Add copy of opus library in deps/third_party.

opus/silk/PLC.c

+/***********************************************************************
+Copyright (c) 2006-2011, Skype Limited. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+- Redistributions of source code must retain the above copyright notice,
+this list of conditions and the following disclaimer.
+- Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+- Neither the name of Internet Society, IETF or IETF Trust, nor the 
+names of specific contributors, may be used to endorse or promote
+products derived from this software without specific prior written
+permission.
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS”
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+***********************************************************************/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "main.h"
+#include "PLC.h"
+
+#define NB_ATT 2
+static const opus_int16 HARM_ATT_Q15[NB_ATT]              = { 32440, 31130 }; /* 0.99, 0.95 */
+static const opus_int16 PLC_RAND_ATTENUATE_V_Q15[NB_ATT]  = { 31130, 26214 }; /* 0.95, 0.8 */
+static const opus_int16 PLC_RAND_ATTENUATE_UV_Q15[NB_ATT] = { 32440, 29491 }; /* 0.99, 0.9 */
+
+static inline void silk_PLC_update(
+    silk_decoder_state                  *psDec,             /* I/O Decoder state        */
+    silk_decoder_control                *psDecCtrl          /* I/O Decoder control      */
+);
+
+static inline void silk_PLC_conceal(
+    silk_decoder_state                  *psDec,             /* I/O Decoder state        */
+    silk_decoder_control                *psDecCtrl,         /* I/O Decoder control      */
+    opus_int16                          frame[]             /* O LPC residual signal    */
+);
+
+
+void silk_PLC_Reset(
+    silk_decoder_state                  *psDec              /* I/O Decoder state        */
+)
+{
+    psDec->sPLC.pitchL_Q8 = silk_LSHIFT( psDec->frame_length, 8 - 1 );
+    psDec->sPLC.prevGain_Q16[ 0 ] = SILK_FIX_CONST( 1, 16 );
+    psDec->sPLC.prevGain_Q16[ 1 ] = SILK_FIX_CONST( 1, 16 );
+    psDec->sPLC.subfr_length = 20;
+    psDec->sPLC.nb_subfr = 2;
+}
+
+void silk_PLC(
+    silk_decoder_state                  *psDec,             /* I/O Decoder state        */
+    silk_decoder_control                *psDecCtrl,         /* I/O Decoder control      */
+    opus_int16                          frame[],            /* I/O  signal              */
+    opus_int                            lost                /* I Loss flag              */
+)
+{
+    /* PLC control function */
+    if( psDec->fs_kHz != psDec->sPLC.fs_kHz ) {
+        silk_PLC_Reset( psDec );
+        psDec->sPLC.fs_kHz = psDec->fs_kHz;
+    }
+
+    if( lost ) {
+        /****************************/
+        /* Generate Signal          */
+        /****************************/
+        silk_PLC_conceal( psDec, psDecCtrl, frame );
+
+        psDec->lossCnt++;
+    } else {
+        /****************************/
+        /* Update state             */
+        /****************************/
