/*====================================================================================
EVS Codec 3GPP TS26.443 Jun 30, 2015. Version CR 26.443-0006
====================================================================================*/
#include "options.h"
#include "cnst.h"
#include "prot.h"
/*-------------------------------------------------------------------*
* Local constants
*-------------------------------------------------------------------*/
#define GAIN_PIT_MAX 1.2f
#define ACELP_GAINS_CONST 0.8f /* adaptive codebook gain constraint */
/*-------------------------------------------------------------------*
* Local functions
*-------------------------------------------------------------------*/
static float adpt_enr( const short codec_mode, const float *exc, const float *h1, float *y1, const short L_subfr, float *gain, float *g_corr,
const short clip_gain, const float *xn, float *xn2, short use_prev_sf_pit_gain );
/*-------------------------------------------------------------------*
* lp_filt_exc_enc()
*
* Low-pass filtering of the adaptive excitation
* Innovation target construction
* Gain quantization limitation
*-------------------------------------------------------------------*/
short lp_filt_exc_enc(
const short codec_mode, /* i : codec mode */
const long core_brate, /* i : core bitrate */
const short Opt_AMR_WB, /* i : flag indicating AMR-WB IO mode */
const short coder_type, /* i : coding type */
const short i_subfr, /* i : subframe index */
float *exc, /* i/o: pointer to excitation signal frame */
const float *h1, /* i : weighted filter input response */
const float *xn, /* i : target vector */
float *y1, /* o : zero-memory filtered adaptive excitation */
float *xn2, /* o : target vector for innovation search */
const short L_subfr, /* i : length of vectors for gain quantization */
const short L_frame, /* i : frame size */
float *g_corr, /* o : ACELP correlation values */
const short clip_gain, /* i : adaptive gain clipping flag */
float *gain_pit, /* o : adaptive excitation gain */
short *lp_flag /* i/o : mode selection */
)
{
float ener, ener_tmp, gain1, gain2, g_corr2[2], exc_tmp[L_FRAME16k], xn2_tmp[L_FRAME16k];
float y1_tmp[L_FRAME16k];
short select, i;
short use_prev_sf_pit_gain;
gain1 = 0.0f;
gain2 = 0.0f;
ener = 0.0f;
ener_tmp = 0.0f;
use_prev_sf_pit_gain = 0;
/*-----------------------------------------------------------------*
* Select LP filtering flag
*-----------------------------------------------------------------*/
if( codec_mode == MODE1 )
{
if ( ( Opt_AMR_WB || coder_type == GENERIC || coder_type == TRANSITION ) && core_brate < ACELP_11k60 )
{
*lp_flag = LOW_PASS;
}
else if ( core_brate >= ACELP_11k60 && coder_type != AUDIO )
{
*lp_flag = NORMAL_OPERATION;
}
else
{
*lp_flag = FULL_BAND;
}
}
/*----------------------------------------------------------------*
* Find energy of the fixed cb. target with respect to adaptive
* exc. filtering
* Find flag about splitting the gain quantizer in half
* - find the target energy if adaptive exc. is not filtered
* - filter the adaptive excitation and find the target energy
* if the exc. is filtered.
*----------------------------------------------------------------*/
if( codec_mode == MODE2 && coder_type == 100 )
{
use_prev_sf_pit_gain = 1;
}
if( *lp_flag == FULL_BAND || *lp_flag == NORMAL_OPERATION )
{
if( use_prev_sf_pit_gain == 1 )
{
ener = adpt_enr( codec_mode, &exc[i_subfr], h1, y1, L_subfr, gain_pit, g_corr, clip_gain, xn, xn2, use_prev_sf_pit_gain );
}
else
{
ener = adpt_enr( codec_mode, &exc[i_subfr], h1, y1, L_subfr, &gain1, g_corr, clip_gain, xn, xn2, use_prev_sf_pit_gain );
}
}
/*----------------------------------------------------------------*
* Find energy of the fixed cb. target with respect to adaptive
* exc. filtering
* filter the adaptive excitation and find the target energy
* if the exc. is filtered.
