summaryrefslogtreecommitdiffstats
path: root/lib/rbcodec/codecs/libopus/silk/PLC.c
blob: d9fda745557a966b0227daff7935165e2eb4036f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
/***********************************************************************
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 "stack_alloc.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;
    VARDECL( opus_int16, exc_buf );
    opus_int16 A_Q12[ MAX_LPC_ORDER ];
    VARDECL( opus_int16, sLTP );
    VARDECL( opus_int32, sLTP_Q14 );
    silk_PLC_struct *psPLC = &psDec->sPLC;
    opus_int32 prevGain_Q10[2];
    SAVE_STACK;

    ALLOC( exc_buf, 2*psPLC->subfr_length, opus_int16 );
    ALLOC( sLTP, psDec->ltp_mem_length, opus_int16 );
    ALLOC( sLTP_Q14, psDec->ltp_mem_length + psDec->frame_length, opus_int32 );

    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;
    }
    RESTORE_STACK;
}

/* Glues concealed frames with new good received 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;
    }
}