+        silk_PLC_update( psDec, psDecCtrl );
+    }
+}
+
+/**************************************************/
+/* Update state of PLC                            */
+/**************************************************/
+static inline void silk_PLC_update(
+    silk_decoder_state                  *psDec,             /* I/O Decoder state        */
+    silk_decoder_control                *psDecCtrl          /* I/O Decoder control      */
+)
+{
+    opus_int32 LTP_Gain_Q14, temp_LTP_Gain_Q14;
+    opus_int   i, j;
+    silk_PLC_struct *psPLC;
+
+    psPLC = &psDec->sPLC;
+
+    /* Update parameters used in case of packet loss */
+    psDec->prevSignalType = psDec->indices.signalType;
+    LTP_Gain_Q14 = 0;
+    if( psDec->indices.signalType == TYPE_VOICED ) {
+        /* Find the parameters for the last subframe which contains a pitch pulse */
+        for( j = 0; j * psDec->subfr_length < psDecCtrl->pitchL[ psDec->nb_subfr - 1 ]; j++ ) {
+            if( j == psDec->nb_subfr ) {
+                break;
+            }
+            temp_LTP_Gain_Q14 = 0;
+            for( i = 0; i < LTP_ORDER; i++ ) {
+                temp_LTP_Gain_Q14 += psDecCtrl->LTPCoef_Q14[ ( psDec->nb_subfr - 1 - j ) * LTP_ORDER  + i ];
+            }
+            if( temp_LTP_Gain_Q14 > LTP_Gain_Q14 ) {
+                LTP_Gain_Q14 = temp_LTP_Gain_Q14;
+                silk_memcpy( psPLC->LTPCoef_Q14,
+                    &psDecCtrl->LTPCoef_Q14[ silk_SMULBB( psDec->nb_subfr - 1 - j, LTP_ORDER ) ],
+                    LTP_ORDER * sizeof( opus_int16 ) );
+
+                psPLC->pitchL_Q8 = silk_LSHIFT( psDecCtrl->pitchL[ psDec->nb_subfr - 1 - j ], 8 );
+            }
+        }
+
+        silk_memset( psPLC->LTPCoef_Q14, 0, LTP_ORDER * sizeof( opus_int16 ) );
+        psPLC->LTPCoef_Q14[ LTP_ORDER / 2 ] = LTP_Gain_Q14;
+
+        /* Limit LT coefs */
+        if( LTP_Gain_Q14 < V_PITCH_GAIN_START_MIN_Q14 ) {
+            opus_int   scale_Q10;
+            opus_int32 tmp;
+
+            tmp = silk_LSHIFT( V_PITCH_GAIN_START_MIN_Q14, 10 );
+            scale_Q10 = silk_DIV32( tmp, silk_max( LTP_Gain_Q14, 1 ) );
+            for( i = 0; i < LTP_ORDER; i++ ) {
+                psPLC->LTPCoef_Q14[ i ] = silk_RSHIFT( silk_SMULBB( psPLC->LTPCoef_Q14[ i ], scale_Q10 ), 10 );
+            }
+        } else if( LTP_Gain_Q14 > V_PITCH_GAIN_START_MAX_Q14 ) {
+            opus_int   scale_Q14;
+            opus_int32 tmp;
+
+            tmp = silk_LSHIFT( V_PITCH_GAIN_START_MAX_Q14, 14 );
+            scale_Q14 = silk_DIV32( tmp, silk_max( LTP_Gain_Q14, 1 ) );
+            for( i = 0; i < LTP_ORDER; i++ ) {
+                psPLC->LTPCoef_Q14[ i ] = silk_RSHIFT( silk_SMULBB( psPLC->LTPCoef_Q14[ i ], scale_Q14 ), 14 );
+            }
+        }
+    } else {
+        psPLC->pitchL_Q8 = silk_LSHIFT( silk_SMULBB( psDec->fs_kHz, 18 ), 8 );
+        silk_memset( psPLC->LTPCoef_Q14, 0, LTP_ORDER * sizeof( opus_int16 ));
+    }
+
+    /* Save LPC coeficients */
+    silk_memcpy( psPLC->prevLPC_Q12, psDecCtrl->PredCoef_Q12[ 1 ], psDec->LPC_order * sizeof( opus_int16 ) );
