Audio.h

#pragma once

#include "sf/Base.h"
#include "sf/Array.h"
#include "sf/Box.h"

namespace sp {

struct AudioSource
{
	static const constexpr uint32_t AdvancePaddingInFloats = 8;

	uint32_t sampleRate;
	uint32_t numChannels;

	virtual void seek(uint32_t sample) = 0;

	// Allowed to read past `dst` by AdvancePaddingInFloats floats!
	virtual uint32_t advance(uint32_t sample, float *dst, uint32_t num) = 0;
};

struct AudioMixOpts
{
	bool loop = false;
	uint32_t sampleRate = 44100;
	float volumeNext[2] = { 1.0f, 1.0f };
	float volumeFadeDuration = 1.0f / 30.0f;
	float pitch = 1.0f;
};

struct AudioSampler
{
	float carryBuf[64];
	uint32_t carryFirstSample = 0;
	uint32_t carryNumSamples = 0;

	uint32_t srcAdvanceSample = 0;
	double srcSampleTime = 0.0;

	uint32_t loopCount = 0;
	bool ended = false;
	bool started = false;

	float volumeT = 1.0f;
	float volumeSrc[2] = { };
	float volumeDst[2] = { };

	void advanceMixStereo(float *dst, uint32_t numDst, AudioSource *source, const AudioMixOpts &opts);

	void advanceMixStereoImp(float *dst, uint32_t numDst, AudioSource *source, const AudioMixOpts &opts);
};

struct AudioLimiter
{
	sf::Array<float> buffer;
	float windowLengthSec = 1.0f / 100.0f;
	float volumeRecoverPerWindow = 0.01f;

	float prevWindowVolume = 1.0f;
	float prevTargetVolume = 1.0f;

	bool bufferEmpty = true;
	uint32_t overflowOffset = 0;
	uint32_t numOverflowSamples = 0;

	void reset();

	float *getStereoBuffer(uint32_t &requiredSamples, uint32_t numSamples, uint32_t sampleRate);
	void limitStereo(float *dstSamples, uint32_t numSamples, uint32_t sampleRate);
};

struct BeginLoopAudioSource : AudioSource
{
	sf::Box<AudioSource> begin;
	sf::Box<AudioSource> loop;

	bool inLoop = false;
	uint32_t loopBeginSample = 0;

	BeginLoopAudioSource();
	BeginLoopAudioSource(sf::Box<AudioSource> begin, sf::Box<AudioSource> loop);

	virtual void seek(uint32_t sample) override;
	virtual uint32_t advance(uint32_t sample, float *dst, uint32_t num) override;
};

struct BeginLoopEndAudioSource : AudioSource
{
	enum State
	{
		Begin,
		Loop,
		End,
	};

	sf::Box<AudioSource> begin;
	sf::Box<AudioSource> loop;
	sf::Box<AudioSource> end;

	uint32_t impStopFlag = 0;
	State impState = Begin;
	uint32_t impBeginSample = 0;

	void stop();
	bool unstop();

	virtual void seek(uint32_t sample) override;
	virtual uint32_t advance(uint32_t sample, float *dst, uint32_t num) override;
};

struct InterruptLoopAudioSource : AudioSource
{
	sf::Box<AudioSource> loop;
	sf::Box<AudioSource> end;

	uint32_t impStopFlag = 0;

	sf::Array<float> fadeBuffer;
	bool hasFadeBuffer = false;
	bool atEnd = false;

	uint64_t totalSamples;

	uint32_t fadeBufferFirstSample;

	uint32_t interruptInterval = 1;

	void stop();
	bool unstop();

	virtual void seek(uint32_t sample) override;
	virtual uint32_t advance(uint32_t sample, float *dst, uint32_t num) override;
};

struct SwappingAudioSource : AudioSource
{
	sf::Box<AudioSource> source[2];
	uint64_t startSample[2] = { };
	uint32_t impShouldStart[2] = { };
	uint32_t impPlaying[2] = { };

	uint32_t swapInterval = 1;

	uint64_t totalSamples = 0;

	void play(uint32_t sourceIndex);
	void unplay(uint32_t sourceIndex);
	bool isPlaying(uint32_t sourceIndex) const;

	virtual void seek(uint32_t sample) override;
	virtual uint32_t advance(uint32_t sample, float *dst, uint32_t num) override;
};

}