pitch_fr.cpp

实现3GPP的GSM中AMR语音的CODECS。

        return -1;
    }

    Pitch_fr_reset(s);
    *state = s;

    return 0;
}

------------------------------------------------------------------------------
 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]

------------------------------------------------------------------------------
*/
Word16 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 *) oscl_malloc(sizeof(Pitch_frState))) == NULL)
    {
        /* fprintf(stderr, "Pitch_fr_init: can not malloc state structure\n"); */
        return -1;
    }

    Pitch_fr_reset(s);
    *state = s;

    return 0;
}


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


/*
------------------------------------------------------------------------------
 FUNCTION NAME: Pitch_fr_reset
------------------------------------------------------------------------------
 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_reset
  Purpose:    Initializes state memory to zero

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

 None

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

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

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

int Pitch_fr_reset (Pitch_frState *state)
{

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

    state->T0_prev_subframe = 0;

    return 0;
}

------------------------------------------------------------------------------
 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]

------------------------------------------------------------------------------
*/
Word16 Pitch_fr_reset(Pitch_frState *state)
{

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

    state->T0_prev_subframe = 0;

    return 0;
}


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


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

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

 Outputs:
    None

 Returns:
    None

 Global Variables Used:
    None

 Local Variables Needed:
    None

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

  Function:   Pitch_fr_exit
  Purpose:    The memory for state is freed.

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

 None

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

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

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

void Pitch_fr_exit (Pitch_frState **state)
{
    if (state == NULL || *state == NULL)
        return;

    // deallocate memory
    free(*state);
    *state = NULL;

    return;
}

------------------------------------------------------------------------------
 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]

------------------------------------------------------------------------------
*/
void Pitch_fr_exit(Pitch_frState **state)
{
    if (state == NULL || *state == NULL)
        return;

    /* deallocate memory */
    oscl_free(*state);
    *state = NULL;

    return;
}

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


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

 Inputs:
    st = pointer to stat structure of type Pitch_frState
    mode = codec mode of type enum Mode
    T_op[] = pointer to open loop pitch lags of type Word16
    exc[] = pointer to excitation buffer of type Word16
    xn[] = pointer to target vector of type Word16
    h[] = pointer to impulse response of synthesis and weighting filters
          of type Word16
    L_subfr = length of subframe of type Word16
    i_subfr = subframe offset of type Word16

 Outputs:
    pit_frac = pointer to pitch period (fractional) of type Word16
    resu3 = pointer to subsample resolution of type Word16
    ana_index = pointer to index of encoding of type Word16

 Returns:
    None

 Global Variables Used:
    None

 Local Variables Needed:
    None

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

   FUNCTION:   Pitch_fr()

   PURPOSE: Find the pitch period with 1/3 or 1/6 subsample resolution
            (closed loop).

   DESCRIPTION:
         - find the normalized correlation between the target and filtered
           past excitation in the search range.
         - select the delay with maximum normalized correlation.
         - interpolate the normalized correlation at fractions -3/6 to 3/6
           with step 1/6 around the chosen delay.
         - The fraction which gives the maximum interpolated value is chosen.

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

 None

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

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

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

Word16 Pitch_fr (        // o   : pitch period (integer)
    Pitch_frState *st,   // i/o : State struct
    enum Mode mode,      // i   : codec mode
    Word16 T_op[],       // i   : open loop pitch lags
    Word16 exc[],        // i   : excitation buffer                      Q0
    Word16 xn[],         // i   : target vector                          Q0
    Word16 h[],          // i   : impulse response of synthesis and
                                  weighting filters                     Q12
    Word16 L_subfr,      // i   : Length of subframe
    Word16 i_subfr,      // i   : subframe offset
    Word16 *pit_frac,    // o   : pitch period (fractional)
    Word16 *resu3,       // o   : subsample resolution 1/3 (=1) or 1/6 (=0)
    Word16 *ana_index    // o   : index of encoding
)
{
    Word16 i;
    Word16 t_min, t_max;
    Word16 t0_min, t0_max;
    Word16 max, lag, frac;
    Word16 tmp_lag;
    Word16 *corr;
    Word16 corr_v[40];    // Total length = t0_max-t0_min+1+2*L_INTER_SRCH

    Word16 max_frac_lag;
    Word16 flag3, flag4;
    Word16 last_frac;
    Word16 delta_int_low, delta_int_range;
    Word16 delta_frc_low, delta_frc_range;
    Word16 pit_min;
    Word16 frame_offset;
    Word16 delta_search;

    //-----------------------------------------------------------------------
     //                      set mode specific variables
     //----------------------------------------------------------------------

    max_frac_lag    = mode_dep_parm[mode].max_frac_lag;
    flag3           = mode_dep_parm[mode].flag3;
    frac            = mode_dep_parm[mode].first_frac;
    last_frac       = mode_dep_parm[mode].last_frac;
    delta_int_low   = mode_dep_parm[mode].delta_int_low;
    delta_int_range = mode_dep_parm[mode].delta_int_range;

    delta_frc_low   = mode_dep_parm[mode].delta_frc_low;
    delta_frc_range = mode_dep_parm[mode].delta_frc_range;
    pit_min         = mode_dep_parm[mode].pit_min;

    //-----------------------------------------------------------------------
    //                 decide upon full or differential search
    //-----------------------------------------------------------------------

    delta_search = 1;

    if ((i_subfr == 0) || (sub(i_subfr,L_FRAME_BY2) == 0)) {

        // Subframe 1 and 3

        if (((sub((Word16)mode, (Word16)MR475) != 0) && (sub((Word16)mode,
            (Word16)MR515) != 0)) ||
            (sub(i_subfr,L_FRAME_BY2) != 0)) {

            // set t0_min, t0_max for full search
            // this is *not* done for mode MR475, MR515 in subframe 3

            delta_search = 0; // no differential search

            // calculate index into T_op which contains the open-loop
            // pitch estimations for the 2 big subframes

            frame_offset = 1;
            if (i_subfr == 0)
                frame_offset = 0;

            // get T_op from the corresponding half frame and
            // set t0_min, t0_max

            getRange (T_op[frame_offset], delta_int_low, delta_int_range,
                      pit_min, PIT_MAX, &t0_min, &t0_max);
        }
        else {

            // mode MR475, MR515 and 3. Subframe: delta search as well
            getRange (st->T0_prev_subframe, delta_frc_low, delta_frc_range,
                      pit_min, PIT_MAX, &t0_min, &t0_max);
        }
    }
    else {

        // for Subframe 2 and 4
        // get range around T0 of previous subframe for delta search

        getRange (st->T0_prev_subframe, delta_frc_low, delta_frc_range,
                  pit_min, PIT_MAX, &t0_min, &t0_max);
    }

    //-----------------------------------------------------------------------
                Find interval to compute normalized correlation
     -----------------------------------------------------------------------

    t_min = sub (t0_min, L_INTER_SRCH);
    t_max = add (t0_max, L_INTER_SRCH);