SetVol 4.0 includes a new feature to allows you to set the audio playback levels of applications running on Windows.
For this, there is a new command line option called 'appaudio'.
So, for example, if you are running the Spotify Windows app and you want to set its volume to 35 percent, you can now use:
setvol 35 appaudio Spotify
You can also use relative values (for example +10 and -5). As well the SetVol 'over' feature works with the appaudio option allowing you to smoothly transition the audio change over time.
A few additional notes:
1. the target application that you want to set the audio level for must be running at the time you issue the SetVol command
2. in my testing I found that Spotify had to be actually playing something so that SetVol could change its audio levels. However VLC only had to be running. So I guess this is going to be hit and miss based on how the target application is designed.
3. it is also possible to run multiple instances of some applications, but not others, on Windows. This is a completely a function of the target application. For example you can run multiple instances of VLC at that same time, but you can't do that with Spotifiy. In any case, if multiple instances of the same app are running, the SetVol command you enter to change the audio level for that applications will be applied to all instances.
4. Internal volume controls within the app my not be automatically adjusted if the audio level is changed by SetVol. Again, this is a function of the target application. Regardless the audio levels you hear should be change as expected based on what you have told SetVol to do.
5. if you want to list all the running applications which SetVol can change the audio levels for, you can use the command
setvol appaudio
6. as with devices, the volume levels you set for an app will survive a reboot.
Also, with version 4.0, there is a new command line option 'debug' which allows for additional diagnostic details to be shown in SetVol's output