From mboxrd@z Thu Jan  1 00:00:00 1970
From: Takashi Iwai <tiwai@suse.de>
Subject: Re: Set up buffers for individual channels?
Date: Wed, 09 Apr 2003 11:22:07 +0200
Sender: alsa-devel-admin@lists.sourceforge.net
Message-ID: <s5h8yukqb40.wl@alsa2.suse.de>
References: <1049752146.3e91f2525897f@webmail.nith.no>
	<s5hllylq93e.wl@alsa2.suse.de>
	<1049827096.3e9317183693a@webmail.nith.no>
Mime-Version: 1.0 (generated by SEMI 1.14.4 - "Hosorogi")
Content-Type: text/plain; charset=US-ASCII
Return-path: <alsa-devel-admin@lists.sourceforge.net>
In-Reply-To: <1049827096.3e9317183693a@webmail.nith.no>
Errors-To: alsa-devel-admin@lists.sourceforge.net
List-Help: <mailto:alsa-devel-request@lists.sourceforge.net?subject=help>
List-Post: <mailto:alsa-devel@lists.sourceforge.net>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/alsa-devel>,
	<mailto:alsa-devel-request@lists.sourceforge.net?subject=subscribe>
List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/alsa-devel>,
	<mailto:alsa-devel-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum=alsa-devel>
To: knuarv@nith.no
Cc: alsa-devel@lists.sourceforge.net
List-Id: alsa-devel@alsa-project.org

At Tue,  8 Apr 2003 20:38:16 +0200,
knuarv@nith.no wrote:
> 
> Quoting Takashi Iwai <tiwai@suse.de>:
> 
> > At Mon,  7 Apr 2003 23:49:06 +0200,
> > knuarv@nith.no wrote:
> > > 
> > > After browsing through the ASIO SDK I see that one can enable individual 
> > > channels of a card, and only enabled channels will have a buffer set up for
> > 
> > > them. Is there a similar way to specify the exact channels one wants to
> > access 
> > > using Alsa (instead of simply number of channels)? 
> > 
> > how about accessing via non-interleaved mode?
> >
> I'm experimenting with non-interleaved mmap now, but I can't say I understand 
> the workings of Alsa yet. From what I can see Alsa sets up memory areas for the 
> requested amount of channels (from 0 to 9 for instance), so I can choose myself 
> which buffers to actually use?

basically, you cannot give the buffer pointers from your side.
the buffer pointer will be given by the driver.

> I was thinking I could perhaps specify _which_ 
> channels I want to use, and get handed buffers for only those
> channels.

yes, in the case of non-interleaved mode, a single buffer will be
split for each channel.  so you can access them apparently as if they
are different buffers.

you can check aplay.c for the non-interleaved playback/recording
case.


ciao,

Takashi


-------------------------------------------------------
This sf.net email is sponsored by:ThinkGeek
Welcome to geek heaven.
http://thinkgeek.com/sf