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/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_AUDIO_RESAMPLER_CUBIC_H
#define ANDROID_AUDIO_RESAMPLER_CUBIC_H
#include <stdint.h>
#include <sys/types.h>
#include <cutils/log.h>
#include "AudioResampler.h"
namespace android {
// ----------------------------------------------------------------------------
class AudioResamplerCubic : public AudioResampler {
public:
AudioResamplerCubic(int bitDepth, int inChannelCount, int32_t sampleRate) :
AudioResampler(bitDepth, inChannelCount, sampleRate) {
}
virtual void resample(int32_t* out, size_t outFrameCount,
AudioBufferProvider* provider);
private:
// number of bits used in interpolation multiply - 14 bits avoids overflow
static const int kNumInterpBits = 14;
// bits to shift the phase fraction down to avoid overflow
static const int kPreInterpShift = kNumPhaseBits - kNumInterpBits;
typedef struct {
int32_t a, b, c, y0, y1, y2, y3;
} state;
void init();
void resampleMono16(int32_t* out, size_t outFrameCount,
AudioBufferProvider* provider);
void resampleStereo16(int32_t* out, size_t outFrameCount,
AudioBufferProvider* provider);
static inline int32_t interp(state* p, int32_t x) {
return (((((p->a * x >> 14) + p->b) * x >> 14) + p->c) * x >> 14) + p->y1;
}
static inline void advance(state* p, int16_t in) {
p->y0 = p->y1;
p->y1 = p->y2;
p->y2 = p->y3;
p->y3 = in;
p->a = (3 * (p->y1 - p->y2) - p->y0 + p->y3) >> 1;
p->b = (p->y2 << 1) + p->y0 - (((5 * p->y1 + p->y3)) >> 1);
p->c = (p->y2 - p->y0) >> 1;
}
state left, right;
};
// ----------------------------------------------------------------------------
}; // namespace android
#endif /*ANDROID_AUDIO_RESAMPLER_CUBIC_H*/
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