ref: fd1a5db140d51e7188e5126db2edc0ab923cfa8c
dir: /src_FLP/SKP_Silk_noise_shape_analysis_FLP.c/
/***********************************************************************
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***********************************************************************/
#include "SKP_Silk_main_FLP.h"
#include "SKP_Silk_perceptual_parameters.h"
/* Compute gain to make warped filter coefficients have a zero mean log frequency response on a */
/* non-warped frequency scale. (So that it can be implemented with a minimum-phase monic filter.) */
SKP_INLINE SKP_float warped_gain(
const SKP_float *coefs,
SKP_float lambda,
SKP_int order
) {
SKP_int i;
SKP_float gain;
lambda = -lambda;
gain = coefs[ order - 1 ];
for( i = order - 2; i >= 0; i-- ) {
gain = lambda * gain + coefs[ i ];
}
return (SKP_float)( 1.0f / ( 1.0f - lambda * gain ) );
}
/* Convert warped filter coefficients to monic pseudo-warped coefficients */
SKP_INLINE void warped_true2monic_coefs(
SKP_float *coefs,
SKP_float lambda,
SKP_int order
) {
SKP_int i;
SKP_float gain;
lambda = -lambda;
for( i = order - 1; i > 0; i-- ) {
coefs[ i - 1 ] += lambda * coefs[ i ];
}
gain = ( 1.0f - lambda * lambda ) / ( 1.0f - lambda * coefs[ 0 ] );
for( i = 0; i < order; i++ ) {
coefs[ i ] *= gain;
}
}
/* Limit max amplitude of monic warped coefficients by using bandwidth expansion on the true coefficients */
SKP_INLINE void limit_warped_coefs(
SKP_float *coefs_syn,
SKP_float *coefs_ana,
SKP_float lambda,
SKP_float limit,
SKP_int order
) {
SKP_int i, iter, ind;
SKP_float tmp, maxabs, chirp;
for( iter = 0; iter < 10; iter++ ) {
/* Find maximum absolute value */
ind = 1;
maxabs = SKP_abs( coefs_syn[ ind ] );
for( i = 2; i < order - 1; i++ ) {
tmp = SKP_abs( coefs_syn[ i ] );
if( tmp > maxabs ) {
maxabs = tmp;
ind = i;
}
}
if( maxabs <= limit ) {
return;
}
/* Convert to true warped coefficients */
for( i = 1; i < order; i++ ) {
coefs_syn[ i - 1 ] += lambda * coefs_syn[ i ];
coefs_ana[ i - 1 ] += lambda * coefs_ana[ i ];
}
/* Apply bandwidth expansion */
chirp = 0.99f - ( 0.8f + 0.1f * iter ) * ( maxabs - limit ) / ( maxabs * ( ind + 1 ) );
SKP_Silk_bwexpander_FLP( coefs_syn, order, chirp );
SKP_Silk_bwexpander_FLP( coefs_ana, order, chirp );
/* Convert back to monic warped coefficients */
for( i = order - 1; i > 0; i-- ) {
coefs_syn[ i - 1 ] -= lambda * coefs_syn[ i ];
coefs_ana[ i - 1 ] -= lambda * coefs_ana[ i ];
}
}
}
/* Compute noise shaping coefficients and initial gain values */
void SKP_Silk_noise_shape_analysis_FLP(
SKP_Silk_encoder_state_FLP *psEnc, /* I/O Encoder state FLP */
SKP_Silk_encoder_control_FLP *psEncCtrl, /* I/O Encoder control FLP */
const SKP_float *pitch_res, /* I LPC residual from pitch analysis */
const SKP_float *x /* I Input signal [frame_length + la_shape] */
)
{
SKP_Silk_shape_state_FLP *psShapeSt = &psEnc->sShape;
SKP_int k, nSamples;
SKP_float SNR_adj_dB, HarmBoost, HarmShapeGain, Tilt;
SKP_float nrg, pre_nrg, log_energy, log_energy_prev, energy_variation;
SKP_float delta, BWExp1, BWExp2, gain_mult, gain_add, strength, b, warping;
SKP_float x_windowed[ SHAPE_LPC_WIN_MAX ];
SKP_float auto_corr[ MAX_SHAPE_LPC_ORDER + 1 ];
const SKP_float *x_ptr, *pitch_res_ptr;
/* Point to start of first LPC analysis block */
x_ptr = x + psEnc->sCmn.la_shape - SHAPE_LPC_WIN_MS * psEnc->sCmn.fs_kHz + psEnc->sCmn.subfr_length;
