Re: Build-in mixer

[Takashi Iwai <tiwai@suse.de>]

At Wed, 08 Oct 2003 07:24:16 -0400,
Paul Davis wrote:
> 
> >I don't know, if the term "mixer" is used correctly, because i am not 
> >expert on it. I have in mind to use ALSA by more than one programs at 
> >the same time (simultaneously), and ALSA itself should mix these audio 
> >streams to one and play it via soundcard.
> 
> just so you know, although this functionality is certain desired by
> many, its not the way that some users want things to work. as a
> result, ALSA makes this possible, but it doesn't do it by default. Put
> another way, it provides a mechanism to do this, but doesn't enforce
> it as a policy.
> 
> >I tried dmix plug-in together with aplay -Dplug:dmix simultaneously from 
> >  two consoles and it works sufficiently (well, "underun!!! (at least 
> >...ms long)" message was there but i don't know, if is is serious bug or 
> >not). I thing that it should work transparently without special swithes 
> >or settings separately for each application or its instance, but i don't 
> >know if it is possible or not.
> 
> the dmix plugin is indeed the way to do this. what you need to do (or
> perhaps ALSA needs to by default) is to set up your ~/.asoundrc so
> that the default device is a dmix configuration.
> 
> all ALSA applications should accept options from the user specifying
> which PCM (or MIDI or ...) device they should open, and they fall back
> to "default" if none is specified. consequently, with this
> configuration setup, you'd get what you are hoping for, but other
> people could still use "hw:1" or specific named devices when they
> don't want dmix to get in the way (e.g. professional audio users).
> 
> unfortunately, i don't know how to write an ~/.asoundrc file that
> would do that :( somebody will, though.

it's becoming an FAQ... :)

pcm.!default {
	type plug
	slave.pcm "dmix"
}

the point is '!' prefix, which means overriding the existing
definition.


Takashi


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