diff --git a/libs/audio/include/psemek/audio/constants.hpp b/libs/audio/include/psemek/audio/constants.hpp
index ac5ae90e..fcdbb013 100644
--- a/libs/audio/include/psemek/audio/constants.hpp
+++ b/libs/audio/include/psemek/audio/constants.hpp
@@ -1,9 +1,22 @@
 #pragma once
 
+#include <cstdint>
+#include <cmath>
+
 namespace psemek::audio
 {
 
 	constexpr int frequency = 44100;
 	constexpr float inv_frequency = 1.f / frequency;
 
+	inline std::int64_t seconds_to_samples(float seconds)
+	{
+		return static_cast<std::int64_t>(2 * std::round(seconds * frequency));
+	}
+
+	inline float samples_to_seconds(std::int64_t samples)
+	{
+		return static_cast<float>(samples) * 0.5f * inv_frequency;
+	}
+
 }
diff --git a/libs/audio/include/psemek/audio/duration.hpp b/libs/audio/include/psemek/audio/duration.hpp
new file mode 100644
index 00000000..2bf22ca1
--- /dev/null
+++ b/libs/audio/include/psemek/audio/duration.hpp
@@ -0,0 +1,67 @@
+#pragma once
+
+#include <psemek/audio/constants.hpp>
+
+#include <cstdint>
+#include <cmath>
+
+namespace psemek::audio
+{
+
+	struct duration
+	{
+		duration()
+			: samples_{0}
+		{}
+
+		duration(std::int64_t samples)
+			: samples_{samples}
+		{}
+
+		duration(std::size_t samples)
+			: samples_{samples}
+		{}
+
+		duration(float seconds)
+			: samples_{seconds_to_samples(seconds)}
+		{}
+
+		duration(duration const & other) = default;
+
+		float seconds() const
+		{
+			return samples_to_seconds(samples_);
+		}
+
+		std::int64_t samples() const
+		{
+			return samples_;
+		}
+
+		duration & operator += (duration const & other)
+		{
+			samples_ += other.samples_;
+			return *this;
+		}
+
+		duration & operator -= (duration const & other)
+		{
+			samples_ -= other.samples_;
+			return *this;
+		}
+
+		friend duration operator + (duration const & d1, duration const & d2)
+		{
+			return duration{d1.samples() + d2.samples()};
+		}
+
+		friend duration operator - (duration const & d1, duration const & d2)
+		{
+			return duration{d1.samples() - d2.samples()};
+		}
+
+	private:
+		std::int64_t samples_;
+	};
+
+}
diff --git a/libs/audio/include/psemek/audio/effect/fade_in.hpp b/libs/audio/include/psemek/audio/effect/fade_in.hpp
index a41ca7d6..fadc2358 100644
--- a/libs/audio/include/psemek/audio/effect/fade_in.hpp
+++ b/libs/audio/include/psemek/audio/effect/fade_in.hpp
@@ -1,10 +1,11 @@
 #pragma once
 
 #include <psemek/audio/stream.hpp>
+#include <psemek/audio/duration.hpp>
 
 namespace psemek::audio
 {
 
-	stream_ptr fade_in(stream_ptr stream, float length, float start = 0.f);
+	stream_ptr fade_in(stream_ptr stream, duration length, duration start = {});
 
 }
diff --git a/libs/audio/include/psemek/audio/effect/fade_out.hpp b/libs/audio/include/psemek/audio/effect/fade_out.hpp
index 68fe8589..33920ed8 100644
--- a/libs/audio/include/psemek/audio/effect/fade_out.hpp
+++ b/libs/audio/include/psemek/audio/effect/fade_out.hpp
@@ -1,10 +1,11 @@
 #pragma once
 
 #include <psemek/audio/stream.hpp>
+#include <psemek/audio/duration.hpp>
 
 namespace psemek::audio
 {
 
-	stream_ptr fade_out(stream_ptr stream, float length, float start = 0.f);
+	stream_ptr fade_out(stream_ptr stream, duration length, duration start = {});
 