+    psPLC->prevLTP_scale_Q14 = psDecCtrl->LTP_scale_Q14;
+
+    /* Save last two gains */
+    silk_memcpy( psPLC->prevGain_Q16, &psDecCtrl->Gains_Q16[ psDec->nb_subfr - 2 ], 2 * sizeof( opus_int32 ) );
+
+    psPLC->subfr_length = psDec->subfr_length;
+    psPLC->nb_subfr = psDec->nb_subfr;
+}
+
+static inline void silk_PLC_conceal(
+    silk_decoder_state                  *psDec,             /* I/O Decoder state        */
+    silk_decoder_control                *psDecCtrl,         /* I/O Decoder control      */
+    opus_int16                          frame[]             /* O LPC residual signal    */
+)
+{
+    opus_int   i, j, k;
+    opus_int   lag, idx, sLTP_buf_idx, shift1, shift2;
+    opus_int32 rand_seed, harm_Gain_Q15, rand_Gain_Q15, inv_gain_Q30;
+    opus_int32 energy1, energy2, *rand_ptr, *pred_lag_ptr;
+    opus_int32 LPC_pred_Q10, LTP_pred_Q12;
+    opus_int16 rand_scale_Q14;
+    opus_int16 *B_Q14, *exc_buf_ptr;
+    opus_int32 *sLPC_Q14_ptr;
+    opus_int16 exc_buf[ 2 * MAX_SUB_FRAME_LENGTH ];
+    opus_int16 A_Q12[ MAX_LPC_ORDER ];
+    opus_int16 sLTP[ MAX_FRAME_LENGTH ];
+    opus_int32 sLTP_Q14[ 2 * MAX_FRAME_LENGTH ];
+    silk_PLC_struct *psPLC = &psDec->sPLC;
+    opus_int32 prevGain_Q10[2];
+
+    prevGain_Q10[0] = silk_RSHIFT( psPLC->prevGain_Q16[ 0 ], 6);
+    prevGain_Q10[1] = silk_RSHIFT( psPLC->prevGain_Q16[ 1 ], 6);
+
+    if( psDec->first_frame_after_reset ) {
+       silk_memset( psPLC->prevLPC_Q12, 0, sizeof( psPLC->prevLPC_Q12 ) );
+    }
+
+    /* Find random noise component */
+    /* Scale previous excitation signal */
+    exc_buf_ptr = exc_buf;
+    for( k = 0; k < 2; k++ ) {
+        for( i = 0; i < psPLC->subfr_length; i++ ) {
+            exc_buf_ptr[ i ] = (opus_int16)silk_SAT16( silk_RSHIFT(
+                silk_SMULWW( psDec->exc_Q14[ i + ( k + psPLC->nb_subfr - 2 ) * psPLC->subfr_length ], prevGain_Q10[ k ] ), 8 ) );
+        }
+        exc_buf_ptr += psPLC->subfr_length;
+    }
+    /* Find the subframe with lowest energy of the last two and use that as random noise generator */
+    silk_sum_sqr_shift( &energy1, &shift1, exc_buf,                         psPLC->subfr_length );
+    silk_sum_sqr_shift( &energy2, &shift2, &exc_buf[ psPLC->subfr_length ], psPLC->subfr_length );
+
+    if( silk_RSHIFT( energy1, shift2 ) < silk_RSHIFT( energy2, shift1 ) ) {
+        /* First sub-frame has lowest energy */
+        rand_ptr = &psDec->exc_Q14[ silk_max_int( 0, ( psPLC->nb_subfr - 1 ) * psPLC->subfr_length - RAND_BUF_SIZE ) ];
+    } else {
+        /* Second sub-frame has lowest energy */
+        rand_ptr = &psDec->exc_Q14[ silk_max_int( 0, psPLC->nb_subfr * psPLC->subfr_length - RAND_BUF_SIZE ) ];
+    }
+
+    /* Set up Gain to random noise component */
+    B_Q14          = psPLC->LTPCoef_Q14;
+    rand_scale_Q14 = psPLC->randScale_Q14;
+
+    /* Set up attenuation gains */
+    harm_Gain_Q15 = HARM_ATT_Q15[ silk_min_int( NB_ATT - 1, psDec->lossCnt ) ];
+    if( psDec->prevSignalType == TYPE_VOICED ) {
