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
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11 - Neither the name of Internet Society, IETF or IETF Trust, nor the
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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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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.h"
33 #include "stack_alloc.h"
34
35 /* Silk VAD noise level estimation */
36 # if !defined(OPUS_X86_MAY_HAVE_SSE4_1)
37 static OPUS_INLINE void silk_VAD_GetNoiseLevels(
38 const opus_int32 pX[ VAD_N_BANDS ], /* I subband energies */
39 silk_VAD_state *psSilk_VAD /* I/O Pointer to Silk VAD state */
40 );
41 #endif
42
43 /**********************************/
44 /* Initialization of the Silk VAD */
45 /**********************************/
silk_VAD_Init(silk_VAD_state * psSilk_VAD)46 opus_int silk_VAD_Init( /* O Return value, 0 if success */
47 silk_VAD_state *psSilk_VAD /* I/O Pointer to Silk VAD state */
48 )
49 {
50 opus_int b, ret = 0;
51
52 /* reset state memory */
53 silk_memset( psSilk_VAD, 0, sizeof( silk_VAD_state ) );
54
55 /* init noise levels */
56 /* Initialize array with approx pink noise levels (psd proportional to inverse of frequency) */
57 for( b = 0; b < VAD_N_BANDS; b++ ) {
58 psSilk_VAD->NoiseLevelBias[ b ] = silk_max_32( silk_DIV32_16( VAD_NOISE_LEVELS_BIAS, b + 1 ), 1 );
59 }
60
61 /* Initialize state */
62 for( b = 0; b < VAD_N_BANDS; b++ ) {
63 psSilk_VAD->NL[ b ] = silk_MUL( 100, psSilk_VAD->NoiseLevelBias[ b ] );
64 psSilk_VAD->inv_NL[ b ] = silk_DIV32( silk_int32_MAX, psSilk_VAD->NL[ b ] );
65 }
66 psSilk_VAD->counter = 15;
67
68 /* init smoothed energy-to-noise ratio*/
69 for( b = 0; b < VAD_N_BANDS; b++ ) {
70 psSilk_VAD->NrgRatioSmth_Q8[ b ] = 100 * 256; /* 100 * 256 --> 20 dB SNR */
71 }
72
73 return( ret );
74 }
75
76 /* Weighting factors for tilt measure */
77 static const opus_int32 tiltWeights[ VAD_N_BANDS ] = { 30000, 6000, -12000, -12000 };
78
79 /***************************************/
80 /* Get the speech activity level in Q8 */
81 /***************************************/
silk_VAD_GetSA_Q8_c(silk_encoder_state * psEncC,const opus_int16 pIn[])82 opus_int silk_VAD_GetSA_Q8_c( /* O Return value, 0 if success */
83 silk_encoder_state *psEncC, /* I/O Encoder state */
84 const opus_int16 pIn[] /* I PCM input */
85 )
86 {
87 opus_int SA_Q15, pSNR_dB_Q7, input_tilt;
88 opus_int decimated_framelength1, decimated_framelength2;
89 opus_int decimated_framelength;
90 opus_int dec_subframe_length, dec_subframe_offset, SNR_Q7, i, b, s;
91 opus_int32 sumSquared, smooth_coef_Q16;
92 opus_int16 HPstateTmp;
93 VARDECL( opus_int16, X );
94 opus_int32 Xnrg[ VAD_N_BANDS ];
95 opus_int32 NrgToNoiseRatio_Q8[ VAD_N_BANDS ];
96 opus_int32 speech_nrg, x_tmp;
97 opus_int X_offset[ VAD_N_BANDS ];
98 opus_int ret = 0;
99 silk_VAD_state *psSilk_VAD = &psEncC->sVAD;
100 SAVE_STACK;
101
102 /* Safety checks */
103 silk_assert( VAD_N_BANDS == 4 );
104 celt_assert( MAX_FRAME_LENGTH >= psEncC->frame_length );
105 celt_assert( psEncC->frame_length <= 512 );
106 celt_assert( psEncC->frame_length == 8 * silk_RSHIFT( psEncC->frame_length, 3 ) );