 }
diff --git a/libs/audio/source/effect/fade_in.cpp b/libs/audio/source/effect/fade_in.cpp
index c1be8153..ab964526 100644
--- a/libs/audio/source/effect/fade_in.cpp
+++ b/libs/audio/source/effect/fade_in.cpp
@@ -12,10 +12,10 @@ namespace psemek::audio
 		struct fade_in_impl
 			: stream
 		{
-			fade_in_impl(stream_ptr stream, float length, float start)
+			fade_in_impl(stream_ptr stream, duration length, duration start)
 				: stream_(std::move(stream))
-				, length_(2 * std::round(length * frequency))
-				, start_samples_(2 * std::round(start * frequency))
+				, length_(length)
+				, start_(start)
 			{}
 
 			std::optional<std::size_t> length() const override
@@ -31,24 +31,24 @@ namespace psemek::audio
 			std::size_t read(float * data, std::size_t sample_count) override
 			{
 				auto const result = stream_->read(data, sample_count);
-				std::fill(data, data + std::min(result, start_samples_), 0.f);
+				std::fill(data, data + std::min<std::size_t>(result, start_.samples()), 0.f);
 
-				if (result <= start_samples_)
+				if (result <= start_.samples())
 				{
-					start_samples_ -= result;
+					start_ -= result;
 				}
 				else
 				{
-					for (std::size_t i = start_samples_; i < result; i += 2)
+					for (std::size_t i = start_.samples(); i < result; i += 2)
 					{
-						float m = static_cast<float>(std::min(current_, length_)) / length_;
+						float m = static_cast<float>(std::min<std::size_t>(current_, length_.samples())) / length_.samples();
 
 						data[i + 0] *= m;
 						data[i + 1] *= m;
 
 						current_ += 2;
 					}
-					start_samples_ = 0;
+					start_ = duration{};
 				}
 
 				return result;
@@ -56,14 +56,14 @@ namespace psemek::audio
 
 		private:
 			stream_ptr stream_;
-			std::size_t length_;
+			duration length_;
+			duration start_;
 			std::size_t current_ = 0;
-			std::size_t start_samples_;
 		};
 
 	}
 
-	stream_ptr fade_in(stream_ptr stream, float length, float start)
+	stream_ptr fade_in(stream_ptr stream, duration length, duration start)
 	{
 		return std::make_shared<fade_in_impl>(std::move(stream), length, start);
 	}
diff --git a/libs/audio/source/effect/fade_out.cpp b/libs/audio/source/effect/fade_out.cpp
index 6d0e2b09..5f8be759 100644
--- a/libs/audio/source/effect/fade_out.cpp
+++ b/libs/audio/source/effect/fade_out.cpp
@@ -12,10 +12,10 @@ namespace psemek::audio
 		struct fade_out_impl
 			: stream
 		{
-			fade_out_impl(stream_ptr stream, float length, float start)
+			fade_out_impl(stream_ptr stream, duration length, duration start)
 				: stream_(std::move(stream))
-				, length_(2 * std::round(length * frequency))
-				, start_samples_(2 * std::round(start * frequency))
+				, length_(length)
+				, start_(start)
 			{}
 
 			std::optional<std::size_t> length() const override
@@ -31,27 +31,27 @@ namespace psemek::audio
 
 			std::size_t read(float * data, std::size_t sample_count) override
 			{
-				if (current_ >= length_)
+				if (current_ >= length_.samples())
 					return 0;
 
 				auto result = stream_->read(data, sample_count);
 
-				if (result <= start_samples_)
+				if (result <= start_.samples())
 				{
-					start_samples_ -= result;
+					start_ -= result;
 				}
 				else
 				{
-					for (std::size_t i = start_samples_; i < result; i += 2)
+					for (std::size_t i = start_.samples(); i < result; i += 2)
 					{
-						float m = static_cast<float>(length_ - std::min(current_, length_)) / length_;
+						float m = static_cast<float>(length_.samples() - std::min<std::size_t>(current_, length_.samples())) / length_.samples();
 
 						data[i + 0] *= m;
 						data[i + 1] *= m;
 
 						current_ += 2;
 					}
-					start_samples_ = 0;
+					start_ = {};
 				}
 
 				return result;
@@ -59,14 +59,14 @@ namespace psemek::audio
 
 		private:
 			stream_ptr stream_;
-			std::size_t length_;
+			duration length_;
+			duration start_;
 			std::size_t current_ = 0;
-			std::size_t start_samples_;
 		};
 
 	}
 
-	stream_ptr fade_out(stream_ptr stream, float length, float start)
+	stream_ptr fade_out(stream_ptr stream, duration length, duration start)
 	{
 		return std::make_shared<fade_out_impl>(std::move(stream), length, start);
 	}