/****************/
/* CONTROL SNR */
/****************/
/* Reduce SNR_dB values if recent bitstream has exceeded TargetRate */
psEncCtrl->current_SNR_dB = psEnc->SNR_dB - 0.05f * psEnc->BufferedInChannel_ms;
/* Reduce SNR_dB if inband FEC used */
if( psEnc->speech_activity > LBRR_SPEECH_ACTIVITY_THRES ) {
psEncCtrl->current_SNR_dB -= psEnc->inBandFEC_SNR_comp;
}
/****************/
/* GAIN CONTROL */
/****************/
/* Input quality is the average of the quality in the lowest two VAD bands */
psEncCtrl->input_quality = 0.5f * ( psEncCtrl->input_quality_bands[ 0 ] + psEncCtrl->input_quality_bands[ 1 ] );
/* Coding quality level, between 0.0 and 1.0 */
psEncCtrl->coding_quality = SKP_sigmoid( 0.25f * ( psEncCtrl->current_SNR_dB - 17.0f ) );
/* Reduce coding SNR during low speech activity */
b = 1.0f - psEnc->speech_activity;
SNR_adj_dB = psEncCtrl->current_SNR_dB -
BG_SNR_DECR_dB * psEncCtrl->coding_quality * ( 0.5f + 0.5f * psEncCtrl->input_quality ) * b * b;
if( psEncCtrl->sCmn.sigtype == SIG_TYPE_VOICED ) {
/* Reduce gains for periodic signals */
SNR_adj_dB += HARM_SNR_INCR_dB * psEnc->LTPCorr;
} else {
/* For unvoiced signals and low-quality input, adjust the quality slower than SNR_dB setting */
SNR_adj_dB += ( -0.4f * psEncCtrl->current_SNR_dB + 6.0f ) * ( 1.0f - psEncCtrl->input_quality );
}
/*************************/
/* SPARSENESS PROCESSING */
/*************************/
/* Set quantizer offset */
if( psEncCtrl->sCmn.sigtype == SIG_TYPE_VOICED ) {
/* Initally set to 0; may be overruled in process_gains(..) */
psEncCtrl->sCmn.QuantOffsetType = 0;
psEncCtrl->sparseness = 0.0f;
} else {
/* Sparseness measure, based on relative fluctuations of energy per 2 milliseconds */
nSamples = 2 * psEnc->sCmn.fs_kHz;
energy_variation = 0.0f;
log_energy_prev = 0.0f;
pitch_res_ptr = pitch_res;
for( k = 0; k < SKP_SMULBB( SUB_FRAME_LENGTH_MS, psEnc->sCmn.nb_subfr ) / 2; k++ ) {
nrg = ( SKP_float )nSamples + ( SKP_float )SKP_Silk_energy_FLP( pitch_res_ptr, nSamples );
log_energy = SKP_Silk_log2( nrg );
if( k > 0 ) {
energy_variation += SKP_abs_float( log_energy - log_energy_prev );
}
log_energy_prev = log_energy;
pitch_res_ptr += nSamples;
}
psEncCtrl->sparseness = SKP_sigmoid( 0.4f * ( energy_variation - 5.0f ) );
/* Set quantization offset depending on sparseness measure */
if( psEncCtrl->sparseness > SPARSENESS_THRESHOLD_QNT_OFFSET ) {
psEncCtrl->sCmn.QuantOffsetType = 0;
} else {
psEncCtrl->sCmn.QuantOffsetType = 1;
}
/* Increase coding SNR for sparse signals */
SNR_adj_dB += SPARSE_SNR_INCR_dB * ( psEncCtrl->sparseness - 0.5f );
}
/*******************************/
/* Control bandwidth expansion */
/*******************************/
delta = LOW_RATE_BANDWIDTH_EXPANSION_DELTA * ( 1.0f - 0.75f * psEncCtrl->coding_quality );
BWExp1 = BANDWIDTH_EXPANSION - delta;
BWExp2 = BANDWIDTH_EXPANSION + delta;
if( psEnc->sCmn.fs_kHz == 24 ) {
/* Less bandwidth expansion for super wideband */
BWExp1 = 1.0f - ( 1.0f - BWExp1 ) * SWB_BANDWIDTH_EXPANSION_REDUCTION;
BWExp2 = 1.0f - ( 1.0f - BWExp2 ) * SWB_BANDWIDTH_EXPANSION_REDUCTION;
}
/* BWExp1 will be applied after BWExp2, so make it relative */
BWExp1 /= BWExp2;
/* Warping coefficient */
psEncCtrl->sCmn.warping_Q16 = psEnc->sCmn.fs_kHz * WARPING_MULTIPLIER_Q16;
psEncCtrl->sCmn.warping_Q16 = SKP_min( psEncCtrl->sCmn.warping_Q16, 32767 );
