```/* <![CDATA[ */
2 ** Copyright 2003-2010, VisualOn, Inc.
3 **
5 ** you may not use this file except in compliance with the License.
6 ** You may obtain a copy of the License at
7 **
9 **
10 ** Unless required by applicable law or agreed to in writing, software
12 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 ** See the License for the specific language governing permissions and
14 ** limitations under the License.
15 */
16
17/***********************************************************************
19*                                                                      *
20*      Description: Voice Activity Detection                           *
21*                                                                      *
22************************************************************************/
23
24#include <stdlib.h>
25#include <stdio.h>
26#include "cnst.h"
28#include "typedef.h"
29#include "basic_op.h"
30#include "math_op.h"
32#include "mem_align.h"
33
34/******************************************************************************
35*  Calculate Log2 and scale the signal:
36*
37*    ilog2(Word32 in) = -1024*log10(in * 2^-31)/log10(2), where in = [1, 2^31-1]
38*
39*  input   output
40*  32768   16384
41*  1       31744
42*
43* When input is in the range of [1,2^16], max error is 0.0380%.
44*********************************************************************************/
45
46static Word16 ilog2(                       /* return: output value of the log2 */
47		Word16 mant                        /* i: value to be converted */
48		)
49{
50	Word16 ex, ex2, res;
51	Word32 i, l_temp;
52
53	if (mant <= 0)
54	{
55		mant = 1;
56	}
57	ex = norm_s(mant);
58	mant = mant << ex;
59
60	for (i = 0; i < 3; i++)
61		mant = vo_mult(mant, mant);
62	l_temp = vo_L_mult(mant, mant);
63
64	ex2 = norm_l(l_temp);
65	mant = extract_h(l_temp << ex2);
66
67	res = (ex + 16) << 10;
68	res = add1(res, (ex2 << 6));
69	res = vo_sub(add1(res, 127), (mant >> 8));
70	return (res);
71}
72
73/******************************************************************************
74*
75*     Function     : filter5
76*     Purpose      : Fifth-order half-band lowpass/highpass filter pair with
77*                    decimation.
78*
79*******************************************************************************/
80
81static void filter5(
82		Word16 * in0,                         /* i/o : input values; output low-pass part  */
83		Word16 * in1,                         /* i/o : input values; output high-pass part */
84		Word16 data[]                         /* i/o : filter memory                       */
85		)
86{
87	Word16 temp0, temp1, temp2;
88
89	temp0 = vo_sub(*in0, vo_mult(COEFF5_1, data[0]));
90	temp1 = add1(data[0], vo_mult(COEFF5_1, temp0));
91	data[0] = temp0;
92
93	temp0 = vo_sub(*in1, vo_mult(COEFF5_2, data[1]));
94	temp2 = add1(data[1], vo_mult(COEFF5_2, temp0));
95	data[1] = temp0;
96
97	*in0 = extract_h((vo_L_add(temp1, temp2) << 15));
98	*in1 = extract_h((vo_L_sub(temp1, temp2) << 15));
99}
100
101/******************************************************************************
102*
103*     Function     : filter3
104*     Purpose      : Third-order half-band lowpass/highpass filter pair with
105*                    decimation.
106*
107*******************************************************************************/
108
109static void filter3(
110		Word16 * in0,                         /* i/o : input values; output low-pass part  */
111		Word16 * in1,                         /* i/o : input values; output high-pass part */
112		Word16 * data                         /* i/o : filter memory                       */
113		)
114{
115	Word16 temp1, temp2;
116
117	temp1 = vo_sub(*in1, vo_mult(COEFF3, *data));
118	temp2 = add1(*data, vo_mult(COEFF3, temp1));
119	*data = temp1;
120
121	*in1 = extract_h((vo_L_sub(*in0, temp2) << 15));
122	*in0 = extract_h((vo_L_add(*in0, temp2) << 15));
123}
124
125/******************************************************************************
126*
127*     Function   : level_calculation
128*     Purpose    : Calculate signal level in a sub-band. Level is calculated
129*                  by summing absolute values of the input data.
130*
131*                  Signal level calculated from of the end of the frame
132*                  (data[count1 - count2]) is stored to (*sub_level)
133*                  and added to the level of the next frame.
