2c87e9c923
This CL contains the first open sourceable version of the audio effect library from NXP software. The effects implemented are: - Bass boost - Virtualizer (stereo widening) - Equalizer - Spectrum analyzer Source file for the effect engines are located under libeffects/lvm/lib The wrapper implementing the interface with the audio effect framework in under libeffects/lvm/wrapper The code of other effect libraries has also been reorganized fo clarity: - the effect factory is now under libeffects/factory - the test equalizer and reverb effects are under libeffect/testlibs - the visualizer is under libeffects/virtualizer Change-Id: I8d91e2181f81b89f8fc0c1e1e6bf552c5809b2eb
144 lines
3.8 KiB
C
144 lines
3.8 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#define LOG_TAG "EFFECTSMATH"
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//#define LOG_NDEBUG 0
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#include <cutils/log.h>
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#include <assert.h>
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#include "EffectsMath.h"
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// gLogTab contains pre-calculated values of log2(1 + ai5*2^-1 + ai4*2^-2 + ai3*2^-3 + ai2*2^-4 + ai1*2^-5 + ai0*2^-6)
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// for integers in the range 0 to 63 (i = ai5*2^5 + ai4*2^4 + ai3*2^3 + ai2*2^2 + ai1*2^1 + ai0*2^0)
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// It is used for a better than piece wise approximation of lin to log2 conversion
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static const uint16_t gLogTab[] =
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{
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0, 733, 1455, 2166,
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2866, 3556, 4236, 4907,
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5568, 6220, 6863, 7498,
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8124, 8742, 9352, 9954,
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10549, 11136, 11716, 12289,
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12855, 13415, 13968, 14514,
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15055, 15589, 16117, 16639,
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17156, 17667, 18173, 18673,
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19168, 19658, 20143, 20623,
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21098, 21568, 22034, 22495,
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22952, 23404, 23852, 24296,
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24736, 25172, 25604, 26031,
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26455, 26876, 27292, 27705,
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28114, 28520, 28922, 29321,
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29717, 30109, 30498, 30884,
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31267, 31647, 32024, 32397,
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32768
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};
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int32_t Effects_log2(uint32_t x) {
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int32_t exp = 31 - __builtin_clz(x);
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uint32_t segStart = x >> (exp - 6);
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uint32_t i = segStart & 0x3F;
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int32_t log = (int32_t)gLogTab[i];
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int32_t logEnd = (int32_t)gLogTab[i+1];
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segStart <<= exp - 6;
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return (exp << 15) + log + (((x - segStart) * (logEnd - log)) >> (exp - 6));
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}
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// gExpTab[i] = (2^(i>>6)) << 22
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static const uint32_t gExpTab[] = {
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4194304, 4239977, 4286147, 4332820,
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4380002, 4427697, 4475911, 4524651,
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4573921, 4623728, 4674077, 4724974,
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4776426, 4828438, 4881016, 4934167,
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4987896, 5042211, 5097117, 5152621,
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5208729, 5265449, 5322786, 5380747,
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5439339, 5498570, 5558445, 5618973,
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5680159, 5742012, 5804539, 5867746,
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5931642, 5996233, 6061528, 6127533,
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6194258, 6261709, 6329894, 6398822,
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6468501, 6538938, 6610143, 6682122,
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6754886, 6828442, 6902799, 6977965,
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7053950, 7130763, 7208412, 7286906,
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7366255, 7446469, 7527555, 7609525,
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7692387, 7776152, 7860829, 7946428,
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8032959, 8120432, 8208857, 8298246,
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8388608
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};
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uint32_t Effects_exp2(int32_t x) {
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int32_t i = x >> 15;
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assert(i < 32);
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x &= (1 << 15) - 1;
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int32_t j = x >> 9;
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x &= (1 << 9) - 1;
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uint32_t exp = gExpTab[j];
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uint32_t expEnd = gExpTab[j+1];
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return ((exp << 9) + (expEnd - exp) * x) >> (31 - i);
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}
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int16_t Effects_MillibelsToLinear16 (int32_t nGain)
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{
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nGain = ((nGain + MB_TO_LIN_K1) << 15 ) / MB_TO_LIN_K2;
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uint32_t exp2 = Effects_exp2(nGain);
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if (exp2 > 32767) exp2 = 32767;
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return (int16_t)exp2;
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}
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int16_t Effects_Linear16ToMillibels (int32_t nGain)
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{
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return (int16_t)(((MB_TO_LIN_K2*Effects_log2(nGain))>>15)-MB_TO_LIN_K1);
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}
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int32_t Effects_Sqrt(int32_t in)
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{
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int32_t tmp;
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int32_t out = 0;
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int32_t i;
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int32_t j;
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if (in == 0) return 0;
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if (in >= 0x10000000)
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{
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out = 0x4000;
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in -= 0x10000000;
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}
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j = 32 - __builtin_clz(in);
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if (j & 1) j++;
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j >>= 1;
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for (i = j; i > 0; i--) {
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tmp = (out << i) + (1 << ((i - 1)*2));
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if (in >= tmp)
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{
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out += 1 << (i-1);
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in -= tmp;
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}
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}
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return out;
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}
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