/***************************************************************************
 *   Copyright (C) 2008 by Sindre Aamås                                    *
 *   sinamas@users.sourceforge.net                                         *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License version 2 as     *
 *   published by the Free Software Foundation.                            *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License version 2 for more details.                *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   version 2 along with this program; if not, write to the               *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.             *
 ***************************************************************************/
#ifndef RESAMPLER_H
#define RESAMPLER_H

#include <cstddef>

class Resampler {
public:
	/** Returns the sampling rate of the input that this resampler expects. */
	long inRate() const { return inRate_; }

	/** Returns the approximate sampling rate of the output. */
	long outRate() const { return outRate_; }

	/**
	  * Can be used to adjust the input and output sampling rates slightly with minimal
	  * disturbance in the output.
	  *
	  * Should only be used for slight changes or the quality could detoriate. It can for
	  * instance be useful to tweak the output rate slightly to synchronize production speed
	  * to playback speed when synchronizing video frame rate to refresh rate while playing
	  * back audio from the same source. This can reduce skipped or duplicated video frames
	  * (or avoid audio underruns if no frame skipping is done).
	  *
	  * @param inRate New input sampling rate.
	  * @param outRate Desired new output sampling rate.
	  */
	virtual void adjustRate(long inRate, long outRate) = 0;

	/**
	  * Returns the exact ratio that this resampler is configured to use, such that the actual
	  * output sampling rate is input_rate * mul / div.
	  *
	  * outRate() and inRate() are not necessarily equal to mul and div.
	  *
	  * Many resamplers are intended for real-time purposes where it does not matter much
	  * whether the output sampling rate is 100% exact.
	  */
	virtual void exactRatio(unsigned long &mul, unsigned long &div) const = 0;

	/**
	  * Returns an upper bound on how many samples are produced for 'inlen' input samples.
	  * Can be used to calculate buffer sizes.
	  */
	virtual std::size_t maxOut(std::size_t inlen) const = 0;

	/**
	  * Resamples the samples in 'in' and puts the resulting samples in 'out'.
	  *
	  * @param inlen The number of samples in 'in' to be resampled/consumed.
	  * @return The number of samples produced in 'out'.
	  */
	virtual std::size_t resample(short *out, short const *in, std::size_t inlen) = 0;

	virtual ~Resampler() {}

protected:
	Resampler() : inRate_(0), outRate_(0) {}
	Resampler(long inRate, long outRate) : inRate_(inRate), outRate_(outRate) {}
	void setRate(long inRate, long outRate) { inRate_ = inRate; outRate_ = outRate; }

private:
	long inRate_;
	long outRate_;
};

#endif
