freeswitch/libs/silk/src/SKP_Silk_tuning_parameters.h

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#ifndef SKP_SILK_TUNING_PARAMETERS_H
#define SKP_SILK_TUNING_PARAMETERS_H

#ifdef __cplusplus
extern "C"
{
#endif

/*******************/
/* Pitch estimator */
/*******************/

/* Level of noise floor for whitening filter LPC analysis in pitch analysis */
#define FIND_PITCH_WHITE_NOISE_FRACTION                 1e-3f

/* Bandwidth expansion for whitening filter in pitch analysis */
#define FIND_PITCH_BANDWITH_EXPANSION                   0.99f

/* Threshold used by pitch estimator for early escape */
#define FIND_PITCH_CORRELATION_THRESHOLD_HC_MODE        0.7f
#define FIND_PITCH_CORRELATION_THRESHOLD_MC_MODE        0.75f
#define FIND_PITCH_CORRELATION_THRESHOLD_LC_MODE        0.8f

/*********************/
/* Linear prediction */
/*********************/

/* LPC analysis defines: regularization and bandwidth expansion */
#define FIND_LPC_COND_FAC                               2.5e-5f
#define FIND_LPC_CHIRP                                  0.99995f

/* LTP analysis defines */
#define FIND_LTP_COND_FAC                               1e-5f
#define LTP_DAMPING                                     0.01f
#define LTP_SMOOTHING                                   0.1f

/* LTP quantization settings */
#define MU_LTP_QUANT_NB                                 0.03f
#define MU_LTP_QUANT_MB                                 0.025f
#define MU_LTP_QUANT_WB                                 0.02f
#define MU_LTP_QUANT_SWB                                0.016f

/***********************/
/* High pass filtering */
/***********************/

/* Smoothing parameters for low end of pitch frequency range estimation */
#define VARIABLE_HP_SMTH_COEF1                          0.1f
#define VARIABLE_HP_SMTH_COEF2                          0.015f

/* Min and max values for low end of pitch frequency range estimation */
#define VARIABLE_HP_MIN_FREQ                            80.0f
#define VARIABLE_HP_MAX_FREQ                            150.0f

/* Max absolute difference between log2 of pitch frequency and smoother state, to enter the smoother */
#define VARIABLE_HP_MAX_DELTA_FREQ                      0.4f

/***********/
/* Various */
/***********/

/* Required speech activity for counting frame as active */
#define WB_DETECT_ACTIVE_SPEECH_LEVEL_THRES             0.7f        

#define SPEECH_ACTIVITY_DTX_THRES                       0.1f

/* Speech Activity LBRR enable threshold (needs tuning) */
#define LBRR_SPEECH_ACTIVITY_THRES                      0.5f        

/*************************/
/* Perceptual parameters */
/*************************/

/* reduction in coding SNR during low speech activity */
#define BG_SNR_DECR_dB                                  4.0f

/* factor for reducing quantization noise during voiced speech */
#define HARM_SNR_INCR_dB                                2.0f

/* factor for reducing quantization noise for unvoiced sparse signals */
#define SPARSE_SNR_INCR_dB                              2.0f

/* threshold for sparseness measure above which to use lower quantization offset during unvoiced */
#define SPARSENESS_THRESHOLD_QNT_OFFSET                 0.75f

/* warping control */
#define WARPING_MULTIPLIER                              0.015f

/* fraction added to first autocorrelation value */
#define SHAPE_WHITE_NOISE_FRACTION                      1e-5f

/* noise shaping filter chirp factor */
#define BANDWIDTH_EXPANSION                             0.95f

/* difference between chirp factors for analysis and synthesis noise shaping filters at low bitrates */
#define LOW_RATE_BANDWIDTH_EXPANSION_DELTA              0.01f

/* gain reduction for fricatives */
#define DE_ESSER_COEF_SWB_dB                            2.0f
#define DE_ESSER_COEF_WB_dB                             1.0f

/* extra harmonic boosting (signal shaping) at low bitrates */
#define LOW_RATE_HARMONIC_BOOST                         0.1f

/* extra harmonic boosting (signal shaping) for noisy input signals */
#define LOW_INPUT_QUALITY_HARMONIC_BOOST                0.1f

/* harmonic noise shaping */
#define HARMONIC_SHAPING                                0.3f

/* extra harmonic noise shaping for high bitrates or noisy input */
#define HIGH_RATE_OR_LOW_QUALITY_HARMONIC_SHAPING       0.2f

/* parameter for shaping noise towards higher frequencies */
#define HP_NOISE_COEF                                   0.3f

/* parameter for shaping noise even more towards higher frequencies during voiced speech */
#define HARM_HP_NOISE_COEF                              0.35f

/* parameter for applying a high-pass tilt to the input signal */
#define INPUT_TILT                                      0.05f

/* parameter for extra high-pass tilt to the input signal at high rates */
#define HIGH_RATE_INPUT_TILT                            0.1f

/* parameter for reducing noise at the very low frequencies */
#define LOW_FREQ_SHAPING                                3.0f

/* less reduction of noise at the very low frequencies for signals with low SNR at low frequencies */
#define LOW_QUALITY_LOW_FREQ_SHAPING_DECR               0.5f

/* noise floor to put a lower limit on the quantization step size */
#define NOISE_FLOOR_dB                                  4.0f

/* noise floor relative to active speech gain level */
#define RELATIVE_MIN_GAIN_dB                            -50.0f

/* subframe smoothing coefficient for determining active speech gain level (lower -> more smoothing) */
#define GAIN_SMOOTHING_COEF                             1e-3f

/* subframe smoothing coefficient for HarmBoost, HarmShapeGain, Tilt (lower -> more smoothing) */
#define SUBFR_SMTH_COEF                                 0.4f

/* parameters defining the R/D tradeoff in the residual quantizer */
#define LAMBDA_OFFSET                                   1.2f
#define LAMBDA_SPEECH_ACT                               -0.3f
#define LAMBDA_DELAYED_DECISIONS                        -0.05f
#define LAMBDA_INPUT_QUALITY                            -0.2f
#define LAMBDA_CODING_QUALITY                           -0.1f
#define LAMBDA_QUANT_OFFSET                             1.5f

#ifdef __cplusplus
}
#endif

#endif // SKP_SILK_TUNING_PARAMETERS_H