69 lines
1.8 KiB
C++
69 lines
1.8 KiB
C++
// SPDX-License-Identifier: GPL-2.0-or-later
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// Copyright The Music Player Daemon Project
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#ifndef MPD_PCM_DITHER_HXX
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#define MPD_PCM_DITHER_HXX
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#include <cstdint>
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enum class SampleFormat : uint8_t;
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class PcmDither {
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int32_t error[3];
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int32_t random;
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public:
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constexpr PcmDither() noexcept
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:error{0, 0, 0}, random(0) {}
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/**
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* Shift the given sample by #SBITS-#DBITS to the right, and
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* apply dithering.
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*
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* @tparam ST the input sample type
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* @tparam SBITS the input bit width
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* @tparam DBITS the output bit width
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* @param sample the input sample value
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*/
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template<typename ST, unsigned SBITS, unsigned DBITS>
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ST DitherShift(ST sample) noexcept;
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void Dither24To16(int16_t *dest, const int32_t *src,
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const int32_t *src_end) noexcept;
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void Dither32To16(int16_t *dest, const int32_t *src,
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const int32_t *src_end) noexcept;
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private:
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/**
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* Shift the given sample by #scale_bits to the right, and
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* apply dithering.
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*
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* @param T the input sample type
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* @param MIN the minimum input sample value
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* @param MAX the maximum input sample value
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* @param scale_bits the number of bits to be discarded
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* @param sample the input sample value
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*/
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template<typename T, T MIN, T MAX, unsigned scale_bits>
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T Dither(T sample) noexcept;
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/**
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* Convert the given sample from one sample format to another,
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* discarding bits.
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*
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* @param ST the input #SampleTraits class
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* @param ST the output #SampleTraits class
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* @param sample the input sample value
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*/
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template<typename ST, typename DT>
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typename DT::value_type DitherConvert(typename ST::value_type sample) noexcept;
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template<typename ST, typename DT>
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void DitherConvert(typename DT::pointer dest,
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typename ST::const_pointer src,
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typename ST::const_pointer src_end) noexcept;
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};
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#endif
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