www.pudn.com > VoiceActivityDetection.rar > wb_vad.c
/******************************************************************************
* INCLUDE FILES
******************************************************************************/
#include
#include
#include
#include
#include "amr_plus.h"
/******************************************************************************
* PRIVATE PROGRAM CODE
******************************************************************************/
/******************************************************************************
*
* Function : filter5
* Purpose : Fifth-order half-band lowpass/highpass filter pair with
* decimation.
*
*******************************************************************************
*/
static void filter5(
float *in0, /* i/o : input values; output low-pass part */
float *in1, /* i/o : input values; output high-pass part */
float data[] /* i/o : updated filter memory */
)
{
float temp0, temp1, temp2;
temp0 = *in0 - COEFF5_1 * data[0];
temp1 = data[0] + COEFF5_1 * temp0;
data[0] = temp0;
temp0 = *in1 - COEFF5_2 * data[1];
temp2 = data[1] + COEFF5_2 * temp0;
data[1] = temp0;
*in0 = (temp1 + temp2)/2.0f;
*in1 = (temp1 - temp2)/2.0f;
}
/******************************************************************************
*
* Function : filter3
* Purpose : Third-order half-band lowpass/highpass filter pair with
* decimation.
*
*******************************************************************************
*/
static void filter3(
float *in0, /* i/o : input values; output low-pass part */
float *in1, /* i/o : input values; output high-pass part */
float *data /* i/o : updated filter memory */
)
{
float temp1, temp2;
temp1 = *in1 - COEFF3 * *data;
temp2 = *data + COEFF3 * temp1;
*data = temp1;
*in1 = (*in0 - temp2)/2.0f;
*in0 = (*in0 + temp2)/2.0f;
}
/******************************************************************************
*
* Function : level_calculation
* Purpose : Calculate signal level in a sub-band. Level is calculated
* by summing absolute values of the input data.
*
* Because speech coder has a lookahead, signal level calculated
* over the lookahead (data[count1 - count2]) is stored (*sub_level)
* and added to the level of the next frame. Additionally, group
* delay and decimation of the filter bank is taken into the count
* for the values of the counters (count1, count2).
*
*******************************************************************************
*/
static float level_calculation( /* return: signal level */
float data[], /* i : signal buffer */
float *sub_level, /* i : level calculated at the end of the previous frame*/
/* o : level of signal calculated from the last */
/* (count2 - count1) samples */
Word16 count1, /* i : number of samples to be counted */
Word16 count2, /* i : number of samples to be counted */
Word16 ind_m, /* i : step size for the index of the data buffer */
Word16 ind_a, /* i : starting index of the data buffer */
float scale /* i : scaling for the level calculation */
)
{
double l_temp1, l_temp2;
float level;
Word16 i;
l_temp1 = 0.0;
for (i = count1; i < count2; i++)
{
l_temp1 += fabs(data[ind_m*i+ind_a]);
}
l_temp1 *= 2.0f;
l_temp2 = l_temp1 + *sub_level/scale;
*sub_level = (float)(l_temp1*scale);
