Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ames!claris!apple!desnoyer
From: desnoyer@Apple.COM (Peter Desnoyers)
Newsgroups: comp.sys.next
Subject: Re: Voice Mail Format -- I sure hope this isn't final.
Keywords: voice mail
Message-ID: <22078@apple.Apple.COM>
Date: 12 Dec 88 21:07:00 GMT
References: <19355@ames.arc.nasa.gov> <21949@apple.Apple.COM> <18109@agate.BERKELEY.EDU>
Distribution: na
Organization: Apple Computer Inc, Cupertino, CA
Lines: 55

In article <18109@agate.BERKELEY.EDU> izumi@violet.berkeley.edu (Izumi Ohzawa) writes:
>
>Are you sure that this is the format NeXT voice mail is transmitted
>over the net? 

I am sure that the file which I grabbed from the net and decoded is in
such a format. I didn't lie to you. Assuming that the person who posted
it is honest, yes, that is the format.

> I grabbed that file, and it was HUGE.
>At 8 kbytes/second of voice, I am not sure if anyone can tolerate
>the traffic.
>
Be real. Ten years ago people were saying that bit-mapped graphics
took an incredible amount of memory/storage/whatever and would never
catch on. Voice takes more bits than text. Any attempt to alter this
degrades voice quality and increases system complexity. In a local net
of workstations with large disks, it is not worth the trouble to
compress voice.

>A lot of foreign e-mail addressees pay  $$$ per kilobyte of
>messages RECEIVED and transmitted.  I think Japanese users pay
>something like $1.00/kilobyte.  That comes to $8/second!
>
Then don't send voice mail to Japan. You don't run NFS servers from
Japan, do you?

>Also, with straight PCM, the much touted DSP chip isn't necessary.

Yup. I bet it comes straight out of the codec.

>Surely, something like LPC (linear prediction coding) or PARCOR
>(I forgot what that stands for) can be implemented easily with
>the DSP chip.

It would be simple to convert to ADPCM, and cut the data size in half.
You wouldn't even need the DSP. Who knows, someone might do this in a
mail bridge. Unfortunately, the format does not seem to allow the type
of coding used to be specified, which seems to eliminate the
possibility of compressing voice mail when sent over expensive routes.

>
>Izumi Ohzawa
>izumi@violet.berkeley.edu
>...ucbvax!violet!izumi

Sorry I seem a bit testy in this posting. I'm sure that someone argued
once that you'd never get an automobile to market because it weighed
too much to go on a horse-drawn trailer. Or something like that. I
think email charges to Japan have about as much relevance to how you
would design a good voice-mail system as horse freight does to
automobiles. 

				Peter Desnoyers
				desnoyer@apple.com