Subject: [ecasound] support for multichannel cards (was: Re: problems with AM_PROG_LIBGTOOLS)
From: Kai Vehmanen (email@example.com)
Date: Tue May 02 2000 - 19:47:28 EEST
On Mon, 1 May 2000, Neil E. Klepeis wrote:
> ALSA apparently supports the Midiman Delta series of professional
> 24-bit/96kHz audio cards.
> But I remember reading something on the ALSA list that applications need
> to have a special kind of multi-channel capability (I don't remember
> exactly). Does, or will, ecasound work with the Delta Series?
At least in theory, all cards supported by ALSA can be used with ecasound.
Multiple channels and s24/s32 sample formats are supported (1.7.x). Only
big thing missing is handling of non-interleaved multichannel devices, but
as far as I know, all current multichannel drivers support interleaved
In real life, there are a few problems. First of all, I know some people
have done some testing, but as of now, I haven't received one solid report
that they have been able to use ecasound with Hammerfall, Midiman or other
ALSA-supported multichannel card. As I only have basic consumer cards
myself, I can only sit and wait.
Another problem is that you can't access individual channels of a
multichannel device. I know ALSA people are working on a set of plugins to
handle this, but now you are forced to use all the channels.... Ie:
ecasound -f:32,10,96000 -i alsa,0,0 -o test.wav
This will sample 32bit/10ch/96000Hz data from the dsp device and write the
output to a wav-file. And of course, that's quite a lot of data. You can
still access individual channels if you use ecasound's -erm and -erc
effects, but this is a bit impractical.
-- Kai Vehmanen <firstname.lastname@example.org> ---------------- CS, University of Turku . . audio software for linux ... http://www.eca.cx . . armchair-tunes mp3/wav/ra .. http://www.wakkanet.fi/sculpcave .
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