100 lines
3.2 KiB
C++
100 lines
3.2 KiB
C++
/*====================================================================================
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EVS Codec 3GPP TS26.443 Nov 13, 2018. Version 12.11.0 / 13.7.0 / 14.3.0 / 15.1.0
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====================================================================================*/
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#include <math.h>
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#include "options.h"
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#include "cnst.h"
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#include "rom_com.h"
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#include "prot.h"
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namespace evs {
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/*-------------------------------------------------------------------*
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* Local constants
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*-------------------------------------------------------------------*/
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#define ATT_LENGHT 64
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#define ATT_SEG_LEN (L_FRAME/ATT_LENGHT)
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#define INV_ATT_SEG_LEN (1.0f/ATT_SEG_LEN)
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#define INV_L_FRAME (1.0f/L_FRAME)
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/*-------------------------------------------------------------------*
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* pre_echo_att()
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*
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* Attenuation of the pre-echo when encoder specifies an attack
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*-------------------------------------------------------------------*/
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void pre_echo_att(
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float *Last_frame_ener, /* i/o: Energy of the last frame */
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float *exc, /* i/o: Excitation of the current frame */
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const short attack_flag, /* i : flag signalling attack encoded by AC mode (GSC) */
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const short last_coder_type /* i : Last coder type */
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)
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{
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float etmp;
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float etmp1;
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float finc[ATT_LENGHT], ratio;
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short attack_pos, i;
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if ( attack_flag == 1 && last_coder_type == AUDIO)
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{
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/*-------------------------------------------------------------------------*
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* Find where the onset (attack) occurs by computing the energy per section
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* The inverse weighting aims to favor the first maxima in case of
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* gradual onset
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*-------------------------------------------------------------------------*/
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for(i = 0; i < ATT_LENGHT; i++)
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{
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finc[i] = sum2_f( exc + i*ATT_SEG_LEN, ATT_SEG_LEN )*((float)(ATT_LENGHT-i)/(ATT_LENGHT));
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}
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etmp = -1;
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attack_pos = maximum(finc, ATT_LENGHT, &etmp);
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/* Scaled the maximum energy and allowed 6 dB increase*/
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etmp *= INV_ATT_SEG_LEN;
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etmp1 = etmp;
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*Last_frame_ener *= 4.0f;
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/* If the maximum normalized energy > last frame energy + 6dB */
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if( etmp > *Last_frame_ener && attack_pos > 0 )
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{
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/* Find the average energy before the attack */
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etmp = sum_f( finc, attack_pos ) + 0.01f;
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etmp /= (attack_pos*ATT_SEG_LEN);
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/* Find the correction factor and apply it before the attack */
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ratio = (float)sqrt(*Last_frame_ener/etmp);
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/* Pre-echo atttenuation should never increase the energy */
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ratio = min(ratio, 1.0f);
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for(i = 0; i < attack_pos*ATT_SEG_LEN; i++)
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{
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exc[i] *= ratio;
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}
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}
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*Last_frame_ener = etmp1;
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}
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else
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{
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/*-------------------------------------------------------*
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* In normal cases, just compute the energy of the frame
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*-------------------------------------------------------*/
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etmp = sum2_f( exc, L_FRAME ) + 0.01f;
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etmp *= INV_L_FRAME;
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*Last_frame_ener = etmp;
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}
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return;
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}
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} // end of namespace
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