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      1 /***********************************************************************
      2 Copyright (c) 2006-2011, Skype Limited. All rights reserved.
      3 Redistribution and use in source and binary forms, with or without
      4 modification, are permitted provided that the following conditions
      5 are met:
      6 - Redistributions of source code must retain the above copyright notice,
      7 this list of conditions and the following disclaimer.
      8 - Redistributions in binary form must reproduce the above copyright
      9 notice, this list of conditions and the following disclaimer in the
     10 documentation and/or other materials provided with the distribution.
     11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
     12 names of specific contributors, may be used to endorse or promote
     13 products derived from this software without specific prior written
     14 permission.
     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
     17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
     19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     25 POSSIBILITY OF SUCH DAMAGE.
     26 ***********************************************************************/
     27 
     28 #ifndef SILK_TUNING_PARAMETERS_H
     29 #define SILK_TUNING_PARAMETERS_H
     30 
     31 #ifdef __cplusplus
     32 extern "C"
     33 {
     34 #endif
     35 
     36 /* Decay time for bitreservoir */
     37 #define BITRESERVOIR_DECAY_TIME_MS                      500
     38 
     39 /*******************/
     40 /* Pitch estimator */
     41 /*******************/
     42 
     43 /* Level of noise floor for whitening filter LPC analysis in pitch analysis */
     44 #define FIND_PITCH_WHITE_NOISE_FRACTION                 1e-3f
     45 
     46 /* Bandwidth expansion for whitening filter in pitch analysis */
     47 #define FIND_PITCH_BANDWIDTH_EXPANSION                  0.99f
     48 
     49 /*********************/
     50 /* Linear prediction */
     51 /*********************/
     52 
     53 /* LPC analysis regularization */
     54 #define FIND_LPC_COND_FAC                               1e-5f
     55 
     56 /* LTP analysis defines */
     57 #define FIND_LTP_COND_FAC                               1e-5f
     58 #define LTP_DAMPING                                     0.05f
     59 #define LTP_SMOOTHING                                   0.1f
     60 
     61 /* LTP quantization settings */
     62 #define MU_LTP_QUANT_NB                                 0.03f
     63 #define MU_LTP_QUANT_MB                                 0.025f
     64 #define MU_LTP_QUANT_WB                                 0.02f
     65 
     66 /* Max cumulative LTP gain */
     67 #define MAX_SUM_LOG_GAIN_DB                             250.0f
     68 
     69 /***********************/
     70 /* High pass filtering */
     71 /***********************/
     72 
     73 /* Smoothing parameters for low end of pitch frequency range estimation */
     74 #define VARIABLE_HP_SMTH_COEF1                          0.1f
     75 #define VARIABLE_HP_SMTH_COEF2                          0.015f
     76 #define VARIABLE_HP_MAX_DELTA_FREQ                      0.4f
     77 
     78 /* Min and max cut-off frequency values (-3 dB points) */
     79 #define VARIABLE_HP_MIN_CUTOFF_HZ                       60
     80 #define VARIABLE_HP_MAX_CUTOFF_HZ                       100
     81 
     82 /***********/
     83 /* Various */
     84 /***********/
     85 
     86 /* VAD threshold */
     87 #define SPEECH_ACTIVITY_DTX_THRES                       0.05f
     88 
     89 /* Speech Activity LBRR enable threshold */
     90 #define LBRR_SPEECH_ACTIVITY_THRES                      0.3f
     91 
     92 /*************************/
     93 /* Perceptual parameters */
     94 /*************************/
     95 
     96 /* reduction in coding SNR during low speech activity */
     97 #define BG_SNR_DECR_dB                                  2.0f
     98 
     99 /* factor for reducing quantization noise during voiced speech */
    100 #define HARM_SNR_INCR_dB                                2.0f
    101 
    102 /* factor for reducing quantization noise for unvoiced sparse signals */
    103 #define SPARSE_SNR_INCR_dB                              2.0f
    104 
    105 /* threshold for sparseness measure above which to use lower quantization offset during unvoiced */
    106 #define SPARSENESS_THRESHOLD_QNT_OFFSET                 0.75f
    107 
    108 /* warping control */
    109 #define WARPING_MULTIPLIER                              0.015f
    110 
    111 /* fraction added to first autocorrelation value */
    112 #define SHAPE_WHITE_NOISE_FRACTION                      5e-5f
    113 
    114 /* noise shaping filter chirp factor */
    115 #define BANDWIDTH_EXPANSION                             0.95f
    116 
    117 /* difference between chirp factors for analysis and synthesis noise shaping filters at low bitrates */
    118 #define LOW_RATE_BANDWIDTH_EXPANSION_DELTA              0.01f
    119 
    120 /* extra harmonic boosting (signal shaping) at low bitrates */
    121 #define LOW_RATE_HARMONIC_BOOST                         0.1f
    122 
    123 /* extra harmonic boosting (signal shaping) for noisy input signals */
    124 #define LOW_INPUT_QUALITY_HARMONIC_BOOST                0.1f
    125 
    126 /* harmonic noise shaping */
    127 #define HARMONIC_SHAPING                                0.3f
    128 
    129 /* extra harmonic noise shaping for high bitrates or noisy input */
    130 #define HIGH_RATE_OR_LOW_QUALITY_HARMONIC_SHAPING       0.2f
    131 
    132 /* parameter for shaping noise towards higher frequencies */
    133 #define HP_NOISE_COEF                                   0.25f
    134 
    135 /* parameter for shaping noise even more towards higher frequencies during voiced speech */
    136 #define HARM_HP_NOISE_COEF                              0.35f
    137 
    138 /* parameter for applying a high-pass tilt to the input signal */
    139 #define INPUT_TILT                                      0.05f
    140 
    141 /* parameter for extra high-pass tilt to the input signal at high rates */
    142 #define HIGH_RATE_INPUT_TILT                            0.1f
    143 
    144 /* parameter for reducing noise at the very low frequencies */
    145 #define LOW_FREQ_SHAPING                                4.0f
    146 
    147 /* less reduction of noise at the very low frequencies for signals with low SNR at low frequencies */
    148 #define LOW_QUALITY_LOW_FREQ_SHAPING_DECR               0.5f
    149 
    150 /* subframe smoothing coefficient for HarmBoost, HarmShapeGain, Tilt (lower -> more smoothing) */
    151 #define SUBFR_SMTH_COEF                                 0.4f
    152 
    153 /* parameters defining the R/D tradeoff in the residual quantizer */
    154 #define LAMBDA_OFFSET                                   1.2f
    155 #define LAMBDA_SPEECH_ACT                               -0.2f
    156 #define LAMBDA_DELAYED_DECISIONS                        -0.05f
    157 #define LAMBDA_INPUT_QUALITY                            -0.1f
    158 #define LAMBDA_CODING_QUALITY                           -0.2f
    159 #define LAMBDA_QUANT_OFFSET                             0.8f
    160 
    161 /* Compensation in bitrate calculations for 10 ms modes */
    162 #define REDUCE_BITRATE_10_MS_BPS                        2200
    163 
    164 /* Maximum time before allowing a bandwidth transition */
    165 #define MAX_BANDWIDTH_SWITCH_DELAY_MS                   5000
    166 
    167 #ifdef __cplusplus
    168 }
    169 #endif
    170 
    171 #endif /* SILK_TUNING_PARAMETERS_H */
    172