134*
135******************************************************************************/
136
137static Word16 level_calculation(                      /* return: signal level */
138		Word16 data[],                        /* i   : signal buffer                                    */
139		Word16 * sub_level,                   /* i   : level calculated at the end of the previous frame*/
140		                                      /* o   : level of signal calculated from the last         */
141		                                      /*       (count2 - count1) samples                        */
142		Word16 count1,                        /* i   : number of samples to be counted                  */
143		Word16 count2,                        /* i   : number of samples to be counted                  */
144		Word16 ind_m,                         /* i   : step size for the index of the data buffer       */
145		Word16 ind_a,                         /* i   : starting index of the data buffer                */
146		Word16 scale                          /* i   : scaling for the level calculation                */
147		)
148{
149	Word32 i, l_temp1, l_temp2;
150	Word16 level;
151
152	l_temp1 = 0L;
153	for (i = count1; i < count2; i++)
154	{
155		l_temp1 += (abs_s(data[ind_m * i + ind_a])<<1);
156	}
157
158	l_temp2 = vo_L_add(l_temp1, L_shl(*sub_level, 16 - scale));
159	*sub_level = extract_h(L_shl(l_temp1, scale));
160
161	for (i = 0; i < count1; i++)
162	{
163		l_temp2 += (abs_s(data[ind_m * i + ind_a])<<1);
164	}
165	level = extract_h(L_shl2(l_temp2, scale));
166
167	return level;
168}
169
170/******************************************************************************
171*
172*     Function     : filter_bank
173*     Purpose      : Divide input signal into bands and calculate level of
174*                    the signal in each band
175*
176*******************************************************************************/
177
178static void filter_bank(
179		VadVars * st,                         /* i/o : State struct               */
180		Word16 in[],                          /* i   : input frame                */
181		Word16 level[]                        /* o   : signal levels at each band */
182		)
183{
184	Word32 i;
185	Word16 tmp_buf[FRAME_LEN];
186
187	/* shift input 1 bit down for safe scaling */
188	for (i = 0; i < FRAME_LEN; i++)
189	{
190		tmp_buf[i] = in[i] >> 1;
191	}
192
193	/* run the filter bank */
194	for (i = 0; i < 128; i++)
195	{
196		filter5(&tmp_buf[2 * i], &tmp_buf[2 * i + 1], st->a_data5[0]);
197	}
198	for (i = 0; i < 64; i++)
199	{
200		filter5(&tmp_buf[4 * i], &tmp_buf[4 * i + 2], st->a_data5[1]);
201		filter5(&tmp_buf[4 * i + 1], &tmp_buf[4 * i + 3], st->a_data5[2]);
202	}
203	for (i = 0; i < 32; i++)
204	{
205		filter5(&tmp_buf[8 * i], &tmp_buf[8 * i + 4], st->a_data5[3]);
206		filter5(&tmp_buf[8 * i + 2], &tmp_buf[8 * i + 6], st->a_data5[4]);
207		filter3(&tmp_buf[8 * i + 3], &tmp_buf[8 * i + 7], &st->a_data3[0]);
208	}
209	for (i = 0; i < 16; i++)
210	{
211		filter3(&tmp_buf[16 * i + 0], &tmp_buf[16 * i + 8], &st->a_data3[1]);
212		filter3(&tmp_buf[16 * i + 4], &tmp_buf[16 * i + 12], &st->a_data3[2]);
213		filter3(&tmp_buf[16 * i + 6], &tmp_buf[16 * i + 14], &st->a_data3[3]);
214	}
215
216	for (i = 0; i < 8; i++)
217	{
218		filter3(&tmp_buf[32 * i + 0], &tmp_buf[32 * i + 16], &st->a_data3[4]);
219		filter3(&tmp_buf[32 * i + 8], &tmp_buf[32 * i + 24], &st->a_data3[5]);
220	}
221
222	/* calculate levels in each frequency band */
223
224	/* 4800 - 6400 Hz */
225	level[11] = level_calculation(tmp_buf, &st->sub_level[11], 16, 64, 4, 1, 14);
226	/* 4000 - 4800 Hz */
227	level[10] = level_calculation(tmp_buf, &st->sub_level[10], 8, 32, 8, 7, 15);
228	/* 3200 - 4000 Hz */
229	level[9] = level_calculation(tmp_buf, &st->sub_level[9],8, 32, 8, 3, 15);
230	/* 2400 - 3200 Hz */
231	level[8] = level_calculation(tmp_buf, &st->sub_level[8],8, 32, 8, 2, 15);