for (i = 0; i < count1; i++)
{
l_temp2 += 2.0f*fabs(data[ind_m*i+ind_a]);
}
level = (float)(l_temp2*scale);
return level;
}
/******************************************************************************
*
* Function : filter_bank
* Purpose : Divide input signal into bands and calculate level of
* the signal in each band
*
*******************************************************************************
*/
static void filter_bank(
VadVars *st, /* i/o : State struct */
float in[], /* i : input frame */
float level[] /* 0 : signal levels at each band */
)
{
Word16 i;
float tmp_buf[FRAME_LEN];
/* shift input 1 bit down for safe scaling */
for (i = 0; i < FRAME_LEN; i++) {
tmp_buf[i] = in[i]/2.0f;
}
/* run the filter bank */
for (i = 0;i < FRAME_LEN/2; i++) {
filter5(&tmp_buf[2*i],&tmp_buf[2*i+1],st->a_data5[0]);
}
for (i = 0;i < FRAME_LEN/4; i++) {
filter5(&tmp_buf[4*i],&tmp_buf[4*i+2],st->a_data5[1]);
filter5(&tmp_buf[4*i+1],&tmp_buf[4*i+3],st->a_data5[2]);
}
for (i = 0; i < FRAME_LEN/8; i++)
{
filter5(&tmp_buf[8*i], &tmp_buf[8*i+4], st->a_data5[3]);
filter5(&tmp_buf[8*i+2], &tmp_buf[8*i+6], st->a_data5[4]);
filter3(&tmp_buf[8*i+3],&tmp_buf[8*i+7],&st->a_data3[0]);
}
for (i = 0; i < FRAME_LEN/16; i++)
{
filter3(&tmp_buf[16*i+0], &tmp_buf[16*i+8], &st->a_data3[1]);
filter3(&tmp_buf[16*i+4], &tmp_buf[16*i+12], &st->a_data3[2]);
filter3(&tmp_buf[16*i+6], &tmp_buf[16*i+14], &st->a_data3[3]);
}
for (i = 0; i < FRAME_LEN/32; i++)
{
filter3(&tmp_buf[32*i+0], &tmp_buf[32*i+16], &st->a_data3[4]);
filter3(&tmp_buf[32*i+8], &tmp_buf[32*i+24], &st->a_data3[5]);
}
/* calculate levels in each frequency band */
/* 4800 - 6400 Hz*/
level[11] = level_calculation(tmp_buf, &st->sub_level[11],
FRAME_LEN/4-48, FRAME_LEN/4, 4, 1, 0.25);
/* 4000 - 4800 Hz*/
level[10] = level_calculation(tmp_buf, &st->sub_level[10],
FRAME_LEN/8-24, FRAME_LEN/8, 8, 7, 0.5);
/* 3200 - 4000 Hz*/
level[9] = level_calculation(tmp_buf, &st->sub_level[9],
FRAME_LEN/8-24, FRAME_LEN/8, 8, 3, 0.5);
/* 2400 - 3200 Hz*/
level[8] = level_calculation(tmp_buf, &st->sub_level[8],
FRAME_LEN/8-24, FRAME_LEN/8, 8, 2, 0.5);
/* 2000 - 2400 Hz*/
level[7] = level_calculation(tmp_buf, &st->sub_level[7],
FRAME_LEN/16-12, FRAME_LEN/16, 16, 14, 1.0);
/* 1600 - 2000 Hz*/
level[6] = level_calculation(tmp_buf, &st->sub_level[6],
FRAME_LEN/16-12, FRAME_LEN/16, 16, 6, 1.0);
/* 1200 - 1600 Hz*/
level[5] = level_calculation(tmp_buf, &st->sub_level[5],
FRAME_LEN/16-12, FRAME_LEN/16, 16, 4, 1.0);
/* 800 - 1200 Hz*/
level[4] = level_calculation(tmp_buf, &st->sub_level[4],
FRAME_LEN/16-12, FRAME_LEN/16, 16, 12, 1.0);
/* 600 - 800 Hz*/
level[3] = level_calculation(tmp_buf, &st->sub_level[3],
FRAME_LEN/32-6, FRAME_LEN/32, 32, 8, 2.0);
/* 400 - 600 Hz*/
level[2] = level_calculation(tmp_buf, &st->sub_level[2],
FRAME_LEN/32-6, FRAME_LEN/32, 32, 24, 2.0);
/* 200 - 400 Hz*/
level[1] = level_calculation(tmp_buf, &st->sub_level[1],
FRAME_LEN/32-6, FRAME_LEN/32, 32, 16, 2.0);
/* 0 - 200 Hz*/
level[0] = level_calculation(tmp_buf, &st->sub_level[0],
FRAME_LEN/32-6, FRAME_LEN/32, 32, 0, 2.0);
}
/******************************************************************************
*
* Function : update_cntrl
* Purpose : Control update of the background noise estimate.
