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/*
* Copyright 2003-2017 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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 for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_PCM_DITHER_HXX
#define MPD_PCM_DITHER_HXX
#include <stdint.h>
enum class SampleFormat : uint8_t;
class PcmDither {
int32_t error[3];
int32_t random;
public:
constexpr PcmDither() noexcept
:error{0, 0, 0}, random(0) {}
/**
* Shift the given sample by #SBITS-#DBITS to the right, and
* apply dithering.
*
* @tparam ST the input sample type
* @tparam SBITS the input bit width
* @tparam DBITS the output bit width
* @param sample the input sample value
*/
template<typename ST, unsigned SBITS, unsigned DBITS>
ST DitherShift(ST sample) noexcept;
void Dither24To16(int16_t *dest, const int32_t *src,
const int32_t *src_end) noexcept;
void Dither32To16(int16_t *dest, const int32_t *src,
const int32_t *src_end) noexcept;
private:
/**
* Shift the given sample by #scale_bits to the right, and
* apply dithering.
*
* @param T the input sample type
* @param MIN the minimum input sample value
* @param MAX the maximum input sample value
* @param scale_bits the number of bits to be discarded
* @param sample the input sample value
*/
template<typename T, T MIN, T MAX, unsigned scale_bits>
T Dither(T sample) noexcept;
/**
* Convert the given sample from one sample format to another,
* discarding bits.
*
* @param ST the input #SampleTraits class
* @param ST the output #SampleTraits class
* @param sample the input sample value
*/
template<typename ST, typename DT>
typename DT::value_type DitherConvert(typename ST::value_type sample) noexcept;
template<typename ST, typename DT>
void DitherConvert(typename DT::pointer_type dest,
typename ST::const_pointer_type src,
typename ST::const_pointer_type src_end) noexcept;
};
#endif
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