noise_shape_analysis_FLP.c (15331B)
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 #ifdef HAVE_CONFIG_H 29 #include "config.h" 30 #endif 31 32 #include "main_FLP.h" 33 #include "tuning_parameters.h" 34 35 /* Compute gain to make warped filter coefficients have a zero mean log frequency response on a */ 36 /* non-warped frequency scale. (So that it can be implemented with a minimum-phase monic filter.) */ 37 /* Note: A monic filter is one with the first coefficient equal to 1.0. In Silk we omit the first */ 38 /* coefficient in an array of coefficients, for monic filters. */ 39 static OPUS_INLINE silk_float warped_gain( 40 const silk_float *coefs, 41 silk_float lambda, 42 opus_int order 43 ) { 44 opus_int i; 45 silk_float gain; 46 47 lambda = -lambda; 48 gain = coefs[ order - 1 ]; 49 for( i = order - 2; i >= 0; i-- ) { 50 gain = lambda * gain + coefs[ i ]; 51 } 52 return (silk_float)( 1.0f / ( 1.0f - lambda * gain ) ); 53 } 54 55 /* Convert warped filter coefficients to monic pseudo-warped coefficients and limit maximum */ 56 /* amplitude of monic warped coefficients by using bandwidth expansion on the true coefficients */ 57 static OPUS_INLINE void warped_true2monic_coefs( 58 silk_float *coefs, 59 silk_float lambda, 60 silk_float limit, 61 opus_int order 62 ) { 63 opus_int i, iter, ind = 0; 64 silk_float tmp, maxabs, chirp, gain; 65 66 /* Convert to monic coefficients */ 67 for( i = order - 1; i > 0; i-- ) { 68 coefs[ i - 1 ] -= lambda * coefs[ i ]; 69 } 70 gain = ( 1.0f - lambda * lambda ) / ( 1.0f + lambda * coefs[ 0 ] ); 71 for( i = 0; i < order; i++ ) { 72 coefs[ i ] *= gain; 73 } 74 75 /* Limit */ 76 for( iter = 0; iter < 10; iter++ ) { 77 /* Find maximum absolute value */ 78 maxabs = -1.0f; 79 for( i = 0; i < order; i++ ) { 80 tmp = silk_abs_float( coefs[ i ] ); 81 if( tmp > maxabs ) { 82 maxabs = tmp; 83 ind = i; 84 } 85 } 86 if( maxabs <= limit ) { 87 /* Coefficients are within range - done */ 88 return; 89 } 90 91 /* Convert back to true warped coefficients */ 92 for( i = 1; i < order; i++ ) { 93 coefs[ i - 1 ] += lambda * coefs[ i ]; 94 } 95 gain = 1.0f / gain; 96 for( i = 0; i < order; i++ ) { 97 coefs[ i ] *= gain; 98 } 99 100 /* Apply bandwidth expansion */ 101 chirp = 0.99f - ( 0.8f + 0.1f * iter ) * ( maxabs - limit ) / ( maxabs * ( ind + 1 ) ); 102 silk_bwexpander_FLP( coefs, order, chirp ); 103 104 /* Convert to monic warped coefficients */ 105 for( i = order - 1; i > 0; i-- ) { 106 coefs[ i - 1 ] -= lambda * coefs[ i ]; 107 } 108 gain = ( 1.0f - lambda * lambda ) / ( 1.0f + lambda * coefs[ 0 ] ); 109 for( i = 0; i < order; i++ ) { 110 coefs[ i ] *= gain; 111 } 112 } 113 silk_assert( 0 ); 114 } 115 116 static OPUS_INLINE void limit_coefs( 117 silk_float *coefs, 118 silk_float limit, 119 opus_int order 120 ) { 121 opus_int i, iter, ind = 0; 122 silk_float tmp, maxabs, chirp; 123 124 for( iter = 0; iter < 10; iter++ ) { 125 /* Find maximum absolute value */ 126 maxabs = -1.0f; 127 for( i = 0; i < order; i++ ) { 128 tmp = silk_abs_float( coefs[ i ] ); 129 if( tmp > maxabs ) { 130 maxabs = tmp; 131 ind = i; 132 } 133 } 134 if( maxabs <= limit ) { 135 /* Coefficients are within range - done */ 136 return; 