*
*******************************************************************************
*/
static void update_cntrl(
VadVars *st, /* i/o : State structure */
float level[] /* i : sub-band levels of the input frame */
)
{
Word16 i;
float stat_rat;
float num, denom;
float alpha;
/* if fullband pitch or tone have been detected for a while, initialize stat_count */
if ((st->pitch_tone & 0x7c00) == 0x7c00)
{
st->stat_count = STAT_COUNT;
}
else
{
/* if 8 last vad-decisions have been "0", reinitialize stat_count */
if ((st->vadreg & 0x7f80) == 0)
{
st->stat_count = STAT_COUNT;
}
else
{
stat_rat = 0;
for (i = 0; i < COMPLEN; i++)
{
if (level[i] > st->ave_level[i])
{
num = level[i];
denom = st->ave_level[i];
}
else
{
num = st->ave_level[i];
denom = level[i];
}
/* Limit nimimum value of num and denom to STAT_THR_LEVEL */
if (num < STAT_THR_LEVEL)
{
num = STAT_THR_LEVEL;
}
if (denom < STAT_THR_LEVEL)
{
denom = STAT_THR_LEVEL;
}
stat_rat += num/denom * 64;
}
/* compare stat_rat with a threshold and update stat_count */
if (stat_rat > STAT_THR)
{
st->stat_count = STAT_COUNT;
}
else
{
if ((st->vadreg & 0x4000) != 0)
{
if (st->stat_count != 0)
{
st->stat_count--;
}
}
}
}
}
/* Update average amplitude estimate for stationarity estimation */
alpha = ALPHA4;
if (st->stat_count == STAT_COUNT)
{
alpha = 1.0;
}
else if ((st->vadreg & 0x4000) == 0)
{
alpha = ALPHA5;
}
for (i = 0; i < COMPLEN; i++)
{
st->ave_level[i] += alpha *(level[i]- st->ave_level[i]);
}
}
/******************************************************************************
*
* Function : hangover_addition
* Purpose : Add hangover after speech bursts
*
*******************************************************************************
*/
static Word16 hangover_addition( /* return: VAD_flag indicating final VAD decision */
VadVars *st, /* i/o : State structure */
Word16 low_power, /* i : flag power of the input frame */
Word16 hang_len, /* i : hangover length */
Word16 burst_len /* i : minimum burst length for hangover addition */
)
{
/* if the input power (pow_sum) is lower than a threshold, clear
counters and set VAD_flag to "0" "fast exit" */
if (low_power != 0)
{
st->burst_count = 0;
st->hang_count = 0;
return 0;
}
/* update the counters (hang_count, burst_count) */
if ((st->vadreg & 0x4000) != 0)
{
st->burst_count++;
if (st->burst_count >= burst_len)
{
st->hang_count = hang_len;
}
return 1;
}
else
{
st->burst_count = 0;
if (st->hang_count > 0)
{
st->hang_count--;
return 1;
}
}
return 0;
}
/******************************************************************************
*
* Function : noise_estimate_update
* Purpose : Update of background noise estimate
*
*******************************************************************************
*/
static void noise_estimate_update(
VadVars *st, /* i/o : State structure */
float level[] /* i : sub-band levels of the input frame */
)
{
Word16 i;
float alpha_up, alpha_down, bckr_add, temp;
/* Control update of bckr_est[] */
update_cntrl(st, level);
/* Choose update speed */
bckr_add = 2.0;
if ((0x7800 & st->vadreg) == 0)
{
alpha_up = ALPHA_UP1;
alpha_down = ALPHA_DOWN1;
}
else
{
if (st->stat_count == 0)
{
alpha_up = ALPHA_UP2;
alpha_down = ALPHA_DOWN2;
}
else
{
alpha_up = 0.0;
alpha_down = ALPHA3;
bckr_add = 0.0;
}
}
/* Update noise estimate (bckr_est) */
for (i = 0; i < COMPLEN; i++)
{
temp = st->old_level[i] - st->bckr_est[i];
if (temp < 0.0)
{ /* update downwards*/
st->bckr_est[i] += -2 + (alpha_down * temp);
/* limit minimum value of the noise estimate to NOISE_MIN */
if (st->bckr_est[i] < NOISE_MIN)
{
st->bckr_est[i] = NOISE_MIN;
}
}
else
{ /* update upwards */
st->bckr_est[i] += bckr_add +(alpha_up * temp);
/* limit maximum value of the noise estimate to NOISE_MAX */
if (st->bckr_est[i] > NOISE_MAX)
{
st->bckr_est[i] = NOISE_MAX;
}
}
}
/* Update signal levels of the previous frame (old_level) */
for(i = 0; i < COMPLEN; i++)
{
st->old_level[i] = level[i];
}
}
/******************************************************************************
*
* Function : vad_decision
* Purpose : Calculates VAD_flag
*
*******************************************************************************
*/
static Word16 vad_decision( /*return value : VAD_flag */
VadVars *st, /* i/o : State structure */
float level[COMPLEN], /* i : sub-band levels of the input frame */
double pow_sum /* i : power of the input frame */
)
{
Word16 i;
double L_snr_sum;
double L_temp;
float vad_thr, temp, noise_level;
Word16 low_power_flag;
Word16 hang_len,burst_len;
float ilog2_speech_level,ilog2_noise_level;
float temp2;
/*
Calculate squared sum of the input levels (level)
divided by the background noise components (bckr_est).
