Subject: Re: [linux-audio-dev] alsamixer+ardour
From: Kai Vehmanen (kaiv_AT_wakkanet.fi)
Date: Thu Mar 08 2001 - 01:24:28 EET
Bit of a late answer...
On Fri, 2 Mar 2001, Frank Carmickle wrote:
>> so you're proposal is to create a software mixer, reading from the
>> inputs, delivering to the outputs, but via a gain stage, right ?
> Correct. Hopefully using ladspa realtime plugins also.
This is pretty close to the definition of ecasound. :) Most of the tasks
you are talking about are already possible with ecasound, and without any
modifications (just install the binaries :)). Let's see...
- input from highend soundcards (both ALSA and OSS are supported);
there are however few catches ... see below for details (*)
- adding effects (native, LADSPA plugins and presets (=combinations))
- controlling the processing with a console-frontend; the
default tool is a CLI based on GNU readline; allows
altering the effect parameters in realtime, start/stop/etc, editing
offline configurations, muting individual chains, etc
- a separate control API (ECI) is available with implementations
in C, C++ and Python --> it's very easy to write frontends for the
abovementioned CLI
(*) Now the problem in ecasound's highend soundcard support can be reduced
to one phrase: I don't have one. ;) So although ecasound does have basic
support in place (24/32bit, multichannel, floats,
uninterleaved/interleaved, etc, etc), I've been reluctant to do any
optimizations until the APIs have become stable. From Paul's experiences,
I'd say the biggest problems are:
- do the current ALSA drivers provide access to a subset
of all device channels? (now, using a single >10ch device
in ecasound is very impractical)
- if yes, is it efficient enough?
OSS drivers have a different approach, and they do provide access to
channel subsets, but the question of efficiency still remains. Now I have
thought about different solutions to this problem, but until I have solid
information about the whole problem area, I don't want to start any
optimizations.
So as a summary, you might be able to handle the whole thing with
ecasound, without any additional work (or little extra work if you want a
custom ncurses-UI for controlling the effects). But if you need to do
modifications, then starting from Ardour is probably best, as it is
without doubt the best Linux sw package for dealing with highend audio
gear...
PS First of all, you should definitely check the following web page:
http://www.wakkanet.fi/~kaiv/ecasound/Documentation/examples.html
... it's by far the best document for understanding what ecasound
is and whether it might suit your needs
-- . http://www.eca.cx ... [ audio software for linux ] /\ . . http://www.eca.cx/aivastus ... [ aivastus net radio ] /\ .
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