Add audio envelope helper based on a sequence of linear or exponential segments

libs/audio/include/psemek/audio/duration.hpp

@@ -3,7 +3,6 @@
 #include <psemek/audio/constants.hpp>
 
 #include <cstdint>
-#include <cmath>
 
 namespace psemek::audio
 {

libs/audio/include/psemek/audio/effect/envelope.hpp

@@ -0,0 +1,72 @@
+#include <psemek/audio/stream.hpp>
+#include <psemek/audio/duration.hpp>
+
+#include <vector>
+
+namespace psemek::audio
+{
+
+	struct segment
+	{
+		enum segment_type
+		{
+			linear,
+			exponential,
+		};
+
+		segment_type type;
+		audio::duration duration;
+	};
+
+	constexpr struct keep_playing_tag {} keep_playing;
+
+	// values.size() must equal smoothing.size() + 1
+	// truncates the stream in the end if keep_playing isn't specified
+	stream_ptr envelope(stream_ptr stream, std::vector<float> values, std::vector<segment> segments);
+	stream_ptr envelope(stream_ptr stream, keep_playing_tag, std::vector<float> values, std::vector<segment> segments);
+
+	namespace detail
+	{
+
+		inline void envelope_helper(std::vector<float> &, std::vector<segment> &)
+		{}
+
+		template <typename ... Args>
+		void envelope_helper(std::vector<float> & values, std::vector<segment> & segments, segment::segment_type type, duration duration, float value, Args ... args)
+		{
+			values.push_back(value);
+			segments.push_back({type, duration});
+			envelope_helper(values, segments, args...);
+		}
+
+		template <typename ... Args>
+		stream_ptr envelope_impl(stream_ptr stream, bool keep_playing, float first_value, Args ... args)
+		{
+			std::vector<float> values;
+			std::vector<segment> segments;
+			values.push_back(first_value);
+			envelope_helper(values, segments, args...);
+			if (keep_playing)
+				return audio::envelope(std::move(stream), audio::keep_playing, std::move(values), std::move(segments));
+			return audio::envelope(std::move(stream), std::move(values), std::move(segments));
+		}
+
+	}
+
+	// Must be called alternating volume levels, segment types, and segment durations,
+	// starting and ending with a volume level, e.g.
+	//     envelope(stream, 0.4, segment::linear, 100_ms, 1.2, segment::exponential, 400_ms, 5.3)
+
+	template <typename ... Args>
+	stream_ptr envelope(stream_ptr stream, float first_value, Args ... args)
+	{
+		return detail::envelope_impl(std::move(stream), false, first_value, args...);
+	}
+
+	template <typename ... Args>
+	stream_ptr envelope(stream_ptr stream, keep_playing_tag, float first_value, Args ... args)
+	{
+		return detail::envelope_impl(std::move(stream), true, first_value, args...);
+	}
+
+}

libs/audio/include/psemek/audio/effect/envelope_base.hpp

@@ -0,0 +1,69 @@
+#include <psemek/audio/stream.hpp>
+#include <psemek/audio/duration.hpp>
+
+namespace psemek::audio
+{
+
+	namespace
+	{
+
+		template <typename EnvelopeFn>
+		struct envelope_base_impl
+			: stream
+		{
+			envelope_base_impl(stream_ptr stream, EnvelopeFn envelope_fn, std::optional<duration> truncate)
+				: stream_(std::move(stream))
+				, envelope_fn_(std::move(envelope_fn))
+				, remaining_(truncate ? std::optional{truncate->samples()} : std::nullopt)
+				, total_length_(truncate ? stream_->played() + *remaining_ : stream_->length())
+			{}
+
+			std::optional<std::size_t> length() const override
+			{
+				return total_length_;
+			}
+
+			std::size_t read(util::span<float> samples) override
+			{
+				std::size_t const max_count = remaining_ ? std::min(*remaining_, samples.size()) : samples.size();
+
+				auto const count = stream_->read(samples.prefix(max_count));
+				if (remaining_)
+					*remaining_ -= count;
+
+				auto out = samples.data();
+				for (std::size_t i = 0; i < count; i += 2)
+				{
+					float gain = envelope_fn_(played_);
+					out[0] *= gain;
+					out[1] *= gain;
+					out += 2;
+					played_ += duration::from_frames(1);
+				}
+
+				return count;
+			}
+
+			std::size_t played() const override
+			{
+				return stream_->played();
+			}
+
+		private:
+			stream_ptr stream_;
+			EnvelopeFn envelope_fn_;
+			duration played_;
+			std::optional<std::size_t> remaining_;
+			std::optional<std::size_t> total_length_;
+		};
+
+	}
+
+	// Guaranteed to call envelope_fn exactly once per audio frame
+	template <typename EnvelopeFn>
+	stream_ptr envelope_base(stream_ptr stream, EnvelopeFn envelope_fn, std::optional<duration> truncate = {})
+	{
+		return std::make_shared<envelope_base_impl<EnvelopeFn>>(std::move(stream), std::move(envelope_fn), truncate);
+	}
+
+}

