[fpc-pascal] SPDIF

[Christophe Fantoni]

Hello Mark,

In fact, my project is an hardware decoder, based on PC architecture for the
moment (with motherboard and power fanless). I have created my own audio
format with lossless compression (3:1) and I would like to build an hardware
decoder to connect him between my DVD player and my amplifier. I use the CD
Audio structure, like CD-AC3 or CD-DTS, but with my own format in each track
and not with the PCM structure. I can only use digital input and output to
detect and decode my own audio stream, or maybe to detect and bypass audio
stream like MPEG-2 multichannel, AC3 or DTS. I can build easilly hardware
A/D converter or D/A converter. Maybe, if I mix my two channels in the right
channel, "format" my stream in SPDIF structure, and installing an hardware
A/D converter after the analog right output, do you you think I can
virtually transform the analog right output in pseudo-SPDIF output ?

Many thanks,

Christophe Fantoni
French Technical Writer

----- Original Message -----
From: "Marc Santhoff" <M.Santhoff at t-online.de>
To: "FPC-Pascal users discussions" <fpc-pascal at lists.freepascal.org>
Sent: Friday, January 28, 2005 4:23 PM
Subject: Re: [fpc-pascal] SPDIF


> Am Fr, den 28.01.2005 schrieb Christophe Fantoni um 15:13:
> > Hello again,
> >
> > I have found many pascal sources to interface the Sound Blaster
compatible
> > drivers, but only for the analog output/input. Nothing for the SPDIF or
> > optical input/output. With sound card like SB Live! or SB Audigy, the
DOS
> > driver to interface DOS program exist... like the SPDIF input/output.
But no
> > program to use it (maybe DOS is too old, and programmers don't support
this
> > new feature in their old program)
> > For me, the problem is to found the technicals informations explain how
to
> > include the digital output structure in the analog ouput sources coded
in
> > Pascal. For example, the SoundLib 2 library in
> >
http://www.crossfire-designs.de/index.php?lang=en&what=sourcecode&name=sl2.h
> > tm , compatible vith FPC, Delphi and BP7, car easilly input and output
sound
> > stream but only in an analog way. No informations in the pascal code
souce
> > to structure and activate the digital input/output... Under Windows,
this
> > problem doesn't exist. Normal, the analog and digital input/out is
managed
> > by the Windows driver, and maybe by DirectX. But under DOS, the problem
is
> > not the same.
>
> I think (and would like to know, too) using a digital output makes no
> difference on the software side. The only matter is to switch to the
> right output.
>
> If you look at it, you're writing out bytes to the analog output. This
> output is some form of D/A-converter for analog signals and nothing but
> a driver for digital signals.
>
> So, if you use the right enconding for sending your sound data stream
> (this may require some software) and switched the soundcard to the SPDIF
> out then anything should work.
>
> HTH,
> Marc
>
>
>
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