fix: Unexpected persistent ducking when combining flutter_soloud with audio_session

[koenhagen]

Description

When using flutter_soloud together with audio_session, background audio (like Spotify) gets ducked continuously after activating the session, even when no sound is playing. I want to play short sounds occasionally and have other audio duck only during playback, similar to how apps like Strava or Google Maps behave.

Steps To Reproduce

1. Play audio in other app (e.g. Spotify)
2. Set up audio_session with

AudioSessionConfiguration(
          androidWillPauseWhenDucked: true,
          androidAudioAttributes: AndroidAudioAttributes(
            usage: AndroidAudioUsage.assistanceNavigationGuidance,
            contentType: AndroidAudioContentType.speech,
          ),
          androidAudioFocusGainType:
          AndroidAudioFocusGainType.gainTransientMayDuck,
          avAudioSessionCategory: AVAudioSessionCategory.playback,
          avAudioSessionCategoryOptions: AVAudioSessionCategoryOptions.duckOthers,
          avAudioSessionMode: AVAudioSessionMode.spokenAudio,
        )

2. Observe that background audio is ducked on app startup
3. Activate the session with setActive(true)
4. Play a sound using flutter_soloud
5. Observe that background audio remains ducked even after playback ends

Expected Behavior

Background audio should duck only during playback and return to normal once the sound finishes.

Additional Context

Tested on iOS with both flutter_soloud 3.3.4 and 3.1.12 (before audio_session support was introduced). I followed the example from audio_context.dart while changing the configuration. The goal is to play occasional sounds while respecting other audio sources.

I haven't tested the later versions of flutter_soloud on Android yet. I recall not having this issue there, but this presumably was before v3.2.1. That may or may not mean that behaviour differs depending on the device (or my configuration differs). Though I do not have an Android device to test this.

[koenhagen]

I just tested again on Android. Everything works how I want it. Background audio is ducked once I play something. When I just boot up the app it does not duck yet.

I can stop the ducking by calling await session.setActive(false); and turn it back on again when I call await session.setActive(true);. although I do not think that is the intended way, looking at the audio_session documentation.
This does not work on iOS. When I turn the session off and on it does not play soloud sound anymore.

[alnitak]

Hi @koenhagen,

there are other issues regarding the audio session on iOS. Unfortunately, I don't have an iPhone, and the simulator is not an option to try this. I was thinking this was somehow fixed in the other issues. Anyway, I have to wait for help from the community to fix this. Sorry.