pitch_fr.cpp

实现3GPP的GSM中AMR语音的CODECS。

        /* Normalize correlation = correlation * (1/sqrt(energy)) */

        s = Mpy_32(corr_h, corr_l, norm_h, norm_l, pOverflow);

        corr_norm[i] = (Word16) s ;

        /* modify the filtered excitation excf[] for the next iteration */
        if (i != t_max)
        {
            k--;
            temp = exc[k];
            p_s_excf = &s_excf[L_subfr - 1];
            p_h = &h[L_subfr - 1];

            p_excf = &s_excf[L_subfr - 2];
            for (j = (L_subfr - 1) >> 1; j != 0; j--)
            {
                s = ((Word32) temp * *(p_h--)) >> h_fac;
                *(p_s_excf--) = (Word16) s  + *(p_excf--);
                s = ((Word32) temp * *(p_h--)) >> h_fac;
                *(p_s_excf--) = (Word16) s  + *(p_excf--);
            }

            s = ((Word32) temp * *(p_h)) >> h_fac;
            *(p_s_excf--) = (Word16) s  + *(p_excf);

            *(p_s_excf) = temp >> scaling;
        }

    }
    return;
}

/****************************************************************************/


/*
------------------------------------------------------------------------------
 FUNCTION NAME: searchFrac
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    lag = pointer to integer pitch of type Word16
    frac = pointer to starting point of search fractional pitch of type Word16
    last_frac = endpoint of search  of type Word16
    corr[] = pointer to normalized correlation of type Word16
    flag3 = subsample resolution (3: =1 / 6: =0) of type Word16

 Outputs:
    None

 Returns:
    None

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

   FUNCTION:   searchFrac()

   PURPOSE: Find fractional pitch

   DESCRIPTION:
      The function interpolates the normalized correlation at the
      fractional positions around lag T0. The position at which the
      interpolation function reaches its maximum is the fractional pitch.
      Starting point of the search is frac, end point is last_frac.
      frac is overwritten with the fractional pitch.

------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 pitch_fr.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

static void searchFrac (
    Word16 *lag,       // i/o : integer pitch
    Word16 *frac,      // i/o : start point of search -
                               fractional pitch
    Word16 last_frac,  // i   : endpoint of search
    Word16 corr[],     // i   : normalized correlation
    Word16 flag3       // i   : subsample resolution
                                (3: =1 / 6: =0)
)
{
    Word16 i;
    Word16 max;
    Word16 corr_int;

    // Test the fractions around T0 and choose the one which maximizes
    // the interpolated normalized correlation.

    max = Interpol_3or6 (&corr[*lag], *frac, flag3); // function result

    for (i = add (*frac, 1); i <= last_frac; i++) {
        corr_int = Interpol_3or6 (&corr[*lag], i, flag3);
        if (sub (corr_int, max) > 0) {
            max = corr_int;
            *frac = i;
        }
    }

    if (flag3 == 0) {
        // Limit the fraction value in the interval [-2,-1,0,1,2,3]

        if (sub (*frac, -3) == 0) {
            *frac = 3;
            *lag = sub (*lag, 1);
        }
    }
    else {
        // limit the fraction value between -1 and 1

        if (sub (*frac, -2) == 0) {
            *frac = 1;
            *lag = sub (*lag, 1);
        }
        if (sub (*frac, 2) == 0) {
            *frac = -1;
            *lag = add (*lag, 1);
        }
    }
}

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

------------------------------------------------------------------------------
*/

static void searchFrac(
    Word16 *lag,       /* i/o : integer pitch           */
    Word16 *frac,      /* i/o : start point of search -
                                fractional pitch        */
    Word16 last_frac,  /* i   : endpoint of search      */
    Word16 corr[],     /* i   : normalized correlation  */
    Word16 flag3,      /* i   : subsample resolution
                                (3: =1 / 6: =0)         */
    Flag   *pOverflow
)
{
    Word16 i;
    Word16 max;
    Word16 corr_int;

