From: neideck@nestvx.enet.dec.com (Burkhard Neidecker-Lutz)
Subject: Re: DECstation audio/XMedia
Organization: CEC Karlsruhe
Date: Mon, 7 Sep 92 15:25:06 GMT

In article <28622@sophia.inria.fr> huitema@mitsou.inria.fr (Christian Huitema) writes:

>Hell, we wanted a simple analog/digital converter
>that would enable us to input output voice and we are delivered a "sound
>processing system" that cannot work without being intertwined with X-Window
>and MOTIF. 

Of course the audio software can be used without X and Motif if you wish
so, that is the whole point of using a separate audio server in the first
place. I agree that the toolkit that is shipped with XMedia Tools in Version
1.1 in fact *is* linked to X and Motif, forcing you to use the somewhat
clumsier Alib interface instead. But it certainly is doable and the
XMedia Tools Developers Kit certainly comes with complete sample programs
that do all of this (without X).

>We are trying to port some audio software on the
>Decstations, and are really dissatisfied with the overall philosophy of the
>"audio server" approach...

Well, let's see what SUN has to say about this (from the man page of audio(4)
on my SparcStation):

  FUTURE DIRECTIONS
     Workstation audio resources should be managed by a networked
     audio  server,  in  the  same  way that the video monitor is
     manipulated by a window system server.  For the time  being,
     we  encourage  you  to  write  your  programs  in  a modular
     fashion, isolating the audio device-specific  functions,  so
     that they may be easily ported to such an environment.

which is to say that even they see the shortcomings of using the /dev/audio
approach to things. Your reaction is similar to the shock that people get
when they move from a PC where you own the whole screen to a windowing
environment such as Windows or X11, where a lot of simple things (like
drawing a line) can become seemingly buried under a lot of surrounding
code. The lack of a X-independent toolkit admittedly is a shortcoming of
the current XMedia offering, but then SUN doesn't offer anything in that
space at all.

> The specs are not delivered with the hardware, and DEC suggest that
>we have to go through studying the "DEC multimedia architecture" before even
>trying to sing "Hello world" through the loudspeaker.

The specs are delivered with the XMedia Tools Developers kit (*not* the specs
of the hardware, the specs of programming with the audioserver, which is
the lowest supported programming interface, very much like /dev/audio
is the lowest supported programming interface on SUN's).

> Does anybody have the spec of the hardware interfaces (/dev/lofi), 
> or will we have to reverse engineer them?

Basically all that interface gives you is a way to map all of the
hardware registers of the audio hardware in your address space, doing
that is a lot harder than using the audioserver.

If you any specific questions regarding a solution to your particular
programming problem, you may ask in the biz.dec.xmedia newsgroup.


		Burkhard Neidecker-Lutz

Multimedia Engineering, CEC Karlsruhe	   EERP Portfolio Manager
Software Motion Pictures		   Multimedia Base Technology
Digital Equipment Corporation
neidecker@nestvx.enet.dec.com