warping = (SKP_float)psEncCtrl->sCmn.warping_Q16 / 65536.0f;
/********************************************/
/* Compute noise shaping AR coefs and gains */
/********************************************/
for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
/* Apply window */
SKP_Silk_apply_sine_window_FLP( x_windowed, x_ptr, 0, SHAPE_LPC_WIN_MS * psEnc->sCmn.fs_kHz );
/* Update pointer: next LPC analysis block */
x_ptr += psEnc->sCmn.subfr_length;
/* Calculate warped auto correlation */
SKP_Silk_warped_autocorrelation_FLP( auto_corr, x_windowed, warping,
SHAPE_LPC_WIN_MS * psEnc->sCmn.fs_kHz, psEnc->sCmn.shapingLPCOrder );
/* Add white noise, as a fraction of energy */
auto_corr[ 0 ] += auto_corr[ 0 ] * SHAPE_WHITE_NOISE_FRACTION;
/* Convert correlations to prediction coefficients, and compute residual energy */
nrg = SKP_Silk_levinsondurbin_FLP( &psEncCtrl->AR2[ k * MAX_SHAPE_LPC_ORDER ], auto_corr, psEnc->sCmn.shapingLPCOrder );
/* Convert residual energy to non-warped scale */
gain_mult = warped_gain( &psEncCtrl->AR2[ k * MAX_SHAPE_LPC_ORDER ], warping, psEnc->sCmn.shapingLPCOrder );
nrg *= gain_mult * gain_mult;
/* Bandwidth expansion for synthesis filter shaping */
SKP_Silk_bwexpander_FLP( &psEncCtrl->AR2[ k * MAX_SHAPE_LPC_ORDER ], psEnc->sCmn.shapingLPCOrder, BWExp2 );
/* Compute noise shaping filter coefficients */
SKP_memcpy(
&psEncCtrl->AR1[ k * MAX_SHAPE_LPC_ORDER ],
&psEncCtrl->AR2[ k * MAX_SHAPE_LPC_ORDER ],
psEnc->sCmn.shapingLPCOrder * sizeof( SKP_float ) );
/* Bandwidth expansion for analysis filter shaping */
SKP_Silk_bwexpander_FLP( &psEncCtrl->AR1[ k * MAX_SHAPE_LPC_ORDER ], psEnc->sCmn.shapingLPCOrder, BWExp1 );
/* Increase residual energy */
nrg += SHAPE_MIN_ENERGY_RATIO * auto_corr[ 0 ];
psEncCtrl->Gains[ k ] = ( SKP_float )sqrt( nrg );
/* Ratio of prediction gains, in energy domain */
SKP_Silk_LPC_inverse_pred_gain_FLP( &pre_nrg, &psEncCtrl->AR2[ k * MAX_SHAPE_LPC_ORDER ], psEnc->sCmn.shapingLPCOrder );
SKP_Silk_LPC_inverse_pred_gain_FLP( &nrg, &psEncCtrl->AR1[ k * MAX_SHAPE_LPC_ORDER ], psEnc->sCmn.shapingLPCOrder );
psEncCtrl->GainsPre[ k ] = 1.0f - 0.7f * ( 1.0f - pre_nrg / nrg );
/* Convert to monic warped prediction coefficients */
warped_true2monic_coefs( &psEncCtrl->AR1[ k * MAX_SHAPE_LPC_ORDER ], warping, psEnc->sCmn.shapingLPCOrder );
warped_true2monic_coefs( &psEncCtrl->AR2[ k * MAX_SHAPE_LPC_ORDER ], warping, psEnc->sCmn.shapingLPCOrder );
/* Limit absolute values */
limit_warped_coefs( &psEncCtrl->AR2[ k * MAX_SHAPE_LPC_ORDER ], &psEncCtrl->AR1[ k * MAX_SHAPE_LPC_ORDER ],
warping, 3.999f, psEnc->sCmn.shapingLPCOrder );
}
/*****************/
/* Gain tweaking */
/*****************/
/* Increase gains during low speech activity and put lower limit on gains */
gain_mult = ( SKP_float )pow( 2.0f, -0.16f * SNR_adj_dB );
gain_add = ( SKP_float )pow( 2.0f, 0.16f * NOISE_FLOOR_dB ) +
( SKP_float )pow( 2.0f, 0.16f * RELATIVE_MIN_GAIN_dB ) * psEnc->avgGain;
for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
psEncCtrl->Gains[ k ] *= gain_mult;
psEncCtrl->Gains[ k ] += gain_add;
psEnc->avgGain += psEnc->speech_activity * GAIN_SMOOTHING_COEF * ( psEncCtrl->Gains[ k ] - psEnc->avgGain );
}
/************************************************/
/* Decrease level during fricatives (de-essing) */
/************************************************/
