1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ANDROID_AUDIO_RESAMPLER_CUBIC_H 18 #define ANDROID_AUDIO_RESAMPLER_CUBIC_H 19 20 #include <stdint.h> 21 #include <sys/types.h> 22 #include <android/log.h> 23 24 #include <media/AudioResampler.h> 25 26 namespace android { 27 // ---------------------------------------------------------------------------- 28 29 class AudioResamplerCubic : public AudioResampler { 30 public: AudioResamplerCubic(int inChannelCount,int32_t sampleRate)31 AudioResamplerCubic(int inChannelCount, int32_t sampleRate) : 32 AudioResampler(inChannelCount, sampleRate, MED_QUALITY) { 33 } 34 virtual size_t resample(int32_t* out, size_t outFrameCount, 35 AudioBufferProvider* provider); 36 private: 37 // number of bits used in interpolation multiply - 14 bits avoids overflow 38 static const int kNumInterpBits = 14; 39 40 // bits to shift the phase fraction down to avoid overflow 41 static const int kPreInterpShift = kNumPhaseBits - kNumInterpBits; 42 typedef struct { 43 int32_t a, b, c, y0, y1, y2, y3; 44 } state; 45 void init(); 46 size_t resampleMono16(int32_t* out, size_t outFrameCount, 47 AudioBufferProvider* provider); 48 size_t resampleStereo16(int32_t* out, size_t outFrameCount, 49 AudioBufferProvider* provider); interp(state * p,int32_t x)50 static inline int32_t interp(state* p, int32_t x) { 51 return (((((p->a * x >> 14) + p->b) * x >> 14) + p->c) * x >> 14) + p->y1; 52 } advance(state * p,int16_t in)53 static inline void advance(state* p, int16_t in) { 54 p->y0 = p->y1; 55 p->y1 = p->y2; 56 p->y2 = p->y3; 57 p->y3 = in; 58 p->a = (3 * (p->y1 - p->y2) - p->y0 + p->y3) >> 1; 59 p->b = (p->y2 << 1) + p->y0 - (((5 * p->y1 + p->y3)) >> 1); 60 p->c = (p->y2 - p->y0) >> 1; 61 } 62 state left, right; 63 }; 64 65 // ---------------------------------------------------------------------------- 66 } // namespace android 67 68 #endif /*ANDROID_AUDIO_RESAMPLER_CUBIC_H*/ 69