Volume buttons default to changing "Music" level; should default to changing current app's volume level

[e-t-l]

When using this app, if I press a hardware volume key, this app's popup shows that it changes the volume level for the global "Music" audio channel. It does this even if there is no music or media playing on the device.

Based on the description of this app, the expected behavior is that pressing the volume buttons would change the volume level for the current app (i.e. whatever app is in the foreground). Instead, what users have to do is press a volume button to bring up the overlay, then manually adjust the slider level for the current app.

The desired behavior would be, for example: If Google Maps is the current foreground app, then pressing a volume button would change the volume level for Google Maps only; then if I switch to a different app like Firefox and press a volume button, it changes the volume setting for Firefox only. If a different app has device Audio Focus (like a music player or phone call), then it would change the volume level for that app only.

This behavior would also benefit #3; if this app defaults to changing the volume level of the foreground app, it is less important to have access to all the different apps' volume sliders in the overlay. (After all, how often do you need to change the volume level of an app that is not currently playing audio?)

[yume-chan]

it changes the volume level for the global "Music" audio channel.

It changes the "suggested" stream volume as the buttons originally does. That's the call volume if you are in a phone call, or voice assistant volume if the assistant is talking, otherwise it's the media volume.

In fact, we don't (and can't) know which stream is the "suggested" one, we just call a method called adjustSuggestedStreamVolume

It does this even if there is no music or media playing on the device.

What do you suggest it to do in this case?

the expected behavior is that pressing the volume buttons would change the volume level for the current app

Sounds good, but what if the foreground app doesn't play any audio, or if the foreground app (like a game) and a background app (like a music player) both plays audio, or even if multiple media players all have audio focuses at the same time (yes Android supports multiple audio focus)?

[e-t-l]

otherwise it's the media volume

Yeah, that's the behavior that should probably be different. It should change the current (foreground) app's volume.

It does this even if there is no music or media playing on the device.

What do you suggest it to do in this case?

Like I said in the original issue, it should default to changing the current app's volume level, not the global "media" level.

what if the foreground app doesn't play any audio, or if the foreground app (like a game) and a background app (like a music player) both plays audio, or even if multiple media players all have audio focuses at the same time (yes Android supports Genymobile/scrcpy#5965 (comment))?

Oh cool, I was unaware there could be multiple audio focus. Before I start describing my suggested solution to those scenarios, I want to point out that the VolumeManager's current implementation doesn't solve any of them. The current behavior, where it only adjusts the global media stream and requires the user to manually adjust per-app volume in all scenarios, is the least useful implementation possible.

I still believe that it should adjust the volume for the app that is currently playing audio, and if there is none, then it should adjust the foreground app's volume.

• If the foreground app doesn't play audio, and there is no audio currently playing, then it doesn't matter. In this case, the user would be intending to adjust some other volume channel manually anyway.
• If multiple apps are playing audio, change the volume levels for those apps. If the user had intended to only change one of them, again, that is an adjustment they would have to perform manually regardless.

[yume-chan]

Tried this idea but doesn't really work.

When foreground app is playing audio, volume button only changes foreground app volume: It may happen that the foreground app’s volume is already at maximum, but because the system volume is too low, the sound is still very quiet.

If also change system volume after foreground app volume reaches max: if system volume overshot, can't change it back because volume down button will turn down foreground app volume first

Unless make it reversable: volume up button first changes foreground app volume, then system volume; volume down button first changes system volume until the original value, then change foreground app volume: too complex and too hard to understand