1 /* //device/include/server/AudioFlinger/AudioPeakingFilter.cpp 2 ** 3 ** Copyright 2007, The Android Open Source Project 4 ** 5 ** Licensed under the Apache License, Version 2.0 (the "License"); 6 ** you may not use this file except in compliance with the License. 7 ** You may obtain a copy of the License at 8 ** 9 ** http://www.apache.org/licenses/LICENSE-2.0 10 ** 11 ** Unless required by applicable law or agreed to in writing, software 12 ** distributed under the License is distributed on an "AS IS" BASIS, 13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 ** See the License for the specific language governing permissions and 15 ** limitations under the License. 16 */ 17 18 #include "AudioPeakingFilter.h" 19 #include "AudioCommon.h" 20 #include "EffectsMath.h" 21 22 #include <new> 23 #include <assert.h> 24 #include <cutils/compiler.h> 25 26 namespace android { 27 // Format of the coefficient table: 28 // kCoefTable[freq][gain][bw][coef] 29 // freq - peak frequency, in octaves below Nyquist,from -9 to -1. 30 // gain - gain, in millibel, starting at -9600, jumps of 1024, to 4736 millibel. 31 // bw - bandwidth, starting at 1 cent, jumps of 1024, to 3073 cents. 32 // coef - 0: b0 33 // 1: b1 34 // 2: b2 35 // 3: -a1 36 // 4: -a2 37 static const size_t kInDims[3] = {9, 15, 4}; 38 static const audio_coef_t kCoefTable[9*15*4*5] = { 39 #include "AudioPeakingFilterCoef.inl" 40 }; 41 42 AudioCoefInterpolator AudioPeakingFilter::mCoefInterp(3, kInDims, 5, (const audio_coef_t*) kCoefTable); 43 44 AudioPeakingFilter::AudioPeakingFilter(int nChannels, int sampleRate) 45 : mBiquad(nChannels, sampleRate) { 46 configure(nChannels, sampleRate); 47 reset(); 48 } 49 50 void AudioPeakingFilter::configure(int nChannels, int sampleRate) { 51 mNiquistFreq = sampleRate * 500; 52 mFrequencyFactor = ((1ull) << 42) / mNiquistFreq; 53 mBiquad.configure(nChannels, sampleRate); 54 setFrequency(mNominalFrequency); 55 commit(true); 56 } 57 58 void AudioPeakingFilter::reset() { 59 setGain(0); 60 setFrequency(0); 61 setBandwidth(2400); 62 commit(true); 63 } 64 65 void AudioPeakingFilter::setFrequency(uint32_t millihertz) { 66 mNominalFrequency = millihertz; 67 if (CC_UNLIKELY(millihertz > mNiquistFreq / 2)) { 68 millihertz = mNiquistFreq / 2; 69 } 70 uint32_t normFreq = static_cast<uint32_t>( 71 (static_cast<uint64_t>(millihertz) * mFrequencyFactor) >> 10); 72 if (CC_LIKELY(normFreq > (1 << 23))) { 73 mFrequency = (Effects_log2(normFreq) - ((32-9) << 15)) << (FREQ_PRECISION_BITS - 15); 74 } else { 75 mFrequency = 0; 76 } 77 } 78 79 void AudioPeakingFilter::setGain(int32_t millibel) { 80 mGain = millibel + 9600; 81 } 82 83 void AudioPeakingFilter::setBandwidth(uint32_t cents) { 84 mBandwidth = cents - 1; 85 } 86 87 void AudioPeakingFilter::commit(bool immediate) { 88 audio_coef_t coefs[5]; 89 int intCoord[3] = { 90 mFrequency >> FREQ_PRECISION_BITS, 91 mGain >> GAIN_PRECISION_BITS, 92 mBandwidth >> BANDWIDTH_PRECISION_BITS 93 }; 94 uint32_t fracCoord[3] = { 95 mFrequency << (32 - FREQ_PRECISION_BITS), 96 static_cast<uint32_t>(mGain) << (32 - GAIN_PRECISION_BITS), 97 mBandwidth << (32 - BANDWIDTH_PRECISION_BITS) 98 }; 99 mCoefInterp.getCoef(intCoord, fracCoord, coefs); 100 mBiquad.setCoefs(coefs, immediate); 101 } 102 103 void AudioPeakingFilter::getBandRange(uint32_t & low, uint32_t & high) const { 104 // Half bandwidth, in octaves, 15-bit precision 105 int32_t halfBW = (((mBandwidth + 1) / 2) << 15) / 1200; 106 107 low = static_cast<uint32_t>((static_cast<uint64_t>(mNominalFrequency) * Effects_exp2(-halfBW + (16 << 15))) >> 16); 108 if (CC_UNLIKELY(halfBW >= (16 << 15))) { 109 high = mNiquistFreq; 110 } else { 111 high = static_cast<uint32_t>((static_cast<uint64_t>(mNominalFrequency) * Effects_exp2(halfBW + (16 << 15))) >> 16); 112 if (CC_UNLIKELY(high > mNiquistFreq)) { 113 high = mNiquistFreq; 114 } 115 } 116 } 117 118 } 119 120