*----------------------------------------------------------------*/
if( *lp_flag == LOW_PASS || *lp_flag == NORMAL_OPERATION )
{
if( codec_mode == MODE2 && L_frame == L_FRAME16k )
{
for (i=0; i<L_subfr; i++)
{
exc_tmp[i] = (float)(0.21f * exc[i-1+i_subfr] + 0.58f * exc[i+i_subfr] + 0.21f * exc[i+1+i_subfr]);
}
}
else
{
for ( i=0; i<L_subfr; i++ )
{
exc_tmp[i] = (float)(0.18f * exc[i-1+i_subfr] + 0.64f * exc[i+i_subfr] + 0.18f * exc[i+1+i_subfr]);
}
}
if( use_prev_sf_pit_gain == 1 )
{
ener_tmp = adpt_enr( codec_mode, exc_tmp, h1, y1_tmp, L_subfr, gain_pit, g_corr2, clip_gain, xn, xn2_tmp, use_prev_sf_pit_gain );
}
else
{
ener_tmp = adpt_enr( codec_mode, exc_tmp, h1, y1_tmp, L_subfr, &gain2, g_corr2, clip_gain, xn, xn2_tmp, use_prev_sf_pit_gain );
}
}
/*-----------------------------------------------------------------*
* use the best prediction (minimize quadratic error)
*-----------------------------------------------------------------*/
if( ( (ener_tmp < ener) && (*lp_flag == NORMAL_OPERATION) ) || (*lp_flag == LOW_PASS) )
{
/* use the LP filter for pitch excitation prediction */
select = LOW_PASS;
mvr2r(exc_tmp, &exc[i_subfr], L_subfr);
mvr2r(y1_tmp, y1, L_subfr);
mvr2r( xn2_tmp, xn2, L_subfr );
if( use_prev_sf_pit_gain == 0 )
{
*gain_pit = gain2;
g_corr[0] = g_corr2[0];
g_corr[1] = g_corr2[1];
}
}
else
{
/* no LP filter used for pitch excitation prediction */
select = FULL_BAND;
if( use_prev_sf_pit_gain == 0 )
{
*gain_pit = gain1;
}
}
return(select);
}
/*-------------------------------------------------------------------*
* adpt_enr()
*
* Find the adaptive excitation energy
* This serves to decide about the filtering of the adaptive excitation
*-------------------------------------------------------------------*/
static float adpt_enr(
const short codec_mode, /* i : codec mode */
const float *exc, /* i : Excitation vector */
const float *h1, /* i : impuls response */
float *y1, /* o : zero-memory filtered adpt. excitation */
const short L_subfr, /* i : vector length */
float *gain, /* o : subframe adaptive gain */
float *g_corr, /* o : correlations for adptive gain */
const short clip_gain, /* i : adaptive gain clipping flag */
const float *xn, /* i : adaptive codebook target */
float *xn2, /* o : algebraic codebook target */
short use_prev_sf_pit_gain /* i : flag to use prev sf pitch gain or not */
)
{
float ener;
conv( exc, h1, y1, L_subfr );
if( use_prev_sf_pit_gain == 0 )
{
*gain = corr_xy1( xn, y1, g_corr, L_subfr, codec_mode==MODE2 );
/* clip gain, if necessary to avoid problems at decoder */
if ( clip_gain == 1 && *gain > 0.95f )
{
*gain = 0.95f;
}
if( clip_gain == 2 && *gain > 0.65f )
{
*gain = 0.65f;
}
}
/* find energy of new target xn2[] */
updt_tar( xn, xn2, y1, *gain, L_subfr );
ener = dotp( xn2, xn2, L_subfr );
return ener;
}
/*-------------------------------------------------------------------*
* corr_xy1()
*
* Find the correlations between the target xn[] and the filtered adaptive
* codebook excitation y1[]. ( <y1,y1> and -2<xn,y1> )
*-------------------------------------------------------------------*/
float corr_xy1( /* o : pitch gain (0..GAIN_PIT_MAX) */
const float xn[], /* i : target signal */
const float y1[], /* i : filtered adaptive codebook excitation */
float g_corr[], /* o : correlations <y1,y1> and -2<xn,y1> */
const short L_subfr, /* i : vector length */
const short norm_flag /* i : flag for constraining pitch contribution */
)
{
float temp1, temp2, gain,gain_p_snr;
/*-----------------------------------------------------------------*
* Find the ACELP correlations and the pitch gain
* (for current subframe)
*-----------------------------------------------------------------*/
/* Compute scalar product <xn[],y1[]> */
temp1 = dotp(xn, y1, L_subfr);
/* Compute scalar product <y1[],y1[]> */
temp2 = dotp(y1, y1, L_subfr) + 0.01f;
g_corr[0] = temp2;
g_corr[1] = -2.0f*temp1 + 0.01f;
/* find pitch gain and bound it by [0,GAIN_PIT_MAX] */
if( norm_flag )
{
gain = (temp1 + 0.01f)/temp2;
}
else
{
gain = temp1/temp2;
}
if( gain < 0.0f )
{
gain = 0.0f;
}
if( gain > GAIN_PIT_MAX )
{
gain = GAIN_PIT_MAX;
}
/*Limit the energy of pitch contribution*/
if( norm_flag )
{
/* Compute scalar product <xn[],xn[]> */
temp1 = dotp(xn, xn, L_subfr);
gain_p_snr = ACELP_GAINS_CONST*sqrt(temp1/temp2);
if( gain>gain_p_snr )
{
gain = gain_p_snr;
}
}
return gain;
}