www.pudn.com > G711-729.rar > VAD.C

/* 
** 
 
** File:        "vad.c" 
** 
** Description:     Voice Activity Detection 
** 
** Functions:       Init_Vad() 
**                  Vad() 
** 
** 
*/ 
/* 
    ITU-T G.723 Speech Coder   ANSI-C Source Code     Version 5.00 
    copyright (c) 1995, AudioCodes, DSP Group, France Telecom, 
    Universite de Sherbrooke.  All rights reserved. 
*/ 
 
#include  
 
#include "typedef.h" 
#include "basop.h" 
#include "cst_lbc.h" 
#include "tab_lbc.h" 
#include "lsp.h" 
#include "vad.h" 
#include "coder.h" 
#include "lbccodec.h" 
 
VADSTATDEF  VadStat ; 
 
void    Init_Vad(void) 
{ 
    int i ; 
    VadStat.Hcnt = 3 ; 
    VadStat.Vcnt = 0 ; 
    VadStat.Penr = 0x00000400L ; 
    VadStat.Nlev = 0x00000400L ; 
 
    VadStat.Aen = 0 ; 
 
    VadStat.Polp[0] = 1 ; 
    VadStat.Polp[1] = 1 ; 
    VadStat.Polp[2] = SubFrLen ; 
    VadStat.Polp[3] = SubFrLen ; 
 
    for(i=0; i < LpcOrder; i++) VadStat.NLpc[i] = 0; 
 
} 
 
Flag Comp_Vad( Word16 *Dpnt) 
{ 
    int i,j ; 
 
    Word32  Acc0,Acc1 ; 
    Word16  Tm0, Tm1, Tm2 ; 
    Word16  Minp ; 
 
    Flag    VadState = 1 ; 
 
    static  Word16  ScfTab[11] = { 
         9170 , 
         9170 , 
         9170 , 
         9170 , 
        10289 , 
        11544 , 
        12953 , 
        14533 , 
        16306 , 
        18296 , 
        20529 , 
    } ; 
 
    if ( !UseVx ) 
        return VadState ; 
 
    /* Find Minimum pitch period */ 
    Minp = PitchMax ; 
    for ( i = 0 ; i < 4 ; i ++ ) { 
        if ( Minp > VadStat.Polp[i] ) 
            Minp = VadStat.Polp[i] ; 
    } 
 
    /* Check that all are multiplies of the minimum */ 
    Tm2 = 0 ; 
    for ( i = 0 ; i < 4 ; i ++ ) { 
        Tm1 = Minp ; 
        for ( j = 0 ; j < 8 ; j ++ ) { 
            Tm0 = sub( Tm1, VadStat.Polp[i] ) ; 
            Tm0 = abs_s( Tm0 ) ; 
            if ( Tm0 <= 3 ) 
                Tm2 ++ ; 
            Tm1 = add( Tm1, Minp ) ; 
        } 
    } 
 
    /* Update adaptation enable counter if not periodic and not sine */ 
    if ( (Tm2 == 4) || (CodStat.SinDet < 0) ) 
        VadStat.Aen += 2 ; 
    else 
        VadStat.Aen -- ; 
 
    /* Clip it */ 
    if ( VadStat.Aen > 6 ) 
        VadStat.Aen = 6 ; 
    if ( VadStat.Aen < 0 ) 
        VadStat.Aen = 0 ; 
 
    /* Inverse filter the data */ 
    Acc1 = 0L ; 
    for ( i = SubFrLen ; i < Frame ; i ++ ) { 
 
        Acc0 = L_mult( Dpnt[i], 0x2000 ) ; 
        for ( j = 0 ; j < LpcOrder ; j ++ ) 
            Acc0 = L_msu( Acc0, Dpnt[i-j-1], VadStat.NLpc[j] ) ; 
        Tm0 = round ( Acc0 ) ; 
        Acc1 = L_mac( Acc1, Tm0, Tm0 ) ; 
    } 
 
    /* Scale the rezidual energy */ 
    Acc1 = L_mls( Acc1, (Word16) 2913 ) ; 
 
    /* Clip noise level in any case */ 
    if ( VadStat.Nlev > VadStat.Penr ) { 
        Acc0 = L_sub( VadStat.Penr, L_shr( VadStat.Penr, 2 ) ) ; 
        VadStat.Nlev = L_add( Acc0, L_shr( VadStat.Nlev, 2 ) ) ; 
    } 
 
 
    /* Update the noise level, if adaptation is enabled */ 
    if ( !VadStat.Aen ) { 
        VadStat.Nlev = L_add( VadStat.Nlev, L_shr( VadStat.Nlev, 5 ) ) ; 
    } 
    /* Decay Nlev by small amount */ 
    else { 
        VadStat.Nlev = L_sub( VadStat.Nlev, L_shr( VadStat.Nlev,11 ) ) ; 
    } 
 
    /* Update previous energy */ 
    VadStat.Penr = Acc1 ; 
 
    /* CLip Noise Level */ 
    if ( VadStat.Nlev < 0x00000080L ) 
        VadStat.Nlev = 0x00000080L ; 
    if ( VadStat.Nlev > 0x0001ffffL ) 
        VadStat.Nlev = 0x0001ffffL ; 
 
    /* Compute the treshold */ 
    Acc0 = L_shl( VadStat.Nlev, 13 ) ; 
    Tm0 = norm_l( Acc0 ) ; 
    Acc0 = L_shl( Acc0, Tm0 ) ; 
    Acc0 &= 0x3f000000L ; 
    Acc0 <<= 1 ; 
    Tm1 = extract_h( Acc0 ) ; 
    Acc0 = L_deposit_h( ScfTab[Tm0] ) ; 
    Acc0 = L_mac( Acc0, Tm1, ScfTab[Tm0-1] ) ; 
    Acc0 = L_msu( Acc0, Tm1, ScfTab[Tm0] ) ; 
    Tm1 = extract_h( Acc0 ) ; 
    Tm0 = extract_l( L_shr( VadStat.Nlev, 2 ) ) ; 
    Acc0 = L_mult( Tm0, Tm1 ) ; 
    Acc0 >>= 11 ; 
 
    /* Compare with the treshold */ 
    if ( Acc0 > Acc1 ) 
        VadState = 0 ; 
 
    /* Do the various counters */ 
    if ( VadState ) { 
        VadStat.Vcnt ++ ; 
        VadStat.Hcnt ++ ; 
    } 
    else { 
        VadStat.Vcnt -- ; 
        if ( VadStat.Vcnt < 0 ) 
            VadStat.Vcnt = 0 ; 
    } 
 
    if ( VadStat.Vcnt >= 2 ) { 
        VadStat.Hcnt = 6 ; 
        if ( VadStat.Vcnt >= 3 ) 
            VadStat.Vcnt = 3 ; 
    } 
 
    if ( VadStat.Hcnt ) { 
        VadState = 1 ; 
        if ( VadStat.Vcnt == 0 ) 
            VadStat.Hcnt -- ; 
    } 
 
    /* Update Periodicy detector */ 
    VadStat.Polp[0] = VadStat.Polp[2] ; 
    VadStat.Polp[1] = VadStat.Polp[3] ; 
 
    return VadState ; 
}