The current audio level can be queried and set at the following url:
http://<address of your dreambox>/cgi-bin/audio
This will return the current audio level and an indication if the DreamBox is currently muted.
The output in a browser will look like:
The raw output looks like:
The value for volume ranges from 0 to 60 where 0 is the loudest and 60 equals mute.
Looking at the default webinterface of Enigma2, the volume bar at the top is divided into 10 blocks, thus each block represents an increase (or decrease) of 6 steps in volume.
The above volume bar represents a volume value of 18 since 7 of the 10 blocks are marked green. 10 out of 10 marked green = 0, 9 out of 10 = 6, 8 out of 10 = 12, 7 out of 10 = 18, etc.
Setting the sound volume is possible by adding the ?volume querystring parameter to the url, i.e.:
http://<address of your dreambox>/cgi-bin/audio?volume=30
Will set the volume of the DreamBox to 50% (since again it ranges from 0 to 60). The returned output will confirm the new volume setting:
To enable or disable mute you can append the ?mute querystring parameter to the url, i.e.:
http://<address of your dreambox>/cgi-bin/audio?mute=0
Providing mute=0 will disable mute (thus enable audio) and mute=1 will enable mute (thus disable audio). The returned output will again confirm the provided command: