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4 modification, are permitted provided that the following conditions
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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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18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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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. */
warped_gain(const silk_float * coefs,silk_float lambda,opus_int order)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 */
warped_true2monic_coefs(silk_float * coefs,silk_float lambda,silk_float limit,opus_int order)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
limit_coefs(silk_float * coefs,silk_float limit,opus_int order)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 */
silk_noise_shape_analysis_FLP(silk_encoder_state_FLP * psEnc,silk_encoder_control_FLP * psEncCtrl,const silk_float * pitch_res,const silk_float * x)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 );
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 }
351