104 lines
2.7 KiB
C++
104 lines
2.7 KiB
C++
/*
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* PacketLossConcealment.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 "PacketLossConcealment.hpp"
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namespace Lc3Dec
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{
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PacketLossConcealment::PacketLossConcealment(uint16_t NE_) :
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NE(NE_),
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plc_seed(24607), // the specification is not very precise here, but we assume that this initialization need not be done every frame
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nbLostCmpt(0),
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alpha(1),
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X_hat_lastGood(nullptr)
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{
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X_hat_lastGood = new double[NE];
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for (uint16_t k=0; k < NE; k++)
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{
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X_hat_lastGood[k] = 0.0;
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}
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}
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PacketLossConcealment::~PacketLossConcealment()
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{
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delete[] X_hat_lastGood;
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}
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void PacketLossConcealment::run(uint8_t BEC_detect, double* X_hat, uint8_t& pitch_present)
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{
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// Appendix B. Packet Loss Concealment (d09r02_F2F)
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if (0==BEC_detect)
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{
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nbLostCmpt = 0;
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alpha = 1;
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for (uint16_t k=0; k < NE; k++)
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{
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X_hat_lastGood[k] = X_hat[k];
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}
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}
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else
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{
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pitch_present = 0; // forces deactivation of LongTermPostfilter
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if (nbLostCmpt < 0xFF)
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{
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nbLostCmpt++;
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}
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// Note: from (d09r02_F2F) its is not perfectly clear,
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// whether alpha is modified before or after applying
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// it to the spectrum -> we may have to check the
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// given implementation with the LC3.exe reference
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if (nbLostCmpt >= 8)
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{
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alpha = 0.85*alpha;
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}
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else if (nbLostCmpt >= 4)
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{
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alpha = 0.9*alpha;
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}
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for (uint16_t k=0; k < NE; k++)
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{
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plc_seed = (16831 + plc_seed*12821) & 0xFFFF;
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if (plc_seed < 0x8000)
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{
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X_hat[k] = alpha*X_hat_lastGood[k];
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}
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else
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{
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X_hat[k] = -alpha*X_hat_lastGood[k];
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}
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}
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}
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}
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void PacketLossConcealment::registerDatapoints(DatapointContainer* datapoints)
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{
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if (nullptr != datapoints)
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{
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datapoints->addDatapoint( "X_hat_lastGood", &X_hat_lastGood[0], sizeof(double)*NE);
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}
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}
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}//namespace Lc3Dec
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