*/
L_snr_sum = 0.0;
for (i = 0; i < COMPLEN; i++)
{
temp = level[i]/st->bckr_est[i];
L_snr_sum += temp * temp;
}
/* Calculate average level of estimated background noise */
L_temp = 0.0;
for (i = 1; i < COMPLEN; i++) /* ignore lowest band */
{
L_temp += st->bckr_est[i];
}
noise_level = (float)(L_temp/16.0f);
/*
if SNR is lower than a threshold (MIN_SPEECH_SNR),
and increase speech_level
*/
temp = noise_level*MIN_SPEECH_SNR*8;
if (st->speech_level < temp) {
st->speech_level = temp;
}
ilog2_noise_level = (float)(-1024.0f*log10(noise_level / 2147483648.0f)/log10(2.0f));
/*
If SNR is very poor, speech_level is probably corrupted by noise level. This
is correctred by subtracting -MIN_SPEECH_SNR*noise_level from speech level
*/
ilog2_speech_level = (float)(-1024.0f*log10((st->speech_level-temp) / 2147483648.0f)/log10(2.0f));
/*ilog2_speech_level = ilog2(st->speech_level);*/
temp = NO_SLOPE * (ilog2_noise_level- NO_P1)+ THR_HIGH;
temp2 = SP_CH_MIN + SP_SLOPE*(ilog2_speech_level - SP_P1);
if (temp2 < SP_CH_MIN) {
temp2 = SP_CH_MIN;
}
if (temp2 > SP_CH_MAX) {
temp2 = SP_CH_MAX;
}
vad_thr = temp + temp2;
if (vad_thr < THR_MIN)
{
vad_thr = THR_MIN;
}
/* Shift VAD decision register */
st->vadreg = (short)((st->vadreg)>>1);
/* Make intermediate VAD decision */
if (L_snr_sum > (vad_thr*(float)COMPLEN/128.0f))
{
st->vadreg = (Word16)(st->vadreg | 0x4000);
}
/* primary vad decsion made */
/* check if the input power (pow_sum) is lower than a threshold" */
if (pow_sum < VAD_POW_LOW)
{
low_power_flag = 1;
}
else
{
low_power_flag = 0;
}
/* Update speech subband background noise estimates */
noise_estimate_update(st, level);
hang_len = (Word16)((Word16)(HANG_SLOPE * (vad_thr - HANG_P1) - 0.5) + HANG_HIGH);
if (hang_len < HANG_LOW) {
hang_len = HANG_LOW;
};
burst_len = (Word16)((Word16)(BURST_SLOPE * (vad_thr - BURST_P1) - 0.5) + BURST_HIGH);
return(hangover_addition(st, low_power_flag, hang_len,burst_len));
}
/******************************************************************************
*
* Estimate_Speech()
* Purpose : Estimate speech level
*
* Maximum signal level is searched and stored to the variable sp_max.
* The speech frames must locate within SP_EST_COUNT number of frames to be counted.
* Thus, noisy frames having occasional VAD = "1" decisions will not
* affect to the estimated speech_level.
*
*******************************************************************************
*/
static void Estimate_Speech(
VadVars *st, /* i/o : State structure */
float in_level /* level of the input frame */
)
{
float alpha, tmp;
/* if the required activity count cannot be achieved, reset counters */
if (SP_ACTIVITY_COUNT > (SP_EST_COUNT - st->sp_est_cnt + st->sp_max_cnt))
{
st->sp_est_cnt = 0;
st->sp_max = 0.0;
st->sp_max_cnt = 0;
}
st->sp_est_cnt++;
if (((st->vadreg & 0x4000) || (in_level > st->speech_level))
&& (in_level > MIN_SPEECH_LEVEL1))
{
if (in_level > st->sp_max) {
st->sp_max = in_level;
}
st->sp_max_cnt++;
if (st->sp_max_cnt >= SP_ACTIVITY_COUNT) {
tmp = st->sp_max/2.0f; /* scale to get "average" speech level*/
if (tmp > st->speech_level) {
alpha = ALPHA_SP_UP;
}
else {
alpha = ALPHA_SP_DOWN;
}
if (tmp > MIN_SPEECH_LEVEL2) {
st->speech_level += alpha*(tmp - st->speech_level);
}
st->sp_max = 0.0;
st->sp_max_cnt = 0;
st->sp_est_cnt = 0;
}
}
}
/******************************************************************************
* PUBLIC PROGRAM CODE
******************************************************************************/
/******************************************************************************
*
* Function: wb_vad_init
* Purpose: Allocates state memory and initializes state memory
*
*******************************************************************************
*/
int wb_vad_init ( /* return: non-zero with error, zero for ok. */
VadVars **state /* i/o : State structure */
)
{
VadVars* s;
if (state == (VadVars **) NULL){
fprintf(stderr, "vad_init: invalid parameter\n");
return -1;
}
*state = NULL;
/* allocate memory */
