Stop sources immediately when the sound is forced to stop

The reason for the previous delay was to allow OpenAL Soft to fade the sound to
silence and avoid a sudden amplitude change, which can cause a "click" or "pop"
noise. However, with OpenAL Soft 1.20, this is a built-in feature of the mixer
so the extra complexity is unnecessary.

src/sound/backend/oalsound.cpp

@@ -185,7 +185,7 @@ class OpenALSoundStream : public SoundStream
 		if(Renderer->FreeSfx.Size() == 0)
 		{
 			FSoundChan *lowest = Renderer->FindLowestChannel();
-			if(lowest) Renderer->ForceStopChannel(lowest);
+			if(lowest) Renderer->StopChannel(lowest);
 
 			if(Renderer->FreeSfx.Size() == 0)
 				return false;
@@ -667,14 +667,6 @@ OpenALSoundRenderer::OpenALSoundRenderer()
 		return;
 	}
 
-	ALCint refresh=0;
-	alcGetIntegerv(Device, ALC_REFRESH, 1, &refresh);
-	if(refresh > 0)
-	{
-		// Round up instead of down
-		UpdateTimeMS = (1000+refresh-1) / refresh;
-	}
-
 	ALCint numMono=0, numStereo=0;
 	alcGetIntegerv(Device, ALC_MONO_SOURCES, 1, &numMono);
 	alcGetIntegerv(Device, ALC_STEREO_SOURCES, 1, &numStereo);
@@ -1212,7 +1204,7 @@ void OpenALSoundRenderer::UnloadSound(SoundHandle sfx)
 			if((ALuint)bufID == buffer)
 			{
 				FSoundChan *next = schan->NextChan;
-				ForceStopChannel(schan);
+				StopChannel(schan);
 				schan = next;
 				continue;
 			}
@@ -1220,20 +1212,6 @@ void OpenALSoundRenderer::UnloadSound(SoundHandle sfx)
 		schan = schan->NextChan;
 	}
 
-	// Make sure to kill any currently fading sounds too
-	for(auto iter = FadingSources.begin();iter != FadingSources.end();)
-	{
-		ALint bufID = 0;
-		alGetSourcei(iter->first, AL_BUFFER, &bufID);
-		if(static_cast<ALuint>(bufID) == buffer)
-		{
-			FreeSource(iter->first);
-			iter = FadingSources.erase(iter);
-		}
-		else
-			++iter;
-	}
-
 	alDeleteBuffers(1, &buffer);
 	getALError();
 }
@@ -1257,7 +1235,7 @@ FISoundChannel *OpenALSoundRenderer::StartSound(SoundHandle sfx, float vol, int
 	if(FreeSfx.Size() == 0)
 	{
 		FSoundChan *lowest = FindLowestChannel();
-		if(lowest) ForceStopChannel(lowest);
+		if(lowest) StopChannel(lowest);
 
 		if(FreeSfx.Size() == 0)
 			return NULL;
@@ -1363,7 +1341,7 @@ FISoundChannel *OpenALSoundRenderer::StartSound3D(SoundHandle sfx, SoundListener
 		{
 			if(lowest->Priority < priority || (lowest->Priority == priority &&
 			                                   lowest->DistanceSqr > dist_sqr))
-				ForceStopChannel(lowest);
+				StopChannel(lowest);
 		}
 		if(FreeSfx.Size() == 0)
 			return NULL;
@@ -1566,8 +1544,15 @@ void OpenALSoundRenderer::ChannelPitch(FISoundChannel *chan, float pitch)
 		alSourcef(source, AL_PITCH, std::max(pitch, 0.0001f));
 }
 
-void OpenALSoundRenderer::FreeSource(ALuint source)
+void OpenALSoundRenderer::StopChannel(FISoundChannel *chan)
 {
+	if(chan == NULL || chan->SysChannel == NULL)
+		return;
+
+	ALuint source = GET_PTRID(chan->SysChannel);
+	// Release first, so it can be properly marked as evicted if it's being killed
+	soundEngine->ChannelEnded(chan);
+
 	alSourceRewind(source);
 	alSourcei(source, AL_BUFFER, 0);
 	getALError();
@@ -1583,41 +1568,6 @@ void OpenALSoundRenderer::FreeSource(ALuint source)
 	FreeSfx.Push(source);
 }
 
-void OpenALSoundRenderer::StopChannel(FISoundChannel *chan)
-{
-	if(chan == NULL || chan->SysChannel == NULL)
-		return;
-
-	ALuint source = GET_PTRID(chan->SysChannel);
-	// Release first, so it can be properly marked as evicted if it's being killed
-	soundEngine->ChannelEnded(chan);
-
-	ALint state = AL_INITIAL;
-	alGetSourcei(source, AL_SOURCE_STATE, &state);
-	if(state != AL_PLAYING)
-		FreeSource(source);
-	else
-	{
-		// The sound is being killed while playing, so set its gain to 0 and track it
-		// as it fades.
-		alSourcef(source, AL_GAIN, 0.f);
-		getALError();
-
-		FadingSources.insert(std::make_pair(
-			source, std::chrono::steady_clock::now().time_since_epoch().count()
-		));
-	}
-}
-
-void OpenALSoundRenderer::ForceStopChannel(FISoundChannel *chan)
-{
-	ALuint source = GET_PTRID(chan->SysChannel);
-	if(!source) return;
-
-	soundEngine->ChannelEnded(chan);
-	FreeSource(source);
-}
-
 
 unsigned int OpenALSoundRenderer::GetPosition(FISoundChannel *chan)
 {
@@ -1884,23 +1834,6 @@ void OpenALSoundRenderer::UpdateSounds()
 {
 	alProcessUpdatesSOFT();
 
-	if(!FadingSources.empty())
-	{
-		auto cur_time = std::chrono::steady_clock::now().time_since_epoch();
-		for(auto iter = FadingSources.begin();iter != FadingSources.end();)
-		{
-			auto time_diff = std::chrono::duration_cast<std::chrono::milliseconds>(cur_time -
-				std::chrono::steady_clock::time_point::duration(iter->second));
-			if(time_diff.count() >= UpdateTimeMS)
-			{
-				FreeSource(iter->first);
-				iter = FadingSources.erase(iter);
-			}
-			else
-				++iter;
-		}
-	}
-
 	if(ALC.EXT_disconnect)
 	{
 		ALCint connected = ALC_TRUE;
@@ -2049,7 +1982,7 @@ void OpenALSoundRenderer::PurgeStoppedSources()
 		{
 			if(schan->SysChannel != NULL && src == GET_PTRID(schan->SysChannel))
 			{
-				ForceStopChannel(schan);
+				StopChannel(schan);
 				break;
 			}
 			schan = schan->NextChan;

src/sound/backend/oalsound.h

@@ -245,10 +245,8 @@ private:
     void RemoveStream(OpenALSoundStream *stream);
 
 	void LoadReverb(const ReverbContainer *env);
-	void FreeSource(ALuint source);
 	void PurgeStoppedSources();
 	static FSoundChan *FindLowestChannel();
-	void ForceStopChannel(FISoundChannel *chan);
 
     std::thread StreamThread;
     std::mutex StreamLock;
@@ -269,10 +267,6 @@ private:
 	TArray<ALuint> ReverbSfx;
 	TArray<ALuint> SfxGroup;
 
-	int UpdateTimeMS;
-	using SourceTimeMap = std::unordered_map<ALuint,int64_t>;
-	SourceTimeMap FadingSources;
-
 	const ReverbContainer *PrevEnvironment;
 
     typedef TMap<uint16_t,ALuint> EffectMap;