Detect window focus state to mute automatically when starting audio

Source/diablo.cpp

@@ -1828,6 +1828,15 @@ void diablo_pause_game()
 bool GameWasAlreadyPaused = false;
 bool MinimizePaused = false;
 
+bool diablo_is_focused()
+{
+#ifndef USE_SDL1
+	return SDL_GetKeyboardFocus() == ghMainWnd;
+#else
+	return true;
+#endif
+}
+
 void diablo_focus_pause()
 {
 	if (!movie_playing && (gbIsMultiplayer || MinimizePaused)) {

Source/diablo.h

@@ -87,6 +87,7 @@ bool StartGame(bool bNewGame, bool bSinglePlayer);
 int DiabloMain(int argc, char **argv);
 bool TryIconCurs();
 void diablo_pause_game();
+bool diablo_is_focused();
 void diablo_focus_pause();
 void diablo_focus_unpause();
 bool PressEscKey();

Source/sound.cpp

@@ -255,6 +255,8 @@ void music_start(uint8_t nTrack)
 			}
 
 			music->setVolume(VolumeLogToLinear(sgOptions.Audio.nMusicVolume, VOLUME_MIN, VOLUME_MAX));
+			if (!diablo_is_focused())
+				music_mute();
 			if (!music->play(/*iterations=*/0)) {
 				LogError(LogCategory::Audio, "Aulib::Stream::play (from music_start): {}", SDL_GetError());
 				CleanupMusic();

Source/storm/storm_svid.cpp

@@ -266,6 +266,8 @@ bool SVidPlayBegin(const char *filename, int flags)
 		    std::make_unique<Aulib::ResamplerSpeex>(*sgOptions.Audio.resamplingQuality), /*closeRw=*/false);
 		const float volume = static_cast<float>(sgOptions.Audio.nSoundVolume - VOLUME_MIN) / -VOLUME_MIN;
 		SVidAudioStream->setVolume(volume);
+		if (!diablo_is_focused())
+			SVidMute();
 		if (!SVidAudioStream->open()) {
 			LogError(LogCategory::Audio, "Aulib::Stream::open (from SVidPlayBegin): {}", SDL_GetError());
 			SVidAudioStream = std::nullopt;