[Alsa-user] Limited access to capture source

[c***@op.pl]

Hi all,

My need is:

Have a linux system (Debian) with automatic voice recording (when user log
in).
Users should not have impact on that process - do not mute mic, do not
change capture source nor recording level.
However audio playback should be unrestricted for all users.

Actually I use ffmpeg with alsa input but this solution blocks pulseaudio.
:(


Should it be done on alsa or pulseaudio level and how ?


Regards.
Tom.

[Clemens Ladisch]

Post by c***@op.pl
Have a linux system (Debian) with automatic voice recording (when user log
in).
Users should not have impact on that process - do not mute mic, do not
change capture source nor recording level.
However audio playback should be unrestricted for all users.

All mixer controls of a card are managed with a single device node
(/dev/snd/controlCx), so it is not possible to use file permissions for
this.

However, in your recording program (or a separate tool), you can call
snd_ctl_elem_lock() for all mixer controls that no other program should
be able to change.


Regards,
Clemens