89 lines
3.0 KiB
C++
89 lines
3.0 KiB
C++
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_AUDIO_RESAMPLER_SINC_H
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#define ANDROID_AUDIO_RESAMPLER_SINC_H
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#include <stdint.h>
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#include <sys/types.h>
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#include <cutils/log.h>
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#include "AudioResampler.h"
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namespace android {
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// ----------------------------------------------------------------------------
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class AudioResamplerSinc : public AudioResampler {
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public:
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AudioResamplerSinc(int bitDepth, int inChannelCount, int32_t sampleRate);
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~AudioResamplerSinc();
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virtual void resample(int32_t* out, size_t outFrameCount,
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AudioBufferProvider* provider);
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private:
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void init();
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template<int CHANNELS>
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void resample(int32_t* out, size_t outFrameCount,
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AudioBufferProvider* provider);
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template<int CHANNELS>
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inline void filterCoefficient(
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int32_t& l, int32_t& r, uint32_t phase, int16_t const *samples);
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template<int CHANNELS>
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inline void interpolate(
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int32_t& l, int32_t& r,
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int32_t const* coefs, int16_t lerp, int16_t const* samples);
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template<int CHANNELS>
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inline void read(int16_t*& impulse, uint32_t& phaseFraction,
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int16_t const* in, size_t inputIndex);
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int16_t *mState;
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int16_t *mImpulse;
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int16_t *mRingFull;
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int32_t const * mFirCoefs;
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static const int32_t mFirCoefsDown[];
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static const int32_t mFirCoefsUp[];
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// ----------------------------------------------------------------------------
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static const int32_t RESAMPLE_FIR_NUM_COEF = 8;
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static const int32_t RESAMPLE_FIR_LERP_INT_BITS = 4;
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// we have 16 coefs samples per zero-crossing
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static const int coefsBits = RESAMPLE_FIR_LERP_INT_BITS; // 4
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static const int cShift = kNumPhaseBits - coefsBits; // 26
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static const uint32_t cMask = ((1<<coefsBits)-1) << cShift; // 0xf<<26 = 3c00 0000
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// and we use 15 bits to interpolate between these samples
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// this cannot change because the mul below rely on it.
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static const int pLerpBits = 15;
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static const int pShift = kNumPhaseBits - coefsBits - pLerpBits; // 11
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static const uint32_t pMask = ((1<<pLerpBits)-1) << pShift; // 0x7fff << 11
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// number of zero-crossing on each side
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static const unsigned int halfNumCoefs = RESAMPLE_FIR_NUM_COEF;
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};
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// ----------------------------------------------------------------------------
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}; // namespace android
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#endif /*ANDROID_AUDIO_RESAMPLER_SINC_H*/
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