69 lines
2.4 KiB
C
69 lines
2.4 KiB
C
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/*
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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_CUBIC_H
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#define ANDROID_AUDIO_RESAMPLER_CUBIC_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 AudioResamplerCubic : public AudioResampler {
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public:
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AudioResamplerCubic(int bitDepth, int inChannelCount, int32_t sampleRate) :
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AudioResampler(bitDepth, inChannelCount, sampleRate) {
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}
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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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// number of bits used in interpolation multiply - 14 bits avoids overflow
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static const int kNumInterpBits = 14;
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// bits to shift the phase fraction down to avoid overflow
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static const int kPreInterpShift = kNumPhaseBits - kNumInterpBits;
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typedef struct {
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int32_t a, b, c, y0, y1, y2, y3;
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} state;
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void init();
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void resampleMono16(int32_t* out, size_t outFrameCount,
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AudioBufferProvider* provider);
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void resampleStereo16(int32_t* out, size_t outFrameCount,
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AudioBufferProvider* provider);
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static inline int32_t interp(state* p, int32_t x) {
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return (((((p->a * x >> 14) + p->b) * x >> 14) + p->c) * x >> 14) + p->y1;
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}
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static inline void advance(state* p, int16_t in) {
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p->y0 = p->y1;
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p->y1 = p->y2;
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p->y2 = p->y3;
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p->y3 = in;
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p->a = (3 * (p->y1 - p->y2) - p->y0 + p->y3) >> 1;
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p->b = (p->y2 << 1) + p->y0 - (((5 * p->y1 + p->y3)) >> 1);
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p->c = (p->y2 - p->y0) >> 1;
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}
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state left, right;
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};
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// ----------------------------------------------------------------------------
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}; // namespace android
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#endif /*ANDROID_AUDIO_RESAMPLER_CUBIC_H*/
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