To mute and unmute sound I successfully use the following command in the terminal (as root):
amixer -D pulse set Master 1+ toggle
But it's not working if I trigger this command via PHP (shell_exec) as user www-data. I get the error:
ALSA lib pulse.c:242:(pulse_connect) PulseAudio: Unable to connect: Connection refused
amixer: Mixer attach pulse error: Connection refused
This probably has to do with user rights, but I can't figure out how to grant these rights to user www-data, can you help?
Additional info from pactl info:
pi@raspberrypi:~ $ pactl info
Server-Zeichenkette: /run/user/1000/pulse/native
Bibliotheks-Protokollversion: 34
Server-Protokollversion: 34
ist lokal: ja
Client-Index: 32
Tile-Größe: 65496
Name des Benutzers: pi
Rechnername: raspberrypi
Name des Servers: pulseaudio
Version des Servers: 14.2
Standard-Abtastwert-Angabe: s16le 2ch 44100Hz
Standard-Kanal-Zuordnung: front-left,front-right
Standard-Ziel: alsa_output.usb-Generic_USB2.0_Device_20130100ph0-00.analog-stere o
Standard-Quelle: alsa_output.usb-Generic_USB2.0_Device_20130100ph0-00.analog-ste reo.monitor
Cookie: 249b:a636
pi@raspberrypi:~ $ stat /run/user/1000/pulse/native
Datei: /run/user/1000/pulse/native
Größe: 0 Blöcke: 0 EA Block: 4096 Socket
Gerät: 20h/32d Inode: 33 Verknüpfungen: 1
Zugriff: (0666/srw-rw-rw-) Uid: ( 1000/ pi) Gid: ( 1000/ pi)
Zugriff: 2021-11-14 11:34:40.192044159 +0100
Modifiziert: 2021-11-12 15:33:34.489999995 +0100
Geändert: 2021-11-12 15:33:34.489999995 +0100
Geburt: -
I finally solved it with the help of Eli Billauer's tech blog: http://billauer.co.il/blog/2014/01/pa-multiple-users/
For more details visit his blog post.
In short, the steps are:
To do as the desktop’s user (in my case 'pi') copy /etc/pulse/default.pa into a file with the same name in the .pulse directory, that is
cp /etc/pulse/default.pa ~/.pulse/
And then edit the file, adding the following line at the end:
load-module module-native-protocol-tcp auth-ip-acl=127.0.0.1
At this point, restart the pulseaudio deamon,
$ pulseaudio -k
$ pulseaudio -D
To do as "www-data" user Now switch to the second user (www-data), and create a file named client.conf under that user’s .pulse subdirectory (I had to create that. in www-data's 'home' direction which is /var/www/)
$ echo "default-server = 127.0.0.1" > ~/.pulse/client.conf
Note that default.pa and client.conf are in completely different directories, each belonging to a different user!