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27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 #include "main.h"
33
34 #define OFFSET ( ( MIN_QGAIN_DB * 128 ) / 6 + 16 * 128 )
35 #define SCALE_Q16 ( ( 65536 * ( N_LEVELS_QGAIN - 1 ) ) / ( ( ( MAX_QGAIN_DB - MIN_QGAIN_DB ) * 128 ) / 6 ) )
36 #define INV_SCALE_Q16 ( ( 65536 * ( ( ( MAX_QGAIN_DB - MIN_QGAIN_DB ) * 128 ) / 6 ) ) / ( N_LEVELS_QGAIN - 1 ) )
37
38 /* Gain scalar quantization with hysteresis, uniform on log scale */
silk_gains_quant(opus_int8 ind[MAX_NB_SUBFR],opus_int32 gain_Q16[MAX_NB_SUBFR],opus_int8 * prev_ind,const opus_int conditional,const opus_int nb_subfr)39 void silk_gains_quant(
40 opus_int8 ind[ MAX_NB_SUBFR ], /* O gain indices */
41 opus_int32 gain_Q16[ MAX_NB_SUBFR ], /* I/O gains (quantized out) */
42 opus_int8 *prev_ind, /* I/O last index in previous frame */
43 const opus_int conditional, /* I first gain is delta coded if 1 */
44 const opus_int nb_subfr /* I number of subframes */
45 )
46 {
47 opus_int k, double_step_size_threshold;
48
49 for( k = 0; k < nb_subfr; k++ ) {
50 /* Convert to log scale, scale, floor() */
51 ind[ k ] = silk_SMULWB( SCALE_Q16, silk_lin2log( gain_Q16[ k ] ) - OFFSET );
52
53 /* Round towards previous quantized gain (hysteresis) */
54 if( ind[ k ] < *prev_ind ) {
55 ind[ k ]++;
56 }
57 ind[ k ] = silk_LIMIT_int( ind[ k ], 0, N_LEVELS_QGAIN - 1 );
58
59 /* Compute delta indices and limit */
60 if( k == 0 && conditional == 0 ) {
61 /* Full index */
62 ind[ k ] = silk_LIMIT_int( ind[ k ], *prev_ind + MIN_DELTA_GAIN_QUANT, N_LEVELS_QGAIN - 1 );
63 *prev_ind = ind[ k ];
64 } else {
65 /* Delta index */
66 ind[ k ] = ind[ k ] - *prev_ind;
67
68 /* Double the quantization step size for large gain increases, so that the max gain level can be reached */
69 double_step_size_threshold = 2 * MAX_DELTA_GAIN_QUANT - N_LEVELS_QGAIN + *prev_ind;
70 if( ind[ k ] > double_step_size_threshold ) {
71 ind[ k ] = double_step_size_threshold + silk_RSHIFT( ind[ k ] - double_step_size_threshold + 1, 1 );
72 }
73
74 ind[ k ] = silk_LIMIT_int( ind[ k ], MIN_DELTA_GAIN_QUANT, MAX_DELTA_GAIN_QUANT );
75
76 /* Accumulate deltas */
77 if( ind[ k ] > double_step_size_threshold ) {
78 *prev_ind += silk_LSHIFT( ind[ k ], 1 ) - double_step_size_threshold;
79 } else {
80 *prev_ind += ind[ k ];
81 }
82
83 /* Shift to make non-negative */
84 ind[ k ] -= MIN_DELTA_GAIN_QUANT;
85 }
86
87 /* Scale and convert to linear scale */
88 gain_Q16[ k ] = silk_log2lin( silk_min_32( silk_SMULWB( INV_SCALE_Q16, *prev_ind ) + OFFSET, 3967 ) ); /* 3967 = 31 in Q7 */
89 }
90 }
91
92 /* Gains scalar dequantization, uniform on log scale */
silk_gains_dequant(opus_int32 gain_Q16[MAX_NB_SUBFR],const opus_int8 ind[MAX_NB_SUBFR],opus_int8 * prev_ind,const opus_int conditional,const opus_int nb_subfr)93 void silk_gains_dequant(
94 opus_int32 gain_Q16[ MAX_NB_SUBFR ], /* O quantized gains */
95 const opus_int8 ind[ MAX_NB_SUBFR ], /* I gain indices */
96 opus_int8 *prev_ind, /* I/O last index in previous frame */
97 const opus_int conditional, /* I first gain is delta coded if 1 */
98 const opus_int nb_subfr /* I number of subframes */
99 )
100 {
101 opus_int k, ind_tmp, double_step_size_threshold;
102
103 for( k = 0; k < nb_subfr; k++ ) {
104 if( k == 0 && conditional == 0 ) {
105 /* Gain index is not allowed to go down more than 16 steps (~21.8 dB) */
106 *prev_ind = silk_max_int( ind[ k ], *prev_ind - 16 );
107 } else {
108 /* Delta index */
109 ind_tmp = ind[ k ] + MIN_DELTA_GAIN_QUANT;
110
111 /* Accumulate deltas */
112 double_step_size_threshold = 2 * MAX_DELTA_GAIN_QUANT - N_LEVELS_QGAIN + *prev_ind;
113 if( ind_tmp > double_step_size_threshold ) {
114 *prev_ind += silk_LSHIFT( ind_tmp, 1 ) - double_step_size_threshold;
115 } else {
116 *prev_ind += ind_tmp;
117 }
118 }
119 *prev_ind = silk_LIMIT_int( *prev_ind, 0, N_LEVELS_QGAIN - 1 );
120
121 /* Scale and convert to linear scale */
122 gain_Q16[ k ] = silk_log2lin( silk_min_32( silk_SMULWB( INV_SCALE_Q16, *prev_ind ) + OFFSET, 3967 ) ); /* 3967 = 31 in Q7 */
123 }
124 }
125
126 /* Compute unique identifier of gain indices vector */
silk_gains_ID(const opus_int8 ind[MAX_NB_SUBFR],const opus_int nb_subfr)127 opus_int32 silk_gains_ID( /* O returns unique identifier of gains */
128 const opus_int8 ind[ MAX_NB_SUBFR ], /* I gain indices */
129 const opus_int nb_subfr /* I number of subframes */
130 )
131 {
132 opus_int k;
133 opus_int32 gainsID;
134
135 gainsID = 0;
136 for( k = 0; k < nb_subfr; k++ ) {
137 gainsID = silk_ADD_LSHIFT32( ind[ k ], gainsID, 8 );
138 }
139
140 return gainsID;
141 }
142