gain_mult = 1.0f + INPUT_TILT + psEncCtrl->coding_quality * HIGH_RATE_INPUT_TILT;
if( psEncCtrl->input_tilt <= 0.0f && psEncCtrl->sCmn.sigtype == SIG_TYPE_UNVOICED ) {
SKP_float essStrength = -psEncCtrl->input_tilt * psEnc->speech_activity * ( 1.0f - psEncCtrl->sparseness );
if( psEnc->sCmn.fs_kHz == 24 ) {
gain_mult *= ( SKP_float )pow( 2.0f, -0.16f * DE_ESSER_COEF_SWB_dB * essStrength );
} else if( psEnc->sCmn.fs_kHz == 16 ) {
gain_mult *= (SKP_float)pow( 2.0f, -0.16f * DE_ESSER_COEF_WB_dB * essStrength );
} else {
SKP_assert( psEnc->sCmn.fs_kHz == 12 || psEnc->sCmn.fs_kHz == 8 );
}
}
for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
psEncCtrl->GainsPre[ k ] *= gain_mult;
}
/************************************************/
/* Control low-frequency shaping and noise tilt */
/************************************************/
/* Less low frequency shaping for noisy inputs */
strength = LOW_FREQ_SHAPING * ( 1.0f + LOW_QUALITY_LOW_FREQ_SHAPING_DECR * ( psEncCtrl->input_quality_bands[ 0 ] - 1.0f ) );
if( psEncCtrl->sCmn.sigtype == SIG_TYPE_VOICED ) {
/* Reduce low frequencies quantization noise for periodic signals, depending on pitch lag */
/*f = 400; freqz([1, -0.98 + 2e-4 * f], [1, -0.97 + 7e-4 * f], 2^12, Fs); axis([0, 1000, -10, 1])*/
for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
b = 0.2f / psEnc->sCmn.fs_kHz + 3.0f / psEncCtrl->sCmn.pitchL[ k ];
psEncCtrl->LF_MA_shp[ k ] = -1.0f + b;
psEncCtrl->LF_AR_shp[ k ] = 1.0f - b - b * strength;
}
Tilt = - HP_NOISE_COEF -
(1 - HP_NOISE_COEF) * HARM_HP_NOISE_COEF * psEnc->speech_activity;
} else {
b = 1.3f / psEnc->sCmn.fs_kHz;
psEncCtrl->LF_MA_shp[ 0 ] = -1.0f + b;
psEncCtrl->LF_AR_shp[ 0 ] = 1.0f - b - b * strength * 0.6f;
for( k = 1; k < psEnc->sCmn.nb_subfr; k++ ) {
psEncCtrl->LF_MA_shp[ k ] = psEncCtrl->LF_MA_shp[ k - 1 ];
psEncCtrl->LF_AR_shp[ k ] = psEncCtrl->LF_AR_shp[ k - 1 ];
}
Tilt = -HP_NOISE_COEF;
}
/****************************/
/* HARMONIC SHAPING CONTROL */
/****************************/
/* Control boosting of harmonic frequencies */
HarmBoost = LOW_RATE_HARMONIC_BOOST * ( 1.0f - psEncCtrl->coding_quality ) * psEnc->LTPCorr;
/* More harmonic boost for noisy input signals */
HarmBoost += LOW_INPUT_QUALITY_HARMONIC_BOOST * ( 1.0f - psEncCtrl->input_quality );
if( USE_HARM_SHAPING && psEncCtrl->sCmn.sigtype == SIG_TYPE_VOICED ) {
/* Harmonic noise shaping */
HarmShapeGain = HARMONIC_SHAPING;
/* More harmonic noise shaping for high bitrates or noisy input */
HarmShapeGain += HIGH_RATE_OR_LOW_QUALITY_HARMONIC_SHAPING *
( 1.0f - ( 1.0f - psEncCtrl->coding_quality ) * psEncCtrl->input_quality );
/* Less harmonic noise shaping for less periodic signals */
HarmShapeGain *= ( SKP_float )sqrt( psEnc->LTPCorr );
} else {
HarmShapeGain = 0.0f;
}
/*************************/
/* Smooth over subframes */
/*************************/
for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) {
psShapeSt->HarmBoost_smth += SUBFR_SMTH_COEF * ( HarmBoost - psShapeSt->HarmBoost_smth );
psEncCtrl->HarmBoost[ k ] = psShapeSt->HarmBoost_smth;
psShapeSt->HarmShapeGain_smth += SUBFR_SMTH_COEF * ( HarmShapeGain - psShapeSt->HarmShapeGain_smth );
psEncCtrl->HarmShapeGain[ k ] = psShapeSt->HarmShapeGain_smth;
psShapeSt->Tilt_smth += SUBFR_SMTH_COEF * ( Tilt - psShapeSt->Tilt_smth );
psEncCtrl->Tilt[ k ] = psShapeSt->Tilt_smth;
}
}