AudioPeakingFilter.cpp revision 2c8e5cab3faa6d360e222b7a6c40a80083d021ac
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 25#define LIKELY( exp ) (__builtin_expect( (exp) != 0, true )) 26#define UNLIKELY( exp ) (__builtin_expect( (exp) != 0, false )) 27 28namespace android { 29// Format of the coefficient table: 30// kCoefTable[freq][gain][bw][coef] 31// freq - peak frequency, in octaves below Nyquist,from -9 to -1. 32// gain - gain, in millibel, starting at -9600, jumps of 1024, to 4736 millibel. 33// bw - bandwidth, starting at 1 cent, jumps of 1024, to 3073 cents. 34// coef - 0: b0 35// 1: b1 36// 2: b2 37// 3: -a1 38// 4: -a2 39static const size_t kInDims[3] = {9, 15, 4}; 40static const audio_coef_t kCoefTable[9*15*4*5] = { 41#include "AudioPeakingFilterCoef.inl" 42}; 43 44AudioCoefInterpolator AudioPeakingFilter::mCoefInterp(3, kInDims, 5, (const audio_coef_t*) kCoefTable); 45 46AudioPeakingFilter::AudioPeakingFilter(int nChannels, int sampleRate) 47 : mBiquad(nChannels, sampleRate) { 48 configure(nChannels, sampleRate); 49 reset(); 50} 51 52void AudioPeakingFilter::configure(int nChannels, int sampleRate) { 53 mNiquistFreq = sampleRate * 500; 54 mFrequencyFactor = ((1ull) << 42) / mNiquistFreq; 55 mBiquad.configure(nChannels, sampleRate); 56 setFrequency(mNominalFrequency); 57 commit(true); 58} 59 60void AudioPeakingFilter::reset() { 61 setGain(0); 62 setFrequency(0); 63 setBandwidth(2400); 64 commit(true); 65} 66 67void AudioPeakingFilter::setFrequency(uint32_t millihertz) { 68 mNominalFrequency = millihertz; 69 if (UNLIKELY(millihertz > mNiquistFreq / 2)) { 70 millihertz = mNiquistFreq / 2; 71 } 72 uint32_t normFreq = static_cast<uint32_t>( 73 (static_cast<uint64_t>(millihertz) * mFrequencyFactor) >> 10); 74 if (LIKELY(normFreq > (1 << 23))) { 75 mFrequency = (Effects_log2(normFreq) - ((32-9) << 15)) << (FREQ_PRECISION_BITS - 15); 76 } else { 77 mFrequency = 0; 78 } 79} 80 81void AudioPeakingFilter::setGain(int32_t millibel) { 82 mGain = millibel + 9600; 83} 84 85void AudioPeakingFilter::setBandwidth(uint32_t cents) { 86 mBandwidth = cents - 1; 87} 88 89void AudioPeakingFilter::commit(bool immediate) { 90 audio_coef_t coefs[5]; 91 int intCoord[3] = { 92 mFrequency >> FREQ_PRECISION_BITS, 93 mGain >> GAIN_PRECISION_BITS, 94 mBandwidth >> BANDWIDTH_PRECISION_BITS 95 }; 96 uint32_t fracCoord[3] = { 97 mFrequency << (32 - FREQ_PRECISION_BITS), 98 static_cast<uint32_t>(mGain) << (32 - GAIN_PRECISION_BITS), 99 mBandwidth << (32 - BANDWIDTH_PRECISION_BITS) 100 }; 101 mCoefInterp.getCoef(intCoord, fracCoord, coefs); 102 mBiquad.setCoefs(coefs, immediate); 103} 104 105void AudioPeakingFilter::getBandRange(uint32_t & low, uint32_t & high) const { 106 // Half bandwidth, in octaves, 15-bit precision 107 int32_t halfBW = (((mBandwidth + 1) / 2) << 15) / 1200; 108 109 low = static_cast<uint32_t>((static_cast<uint64_t>(mNominalFrequency) * Effects_exp2(-halfBW + (16 << 15))) >> 16); 110 if (UNLIKELY(halfBW >= (16 << 15))) { 111 high = mNiquistFreq; 112 } else { 113 high = static_cast<uint32_t>((static_cast<uint64_t>(mNominalFrequency) * Effects_exp2(halfBW + (16 << 15))) >> 16); 114 if (UNLIKELY(high > mNiquistFreq)) { 115 high = mNiquistFreq; 116 } 117 } 118} 119 120} 121 122