+        rand_Gain_Q15 = PLC_RAND_ATTENUATE_V_Q15[  silk_min_int( NB_ATT - 1, psDec->lossCnt ) ];
+    } else {
+        rand_Gain_Q15 = PLC_RAND_ATTENUATE_UV_Q15[ silk_min_int( NB_ATT - 1, psDec->lossCnt ) ];
+    }
+
+    /* LPC concealment. Apply BWE to previous LPC */
+    silk_bwexpander( psPLC->prevLPC_Q12, psDec->LPC_order, SILK_FIX_CONST( BWE_COEF, 16 ) );
+
+    /* Preload LPC coeficients to array on stack. Gives small performance gain */
+    silk_memcpy( A_Q12, psPLC->prevLPC_Q12, psDec->LPC_order * sizeof( opus_int16 ) );
+
+    /* First Lost frame */
+    if( psDec->lossCnt == 0 ) {
+        rand_scale_Q14 = 1 << 14;
+
+        /* Reduce random noise Gain for voiced frames */
+        if( psDec->prevSignalType == TYPE_VOICED ) {
+            for( i = 0; i < LTP_ORDER; i++ ) {
+                rand_scale_Q14 -= B_Q14[ i ];
+            }
+            rand_scale_Q14 = silk_max_16( 3277, rand_scale_Q14 ); /* 0.2 */
+            rand_scale_Q14 = (opus_int16)silk_RSHIFT( silk_SMULBB( rand_scale_Q14, psPLC->prevLTP_scale_Q14 ), 14 );
+        } else {
+            /* Reduce random noise for unvoiced frames with high LPC gain */
+            opus_int32 invGain_Q30, down_scale_Q30;
+
+            invGain_Q30 = silk_LPC_inverse_pred_gain( psPLC->prevLPC_Q12, psDec->LPC_order );
+
+            down_scale_Q30 = silk_min_32( silk_RSHIFT( (opus_int32)1 << 30, LOG2_INV_LPC_GAIN_HIGH_THRES ), invGain_Q30 );
+            down_scale_Q30 = silk_max_32( silk_RSHIFT( (opus_int32)1 << 30, LOG2_INV_LPC_GAIN_LOW_THRES ), down_scale_Q30 );
+            down_scale_Q30 = silk_LSHIFT( down_scale_Q30, LOG2_INV_LPC_GAIN_HIGH_THRES );
+
+            rand_Gain_Q15 = silk_RSHIFT( silk_SMULWB( down_scale_Q30, rand_Gain_Q15 ), 14 );
+        }
+    }
+
+    rand_seed    = psPLC->rand_seed;
+    lag          = silk_RSHIFT_ROUND( psPLC->pitchL_Q8, 8 );
+    sLTP_buf_idx = psDec->ltp_mem_length;
+
+    /* Rewhiten LTP state */
+    idx = psDec->ltp_mem_length - lag - psDec->LPC_order - LTP_ORDER / 2;
+    silk_assert( idx > 0 );
+    silk_LPC_analysis_filter( &sLTP[ idx ], &psDec->outBuf[ idx ], A_Q12, psDec->ltp_mem_length - idx, psDec->LPC_order );
+    /* Scale LTP state */
+    inv_gain_Q30 = silk_INVERSE32_varQ( psPLC->prevGain_Q16[ 1 ], 46 );
+    inv_gain_Q30 = silk_min( inv_gain_Q30, silk_int32_MAX >> 1 );
+    for( i = idx + psDec->LPC_order; i < psDec->ltp_mem_length; i++ ) {
+        sLTP_Q14[ i ] = silk_SMULWB( inv_gain_Q30, sLTP[ i ] );
+    }
+
+    /***************************/
+    /* LTP synthesis filtering */
+    /***************************/
+    for( k = 0; k < psDec->nb_subfr; k++ ) {
+        /* Set up pointer */
+        pred_lag_ptr = &sLTP_Q14[ sLTP_buf_idx - lag + LTP_ORDER / 2 ];
+        for( i = 0; i < psDec->subfr_length; i++ ) {
+            /* Unrolled loop */
+            /* Avoids introducing a bias because silk_SMLAWB() always rounds to -inf */
+            LTP_pred_Q12 = 2;
+            LTP_pred_Q12 = silk_SMLAWB( LTP_pred_Q12, pred_lag_ptr[  0 ], B_Q14[ 0 ] );
+            LTP_pred_Q12 = silk_SMLAWB( LTP_pred_Q12, pred_lag_ptr[ -1 ], B_Q14[ 1 ] );
