From: raymondu@terapin.com (Raymond Ulibarri)
Newsgroups: comp.sys.amiga.multimedia
Subject: Re: Read Music CD Data with CDTV?
Date: 3 Oct 92 21:29:52 PST
Organization: BBS

In article <1992Oct2.110142.1109@usage.csd.unsw.OZ.AU>,
amiga@spectrum.cs.unsw.oz.au (Amiga Utilities) writes:
>In article <04101.AA04101@digitm.UUCP> steed@digitm.UUCP (Steed Kulka) writes:
>>
>>In article <1992Sep25.004949.16407@coli.uni-sb.de> fritsch@fsinfo.cs.uni-
>>sb.de (Lothar Fritsch) writes:
>>
>>>My question  is now: is it possible to to some kind of
>>>raw read to an audio CD that is in the CDTV?
>>
>>CD-DA tracks can't be sent to the CDTV RAM. The audio and the computer
>>subsystems are two separate entities, for copyright reasons.
>
>Bummer. But I think there might be a way of hacking it. After all the
>data from the CD-ROM must get to the CPU somehow in order to execute
>the code that is stored there. I am not saying that CD-DA goes the
>same way, but there must be a register somewhere in there that tells
>the disc subsystem where to throw it's data.
>
>Now, from the docs that I have the disc sub-system spews the data at
>the cpu at ~170K/s. The data comes in bursts, about 3ms(?) apart. Now,
>that leads me to an assumption that somewhere in there hides the
>error correction that the machine performs. But wait, there's more...
>It also says in these magic books that there is a buffer which is
>split into three parts: Raw data, Data being corrected and the end
>product.
>
>Hell, if CBM will give me enough info to bash the hardware or provide
>some device calls to gimme enough control over what I'm getting from
>the disc, I will write a PD utility to take samples from the CD.
>
>>>That would be much easier and of a much better qualitiy than sampling the
>>>sound via audio output and sampler.
>
>Ofcourse it would be, it would also be a very sensible way of doing
>it since you can finetune your timing.
>
>>Even if you could directly read DA tracks into memory, you'd get something
>>different from the usual Amiga raw audio data.
>>
>>Steed Kulka @ Digiteam Srl
>>"Sure I'm drunk - do you think I program this way all the time?"
>
>As if it was hard to convert that to 8-bit samples. At the simplest
>level you could just take the upper byte from the word stored on CD.
>If you want to get sophisticated you can always do some processing
>of the sound. Chances are that you will want to down-sample the data
>from 41kHz down to about 18kHz, but all of that isn't that much work.
>
>                       Peter.

CDTV sound _CAN_ be controlled.  Scala Multimedia does it via its EX control
modules.  An excerpt from the ScalaMM manual:
   "Scala Multimedia supports the most common file formats, IFF sample for
playinf "raw" sampled sound, SMUS, SoundTracker (MODs), DSS (GVP) modules.
   The Amiga sound chip lets you add sound to your scripts without buying lots
of extra hardware and software.  The internal sound chip currently offers only
8-bit [sound] resolution, which may not be sufficient for professionals.  For
better sound quality, use an external MIDI sampler and control it with the MIDI
EX, or conrtol a Commodore CDTV with the CDTV EX."

   The CDTV connects to your Amiga via a null modem cable, and both the Amiga
and CDTV run Scala at the same time.

   For more information about ScalaMM200 and its CDTV control, call Scala, Inc.
at (703) 709-8242.


Raymond Ulibarri
Vice President
MultiCon
Multimedia Concepts
(510)261-1001
Xref: sparky comp.sys.amiga.multimedia:1335 comp.sys.amiga.hardware:16459