232	/* 2000 - 2400 Hz */
233	level[7] = level_calculation(tmp_buf, &st->sub_level[7],4, 16, 16, 14, 16);
234	/* 1600 - 2000 Hz */
235	level[6] = level_calculation(tmp_buf, &st->sub_level[6],4, 16, 16, 6, 16);
236	/* 1200 - 1600 Hz */
237	level[5] = level_calculation(tmp_buf, &st->sub_level[5],4, 16, 16, 4, 16);
238	/* 800 - 1200 Hz */
239	level[4] = level_calculation(tmp_buf, &st->sub_level[4],4, 16, 16, 12, 16);
240	/* 600 - 800 Hz */
241	level[3] = level_calculation(tmp_buf, &st->sub_level[3],2, 8, 32, 8, 17);
242	/* 400 - 600 Hz */
243	level[2] = level_calculation(tmp_buf, &st->sub_level[2],2, 8, 32, 24, 17);
244	/* 200 - 400 Hz */
245	level[1] = level_calculation(tmp_buf, &st->sub_level[1],2, 8, 32, 16, 17);
246	/* 0 - 200 Hz */
247	level[0] = level_calculation(tmp_buf, &st->sub_level[0],2, 8, 32, 0, 17);
248}
249
250/******************************************************************************
251*
252*     Function   : update_cntrl
253*     Purpose    : Control update of the background noise estimate.
254*
255*******************************************************************************/
256
257static void update_cntrl(
258		VadVars * st,                         /* i/o : State structure                    */
259		Word16 level[]                        /* i   : sub-band levels of the input frame */
260		)
261{
262	Word32 i;
263	Word16 num, temp, stat_rat, exp, denom;
264	Word16 alpha;
265
266	/* if a tone has been detected for a while, initialize stat_count */
267	if (sub((Word16) (st->tone_flag & 0x7c00), 0x7c00) == 0)
268	{
269		st->stat_count = STAT_COUNT;
270	} else
271	{
272		/* if 8 last vad-decisions have been "0", reinitialize stat_count */
273		if ((st->vadreg & 0x7f80) == 0)
274		{
275			st->stat_count = STAT_COUNT;
276		} else
277		{
278			stat_rat = 0;
279			for (i = 0; i < COMPLEN; i++)
280			{
281				if(level[i] > st->ave_level[i])
282				{
283					num = level[i];
284					denom = st->ave_level[i];
285				} else
286				{
287					num = st->ave_level[i];
288					denom = level[i];
289				}
290				/* Limit nimimum value of num and denom to STAT_THR_LEVEL */
291				if(num < STAT_THR_LEVEL)
292				{
293					num = STAT_THR_LEVEL;
294				}
295				if(denom < STAT_THR_LEVEL)
296				{
297					denom = STAT_THR_LEVEL;
298				}
299				exp = norm_s(denom);
300				denom = denom << exp;
301
302				/* stat_rat = num/denom * 64 */
303				temp = div_s(num >> 1, denom);
304				stat_rat = add1(stat_rat, shr(temp, (8 - exp)));
305			}
306
307			/* compare stat_rat with a threshold and update stat_count */
308			if(stat_rat > STAT_THR)
309			{
310				st->stat_count = STAT_COUNT;
311			} else
312			{
313				if ((st->vadreg & 0x4000) != 0)
314				{
315
316					if (st->stat_count != 0)
317					{
318						st->stat_count = st->stat_count - 1;
319					}
320				}
321			}
322		}
323	}
324
325	/* Update average amplitude estimate for stationarity estimation */
326	alpha = ALPHA4;
327	if(st->stat_count == STAT_COUNT)
328	{
329		alpha = 32767;
330	} else if ((st->vadreg & 0x4000) == 0)
331	{
332		alpha = ALPHA5;
333	}
334	for (i = 0; i < COMPLEN; i++)
335	{
336		st->ave_level[i] = add1(st->ave_level[i], vo_mult_r(alpha, vo_sub(level[i], st->ave_level[i])));
337	}
338}
339
340/******************************************************************************
341*
343*     Purpose      : Add hangover after speech bursts
344*
345*******************************************************************************/
346
348		VadVars * st,                         /* i/o : State structure                     */
349		Word16 low_power,                     /* i   : flag power of the input frame    */
350		Word16 hang_len,                      /* i   : hangover length */
351		Word16 burst_len                      /* i   : minimum burst length for hangover addition */
352		)
353{
354	/* if the input power (pow_sum) is lower than a threshold, clear counters and set VAD_flag to "0"         */
