Audio: query actual frequency & channels, initialize effects based on that

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

@@ -11,6 +11,8 @@ namespace psemek::audio
 	{
 		virtual std::string_view name() const = 0;
 
+		virtual void init(int frequency, int channels) = 0;
+
 		virtual void operator()(std::int16_t * data, std::size_t count) = 0;
 
 		virtual ~effect() {}

libs/audio/include/psemek/audio/engine.hpp

@@ -12,12 +12,12 @@ namespace psemek::audio
 
 	struct engine
 	{
-		static const int frequency = 44100;
-		static const int channels = 2;
-
 		engine();
 		~engine();
 
+		int frequency() const;
+		int channels() const;
+
 		std::shared_ptr<track> load_raw(std::int16_t const * data, std::size_t sample_count, bool copy = true);
 		std::shared_ptr<track> load(char const * data, std::size_t size);
 

libs/audio/source/echo.cpp

@@ -15,9 +15,13 @@ namespace psemek::audio
 			: audio::effect
 		{
 			echo_impl(float delay, float volume)
-				: volume_(volume)
+				: delay_(delay)
+				, volume_(volume)
+			{}
+
+			void init(int frequency, int channels) override
 			{
-				int sample_count = std::round(delay * audio::engine::frequency * audio::engine::channels);
+				int sample_count = std::round(delay_ * frequency) * channels;
 				samples_.reserve(sample_count);
 			}
 
@@ -55,6 +59,7 @@ namespace psemek::audio
 		private:
 			std::vector<std::int16_t> samples_;
 			std::size_t pos_ = 0;
+			float delay_;
 			float volume_;
 		};
 

libs/audio/source/engine.cpp

@@ -35,6 +35,12 @@ namespace psemek::audio
 			}
 		};
 
+		struct spec_t
+		{
+			int frequency = 44100;
+			int channels = 2;
+		};
+
 		struct track_impl
 			: track
 		{
@@ -69,12 +75,15 @@ namespace psemek::audio
 			std::shared_ptr<track_impl> track;
 			bool loop;
 
+			spec_t spec;
+
 			std::vector<std::shared_ptr<effect>> effects;
 
-			stream_impl(int channel, std::shared_ptr<track_impl> track, bool loop)
+			stream_impl(int channel, std::shared_ptr<track_impl> track, bool loop, spec_t spec)
 				: channel(channel)
 				, track(track)
 				, loop(loop)
+				, spec(spec)
 			{}
 
 			void volume(float value)
@@ -85,6 +94,7 @@ namespace psemek::audio
 
 			void push_effect(std::shared_ptr<effect> e) override
 			{
+				e->init(spec.frequency, spec.channels);
 				effects.push_back(e);
 				Mix_RegisterEffect(channel, &effect_func, nullptr, e.get());
 			}
@@ -143,6 +153,8 @@ namespace psemek::audio
 		std::shared_ptr<void> sdl_init;
 		sdl2_mixer_initializer mix_init;
 
+		spec_t spec;
+
 		struct channel
 		{
 			std::shared_ptr<stream_impl> stream;
@@ -181,12 +193,18 @@ namespace psemek::audio
 	engine::impl::impl()
 		: sdl_init(sdl2::init(SDL_INIT_AUDIO))
 	{
-		if (Mix_OpenAudio(engine::frequency, AUDIO_S16SYS, engine::channels, 4096) != 0)
+		if (Mix_OpenAudio(spec.frequency, AUDIO_S16SYS, spec.channels, 4096) != 0)
 			mix_fail("Mix_OpenAudio: ");
 
+		Uint16 format;
+		Mix_QuerySpec(&spec.frequency, &format, &spec.channels);
+
+		if (format != AUDIO_S16SYS)
+			throw std::runtime_error("Failed to initialize audio with int16 samples");
+
 		Mix_ChannelFinished(&channel_finished);
 
-		log::info() << "Initialized audio";
+		log::info() << "Initialized audio: " << spec.channels << " channels, " << spec.frequency << " Hz";
 	}
 
 	engine::impl::~impl()
@@ -226,7 +244,7 @@ namespace psemek::audio
 			ch = c;
 		}
 
-		auto str = std::make_shared<stream_impl>(*ch, std::move(ss), loop);
+		auto str = std::make_shared<stream_impl>(*ch, std::move(ss), loop, spec);
 
 		channels[*ch].stream = str;
 
@@ -253,6 +271,16 @@ namespace psemek::audio
 	engine::~engine()
 	{}
 
+	int engine::frequency() const
+	{
+		return impl::instance()->spec.frequency;
+	}
+
+	int engine::channels() const
+	{
+		return impl::instance()->spec.channels;
+	}
+
 	std::shared_ptr<track> engine::load(char const * data, std::size_t size)
 	{
 		return std::make_shared<track_impl>(Mix_LoadWAV_RW(SDL_RWFromConstMem(data, size), 1));