if ((s = (VadVars *) malloc(sizeof(VadVars))) == NULL){
fprintf(stderr, "vad_init: can not malloc state structure\n");
return -1;
}
wb_vad_reset(s);
*state = s;
return 0;
}
/******************************************************************************
*
* Function: wb_vad_reset
* Purpose: Initializes state memory to zero
*
*******************************************************************************
*******************************************************************************
*/
int wb_vad_reset ( /* return: non-zero with error, zero for ok. */
VadVars *state /* i/o : State structure */
)
{
Word16 i, j;
if (state == (VadVars *) NULL){
fprintf(stderr, "vad_reset: invalid parameter\n");
return -1;
}
/* Initialize pitch detection variables */
state->pitch_tone = 0;
state->vadreg = 0;
state->hang_count = 0;
state->burst_count = 0;
state->hang_count = 0;
/* initialize memory used by the filter bank */
for (i = 0; i < F_5TH_CNT; i++)
{
for (j = 0; j < 2; j++)
{
state->a_data5[i][j] = 0.0;
}
}
for (i = 0; i < F_3TH_CNT; i++)
{
state->a_data3[i] = 0.0;
}
/* initialize the rest of the memory */
for (i = 0; i < COMPLEN; i++)
{
state->bckr_est[i] = NOISE_INIT;
state->old_level[i] = NOISE_INIT;
state->ave_level[i] = NOISE_INIT;
state->sub_level[i] = 0;
state->level[i] = 0.0;
state->prevLevel[i] = 0.0;
}
state->sp_est_cnt = 0;
state->sp_max = 0;
state->sp_max_cnt = 0;
state->speech_level = SPEECH_LEVEL_INIT;
state->prev_pow_sum = 0;
return 0;
}
/******************************************************************************
*
* Function: wb_vad_exit
* Purpose: The memory used for state memory is freed
*
*******************************************************************************
*******************************************************************************
*/
void wb_vad_exit (
VadVars **state /* i/o : State structure */
)
{
if (state == NULL || *state == NULL)
return;
/* deallocate memory */
free(*state);
*state = NULL;
return;
}
/******************************************************************************
*
* Function : wb_vad_tone_detection
* Purpose : Set tone flag if pitch gain is high. This is used to detect
* signaling tones and other signals with high pitch gain.
*
*******************************************************************************
*/
void wb_vad_pitch_tone_detection (
VadVars *st, /* i/o : State struct */
float p_gain /* pitch gain */
)
{
/* update tone flag and pitch flag */
st->pitch_tone = (Word16)((st->pitch_tone)>>1);
/* if (pitch_gain > TONE_THR)
set tone flag
*/
if (p_gain > TONE_THR)
{
st->pitch_tone = (Word16)(st->pitch_tone | 0x4000);
}
}
/******************************************************************************
*
* Function : wb_vad
* Purpose : Main program for Voice Activity Detection (VAD) for AMR
*
*******************************************************************************
*/
Word16 wb_vad( /* Return value : VAD Decision, 1 = speech, 0 = noise */
VadVars *st, /* i/o : State structure */
float in_buf[] /* i : samples of the input frame */
)
{
Word16 i;
Word16 VAD_flag;
float temp;
double L_temp, pow_sum;
for(i=0;iprevLevel[i] = st->level[i];
}
/* Calculate power of the input frame. */
L_temp = 0.0;
for (i = 0; i < FRAME_LEN; i++)
{
L_temp += in_buf[i] * in_buf[i];
}
L_temp *= 2.0;
/* pow_sum = power of current frame and previous frame */
pow_sum = L_temp + st->prev_pow_sum;
/* save power of current frame for next call */
st->prev_pow_sum = L_temp;
/* If input power is very low, clear tone flag */
if (pow_sum < POW_PITCH_TONE_THR)
{
st->pitch_tone = (Word16)(st->pitch_tone & 0x1fff);
}
/* Run the filter bank and calculate signal levels at each band */
filter_bank(st, in_buf, st->level);
/* compute VAD decision */
VAD_flag = vad_decision(st, st->level, pow_sum);
/* Calculate input level */
L_temp = 0.0;
for (i = 1; i < COMPLEN; i++) /* ignore lowest band */
{
L_temp += st->level[i];
}
temp = (float)(L_temp/16.0f);
Estimate_Speech(st, temp); /* Estimate speech level */
return(VAD_flag);
}