC takes audio data as PCM
but converts it on board to ADM using a Voice Processor chip that I
believe to be manufactured by Toshiba.  There are no part numbers on the
chip or in the documentation.

What I need is an algorithm (especially in the form of a C program) for
converting between the ADM and PCM just as the Voice Processor chip does. 

Can anyone help?

Thanks,

Tom Scott
EMAIL: {uunet!masscomp, rutgers, princeton}!petsd!pecnos!tom
PHONE: 201/758-7257

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!gatech!rutgers!att!mtune!petsd!tom
From: tom@petsd.UUCP (Thomas Scott)
Newsgroups: sci.electronics,comp.sys.ibm.pc
Subject: help with Digital Voice Card
Keywords: Voice Processor, ADM, PCM
Message-ID: <1551@petsd.UUCP>
Date: 10 May 89 23:10:31 GMT
Distribution: usa
Organization: Perkin-Elmer DSG, Tinton Falls, N.J.
Lines: 24