libs/audio/include/psemek/audio/literals.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <psemek/audio/duration.hpp>
+#include <psemek/audio/constants.hpp>
+
+#include <cmath>
+
+namespace psemek::audio::literals
+{
+
+	duration operator ""_s (unsigned long long value)
+	{
+		return duration::from_frames(value * frequency);
+	}
+
+	duration operator ""_ms (unsigned long long value)
+	{
+		return duration::from_frames((value * frequency) / 1000);
+	}
+
+	duration operator ""_s (long double value)
+	{
+		return duration::from_frames(std::round(value * frequency));
+	}
+
+	duration operator ""_ms (long double value)
+	{
+		return duration::from_frames(std::round(value * frequency / 1000.0));
+	}
+
+}

libs/audio/source/effect/envelope.cpp

@@ -0,0 +1,85 @@
+#include <psemek/audio/effect/envelope.hpp>
+#include <psemek/audio/effect/envelope_base.hpp>
+#include <psemek/util/exception.hpp>
+#include <psemek/util/enum.hpp>
+
+namespace psemek::audio
+{
+
+	namespace
+	{
+
+		float compute_param(float v0, float v1, segment::segment_type type)
+		{
+			switch (type)
+			{
+			case segment::linear:
+				return v1 - v0;
+			case segment::exponential:
+				// f(t) = Aexp(Bt)
+				// t=0 => A=v0
+				// t=1 => Aexp(B)=v1 => B = log(v1/v0)
+				return std::log(v1 / v0);
+			}
+
+			throw util::unknown_enum_value_exception(type);
+		}
+
+		float interpolate(float v0, float /* v1 */, float t, segment::segment_type type, float param)
+		{
+			switch (type)
+			{
+			case segment::linear:
+				return v0 + param * t;
+			case segment::exponential:
+				return v0 * std::exp(param * t);
+			}
+
+			throw util::unknown_enum_value_exception(type);
+		}
+
+		stream_ptr envelope_impl(stream_ptr stream, bool keep_playing, std::vector<float> values, std::vector<segment> segments)
+		{
+			if (values.size() != segments.size() + 1)
+				throw util::exception("Invalid envelope");
+
+			std::optional<duration> truncate;
+			if (!keep_playing)
+			{
+				truncate = duration::from_frames(0);
+				for (auto const & segment : segments)
+					*truncate += segment.duration;
+			}
+
+			std::vector<float> params(segments.size());
+			for (std::size_t i = 0; i < segments.size(); ++i)
+				params[i] = compute_param(values[i], values[i + 1], segments[i].type);
+
+			return envelope_base(std::move(stream), [values = std::move(values), segments = std::move(segments), params = std::move(params), index = 0, played = std::size_t{0}](duration) mutable {
+				played += 1;
+				while (index < segments.size() && played >= segments[index].duration.frames())
+				{
+					++index;
+					played = 0;
+				}
+
+				if (index == segments.size())
+					return values.back();
+
+				return interpolate(values[index], values[index + 1], played * 1.f / segments[index].duration.frames(), segments[index].type, params[index]);
+			}, truncate);
+		}
+
+	}
+
+	stream_ptr envelope(stream_ptr stream, std::vector<float> values, std::vector<segment> segments)
+	{
+		return envelope_impl(std::move(stream), false, std::move(values), std::move(segments));
+	}
+
+	stream_ptr envelope(stream_ptr stream, keep_playing_tag, std::vector<float> values, std::vector<segment> segments)
+	{
+		return envelope_impl(std::move(stream), true, std::move(values), std::move(segments));
+	}
+
+}

libs/audio/source/effect/fade_in.cpp

@@ -1,71 +1,15 @@
-#include <psemek/audio/effect/fade_in.hpp>
-#include <psemek/audio/constants.hpp>
-
-#include <algorithm>
+#include <psemek/audio/effect/fade_out.hpp>
+#include <psemek/audio/effect/envelope_base.hpp>
+#include <psemek/math/interval.hpp>
 