+            LTP_pred_Q12 = silk_SMLAWB( LTP_pred_Q12, pred_lag_ptr[ -2 ], B_Q14[ 2 ] );
+            LTP_pred_Q12 = silk_SMLAWB( LTP_pred_Q12, pred_lag_ptr[ -3 ], B_Q14[ 3 ] );
+            LTP_pred_Q12 = silk_SMLAWB( LTP_pred_Q12, pred_lag_ptr[ -4 ], B_Q14[ 4 ] );
+            pred_lag_ptr++;
+
+            /* Generate LPC excitation */
+            rand_seed = silk_RAND( rand_seed );
+            idx = silk_RSHIFT( rand_seed, 25 ) & RAND_BUF_MASK;
+            sLTP_Q14[ sLTP_buf_idx ] = silk_LSHIFT32( silk_SMLAWB( LTP_pred_Q12, rand_ptr[ idx ], rand_scale_Q14 ), 2 );
+            sLTP_buf_idx++;
+        }
+
+        /* Gradually reduce LTP gain */
+        for( j = 0; j < LTP_ORDER; j++ ) {
+            B_Q14[ j ] = silk_RSHIFT( silk_SMULBB( harm_Gain_Q15, B_Q14[ j ] ), 15 );
+        }
+        /* Gradually reduce excitation gain */
+        rand_scale_Q14 = silk_RSHIFT( silk_SMULBB( rand_scale_Q14, rand_Gain_Q15 ), 15 );
+
+        /* Slowly increase pitch lag */
+        psPLC->pitchL_Q8 = silk_SMLAWB( psPLC->pitchL_Q8, psPLC->pitchL_Q8, PITCH_DRIFT_FAC_Q16 );
+        psPLC->pitchL_Q8 = silk_min_32( psPLC->pitchL_Q8, silk_LSHIFT( silk_SMULBB( MAX_PITCH_LAG_MS, psDec->fs_kHz ), 8 ) );
+        lag = silk_RSHIFT_ROUND( psPLC->pitchL_Q8, 8 );
+    }
+
+    /***************************/
+    /* LPC synthesis filtering */
+    /***************************/
+    sLPC_Q14_ptr = &sLTP_Q14[ psDec->ltp_mem_length - MAX_LPC_ORDER ];
+
+    /* Copy LPC state */
+    silk_memcpy( sLPC_Q14_ptr, psDec->sLPC_Q14_buf, MAX_LPC_ORDER * sizeof( opus_int32 ) );
+
+    silk_assert( psDec->LPC_order >= 10 ); /* check that unrolling works */
+    for( i = 0; i < psDec->frame_length; i++ ) {
+        /* partly unrolled */
+        /* Avoids introducing a bias because silk_SMLAWB() always rounds to -inf */
+        LPC_pred_Q10 = silk_RSHIFT( psDec->LPC_order, 1 );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  1 ], A_Q12[ 0 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  2 ], A_Q12[ 1 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  3 ], A_Q12[ 2 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  4 ], A_Q12[ 3 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  5 ], A_Q12[ 4 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  6 ], A_Q12[ 5 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  7 ], A_Q12[ 6 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  8 ], A_Q12[ 7 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i -  9 ], A_Q12[ 8 ] );
+        LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i - 10 ], A_Q12[ 9 ] );
+        for( j = 10; j < psDec->LPC_order; j++ ) {
+            LPC_pred_Q10 = silk_SMLAWB( LPC_pred_Q10, sLPC_Q14_ptr[ MAX_LPC_ORDER + i - j - 1 ], A_Q12[ j ] );
+        }
+
+        /* Add prediction to LPC excitation */
+        sLPC_Q14_ptr[ MAX_LPC_ORDER + i ] = silk_ADD_LSHIFT32( sLPC_Q14_ptr[ MAX_LPC_ORDER + i ], LPC_pred_Q10, 4 );
+
+        /* Scale with Gain */
