From alsa-devel-owner@alsa.jcu.cz  Fri Dec  4 11:06:39 1998
Received: from entry.jcu.cz (IDENT:perex@entry.jcu.cz [160.217.1.111])
	by marvin.jcu.cz (8.9.1a/8.9.1) with SMTP id LAA31231;
	Fri, 4 Dec 1998 11:04:23 +0100
Date: Fri, 4 Dec 1998 11:04:23 +0100 (CET)
From: Jaroslav Kysela <perex@jcu.cz>
To: Kenneth Crudup <kenny@panix.com>
cc: alsa-devel@alsa.jcu.cz
Subject: Re: Alsa development questions
In-Reply-To: <199812040120.UAA12557@panix2.panix.com>
Message-ID: <Pine.LNX.3.96.981204105840.28631C-100000@entry.jcu.cz>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Reply-To: alsa-devel@alsa.jcu.cz
Sender: alsa-devel-owner@alsa.jcu.cz
Precedence: list

On Thu, 3 Dec 1998, Kenneth Crudup wrote:

> 
>   Better documentation is on the way and I'm ready answer some questions.
> 
> Good, 'cause now that I have the time to really get onto the Maestro-2
> driver (with AK4540 AC-97 codec, which should be a drop-in, if I'm
> understanding all this correctly), I've got *lots* of questions.
> 
> For instance, the codec on my machine takes 16-20 bit, 48KHz samples, which
> means that it *always* expects that data rate. I guess this means that if
> I had 48K, stereo samples in memory, that I could just hand them off to
> the codec, and not use the sound chip at all (except as a transfer device)?

I mean questions about ALSA driver internals, not how is soundcard
working. I'm sorry, but soundcard's hardware is different and you have
probably data-sheet which describes transfers from/to OS memory.

If you have PCI soundcard with AC'97 codec - yes, sound chip does only
transfer samples to codec D/A or from A/D converters and sample
rate/format conversion.

ALSA doesn't have support for 16-bit plus sample wide, but I'll add this
support to PCM routines in near future, but I still don't know these
things:

1) how is 16-bit plus samples stored in PCM stream (endian, bytes etc..)
2) exact list of used wides (18,20,24,32 ?)

							Jaroslav

-----
Jaroslav Kysela <perex@jcu.cz>
Academic Computer Centre, University of South Bohemia
Branisovska 31, C. Budejovice, CZ-370 05 Czech Republic


