Re: SP0250 data format

>At 09:50 AM 6/12/97 -0800, you wrote:
>The SP0256 was GI's formant synth version of the chip. They simply took the
>SP0250 added an internal ROM of LPC recorded formant phrases for 56(?)
>different parts of speech. Then instead of accessing full phrases, you
>accessed formants and strung them together to create phrases.

Seems like we've gone over this before... Anyway, this is the message from
Larry to me. (My quotes are double ">>", Larry's are ">")...

>>I have a kind-of trivia question for you. Since you've been doing voice
>>compression for quite a while I wonder if you ever ran across or knew
>>anything about the General Instruments SPO-250 "Orator" chip. The
>>SPO-256AL2 was their little phoneme synth that was used in quite a few
>>gizmo's of the early 80's (maybe the Intellivision Voice module I think),
>>but the Orator was used in some Sega Arcade games (like Star Trek) and
>>sounded *very* nice for the era. I assumed that it was some form of LPC
>>since the voices didn't really sound digitized like an ADPCM or something.
>>Very faint "robotic" overtones sometimes on vowels... Any thoughts?
>>
> I definitely remember the name and number, and I'm pretty sure that I've
>seen a spec sheet for it. The memories are faint (and not just about speech
>stuff!), but I think this was a formant synthesizer. The SP0256 was
>essentially the same part preprogrammed with a phoneme/allophone set. At
>the time, formant synthesizers were the clear favorites for doing
>text-to-speech. Conventional wisdom was that "they" would have the kinks
>worked out of TTS in short order and then there would be no need for voice
>coders- at least for playback-only systems. Co-incidentally, that was about
>the time one of my partners here started on his 8-year TTS research project
>at CNET in France. In spite of being one of the world's best systems at the
>time, neither it nor the others have ever really been good enough for the
>big time-- Michel refuses to touch the stuff now!
> Back to the 0250; the problem for formant synthesizers in that period was
>(the lack of) automatic formant tracking. As it happens, the most popular
>filter control parameters these days are line spectrum pairs (of
>frequencies- LSPs) which come pretty close to tracking what a shadetree
>like myself would consider to be formants, though this time around, no one
>pretends that there's a one-to-one relationship. Sorry-- got carried away
>there.....

That went over my head pretty fast, but maybe it's useful to others... ;-)

-Clay

Clayton N. Cowgill Engineering Manager
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/\ Diamond Multimedia Systems, Inc. clay@supra.com
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Received on Thu Jun 12 10:39:11 1997