1/* /android/src/frameworks/base/libs/audioflinger/AudioShelvingFilter.cpp
2**
3** Copyright 2009, 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 "AudioShelvingFilter.h"
19#include "AudioCommon.h"
20#include "EffectsMath.h"
21
22#include <new>
23#include <assert.h>
24#include <cutils/compiler.h>
25
26namespace android {
27// Format of the coefficient tables:
28// kCoefTable[freq][gain][coef]
29// freq  - cutoff frequency, in octaves below Nyquist,from -10 to -6 in low
30//         shelf, -2 to 0 in high shelf.
31// gain  - gain, in millibel, starting at -9600, jumps of 1024, to 4736 millibel.
32// coef - 0: b0
33//        1: b1
34//        2: b2
35//        3: -a1
36//        4: -a2
37static const size_t kHiInDims[2] = {3, 15};
38static const audio_coef_t kHiCoefTable[3*15*5] = {
39#include "AudioHighShelfFilterCoef.inl"
40};
41static const size_t kLoInDims[2] = {5, 15};
42static const audio_coef_t kLoCoefTable[5*15*5] = {
43#include "AudioLowShelfFilterCoef.inl"
44};
45
46AudioCoefInterpolator AudioShelvingFilter::mHiCoefInterp(2, kHiInDims, 5, (const audio_coef_t*) kHiCoefTable);
47AudioCoefInterpolator AudioShelvingFilter::mLoCoefInterp(2, kLoInDims, 5, (const audio_coef_t*) kLoCoefTable);
48
49AudioShelvingFilter::AudioShelvingFilter(ShelfType type, int nChannels,
50                                         int sampleRate)
51        : mType(type),
52          mBiquad(nChannels, sampleRate)  {
53    configure(nChannels, sampleRate);
54}
55
56void AudioShelvingFilter::configure(int nChannels, int sampleRate) {
57    mNiquistFreq = sampleRate * 500;
58    mFrequencyFactor = ((1ull) << 42) / mNiquistFreq;
59    mBiquad.configure(nChannels, sampleRate);
60    setFrequency(mNominalFrequency);
61    commit(true);
62}
63
64void AudioShelvingFilter::reset() {
65    setGain(0);
66    setFrequency(mType == kLowShelf ? 0 : mNiquistFreq);
67    commit(true);
68}
69
70void AudioShelvingFilter::setFrequency(uint32_t millihertz) {
71    mNominalFrequency = millihertz;
72    if (CC_UNLIKELY(millihertz > mNiquistFreq / 2)) {
73        millihertz = mNiquistFreq / 2;
74    }
75    uint32_t normFreq = static_cast<uint32_t>(
76            (static_cast<uint64_t>(millihertz) * mFrequencyFactor) >> 10);
77    uint32_t log2minFreq = (mType == kLowShelf ? (32-10) : (32-2));
78    if (CC_LIKELY(normFreq > (1U << log2minFreq))) {
79        mFrequency = (Effects_log2(normFreq) - (log2minFreq << 15)) << (FREQ_PRECISION_BITS - 15);
80    } else {
81        mFrequency = 0;
82    }
83}
84
85void AudioShelvingFilter::setGain(int32_t millibel) {
86    mGain = millibel + 9600;
87}
88
89void AudioShelvingFilter::commit(bool immediate) {
90    audio_coef_t coefs[5];
91    int intCoord[2] = {
92        mFrequency >> FREQ_PRECISION_BITS,
93        mGain >> GAIN_PRECISION_BITS
94    };
95    uint32_t fracCoord[2] = {
96        mFrequency << (32 - FREQ_PRECISION_BITS),
97        static_cast<uint32_t>(mGain) << (32 - GAIN_PRECISION_BITS)
98    };
99    if (mType == kHighShelf) {
100        mHiCoefInterp.getCoef(intCoord, fracCoord, coefs);
101    } else {
102        mLoCoefInterp.getCoef(intCoord, fracCoord, coefs);
103    }
104    mBiquad.setCoefs(coefs, immediate);
105}
106
107}
108