fingerprint_matcher.h

// Copyright (C) 2016  Lukas Lalinsky
// Distributed under the MIT license, see the LICENSE file for details.

#ifndef CHROMAPRINT_FINGERPRINT_MATCHER_H_
#define CHROMAPRINT_FINGERPRINT_MATCHER_H_

#include <vector>
#include <memory>
#include <cstdint>
#include <cassert>

namespace chromaprint {

class FingerprinterConfiguration;

struct Segment
{
	size_t pos1;
	size_t pos2;
	size_t duration;
	double score;
	double left_score;
	double right_score;

	Segment(size_t pos1, size_t pos2, size_t duration, double score)
		: pos1(pos1), pos2(pos2), duration(duration), score(score), left_score(score), right_score(score) {}

	Segment(size_t pos1, size_t pos2, size_t duration, double score, double left_score, double right_score)
		: pos1(pos1), pos2(pos2), duration(duration), score(score), left_score(left_score), right_score(right_score) {}

	int public_score() const {
		//return std::max(0, int(100 - std::round(score * (100.0 / 14.0))));
		//return std::max(0, int(100 - std::round(score * (100.0 / 14.0))));
		return int(score * 100 + 0.5);
	}

	Segment merged(const Segment &other) {
		assert(pos1 + duration == other.pos1);
		assert(pos2 + duration == other.pos2);
		const auto new_duration = duration + other.duration;
		const auto new_score = (score * duration + other.score * other.duration) / new_duration;
		return Segment(pos1, pos2, new_duration, new_score, score, other.score);
	}

};

class FingerprintMatcher
{
public:
	FingerprintMatcher(FingerprinterConfiguration *config);

	// Anything above this is not considered a match.
	void set_match_threshold(double t) { m_match_threshold = t; }
	double match_threshold() const { return m_match_threshold; }
	static constexpr double kDefaultMatchThreshold = 10.0;

	bool Match(const std::vector<uint32_t> &fp1, const std::vector<uint32_t> &fp2);
	bool Match(const uint32_t fp1_data[], size_t fp1_size, const uint32_t fp2_data[], size_t fp2_size);

	double GetHashTime(size_t i) const;
	double GetHashDuration(size_t i) const;

	const std::vector<Segment> &segments() const { return m_segments; };

private:
	std::unique_ptr<FingerprinterConfiguration> m_config;
	std::vector<uint32_t> m_offsets;
	std::vector<uint32_t> m_histogram;
	std::vector<std::pair<uint32_t, uint32_t>> m_best_alignments;
	std::vector<Segment> m_segments;
	double m_match_threshold = kDefaultMatchThreshold;
};

}; // namespace chromaprint

#endif