Fix audio clips streaming to be thread-safe when audio sources play

#786

Source/Engine/Audio/AudioClip.cpp

@@ -20,10 +20,11 @@ bool AudioClip::StreamingTask::Run()
 {
     AssetReference<AudioClip> ref = _asset.Get();
     if (ref == nullptr)
-    {
         return true;
-    }
+    ScopeLock lock(ref->Locker);
     const auto& queue = ref->StreamingQueue;
+    if (queue.Count() == 0)
+        return false;
     auto clip = ref.Get();
 
     // Update the buffers
@@ -108,7 +109,6 @@ bool AudioClip::StreamingTask::Run()
     for (int32 sourceIndex = 0; sourceIndex < Audio::Sources.Count(); sourceIndex++)
     {
         // TODO: collect refs to audio clip from sources and use faster iteration (but do it thread-safe)
-
         const auto src = Audio::Sources[sourceIndex];
         if (src->Clip == clip && src->GetState() == AudioSource::States::Playing)
         {

Source/Engine/Audio/AudioSource.cpp

@@ -132,7 +132,7 @@ void AudioSource::Play()
             Clip->RequestStreamingUpdate();
 
             // If we are looping and streaming also update streaming buffers
-            if(_loop)
+            if (_loop)
                 RequestStreamingBuffersUpdate();
         }
     }
@@ -372,6 +372,7 @@ void AudioSource::Update()
     if (!UseStreaming() || SourceIDs.IsEmpty())
         return;
     auto clip = Clip.Get();
+    clip->Locker.Lock();
 
     // Handle streaming buffers queue submit (ensure that clip has loaded the first chunk with audio data)
     if (_needToUpdateStreamingBuffers && clip->Buffers[_streamingFirstChunk] != AUDIO_BUFFER_ID_INVALID)
@@ -441,6 +442,8 @@ void AudioSource::Update()
             clip->RequestStreamingUpdate();
         }
     }
+
+    clip->Locker.Unlock();
 }
 
 void AudioSource::OnEnable()

Source/Engine/Audio/OpenAL/AudioBackendOAL.cpp

@@ -139,10 +139,12 @@ namespace ALC
 
                 alSourcef(sourceID, AL_GAIN, source->GetVolume());
                 alSourcef(sourceID, AL_PITCH, source->GetPitch());
+                alSourcef(sourceID, AL_SEC_OFFSET, 0.0f);
                 alSourcef(sourceID, AL_REFERENCE_DISTANCE, source->GetMinDistance());
                 alSourcef(sourceID, AL_ROLLOFF_FACTOR, source->GetAttenuation());
                 alSourcei(sourceID, AL_LOOPING, loop);
                 alSourcei(sourceID, AL_SOURCE_RELATIVE, !is3D);
+                alSourcei(sourceID, AL_BUFFER, 0);
                 alSource3f(sourceID, AL_POSITION, FLAX_POS_TO_OAL(position));
                 alSource3f(sourceID, AL_VELOCITY, FLAX_POS_TO_OAL(velocity));
             }