    /* Test the fractions around T0 and choose the one which maximizes   */
    /* the interpolated normalized correlation.                          */

    max = Interpol_3or6(&corr[*lag], *frac, flag3, pOverflow);
    /* function result */

    for (i = *frac + 1; i <= last_frac; i++)
    {
        corr_int = Interpol_3or6(&corr[*lag], i, flag3, pOverflow);
        if (corr_int > max)
        {
            max = corr_int;
            *frac = i;
        }
    }

    if (flag3 == 0)
    {
        /* Limit the fraction value in the interval [-2,-1,0,1,2,3] */

        if (*frac == -3)
        {
            *frac = 3;
            (*lag)--;
        }
    }
    else
    {
        /* limit the fraction value between -1 and 1 */

        if (*frac == -2)
        {
            *frac = 1;
            (*lag)--;
        }
        if (*frac == 2)
        {
            *frac = -1;
            (*lag)++;
        }
    }
}

/****************************************************************************/


/*
------------------------------------------------------------------------------
 FUNCTION NAME: getRange
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    T0 = integer pitch of type Word16
    delta_low = search start offset of type Word16
    delta_range = search range of type Word16
    pitmin = minimum pitch of type Word16
    pitmax = maximum pitch of type Word16
    t0_min = search range minimum of type Word16
    t0_max = search range maximum of type Word16

 Outputs:
    pOverflow = 1 if the math functions called result in overflow else zero.

 Returns:
    None

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

   FUNCTION:   getRange()

   PURPOSE: Sets range around open-loop pitch or integer pitch of last subframe

   DESCRIPTION:
      Takes integer pitch T0 and calculates a range around it with
        t0_min = T0-delta_low  and t0_max = (T0-delta_low) + delta_range
      t0_min and t0_max are bounded by pitmin and pitmax
------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 pitch_fr.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

static void getRange (
    Word16 T0,           // i : integer pitch
    Word16 delta_low,    // i : search start offset
    Word16 delta_range,  // i : search range
    Word16 pitmin,       // i : minimum pitch
    Word16 pitmax,       // i : maximum pitch
    Word16 *t0_min,      // o : search range minimum
    Word16 *t0_max)      // o : search range maximum
{
    *t0_min = sub(T0, delta_low);
    if (sub(*t0_min, pitmin) < 0) {
        *t0_min = pitmin;
    }
    *t0_max = add(*t0_min, delta_range);
    if (sub(*t0_max, pitmax) > 0) {
        *t0_max = pitmax;
        *t0_min = sub(*t0_max, delta_range);
    }
}

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

------------------------------------------------------------------------------
*/
static void getRange(
    Word16 T0,           /* i : integer pitch          */
    Word16 delta_low,    /* i : search start offset    */
    Word16 delta_range,  /* i : search range           */
    Word16 pitmin,       /* i : minimum pitch          */
    Word16 pitmax,       /* i : maximum pitch          */
    Word16 *t0_min,      /* o : search range minimum   */
    Word16 *t0_max,      /* o : search range maximum   */
    Flag   *pOverflow)
{

    Word16 temp;
    OSCL_UNUSED_ARG(pOverflow);

    temp = *t0_min;
    temp = T0 - delta_low;
    if (temp < pitmin)
    {
        temp = pitmin;
    }
    *t0_min = temp;

    temp +=  delta_range;
    if (temp > pitmax)
    {
        temp = pitmax;
        *t0_min = pitmax - delta_range;
    }
    *t0_max = temp;

}


/****************************************************************************/


/*
------------------------------------------------------------------------------
 FUNCTION NAME: Pitch_fr_init
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    state = pointer to a pointer of structure type Pitch_fr_State.

 Outputs:
    None

 Returns:
    Returns a zero if successful and -1 if not successful.

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

  Function:   Pitch_fr_init
  Purpose:    Allocates state memory and initializes state memory

------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 pitch_fr.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

int Pitch_fr_init (Pitch_frState **state)
{
    Pitch_frState* s;

    if (state == (Pitch_frState **) NULL){
        // fprintf(stderr, "Pitch_fr_init: invalid parameter\n");
        return -1;
    }
    *state = NULL;

    // allocate memory
    if ((s= (Pitch_frState *) malloc(sizeof(Pitch_frState))) == NULL){
        // fprintf(stderr, "Pitch_fr_init: can not malloc state structure\n");