355	if (low_power != 0)
356	{
357		st->burst_count = 0;
358		st->hang_count = 0;
359		return 0;
360	}
361	/* update the counters (hang_count, burst_count) */
362	if ((st->vadreg & 0x4000) != 0)
363	{
364		st->burst_count = st->burst_count + 1;
365		if(st->burst_count >= burst_len)
366		{
367			st->hang_count = hang_len;
368		}
369		return 1;
370	} else
371	{
372		st->burst_count = 0;
373		if (st->hang_count > 0)
374		{
375			st->hang_count = st->hang_count - 1;
376			return 1;
377		}
378	}
379	return 0;
380}
381
382/******************************************************************************
383*
384*     Function   : noise_estimate_update
385*     Purpose    : Update of background noise estimate
386*
387*******************************************************************************/
388
389static void noise_estimate_update(
390		VadVars * st,                         /* i/o : State structure                       */
391		Word16 level[]                        /* i   : sub-band levels of the input frame */
392		)
393{
394	Word32 i;
395	Word16 alpha_up, alpha_down, bckr_add = 2;
396
397	/* Control update of bckr_est[] */
398	update_cntrl(st, level);
399
400	/* Choose update speed */
401	if ((0x7800 & st->vadreg) == 0)
402	{
403		alpha_up = ALPHA_UP1;
404		alpha_down = ALPHA_DOWN1;
405	} else
406	{
407		if ((st->stat_count == 0))
408		{
409			alpha_up = ALPHA_UP2;
410			alpha_down = ALPHA_DOWN2;
411		} else
412		{
413			alpha_up = 0;
414			alpha_down = ALPHA3;
416		}
417	}
418
419	/* Update noise estimate (bckr_est) */
420	for (i = 0; i < COMPLEN; i++)
421	{
422		Word16 temp;
423		temp = (st->old_level[i] - st->bckr_est[i]);
424
425		if (temp < 0)
426		{                                  /* update downwards */
428			/* limit minimum value of the noise estimate to NOISE_MIN */
429			if(st->bckr_est[i] < NOISE_MIN)
430			{
431				st->bckr_est[i] = NOISE_MIN;
432			}
433		} else
434		{                                  /* update upwards */
436
437			/* limit maximum value of the noise estimate to NOISE_MAX */
438			if(st->bckr_est[i] > NOISE_MAX)
439			{
440				st->bckr_est[i] = NOISE_MAX;
441			}
442		}
443	}
444
445	/* Update signal levels of the previous frame (old_level) */
446	for (i = 0; i < COMPLEN; i++)
447	{
448		st->old_level[i] = level[i];
449	}
450}
451
452/******************************************************************************
453*
456*
457*******************************************************************************/
458
460		VadVars * st,                         /* i/o : State structure                       */
461		Word16 level[COMPLEN],                /* i   : sub-band levels of the input frame */
462		Word32 pow_sum                        /* i   : power of the input frame           */
463		)
464{
465	Word32 i;
466	Word32 L_snr_sum;
467	Word32 L_temp;
469	Word16 low_power_flag;
470	Word16 hang_len, burst_len;
471	Word16 ilog2_speech_level, ilog2_noise_level;
472	Word16 temp2;
473
474	/* Calculate squared sum of the input levels (level) divided by the background noise components
475	 * (bckr_est). */
476	L_snr_sum = 0;
477	for (i = 0; i < COMPLEN; i++)
478	{
479		Word16 exp;
480
481		exp = norm_s(st->bckr_est[i]);
482		temp = (st->bckr_est[i] << exp);
483		temp = div_s((level[i] >> 1), temp);
484		temp = shl(temp, (exp - (UNIRSHFT - 1)));
485		L_snr_sum = L_mac(L_snr_sum, temp, temp);
486	}
487
488	/* Calculate average level of estimated background noise */
489	L_temp = 0;
490	for (i = 1; i < COMPLEN; i++)          /* ignore lowest band */
491	{
493	}
494
495	noise_level = extract_h((L_temp << 12));
496	/* if SNR is lower than a threshold (MIN_SPEECH_SNR), and increase speech_level */
497	temp = vo_mult(noise_level, MIN_SPEECH_SNR) << 3;
498
499	if(st->speech_level < temp)
500	{
501		st->speech_level = temp;
502	}
503	ilog2_noise_level = ilog2(noise_level);
504