+        frame[ i ] = (opus_int16)silk_SAT16( silk_SAT16( silk_RSHIFT_ROUND( silk_SMULWW( sLPC_Q14_ptr[ MAX_LPC_ORDER + i ], prevGain_Q10[ 1 ] ), 8 ) ) );
+    }
+
+    /* Save LPC state */
+    silk_memcpy( psDec->sLPC_Q14_buf, &sLPC_Q14_ptr[ psDec->frame_length ], MAX_LPC_ORDER * sizeof( opus_int32 ) );
+
+    /**************************************/
+    /* Update states                      */
+    /**************************************/
+    psPLC->rand_seed     = rand_seed;
+    psPLC->randScale_Q14 = rand_scale_Q14;
+    for( i = 0; i < MAX_NB_SUBFR; i++ ) {
+        psDecCtrl->pitchL[ i ] = lag;
+    }
+}
+
+/* Glues concealed frames with new good recieved frames */
+void silk_PLC_glue_frames(
+    silk_decoder_state                  *psDec,             /* I/O decoder state        */
+    opus_int16                          frame[],            /* I/O signal               */
+    opus_int                            length              /* I length of signal       */
+)
+{
+    opus_int   i, energy_shift;
+    opus_int32 energy;
+    silk_PLC_struct *psPLC;
+    psPLC = &psDec->sPLC;
+
+    if( psDec->lossCnt ) {
+        /* Calculate energy in concealed residual */
+        silk_sum_sqr_shift( &psPLC->conc_energy, &psPLC->conc_energy_shift, frame, length );
+
+        psPLC->last_frame_lost = 1;
+    } else {
+        if( psDec->sPLC.last_frame_lost ) {
+            /* Calculate residual in decoded signal if last frame was lost */
+            silk_sum_sqr_shift( &energy, &energy_shift, frame, length );
+
+            /* Normalize energies */
+            if( energy_shift > psPLC->conc_energy_shift ) {
+                psPLC->conc_energy = silk_RSHIFT( psPLC->conc_energy, energy_shift - psPLC->conc_energy_shift );
+            } else if( energy_shift < psPLC->conc_energy_shift ) {
+                energy = silk_RSHIFT( energy, psPLC->conc_energy_shift - energy_shift );
+            }
+
+            /* Fade in the energy difference */
+            if( energy > psPLC->conc_energy ) {
+                opus_int32 frac_Q24, LZ;
+                opus_int32 gain_Q16, slope_Q16;
+
+                LZ = silk_CLZ32( psPLC->conc_energy );
+                LZ = LZ - 1;
+                psPLC->conc_energy = silk_LSHIFT( psPLC->conc_energy, LZ );
+                energy = silk_RSHIFT( energy, silk_max_32( 24 - LZ, 0 ) );
+
+                frac_Q24 = silk_DIV32( psPLC->conc_energy, silk_max( energy, 1 ) );
+
+                gain_Q16 = silk_LSHIFT( silk_SQRT_APPROX( frac_Q24 ), 4 );
+                slope_Q16 = silk_DIV32_16( ( (opus_int32)1 << 16 ) - gain_Q16, length );
+                /* Make slope 4x steeper to avoid missing onsets after DTX */
+                slope_Q16 = silk_LSHIFT( slope_Q16, 2 );
+
+                for( i = 0; i < length; i++ ) {
+                    frame[ i ] = silk_SMULWB( gain_Q16, frame[ i ] );
+                    gain_Q16 += slope_Q16;
+                    if( gain_Q16 > (opus_int32)1 << 16 ) {
+                        break;
+                    }
+                }
+            }
+        }
+        psPLC->last_frame_lost = 0;
+    }
+}