137 } 138 139 /* Apply bandwidth expansion */ 140 chirp = 0.99f - ( 0.8f + 0.1f * iter ) * ( maxabs - limit ) / ( maxabs * ( ind + 1 ) ); 141 silk_bwexpander_FLP( coefs, order, chirp ); 142 } 143 silk_assert( 0 ); 144 } 145 146 /* Compute noise shaping coefficients and initial gain values */ 147 void silk_noise_shape_analysis_FLP( 148 silk_encoder_state_FLP *psEnc, /* I/O Encoder state FLP */ 149 silk_encoder_control_FLP *psEncCtrl, /* I/O Encoder control FLP */ 150 const silk_float *pitch_res, /* I LPC residual from pitch analysis */ 151 const silk_float *x /* I Input signal [frame_length + la_shape] */ 152 ) 153 { 154 silk_shape_state_FLP *psShapeSt = &psEnc->sShape; 155 opus_int k, nSamples, nSegs; 156 silk_float SNR_adj_dB, HarmShapeGain, Tilt; 157 silk_float nrg, log_energy, log_energy_prev, energy_variation; 158 silk_float BWExp, gain_mult, gain_add, strength, b, warping; 159 silk_float x_windowed[ SHAPE_LPC_WIN_MAX ]; 160 silk_float auto_corr[ MAX_SHAPE_LPC_ORDER + 1 ]; 161 silk_float rc[ MAX_SHAPE_LPC_ORDER + 1 ]; 162 const silk_float *x_ptr, *pitch_res_ptr; 163 164 /* Point to start of first LPC analysis block */ 165 x_ptr = x - psEnc->sCmn.la_shape; 166 167 /****************/ 168 /* GAIN CONTROL */ 169 /****************/ 170 SNR_adj_dB = psEnc->sCmn.SNR_dB_Q7 * ( 1 / 128.0f ); 171 172 /* Input quality is the average of the quality in the lowest two VAD bands */ 173 psEncCtrl->input_quality = 0.5f * ( psEnc->sCmn.input_quality_bands_Q15[ 0 ] + psEnc->sCmn.input_quality_bands_Q15[ 1 ] ) * ( 1.0f / 32768.0f ); 174 175 /* Coding quality level, between 0.0 and 1.0 */ 176 psEncCtrl->coding_quality = silk_sigmoid( 0.25f * ( SNR_adj_dB - 20.0f ) ); 177 178 if( psEnc->sCmn.useCBR == 0 ) { 179 /* Reduce coding SNR during low speech activity */ 180 b = 1.0f - psEnc->sCmn.speech_activity_Q8 * ( 1.0f / 256.0f ); 181 SNR_adj_dB -= BG_SNR_DECR_dB * psEncCtrl->coding_quality * ( 0.5f + 0.5f * psEncCtrl->input_quality ) * b * b; 182 } 183 184 if( psEnc->sCmn.indices.signalType == TYPE_VOICED ) { 185 /* Reduce gains for periodic signals */ 186 SNR_adj_dB += HARM_SNR_INCR_dB * psEnc->LTPCorr; 187 } else { 188 /* For unvoiced signals and low-quality input, adjust the quality slower than SNR_dB setting */ 189 SNR_adj_dB += ( -0.4f * psEnc->sCmn.SNR_dB_Q7 * ( 1 / 128.0f ) + 6.0f ) * ( 1.0f - psEncCtrl->input_quality ); 190 } 191 192 /*************************/ 193 /* SPARSENESS PROCESSING */ 194 /*************************/ 195 /* Set quantizer offset */ 196 if( psEnc->sCmn.indices.signalType == TYPE_VOICED ) { 197 /* Initially set to 0; may be overruled in process_gains(..) */ 198 psEnc->sCmn.indices.quantOffsetType = 0; 199 } else { 200 /* Sparseness measure, based on relative fluctuations of energy per 2 milliseconds */ 201 nSamples = 2 * psEnc->sCmn.fs_kHz; 202 energy_variation = 0.0f; 203 log_energy_prev = 0.0f; 204 pitch_res_ptr = pitch_res; 205 nSegs = silk_SMULBB( SUB_FRAME_LENGTH_MS, psEnc->sCmn.nb_subfr ) / 2; 206 for( k = 0; k < nSegs; k++ ) { 207 nrg = ( silk_float )nSamples + ( silk_float )silk_energy_FLP( pitch_res_ptr, nSamples ); 208 log_energy = silk_log2( nrg ); 209 if( k > 0 ) { 210 energy_variation += silk_abs_float( log_energy - log_energy_prev ); 211 } 212 log_energy_prev = log_energy; 213 pitch_res_ptr += nSamples; 214 } 215 216 /* Set quantization offset depending on sparseness measure */ 217 if( energy_variation > ENERGY_VARIATION_THRESHOLD_QNT_OFFSET * (nSegs-1) ) { 218 psEnc->sCmn.indices.quantOffsetType = 0; 219 } else { 220 psEnc->sCmn.indices.quantOffsetType = 1; 221 } 222 } 223 224 /*******************************/ 225 /* Control bandwidth expansion */ 226 /*******************************/ 227 /* More BWE for signals with high prediction gain */ 228 strength = FIND_PITCH_WHITE_NOISE_FRACTION * psEncCtrl->predGain; /* between 0.0 and 1.0 */ 229 BWExp = BANDWIDTH_EXPANSION / ( 1.0f + strength * strength ); 230 231 /* Slightly more warping in analysis will move quantization noise up in frequency, where it's better masked */ 232 warping = (silk_float)psEnc->sCmn.warping_Q16 / 65536.0f + 0.01f * psEncCtrl->coding_quality; 233 234 /********************************************/ 235 /* Compute noise shaping AR coefs and gains */ 236 /********************************************/ 237 for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) { 238 /* Apply window: sine slope followed by flat part followed by cosine slope */ 239 opus_int shift, slope_part, flat_part; 240 flat_part = psEnc->sCmn.fs_kHz * 3; 241 slope_part = ( psEnc->sCmn.shapeWinLength - flat_part ) / 2; 242 243 silk_apply_sine_window_FLP( x_windowed, x_ptr, 1, slope_part ); 244 shift = slope_part; 245 silk_memcpy( x_windowed + shift, x_ptr + shift, flat_part * sizeof(silk_float) ); 246 shift += flat_part; 247 silk_apply_sine_window_FLP( x_windowed + shift, x_ptr + shift, 2, slope_part ); 248 249 /* Update pointer: next LPC analysis block */ 250 x_ptr += psEnc->sCmn.subfr_length; 251 252 if( psEnc->sCmn.warping_Q16 > 0 ) { 253 /* Calculate warped auto correlation */ 254 silk_warped_autocorrelation_FLP( auto_corr, x_windowed, warping, 255 psEnc->sCmn.shapeWinLength, psEnc->sCmn.shapingLPCOrder ); 256 } else { 257 /* Calculate regular auto correlation */ 258 silk_autocorrelation_FLP( auto_corr, x_windowed, psEnc->sCmn.shapeWinLength, psEnc->sCmn.shapingLPCOrder + 1, psEnc->sCmn.arch ); 259 } 260 261 /* Add white noise, as a fraction of energy */ 262 auto_corr[ 0 ] += auto_corr[ 0 ] * SHAPE_WHITE_NOISE_FRACTION + 1.0f; 263 264 /* Convert correlations to prediction coefficients, and compute residual energy */ 265 nrg = silk_schur_FLP( rc, auto_corr, psEnc->sCmn.shapingLPCOrder ); 266 silk_k2a_FLP( &psEncCtrl->AR[ k * MAX_SHAPE_LPC_ORDER ], rc, psEnc->sCmn.shapingLPCOrder ); 267 psEncCtrl->Gains[ k ] = ( silk_float )sqrt( nrg ); 268 269 if( psEnc->sCmn.warping_Q16 > 0 ) { 270 /* Adjust gain for warping */ 271 psEncCtrl->Gains[ k ] *= warped_gain( &psEncCtrl->AR[ k * MAX_SHAPE_LPC_ORDER ], warping, psEnc->sCmn.shapingLPCOrder ); 272 } 273 274 /* Bandwidth expansion for synthesis filter shaping */ 275 silk_bwexpander_FLP( &psEncCtrl->AR[ k * MAX_SHAPE_LPC_ORDER ], psEnc->sCmn.shapingLPCOrder, BWExp ); 276 277 if( psEnc->sCmn.warping_Q16 > 0 ) { 278 /* Convert to monic warped prediction coefficients and limit absolute values */ 279 warped_true2monic_coefs( &psEncCtrl->AR[ k * MAX_SHAPE_LPC_ORDER ], warping, 3.999f, psEnc->sCmn.shapingLPCOrder ); 280 } else { 281 /* Limit absolute values */ 282 limit_coefs( &psEncCtrl->AR[ k * MAX_SHAPE_LPC_ORDER ], 3.999f, psEnc->sCmn.shapingLPCOrder ); 283 } 284 } 285 286 /*****************/ 287 /* Gain tweaking */ 288 /*****************/ 289 /* Increase gains during low speech activity */ 290 gain_mult = (silk_float)pow( 2.0f, -0.16f * SNR_adj_dB ); 291 gain_add = (silk_float)pow( 2.0f, 0.16f * MIN_QGAIN_DB ); 292 for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) { 293 psEncCtrl->Gains[ k ] *= gain_mult; 294 psEncCtrl->Gains[ k ] += gain_add; 295 } 296 297 /************************************************/ 298 /* Control low-frequency shaping and noise tilt */ 299 /************************************************/ 300 /* Less low frequency shaping for noisy inputs */ 301 strength = LOW_FREQ_SHAPING * ( 1.0f + LOW_QUALITY_LOW_FREQ_SHAPING_DECR * ( psEnc->sCmn.input_quality_bands_Q15[ 0 ] * ( 1.0f / 32768.0f ) - 1.0f ) ); 302 strength *= psEnc->sCmn.speech_activity_Q8 * ( 1.0f / 256.0f ); 303 if( psEnc->sCmn.indices.signalType == TYPE_VOICED ) { 304 /* Reduce low frequencies quantization noise for periodic signals, depending on pitch lag */ 305 /*f = 400; freqz([1, -0.98 + 2e-4 * f], [1, -0.97 + 7e-4 * f], 2^12, Fs); axis([0, 1000, -10, 1])*/ 306 for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) { 307 b = 0.2f / psEnc->sCmn.fs_kHz + 3.0f / psEncCtrl->pitchL[ k ]; 308 psEncCtrl->LF_MA_shp[ k ] = -1.0f + b; 309 psEncCtrl->LF_AR_shp[ k ] = 1.0f - b - b * strength; 310 } 311 Tilt = - HP_NOISE_COEF - 312 (1 - HP_NOISE_COEF) * HARM_HP_NOISE_COEF * psEnc->sCmn.speech_activity_Q8 * ( 1.0f / 256.0f ); 313 } else { 314 b = 1.3f / psEnc->sCmn.fs_kHz; 315 psEncCtrl->LF_MA_shp[ 0 ] = -1.0f + b; 316 psEncCtrl->LF_AR_shp[ 0 ] = 1.0f - b - b * strength * 0.6f; 317 for( k = 1; k < psEnc->sCmn.nb_subfr; k++ ) { 318 psEncCtrl->LF_MA_shp[ k ] = psEncCtrl->LF_MA_shp[ 0 ]; 319 psEncCtrl->LF_AR_shp[ k ] = psEncCtrl->LF_AR_shp[ 0 ]; 320 } 321 Tilt = -HP_NOISE_COEF; 322 } 323 324 /****************************/ 325 /* HARMONIC SHAPING CONTROL */ 326 /****************************/ 327 if( USE_HARM_SHAPING && psEnc->sCmn.indices.signalType == TYPE_VOICED ) { 328 /* Harmonic noise shaping */ 329 HarmShapeGain = HARMONIC_SHAPING; 330 331 /* More harmonic noise shaping for high bitrates or noisy input */ 332 HarmShapeGain += HIGH_RATE_OR_LOW_QUALITY_HARMONIC_SHAPING * 333 ( 1.0f - ( 1.0f - psEncCtrl->coding_quality ) * psEncCtrl->input_quality ); 334 335 /* Less harmonic noise shaping for less periodic signals */ 336 HarmShapeGain *= ( silk_float )sqrt( psEnc->LTPCorr ); 337 } else { 338 HarmShapeGain = 0.0f; 339 } 340 341 /*************************/ 342 /* Smooth over subframes */ 343 /*************************/ 344 for( k = 0; k < psEnc->sCmn.nb_subfr; k++ ) { 345 psShapeSt->HarmShapeGain_smth += SUBFR_SMTH_COEF * ( HarmShapeGain - psShapeSt->HarmShapeGain_smth ); 346 psEncCtrl->HarmShapeGain[ k ] = psShapeSt->HarmShapeGain_smth; 347 psShapeSt->Tilt_smth += SUBFR_SMTH_COEF * ( Tilt - psShapeSt->Tilt_smth ); 348 psEncCtrl->Tilt[ k ] = psShapeSt->Tilt_smth; 349 } 350 }