505	/* If SNR is very poor, speech_level is probably corrupted by noise level. This is correctred by
506	 * subtracting MIN_SPEECH_SNR*noise_level from speech level */
507	ilog2_speech_level = ilog2(st->speech_level - temp);
508
509	temp = add1(vo_mult(NO_SLOPE, (ilog2_noise_level - NO_P1)), THR_HIGH);
510
511	temp2 = add1(SP_CH_MIN, vo_mult(SP_SLOPE, (ilog2_speech_level - SP_P1)));
512	if (temp2 < SP_CH_MIN)
513	{
514		temp2 = SP_CH_MIN;
515	}
516	if (temp2 > SP_CH_MAX)
517	{
518		temp2 = SP_CH_MAX;
519	}
520	vad_thr = temp + temp2;
521
523	{
525	}
526	/* Shift VAD decision register */
528
529	/* Make intermediate VAD decision */
530	if(L_snr_sum > vo_L_mult(vad_thr, (512 * COMPLEN)))
531	{
533	}
534	/* check if the input power (pow_sum) is lower than a threshold" */
536	{
537		low_power_flag = 1;
538	} else
539	{
540		low_power_flag = 0;
541	}
542	/* Update background noise estimates */
543	noise_estimate_update(st, level);
544
545	/* Calculate values for hang_len and burst_len based on vad_thr */
547	if(hang_len < HANG_LOW)
548	{
549		hang_len = HANG_LOW;
550	}
552
553	return (hangover_addition(st, low_power_flag, hang_len, burst_len));
554}
555
556/******************************************************************************
557*
558*     Function : Estimate_Speech()
559*     Purpose  : Estimate speech level
560*
561* Maximum signal level is searched and stored to the variable sp_max.
562* The speech frames must locate within SP_EST_COUNT number of frames.
563* Thus, noisy frames having occasional VAD = "1" decisions will not
564* affect to the estimated speech_level.
565*
566*******************************************************************************/
567
568static void Estimate_Speech(
569		VadVars * st,                         /* i/o : State structure    */
570		Word16 in_level                       /* level of the input frame */
571		)
572{
573	Word16 alpha;
574
575	/* if the required activity count cannot be achieved, reset counters */
576	if((st->sp_est_cnt - st->sp_max_cnt) > (SP_EST_COUNT - SP_ACTIVITY_COUNT))
577	{
578		st->sp_est_cnt = 0;
579		st->sp_max = 0;
580		st->sp_max_cnt = 0;
581	}
582	st->sp_est_cnt += 1;
583
584	if (((st->vadreg & 0x4000)||(in_level > st->speech_level)) && (in_level > MIN_SPEECH_LEVEL1))
585	{
586		/* update sp_max */
587		if(in_level > st->sp_max)
588		{
589			st->sp_max = in_level;
590		}
591		st->sp_max_cnt += 1;
592
593		if(st->sp_max_cnt >= SP_ACTIVITY_COUNT)
594		{
595			Word16 tmp;
596			/* update speech estimate */
597			tmp = (st->sp_max >> 1);      /* scale to get "average" speech level */
598
599			/* select update speed */
600			if(tmp > st->speech_level)
601			{
602				alpha = ALPHA_SP_UP;
603			} else
604			{
605				alpha = ALPHA_SP_DOWN;
606			}
607			if(tmp > MIN_SPEECH_LEVEL2)
608			{
609				st->speech_level = add1(st->speech_level, vo_mult_r(alpha, vo_sub(tmp, st->speech_level)));
610			}
611			/* clear all counters used for speech estimation */
612			st->sp_max = 0;
613			st->sp_max_cnt = 0;
614			st->sp_est_cnt = 0;
615		}
616	}
617}
618
619/******************************************************************************
620*
622*  Purpose:    Allocates state memory and initializes state memory
623*
624*******************************************************************************/
625
626Word16 wb_vad_init(                        /* return: non-zero with error, zero for ok. */
627		VadVars ** state,                     /* i/o : State structure    */
628		VO_MEM_OPERATOR *pMemOP
629		)
630{
632
633	if (state == (VadVars **) NULL)
634	{
636		return -1;
637	}
638	*state = NULL;
639
640	/* allocate memory */
641	if ((s = (VadVars *) mem_malloc(pMemOP, sizeof(VadVars), 32, VO_INDEX_ENC_AMRWB)) == NULL)
642	{
643		fprintf(stderr, "vad_init: can not malloc state structure\n");
644		return -1;
645	}
647
648	*state = s;
649
650	return 0;
651}
652
653/******************************************************************************
