[alsa-devel] Softvol controls

Lennart Poettering mznyfn at 0pointer.de
Fri Nov 30 01:08:11 CET 2007

On Thu, 29.11.07 15:46, John Utz (john.utz at dmx.com) wrote:


> > > Check snd_ctl_elem_info_is_user().  All softvol controls are
> > > implemented as user elements.
> > 
> > Hmm, how am I supposed to get the snd_ctl_elem_info_t from a
> > snd_mixer_elem_t or snd_mixer_selem_id_t?
> > 
> > I figure there is no useful documentation or even example how this is
> > supposed to work? Hmm, is there any real documentation available which
> > describes the relation of ctl, hctl, mixer and smixer at all? For the
> > uninitated the whols structure looks overly complex and redundant.
> Here's my take on it....HTH
> dont hesitate to ask

Hu? Neither "snd_ctl_elem_info_t" nor "snd_ctl_elem_info_is_user()"
is even mentioned in your source code excerpt?

I know how to change volumes and stuff via the ALSA mixer API. What I
am looking for is a way to detect whether a mixer element is
implemented in softwaer only and thus doesn't influence your ouput
when you open a PCM device with "hw:0", "front:0", "surround51:0" and


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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