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
26 namespace 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
37 static const size_t kHiInDims[2] = {3, 15};
38 static const audio_coef_t kHiCoefTable[3*15*5] = {
39 #include "AudioHighShelfFilterCoef.inl"
40 };
41 static const size_t kLoInDims[2] = {5, 15};
42 static const audio_coef_t kLoCoefTable[5*15*5] = {
43 #include "AudioLowShelfFilterCoef.inl"
44 };
45
46 AudioCoefInterpolator AudioShelvingFilter::mHiCoefInterp(2, kHiInDims, 5, (const audio_coef_t*) kHiCoefTable);
47 AudioCoefInterpolator AudioShelvingFilter::mLoCoefInterp(2, kLoInDims, 5, (const audio_coef_t*) kLoCoefTable);
48
AudioShelvingFilter(ShelfType type,int nChannels,int sampleRate)49 AudioShelvingFilter::AudioShelvingFilter(ShelfType type, int nChannels,
50 int sampleRate)
51 : mType(type),
52 mBiquad(nChannels, sampleRate) {
53 configure(nChannels, sampleRate);
54 }
55
configure(int nChannels,int sampleRate)56 void 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
reset()64 void AudioShelvingFilter::reset() {
65 setGain(0);
66 setFrequency(mType == kLowShelf ? 0 : mNiquistFreq);
67 commit(true);
68 }
69
setFrequency(uint32_t millihertz)70 void 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
setGain(int32_t millibel)85 void AudioShelvingFilter::setGain(int32_t millibel) {
86 mGain = millibel + 9600;
87 }
88
commit(bool immediate)89 void AudioShelvingFilter::commit(bool immediate) {
90 audio_coef_t coefs[5];
91 int intCoord[2] = {
92 (int)(mFrequency >> FREQ_PRECISION_BITS),
93 (int)(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