654*
656*  Purpose:    Initializes state memory
657*
658*******************************************************************************/
659
660Word16 wb_vad_reset(                       /* return: non-zero with error, zero for ok. */
661		VadVars * state                       /* i/o : State structure    */
662		)
663{
664	Word32 i, j;
665
666	if (state == (VadVars *) NULL)
667	{
669		return -1;
670	}
671	state->tone_flag = 0;
673	state->hang_count = 0;
674	state->burst_count = 0;
675	state->hang_count = 0;
676
677	/* initialize memory used by the filter bank */
678	for (i = 0; i < F_5TH_CNT; i++)
679	{
680		for (j = 0; j < 2; j++)
681		{
682			state->a_data5[i][j] = 0;
683		}
684	}
685
686	for (i = 0; i < F_3TH_CNT; i++)
687	{
688		state->a_data3[i] = 0;
689	}
690
691	/* initialize the rest of the memory */
692	for (i = 0; i < COMPLEN; i++)
693	{
694		state->bckr_est[i] = NOISE_INIT;
695		state->old_level[i] = NOISE_INIT;
696		state->ave_level[i] = NOISE_INIT;
697		state->sub_level[i] = 0;
698	}
699
700	state->sp_est_cnt = 0;
701	state->sp_max = 0;
702	state->sp_max_cnt = 0;
703	state->speech_level = SPEECH_LEVEL_INIT;
704	state->prev_pow_sum = 0;
705	return 0;
706}
707
708/******************************************************************************
709*
711*  Purpose:    The memory used for state memory is freed
712*
713*******************************************************************************/
714
716		VadVars ** state,                      /* i/o : State structure    */
717		VO_MEM_OPERATOR *pMemOP
718		)
719{
720	if (state == NULL || *state == NULL)
721		return;
722	/* deallocate memory */
723	mem_free(pMemOP, *state, VO_INDEX_ENC_AMRWB);
724	*state = NULL;
725	return;
726}
727
728/******************************************************************************
729*
731*     Purpose      : Search maximum pitch gain from a frame. Set tone flag if
732*                    pitch gain is high. This is used to detect
733*                    signaling tones and other signals with high pitch gain.
734*
735*******************************************************************************/
736
738		VadVars * st,                         /* i/o : State struct            */
739		Word16 p_gain                         /* pitch gain      */
740		)
741{
742	/* update tone flag */
743	st->tone_flag = (st->tone_flag >> 1);
744
745	/* if (pitch_gain > TONE_THR) set tone flag */
746	if (p_gain > TONE_THR)
747	{
748		st->tone_flag = (Word16) (st->tone_flag | 0x4000);
749	}
750}
751
752/******************************************************************************
753*
755*     Purpose      : Main program for Voice Activity Detection (VAD) for AMR
756*
757*******************************************************************************/
758
759Word16 wb_vad(                                /* Return value : VAD Decision, 1 = speech, 0 = noise */
760		VadVars * st,                         /* i/o : State structure                 */
761		Word16 in_buf[]                       /* i   : samples of the input frame   */
762	     )
763{
764	Word16 level[COMPLEN];
765	Word32 i;
767	Word32 L_temp, pow_sum;
768
769	/* Calculate power of the input frame. */
770	L_temp = 0L;
771	for (i = 0; i < FRAME_LEN; i++)
772	{
773		L_temp = L_mac(L_temp, in_buf[i], in_buf[i]);
774	}
775
776	/* pow_sum = power of current frame and previous frame */
778
779	/* save power of current frame for next call */
780	st->prev_pow_sum = L_temp;
781
782	/* If input power is very low, clear tone flag */
783	if (pow_sum < POW_TONE_THR)
784	{
785		st->tone_flag = (Word16) (st->tone_flag & 0x1fff);
786	}
787	/* Run the filter bank and calculate signal levels at each band */
788	filter_bank(st, in_buf, level);
789
790	/* compute VAD decision */
792
793	/* Calculate input level */
794	L_temp = 0;
795	for (i = 1; i < COMPLEN; i++)          /* ignore lowest band */
796	{