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15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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26 ***********************************************************************/
27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 #include "main.h"
33 #include "tuning_parameters.h"
34
35 /* Control SNR of redidual quantizer */
silk_control_SNR(silk_encoder_state * psEncC,opus_int32 TargetRate_bps)36 opus_int silk_control_SNR(
37 silk_encoder_state *psEncC, /* I/O Pointer to Silk encoder state */
38 opus_int32 TargetRate_bps /* I Target max bitrate (bps) */
39 )
40 {
41 opus_int k, ret = SILK_NO_ERROR;
42 opus_int32 frac_Q6;
43 const opus_int32 *rateTable;
44
45 /* Set bitrate/coding quality */
46 TargetRate_bps = silk_LIMIT( TargetRate_bps, MIN_TARGET_RATE_BPS, MAX_TARGET_RATE_BPS );
47 if( TargetRate_bps != psEncC->TargetRate_bps ) {
48 psEncC->TargetRate_bps = TargetRate_bps;
49
50 /* If new TargetRate_bps, translate to SNR_dB value */
51 if( psEncC->fs_kHz == 8 ) {
52 rateTable = silk_TargetRate_table_NB;
53 } else if( psEncC->fs_kHz == 12 ) {
54 rateTable = silk_TargetRate_table_MB;
55 } else {
56 rateTable = silk_TargetRate_table_WB;
57 }
58
59 /* Reduce bitrate for 10 ms modes in these calculations */
60 if( psEncC->nb_subfr == 2 ) {
61 TargetRate_bps -= REDUCE_BITRATE_10_MS_BPS;
62 }
63
64 /* Find bitrate interval in table and interpolate */
65 for( k = 1; k < TARGET_RATE_TAB_SZ; k++ ) {
66 if( TargetRate_bps <= rateTable[ k ] ) {
67 frac_Q6 = silk_DIV32( silk_LSHIFT( TargetRate_bps - rateTable[ k - 1 ], 6 ),
68 rateTable[ k ] - rateTable[ k - 1 ] );
69 psEncC->SNR_dB_Q7 = silk_LSHIFT( silk_SNR_table_Q1[ k - 1 ], 6 ) + silk_MUL( frac_Q6, silk_SNR_table_Q1[ k ] - silk_SNR_table_Q1[ k - 1 ] );
70 break;
71 }
72 }
73
74 /* Reduce coding quality whenever LBRR is enabled, to free up some bits */
75 if( psEncC->LBRR_enabled ) {
76 psEncC->SNR_dB_Q7 = silk_SMLABB( psEncC->SNR_dB_Q7, 12 - psEncC->LBRR_GainIncreases, SILK_FIX_CONST( -0.25, 7 ) );
77 }
78 }
79
80 return ret;
81 }
82