audio system basic interface

src/audio/audio.h

@@ -0,0 +1,94 @@
+#ifndef AUDIO_AUDIO_H_
+#define AUDIO_AUDIO_H_
+
+#include <vector>
+#include <memory>
+#include <glm/glm.hpp>
+#include "../typedefs.h"
+
+namespace audio {
+    using speakerid_t = int64_t;
+    /// @brief duration unit is second
+    using duration_t = float;
+
+    /// @brief Pulse-code modulation data
+    struct PCM {
+        /// @brief May contain 8 bit and 16 bit PCM data
+        std::vector<char> data;
+        uint8_t channels;
+        uint8_t bitsPerSample;
+        uint sampleRate;
+
+        constexpr inline size_t countSamples() const {
+            return data.size() / channels / (bitsPerSample / 8);
+        }
+
+        constexpr inline duration_t getDuration() const {
+            return countSamples() / static_cast<duration_t>(sampleRate);
+        }
+    };
+
+    /// @brief Sound is an audio asset that supposed to support many 
+    /// simultaneously playing instances with different sources.
+    /// So it's audio data is stored in memory.
+    class Sound {
+    public:
+        virtual ~Sound() {}
+
+        /// @brief Get sound duration
+        /// @return duration in seconds (>= 0.0)
+        virtual duration_t getDuration() const = 0;
+
+        /// @brief Get sound PCM data
+        /// @return PCM data or nullptr
+        virtual std::shared_ptr<PCM> getPCM() const = 0;
+
+        /// @brief Create new sound instance
+        /// @param priority instance priority. High priority instance can 
+        /// take out speaker from low priority instance
+        /// @return new speaker id with sound bound or 0 
+        /// if all speakers are in use
+        virtual speakerid_t newInstance(int priority) const = 0;
+    };
+
+    class Backend {
+    public:
+        virtual ~Backend() {};
+
+        /// @brief Create new sound from PCM data
+        /// @param pcm PCM data
+        /// @param keepPCM store PCM data in sound to make it accessible with 
+        /// Sound::getPCM
+        /// @return new Sound instance 
+        virtual Sound* createSound(std::shared_ptr<PCM> pcm, bool keepPCM) = 0;
+
+        virtual void setListener(
+            glm::vec3 position, 
+            glm::vec3 velocity, 
+            glm::vec3 lookAt, 
+            glm::vec3 up
+        ) = 0;
+    };
+
+    extern Backend* backend;
+
+    /// @brief Initialize audio system or use no audio mode
+    /// @param enabled try to initialize actual audio
+    extern void initialize(bool enabled);
+
+    /// @brief Configure 3D listener
+    /// @param position listener position
+    /// @param velocity listener velocity (used for Doppler effect)
+    /// @param lookAt point the listener look at
+    /// @param up camera up vector
+    extern void setListener(
+        glm::vec3 position, 
+        glm::vec3 velocity, 
+        glm::vec3 lookAt, 
+        glm::vec3 up
+    );
+    /// @brief Finalize audio system
+    extern void close();
+};
+
+#endif // AUDIO_AUDIO_H_