 namespace psemek::audio
 {
 
-	namespace
-	{
-
-		struct fade_in_impl
-			: stream
-		{
-			fade_in_impl(stream_ptr stream, duration length, duration start)
-				: stream_(std::move(stream))
-				, length_(length)
-				, start_(start)
-			{}
-
-			std::optional<std::size_t> length() const override
-			{
-				return stream_->length();
-			}
-
-			std::size_t played() const override
-			{
-				return stream_->played();
-			}
-
-			std::size_t read(util::span<float> samples) override
-			{
-				auto const count = stream_->read(samples);
-				std::fill(samples.begin(), samples.begin() + std::min<std::size_t>(count, start_.samples()), 0.f);
-
-				if (count <= start_.samples())
-				{
-					start_ -= count;
-				}
-				else
-				{
-					for (std::size_t i = start_.samples(); i < count; i += 2)
-					{
-						float m = static_cast<float>(std::min<std::size_t>(current_, length_.samples())) / length_.samples();
-
-						samples[i + 0] *= m;
-						samples[i + 1] *= m;
-
-						current_ += 2;
-					}
-					start_ = duration{};
-				}
-
-				return count;
-			}
-
-		private:
-			stream_ptr stream_;
-			duration length_;
-			duration start_;
-			std::size_t current_ = 0;
-		};
-
-	}
-
 	stream_ptr fade_in(stream_ptr stream, duration length, duration start)
 	{
-		return std::make_shared<fade_in_impl>(std::move(stream), length, start);
+		return envelope_base(std::move(stream), [start, length](duration time){
+			return math::clamp(static_cast<float>(time.frames() - start.frames()) / length.frames(), {0.f, 1.f});
+		});
 	}
 
 }

libs/audio/source/effect/fade_out.cpp

@@ -1,75 +1,15 @@
 #include <psemek/audio/effect/fade_out.hpp>
-#include <psemek/audio/constants.hpp>
-
-#include <algorithm>
+#include <psemek/audio/effect/envelope_base.hpp>
+#include <psemek/math/interval.hpp>
 
 namespace psemek::audio
 {
 
-	namespace
-	{
-
-		struct fade_out_impl
-			: stream
-		{
-			fade_out_impl(stream_ptr stream, duration length, duration start)
-				: stream_(std::move(stream))
-				, length_(length)
-				, start_(start)
-				, total_length_(stream_->played() + start_.samples() + length_.samples())
-			{}
-
-			std::optional<std::size_t> length() const override
-			{
-				return total_length_;
-			}
-
-			std::size_t played() const override
-			{
-				return stream_->played();
-			}
-
-			std::size_t read(util::span<float> samples) override
-			{
-				if (current_ >= length_.samples())
-					return 0;
-
-				auto result = stream_->read(samples);
-
-				if (result <= start_.samples())
-				{
-					start_ -= duration::from_samples(result);
-				}
-				else
-				{
-					for (std::size_t i = start_.samples(); i < result; i += 2)
-					{
-						float m = static_cast<float>(length_.samples() - std::min<std::size_t>(current_, length_.samples())) / length_.samples();
-
-						samples[i + 0] *= m;
-						samples[i + 1] *= m;
-
-						current_ += 2;
-					}
-					start_ = {};
-				}
-
-				return result;
-			}
-
-		private:
-			stream_ptr stream_;
-			duration length_;
-			duration start_;
-			std::size_t current_ = 0;
-			std::size_t total_length_ = 0;
-		};
-
-	}
-
 	stream_ptr fade_out(stream_ptr stream, duration length, duration start)
 	{
-		return std::make_shared<fade_out_impl>(std::move(stream), length, start);
+		return envelope_base(std::move(stream), [start, length](duration time){
+			return math::clamp(static_cast<float>(length.frames() + start.frames() - time.frames()) / length.frames(), {0.f, 1.f});
+		}, start + length);
 	}
 
 }

libs/audio/source/effect/truncate.cpp

@@ -13,19 +13,21 @@ namespace psemek::audio
 		{
 			truncate_impl(stream_ptr stream, duration length)
 				: stream_(std::move(stream))
-				, length_(length)
+				, remaining_(length.samples())
+				, total_length_(stream_->played() + remaining_)
 			{}
 
 			std::optional<std::size_t> length() const override
 			{
-				return length_.samples();
+				return total_length_;
 			}
 
 			std::size_t read(util::span<float> samples) override
 			{
-				auto played = stream_->played();
-				auto max_count = std::min<std::size_t>(length_.samples() - played, samples.size());
-				return stream_->read(samples.prefix(max_count));
+				auto const max_count = std::min<std::size_t>(remaining_, samples.size());
+				auto const count = stream_->read(samples.prefix(max_count));
+				remaining_ -= count;
+				return count;
 			}
 
 			std::size_t played() const override
@@ -35,7 +37,8 @@ namespace psemek::audio
 
 		private:
 			stream_ptr stream_;
-			duration length_;
+			std::size_t remaining_;
+			std::size_t total_length_;
 		};
 
 	}