To get the current volume value on Android in Unity without plugin you can use this c# script.
Thanks to the Java Native Interface.
You will get an integer between 0 and ?, 15, 13, 25, …
NB: Actually the max volume value depends of the OS version.
public int GetVolume ()
{
AndroidJavaObject currentActivity = unityPlayerClass.GetStatic ( "currentActivity" );
AndroidJavaObject packageManager = currentActivity.Call ( "getPackageManager" );
AndroidJavaObject context = currentActivity.Call ( "getApplicationContext" );
AndroidJavaClass audioManagerClass = new AndroidJavaClass ( "android.media.AudioManager" );
AndroidJavaClass contextClass = new AndroidJavaClass ( "android.content.Context" );
int AudioManager_STREAM_MUSIC = audioManagerClass.GetStatic<int> ( "STREAM_MUSIC" );
string Context_AUDIO_SERVICE = contextClass.GetStatic<string> ( "AUDIO_SERVICE" );
AndroidJavaObject audioService = context.Call<AndroidJavaObject> ( "getSystemService", Context_AUDIO_SERVICE );
return audioService.Call<int> ( "getStreamVolume", AudioManager_STREAM_MUSIC );
}
