Constrains accumulated pitch gain to avoid potential instability.
[opus.git] / silk / quant_LTP_gains.c
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27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 #include "main.h"
33 #include "tuning_parameters.h"
34
35 void silk_quant_LTP_gains(
36     opus_int16                  B_Q14[ MAX_NB_SUBFR * LTP_ORDER ],          /* I/O  (un)quantized LTP gains         */
37     opus_int8                   cbk_index[ MAX_NB_SUBFR ],                  /* O    Codebook Index                  */
38     opus_int8                   *periodicity_index,                         /* O    Periodicity Index               */
39         opus_int32                                      *sum_log_gain_Q7,                                                       /* I/O  Cumulative max prediction gain  */
40     const opus_int32            W_Q18[ MAX_NB_SUBFR*LTP_ORDER*LTP_ORDER ],  /* I    Error Weights in Q18            */
41     opus_int                    mu_Q9,                                      /* I    Mu value (R/D tradeoff)         */
42     opus_int                    lowComplexity,                              /* I    Flag for low complexity         */
43     const opus_int              nb_subfr                                    /* I    number of subframes             */
44 )
45 {
46     opus_int             j, k, cbk_size;
47     opus_int8            temp_idx[ MAX_NB_SUBFR ];
48     const opus_uint8     *cl_ptr_Q5;
49     const opus_int8      *cbk_ptr_Q7;
50     const opus_int16     *b_Q14_ptr;
51     const opus_int32     *W_Q18_ptr;
52     opus_int32           rate_dist_Q14_subfr, rate_dist_Q14, min_rate_dist_Q14;
53         opus_int32           sum_log_gain_tmp_Q7, best_sum_log_gain_Q7, max_gain_Q7, gain_Q7;
54
55     /***************************************************/
56     /* iterate over different codebooks with different */
57     /* rates/distortions, and choose best */
58     /***************************************************/
59     min_rate_dist_Q14 = silk_int32_MAX;
60     best_sum_log_gain_Q7 = 0;
61     for( k = 0; k < 3; k++ ) {
62         cl_ptr_Q5  = silk_LTP_gain_BITS_Q5_ptrs[ k ];
63         cbk_ptr_Q7 = silk_LTP_vq_ptrs_Q7[        k ];
64         cbk_size   = silk_LTP_vq_sizes[          k ];
65
66         /* Set up pointer to first subframe */
67         W_Q18_ptr = W_Q18;
68         b_Q14_ptr = B_Q14;
69
70         rate_dist_Q14 = 0;
71                 sum_log_gain_tmp_Q7 = *sum_log_gain_Q7;
72         for( j = 0; j < nb_subfr; j++ ) {
73                         max_gain_Q7 = silk_log2lin( ( SILK_FIX_CONST( MAX_SUM_LOG_GAIN_DB / 6.0, 7 ) - sum_log_gain_tmp_Q7 ) 
74                                                                                 + SILK_FIX_CONST( 7, 7 ) ) - SILK_FIX_CONST( 0.5, 7 );
75
76             silk_VQ_WMat_EC(
77                 &temp_idx[ j ],         /* O    index of best codebook vector                           */
78                 &rate_dist_Q14_subfr,   /* O    best weighted quantization error + mu * rate            */
79                                 &gain_Q7,               /* O    sum of absolute LTP coefficients                        */
80                 b_Q14_ptr,              /* I    input vector to be quantized                            */
81                 W_Q18_ptr,              /* I    weighting matrix                                        */
82                 cbk_ptr_Q7,             /* I    codebook                                                */
83                 cl_ptr_Q5,              /* I    code length for each codebook vector                    */
84                 mu_Q9,                  /* I    tradeoff between weighted error and rate                */
85                                 max_gain_Q7,            /* I    maximum sum of absolute LTP coefficients                */
86                 cbk_size                /* I    number of vectors in codebook                           */
87             );
88
89             rate_dist_Q14 = silk_ADD_POS_SAT32( rate_dist_Q14, rate_dist_Q14_subfr );
90                         sum_log_gain_tmp_Q7 += silk_lin2log( SILK_FIX_CONST( 0.5, 7 ) + gain_Q7 ) - SILK_FIX_CONST( 7, 7 );
91
92             b_Q14_ptr += LTP_ORDER;
93             W_Q18_ptr += LTP_ORDER * LTP_ORDER;
94         }
95
96         /* Avoid never finding a codebook */
97         rate_dist_Q14 = silk_min( silk_int32_MAX - 1, rate_dist_Q14 );
98
99         if( rate_dist_Q14 < min_rate_dist_Q14 ) {
100             min_rate_dist_Q14 = rate_dist_Q14;
101             *periodicity_index = (opus_int8)k;
102             silk_memcpy( cbk_index, temp_idx, nb_subfr * sizeof( opus_int8 ) );
103                         best_sum_log_gain_Q7 = sum_log_gain_tmp_Q7;
104         }
105
106         /* Break early in low-complexity mode if rate distortion is below threshold */
107         if( lowComplexity && ( rate_dist_Q14 < silk_LTP_gain_middle_avg_RD_Q14 ) ) {
108             break;
109         }
110     }
111
112     cbk_ptr_Q7 = silk_LTP_vq_ptrs_Q7[ *periodicity_index ];
113     for( j = 0; j < nb_subfr; j++ ) {
114         for( k = 0; k < LTP_ORDER; k++ ) {
115             B_Q14[ j * LTP_ORDER + k ] = silk_LSHIFT( cbk_ptr_Q7[ cbk_index[ j ] * LTP_ORDER + k ], 7 );
116         }
117     }
118         *sum_log_gain_Q7 = best_sum_log_gain_Q7;
119 }
120