124 lines
4.1 KiB
C++
124 lines
4.1 KiB
C++
/*
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* AttackDetector.cpp
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*
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* Copyright 2019 HIMSA II K/S - www.himsa.dk. Represented by EHIMA - www.ehima.com
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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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#include "AttackDetector.hpp"
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#include <cmath>
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namespace Lc3Enc
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{
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AttackDetector::AttackDetector(const Lc3Config& lc3Config_) :
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lc3Config(lc3Config_),
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M_F( (lc3Config.N_ms == Lc3Config::FrameDuration::d10ms) ? 160 : 120), // 16*N_ms
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F_att(0),
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E_att_last(0),
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A_att_last(0),
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P_att_last(-1)
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{
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// make sure these states are initially zero as demanded by the specification
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x_att_last[0] = 0;
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x_att_last[1] = 0;
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}
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AttackDetector::~AttackDetector()
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{
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}
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void AttackDetector::run(const int16_t* const x_s, uint16_t nbytes)
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{
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// 3.3.6.1 Overview (d09r06_FhG)
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// -> attack detection active only for higher bitrates and fs>=32000; otherwise defaults are set
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F_att = 0;
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if ( lc3Config.Fs < 32000 )
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{
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return;
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}
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bool isActive =
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( (lc3Config.N_ms == Lc3Config::FrameDuration::d10ms) && (lc3Config.Fs==32000) && (nbytes>80) ) ||
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( (lc3Config.N_ms == Lc3Config::FrameDuration::d10ms) && (lc3Config.Fs>=44100) && (nbytes>=100) ) ||
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( (lc3Config.N_ms == Lc3Config::FrameDuration::d7p5ms) && (lc3Config.Fs==32000) && (nbytes>=61) && (nbytes<150) ) ||
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( (lc3Config.N_ms == Lc3Config::FrameDuration::d7p5ms) && (lc3Config.Fs>=44100) && (nbytes>=75) && (nbytes<150) );
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if ( !isActive )
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{
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// Note: in bitrate switching situations we have to set proper states
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E_att_last = 0;
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A_att_last = 0;
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P_att_last = -1;
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return;
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}
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// 3.3.6.2 Downsampling and filtering of input signal (d09r02_F2F)
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// Note: the following section might be converted to int32 instead
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// of double computation (maybe something for optimization)
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double x_att_extended[M_F+2];
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x_att_extended[0] = x_att_last[0];
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x_att_extended[1] = x_att_last[1];
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double* x_att = &x_att_extended[2];
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for (uint8_t n=0; n < M_F; n++) // downsampling
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{
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x_att[n] = 0;
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for (uint8_t m=0; m < lc3Config.NF/M_F; m++)
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{
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x_att[n] += x_s[ lc3Config.NF/M_F*n + m ];
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}
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}
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x_att_last[0] = x_att[M_F-2];
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x_att_last[1] = x_att[M_F-1];
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double* x_hp = x_att_extended; // just for improve readability
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for (uint8_t n=0; n < M_F; n++) // highpass-filtering (in-place!)
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{
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x_hp[n] = 0.375*x_att[n] - 0.5*x_att[n-1] + 0.125*x_att[n-2];
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}
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// 3.3.6.3 Energy calculation & 3.3.6.4 Attack detection (d09r06_FhG)
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int8_t P_att = -1;
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const uint8_t N_blocks = (lc3Config.N_ms == Lc3Config::FrameDuration::d10ms) ? 4 : 3; // N_ms/2.5
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for (uint8_t n=0; n < N_blocks; n++)
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{
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double E_att = 0;
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for (uint8_t l=40*n; l <= (40*n+39); l++)
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{
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E_att += x_hp[l]*x_hp[l];
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}
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double A_att = (0.25*A_att_last > E_att_last) ? 0.25*A_att_last : E_att_last;
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if (E_att > 8.5*A_att)
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{
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// attack detected
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P_att = n;
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}
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E_att_last = E_att;
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A_att_last = A_att;
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}
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const uint8_t T_att = (lc3Config.N_ms == Lc3Config::FrameDuration::d10ms) ? 2 : 1; // floor(N_blocks/2)
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F_att = (P_att >= 0) || (P_att_last >= T_att);
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P_att_last = P_att; // prepare next frame
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}
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void AttackDetector::registerDatapoints(DatapointContainer* datapoints)
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{
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if (nullptr != datapoints)
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{
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datapoints->addDatapoint( "F_att", &F_att, sizeof(F_att) );
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}
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}
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}//namespace Lc3Enc
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