I’ve been trying to get some sounds into our game lately, but I have encountered some problems with this on Android devices. On Android, there are two kinds of volume for audio: ring tone volume and media volume.
Normally when apps use audio, when you press the volume buttons on your phone, you can change the media volume.
When I run my app, and press volume buttons, the ring tone volume changes. When a sound effect is currently playing, the media volume changes. But it would be better, if the media volume would change all the time. Maybe you could consider this for your engine?
But there have been some other problems too. I use WAV files for my game, with 44kHz and 1411 kBit/s. These should work on Android, because there’s no error message in the log output. (When I use some other formats like 8kHz the LogCat prints error messages). But for some reason it seems the sounds are played with volume 0, although the media volume is set to full, and settings.soundEnabled is set to true. I actually fixed this problem by “volume: 1” for the Sound element, but without this it didn’t work.
Also a general question: What WAV format is the best for mobile/V-Play applications?