Support retrieving the number of already played samples from a stream

libs/audio/include/psemek/audio/stream.hpp

@@ -16,6 +16,10 @@ namespace psemek::audio
 		// Must be called from mixing thread
 		virtual std::size_t read(float * data, std::size_t sample_count) = 0;
 
+		// The number of samples already played from this stream
+		// Must be called from mixing thread
+		virtual std::size_t played() const = 0;
+
 		virtual ~stream() {}
 	};
 

libs/audio/include/psemek/audio/wave/generator.hpp

@@ -19,6 +19,11 @@ namespace psemek::audio
 			return std::nullopt;
 		}
 
+		std::size_t played() const override
+		{
+			return played_;
+		}
+
 		std::size_t read(float * data, std::size_t sample_count) override
 		{
 			auto end = data + sample_count;
@@ -28,11 +33,13 @@ namespace psemek::audio
 				*p++ = v;
 				*p++ = v;
 			}
+			played_ += sample_count;
 			return sample_count;
 		}
 
 	private:
 		Func func_;
+		std::size_t played_ = 0;
 	};
 
 }

libs/audio/source/duplicate.cpp

@@ -32,6 +32,11 @@ namespace psemek::audio
 				return common_->stream->length();
 			}
 
+			std::size_t played() const override
+			{
+				return common_->stream->played();
+			}
+
 			std::size_t read(float * data, std::size_t sample_count) override
 			{
 				if (counter_ == common_->counter)

libs/audio/source/effect/fade_in.cpp

@@ -23,6 +23,11 @@ namespace psemek::audio
 				return stream_->length();
 			}
 
+			std::size_t played() const override
+			{
+				return stream_->played();
+			}
+
 			std::size_t read(float * data, std::size_t sample_count) override
 			{
 				auto const result = stream_->read(data, sample_count);

libs/audio/source/effect/fade_out.cpp

@@ -24,6 +24,11 @@ namespace psemek::audio
 				return stream_->length();
 			}
 
+			std::size_t played() const override
+			{
+				return stream_->played();
+			}
+
 			std::size_t read(float * data, std::size_t sample_count) override
 			{
 				if (current_ >= length_)

libs/audio/source/effect/volume.cpp

@@ -26,6 +26,11 @@ namespace psemek::audio
 				return stream_->length();
 			}
 
+			std::size_t played() const override
+			{
+				return stream_->played();
+			}
+
 			std::size_t read(float * data, std::size_t sample_count) override
 			{
 				auto result = stream_->read(data, sample_count);

libs/audio/source/mixer.cpp

@@ -23,6 +23,11 @@ namespace psemek::audio
 				return std::nullopt;
 			}
 
+			std::size_t played() const override
+			{
+				return played_;
+			}
+
 		private:
 			std::vector<channel_ptr> channels_;
 			std::vector<channel_ptr> alive_channels_;
@@ -31,6 +36,8 @@ namespace psemek::audio
 
 			std::mutex new_channels_mutex_;
 			std::vector<channel_ptr> new_channels_;
+
+			std::size_t played_ = 0;
 		};
 
 		channel_ptr mixer_impl::add(stream_ptr stream)
@@ -89,6 +96,8 @@ namespace psemek::audio
 			std::swap(channels_, alive_channels_);
 			alive_channels_.clear();
 
+			played_ += sample_count;
+
 			return sample_count;
 		}
 

libs/audio/source/stereo.cpp

@@ -29,6 +29,11 @@ namespace psemek::audio
 					return right;
 			}
 
+			std::size_t played() const override
+			{
+				return std::min(left_->played(), right_->played());
+			}
+
 			std::size_t read(float * data, std::size_t sample_count) override
 			{
 				if (buffer_.size() < sample_count)

libs/audio/source/wave/silence.cpp

@@ -12,6 +12,7 @@ namespace psemek::audio
 			std::size_t read(float * data, std::size_t sample_count) override
 			{
 				std::fill(data, data + sample_count, 0.f);
+				played_ += sample_count;
 				return sample_count;
 			}
 
@@ -19,6 +20,14 @@ namespace psemek::audio
 			{
 				return std::nullopt;
 			}
+
+			std::size_t played() const override
+			{
+				return played_;
+			}
+
+		private:
+			std::size_t played_ = 0;
 		};
 
 	}