107
108 /***********************/
109 /* Filter and Decimate */
110 /***********************/
111 decimated_framelength1 = silk_RSHIFT( psEncC->frame_length, 1 );
112 decimated_framelength2 = silk_RSHIFT( psEncC->frame_length, 2 );
113 decimated_framelength = silk_RSHIFT( psEncC->frame_length, 3 );
114 /* Decimate into 4 bands:
115 0 L 3L L 3L 5L
116 - -- - -- --
117 8 8 2 4 4
118
119 [0-1 kHz| temp. |1-2 kHz| 2-4 kHz | 4-8 kHz |
120
121 They're arranged to allow the minimal ( frame_length / 4 ) extra
122 scratch space during the downsampling process */
123 X_offset[ 0 ] = 0;
124 X_offset[ 1 ] = decimated_framelength + decimated_framelength2;
125 X_offset[ 2 ] = X_offset[ 1 ] + decimated_framelength;
126 X_offset[ 3 ] = X_offset[ 2 ] + decimated_framelength2;
127 ALLOC( X, X_offset[ 3 ] + decimated_framelength1, opus_int16 );
128
129 /* 0-8 kHz to 0-4 kHz and 4-8 kHz */
130 silk_ana_filt_bank_1( pIn, &psSilk_VAD->AnaState[ 0 ],
131 X, &X[ X_offset[ 3 ] ], psEncC->frame_length );
132
133 /* 0-4 kHz to 0-2 kHz and 2-4 kHz */
134 silk_ana_filt_bank_1( X, &psSilk_VAD->AnaState1[ 0 ],
135 X, &X[ X_offset[ 2 ] ], decimated_framelength1 );
136
137 /* 0-2 kHz to 0-1 kHz and 1-2 kHz */
138 silk_ana_filt_bank_1( X, &psSilk_VAD->AnaState2[ 0 ],
139 X, &X[ X_offset[ 1 ] ], decimated_framelength2 );
140
141 /*********************************************/
142 /* HP filter on lowest band (differentiator) */
143 /*********************************************/
144 X[ decimated_framelength - 1 ] = silk_RSHIFT( X[ decimated_framelength - 1 ], 1 );
145 HPstateTmp = X[ decimated_framelength - 1 ];
146 for( i = decimated_framelength - 1; i > 0; i-- ) {
147 X[ i - 1 ] = silk_RSHIFT( X[ i - 1 ], 1 );
148 X[ i ] -= X[ i - 1 ];
149 }
150 X[ 0 ] -= psSilk_VAD->HPstate;
151 psSilk_VAD->HPstate = HPstateTmp;
152
153 /*************************************/
154 /* Calculate the energy in each band */
155 /*************************************/
156 for( b = 0; b < VAD_N_BANDS; b++ ) {
157 /* Find the decimated framelength in the non-uniformly divided bands */
158 decimated_framelength = silk_RSHIFT( psEncC->frame_length, silk_min_int( VAD_N_BANDS - b, VAD_N_BANDS - 1 ) );
159
160 /* Split length into subframe lengths */
161 dec_subframe_length = silk_RSHIFT( decimated_framelength, VAD_INTERNAL_SUBFRAMES_LOG2 );
162 dec_subframe_offset = 0;
163
164 /* Compute energy per sub-frame */
165 /* initialize with summed energy of last subframe */
166 Xnrg[ b ] = psSilk_VAD->XnrgSubfr[ b ];
167 for( s = 0; s < VAD_INTERNAL_SUBFRAMES; s++ ) {
168 sumSquared = 0;
169 for( i = 0; i < dec_subframe_length; i++ ) {
170 /* The energy will be less than dec_subframe_length * ( silk_int16_MIN / 8 ) ^ 2. */
171 /* Therefore we can accumulate with no risk of overflow (unless dec_subframe_length > 128) */
172 x_tmp = silk_RSHIFT(
173 X[ X_offset[ b ] + i + dec_subframe_offset ], 3 );
174 sumSquared = silk_SMLABB( sumSquared, x_tmp, x_tmp );
175
176 /* Safety check */
177 silk_assert( sumSquared >= 0 );
178 }
179
180 /* Add/saturate summed energy of current subframe */
181 if( s < VAD_INTERNAL_SUBFRAMES - 1 ) {
182 Xnrg[ b ] = silk_ADD_POS_SAT32( Xnrg[ b ], sumSquared );
183 } else {
184 /* Look-ahead subframe */
185 Xnrg[ b ] = silk_ADD_POS_SAT32( Xnrg[ b ], silk_RSHIFT( sumSquared, 1 ) );
186 }
187
188 dec_subframe_offset += dec_subframe_length;
189 }
190 psSilk_VAD->XnrgSubfr[ b ] = sumSquared;
191 }
192
193 /********************/
194 /* Noise estimation */
195 /********************/
196 silk_VAD_GetNoiseLevels( &Xnrg[ 0 ], psSilk_VAD );
197
198 /***********************************************/
199 /* Signal-plus-noise to noise ratio estimation */
200 /***********************************************/
201 sumSquared = 0;
202 input_tilt = 0;
203 for( b = 0; b < VAD_N_BANDS; b++ ) {
204 speech_nrg = Xnrg[ b ] - psSilk_VAD->NL[ b ];
205 if( speech_nrg > 0 ) {
206 /* Divide, with sufficient resolution */
207 if( ( Xnrg[ b ] & 0xFF800000 ) == 0 ) {
208 NrgToNoiseRatio_Q8[ b ] = silk_DIV32( silk_LSHIFT( Xnrg[ b ], 8 ), psSilk_VAD->NL[ b ] + 1 );
209 } else {
210 NrgToNoiseRatio_Q8[ b ] = silk_DIV32( Xnrg[ b ], silk_RSHIFT( psSilk_VAD->NL[ b ], 8 ) + 1 );
211 }
212
213 /* Convert to log domain */
214 SNR_Q7 = silk_lin2log( NrgToNoiseRatio_Q8[ b ] ) - 8 * 128;
215
216 /* Sum-of-squares */
217 sumSquared = silk_SMLABB( sumSquared, SNR_Q7, SNR_Q7 ); /* Q14 */
218
219 /* Tilt measure */
220 if( speech_nrg < ( (opus_int32)1 << 20 ) ) {
221 /* Scale down SNR value for small subband speech energies */
222 SNR_Q7 = silk_SMULWB( silk_LSHIFT( silk_SQRT_APPROX( speech_nrg ), 6 ), SNR_Q7 );
223 }
224 input_tilt = silk_SMLAWB( input_tilt, tiltWeights[ b ], SNR_Q7 );
225 } else {
226 NrgToNoiseRatio_Q8[ b ] = 256;
227 }
228 }
229
230 /* Mean-of-squares */
231 sumSquared = silk_DIV32_16( sumSquared, VAD_N_BANDS ); /* Q14 */
232
233 /* Root-mean-square approximation, scale to dBs, and write to output pointer */
234 pSNR_dB_Q7 = (opus_int16)( 3 * silk_SQRT_APPROX( sumSquared ) ); /* Q7 */
235
236 /*********************************/
237 /* Speech Probability Estimation */
238 /*********************************/
239 SA_Q15 = silk_sigm_Q15( silk_SMULWB( VAD_SNR_FACTOR_Q16, pSNR_dB_Q7 ) - VAD_NEGATIVE_OFFSET_Q5 );
240
241 /**************************/
242 /* Frequency Tilt Measure */
243 /**************************/
244 psEncC->input_tilt_Q15 = silk_LSHIFT( silk_sigm_Q15( input_tilt ) - 16384, 1 );
245
246 /**************************************************/
247 /* Scale the sigmoid output based on power levels */
248 /**************************************************/
249 speech_nrg = 0;
250 for( b = 0; b < VAD_N_BANDS; b++ ) {
251 /* Accumulate signal-without-noise energies, higher frequency bands have more weight */
252 speech_nrg += ( b + 1 ) * silk_RSHIFT( Xnrg[ b ] - psSilk_VAD->NL[ b ], 4 );
253 }
254
255 if( psEncC->frame_length == 20 * psEncC->fs_kHz ) {
256 speech_nrg = silk_RSHIFT32( speech_nrg, 1 );
257 }
258 /* Power scaling */
259 if( speech_nrg <= 0 ) {
260 SA_Q15 = silk_RSHIFT( SA_Q15, 1 );
261 } else if( speech_nrg < 16384 ) {
262 speech_nrg = silk_LSHIFT32( speech_nrg, 16 );
263
264 /* square-root */
265 speech_nrg = silk_SQRT_APPROX( speech_nrg );
266 SA_Q15 = silk_SMULWB( 32768 + speech_nrg, SA_Q15 );
267 }
268
269 /* Copy the resulting speech activity in Q8 */
270 psEncC->speech_activity_Q8 = silk_min_int( silk_RSHIFT( SA_Q15, 7 ), silk_uint8_MAX );
271
272 /***********************************/
273 /* Energy Level and SNR estimation */
274 /***********************************/
275 /* Smoothing coefficient */
276 smooth_coef_Q16 = silk_SMULWB( VAD_SNR_SMOOTH_COEF_Q18, silk_SMULWB( (opus_int32)SA_Q15, SA_Q15 ) );
277
278 if( psEncC->frame_length == 10 * psEncC->fs_kHz ) {
279 smooth_coef_Q16 >>= 1;
280 }
281
282 for( b = 0; b < VAD_N_BANDS; b++ ) {
283 /* compute smoothed energy-to-noise ratio per band */
284 psSilk_VAD->NrgRatioSmth_Q8[ b ] = silk_SMLAWB( psSilk_VAD->NrgRatioSmth_Q8[ b ],
285 NrgToNoiseRatio_Q8[ b ] - psSilk_VAD->NrgRatioSmth_Q8[ b ], smooth_coef_Q16 );
286
287 /* signal to noise ratio in dB per band */
288 SNR_Q7 = 3 * ( silk_lin2log( psSilk_VAD->NrgRatioSmth_Q8[b] ) - 8 * 128 );
289 /* quality = sigmoid( 0.25 * ( SNR_dB - 16 ) ); */
290 psEncC->input_quality_bands_Q15[ b ] = silk_sigm_Q15( silk_RSHIFT( SNR_Q7 - 16 * 128, 4 ) );
291 }
292
293 RESTORE_STACK;
294 return( ret );
295 }
296
297 /**************************/
298 /* Noise level estimation */
299 /**************************/
300 # if !defined(OPUS_X86_MAY_HAVE_SSE4_1)
301 static OPUS_INLINE
302 #endif
silk_VAD_GetNoiseLevels(const opus_int32 pX[VAD_N_BANDS],silk_VAD_state * psSilk_VAD)303 void silk_VAD_GetNoiseLevels(
304 const opus_int32 pX[ VAD_N_BANDS ], /* I subband energies */
305 silk_VAD_state *psSilk_VAD /* I/O Pointer to Silk VAD state */
306 )
307 {
308 opus_int k;
309 opus_int32 nl, nrg, inv_nrg;
310 opus_int coef, min_coef;
311
312 /* Initially faster smoothing */
313 if( psSilk_VAD->counter < 1000 ) { /* 1000 = 20 sec */
314 min_coef = silk_DIV32_16( silk_int16_MAX, silk_RSHIFT( psSilk_VAD->counter, 4 ) + 1 );
315 } else {
316 min_coef = 0;
317 }
318
319 for( k = 0; k < VAD_N_BANDS; k++ ) {
320 /* Get old noise level estimate for current band */
321 nl = psSilk_VAD->NL[ k ];
322 silk_assert( nl >= 0 );
323
324 /* Add bias */
325 nrg = silk_ADD_POS_SAT32( pX[ k ], psSilk_VAD->NoiseLevelBias[ k ] );
326 silk_assert( nrg > 0 );
327
328 /* Invert energies */
329 inv_nrg = silk_DIV32( silk_int32_MAX, nrg );
330 silk_assert( inv_nrg >= 0 );
331
332 /* Less update when subband energy is high */
333 if( nrg > silk_LSHIFT( nl, 3 ) ) {
334 coef = VAD_NOISE_LEVEL_SMOOTH_COEF_Q16 >> 3;
335 } else if( nrg < nl ) {
336 coef = VAD_NOISE_LEVEL_SMOOTH_COEF_Q16;
337 } else {
338 coef = silk_SMULWB( silk_SMULWW( inv_nrg, nl ), VAD_NOISE_LEVEL_SMOOTH_COEF_Q16 << 1 );
339 }
340
341 /* Initially faster smoothing */
342 coef = silk_max_int( coef, min_coef );
343
344 /* Smooth inverse energies */
345 psSilk_VAD->inv_NL[ k ] = silk_SMLAWB( psSilk_VAD->inv_NL[ k ], inv_nrg - psSilk_VAD->inv_NL[ k ], coef );
346 silk_assert( psSilk_VAD->inv_NL[ k ] >= 0 );
347
348 /* Compute noise level by inverting again */
349 nl = silk_DIV32( silk_int32_MAX, psSilk_VAD->inv_NL[ k ] );
350 silk_assert( nl >= 0 );
351
352 /* Limit noise levels (guarantee 7 bits of head room) */
353 nl = silk_min( nl, 0x00FFFFFF );
354
355 /* Store as part of state */
356 psSilk_VAD->NL[ k ] = nl;
357 }
358
359 /* Increment frame counter */
360 psSilk_VAD->counter++;
361 }
362