dec_amr.cpp

实现3GPP的GSM中AMR语音的CODECS。

         *-------------------------------------------------------*/
        if ((mode == MR475) || (mode == MR515))
        {   /* MR475, MR515 */
            index = *parm++;        /* index of position */
            i = *parm++;            /* signs             */

            decode_2i40_9bits(subfrNr, i, index, code, pOverflow);

            L_temp = (Word32)st->sharp << 1;
            if (L_temp != (Word32)((Word16) L_temp))
            {
                pit_sharp = (st->sharp > 0) ? MAX_16 : MIN_16;
            }
            else
            {
                pit_sharp = (Word16) L_temp;
            }
        }
        else if (mode == MR59)
        {   /* MR59 */
            index = *parm++;        /* index of position */
            i = *parm++;            /* signs             */

            decode_2i40_11bits(i, index, code);

            L_temp = (Word32)st->sharp << 1;
            if (L_temp != (Word32)((Word16) L_temp))
            {
                pit_sharp = (st->sharp > 0) ? MAX_16 : MIN_16;
            }
            else
            {
                pit_sharp = (Word16) L_temp;
            }
        }
        else if (mode == MR67)
        {   /* MR67 */
            index = *parm++;        /* index of position */
            i = *parm++;            /* signs             */

            decode_3i40_14bits(i, index, code);

            L_temp = (Word32)st->sharp << 1;
            if (L_temp != (Word32)((Word16) L_temp))
            {
                pit_sharp = (st->sharp > 0) ? MAX_16 : MIN_16;
            }
            else
            {
                pit_sharp = (Word16) L_temp;
            }
        }
        else if (mode <= MR795)
        {   /* MR74, MR795 */
            index = *parm++;        /* index of position */
            i = *parm++;            /* signs             */

            decode_4i40_17bits(i, index, code);

            L_temp = (Word32)st->sharp << 1;
            if (L_temp != (Word32)((Word16) L_temp))
            {
                pit_sharp = (st->sharp > 0) ? MAX_16 : MIN_16;
            }
            else
            {
                pit_sharp = (Word16) L_temp;
            }
        }
        else if (mode == MR102)
        {  /* MR102 */
            dec_8i40_31bits(parm, code, pOverflow);
            parm += 7;

            L_temp = (Word32)st->sharp << 1;
            if (L_temp != (Word32)((Word16) L_temp))
            {
                pit_sharp = (st->sharp > 0) ? MAX_16 : MIN_16;
            }
            else
            {
                pit_sharp = (Word16) L_temp;
            }
        }
        else
        {  /* MR122 */
            index = *parm++;

            if (bfi != 0)
            {
                ec_gain_pitch(
                    &(st->ec_gain_p_st),
                    st->state,
                    &gain_pit,
                    pOverflow);
            }
            else
            {
                gain_pit = d_gain_pitch(mode, index);
            }
            ec_gain_pitch_update(
                &(st->ec_gain_p_st),
                bfi,
                st->prev_bf,
                &gain_pit,
                pOverflow);


            dec_10i40_35bits(parm, code);
            parm += 10;

            /* pit_sharp = gain_pit;                   */
            /* if (pit_sharp > 1.0) pit_sharp = 1.0;   */

            L_temp = (Word32)gain_pit << 1;
            if (L_temp != (Word32)((Word16) L_temp))
            {
                pit_sharp = (gain_pit > 0) ? MAX_16 : MIN_16;
            }
            else
            {
                pit_sharp = (Word16) L_temp;
            }
        }
        /*-------------------------------------------------------*
         * - Add the pitch contribution to code[].               *
         *-------------------------------------------------------*/
        for (i = T0; i < L_SUBFR; i++)
        {
            temp = mult(*(code + i - T0), pit_sharp, pOverflow);
            *(code + i) = add(*(code + i), temp, pOverflow);

        }

        /*------------------------------------------------------------*
         * - Decode codebook gain (MR122) or both pitch               *
         *   gain and codebook gain (all others)                      *
         * - Update pitch sharpening "sharp" with quantized gain_pit  *
         *------------------------------------------------------------*/
        if (mode == MR475)
        {
            /* read and decode pitch and code gain */

            if (evenSubfr != 0)
            {
                index_mr475 = *parm++;         /* index of gain(s) */
            }

            if (bfi == 0)
            {
                Dec_gain(
                    &(st->pred_state),
                    mode,
                    index_mr475,
                    code,
                    evenSubfr,
                    &gain_pit,
                    &gain_code,
                    pOverflow);
            }
            else
            {
                ec_gain_pitch(
                    &(st->ec_gain_p_st),
                    st->state,
                    &gain_pit,
                    pOverflow);

                ec_gain_code(
                    &(st->ec_gain_c_st),
                    &(st->pred_state),
                    st->state,
                    &gain_code,
                    pOverflow);
            }
            ec_gain_pitch_update(
                &st->ec_gain_p_st,
                bfi,
                st->prev_bf,
                &gain_pit,
                pOverflow);

            ec_gain_code_update(
                &st->ec_gain_c_st,
                bfi,
                st->prev_bf,
                &gain_code,
                pOverflow);

            pit_sharp = gain_pit;

            if (pit_sharp > SHARPMAX)
            {
                pit_sharp = SHARPMAX;
            }

        }
        else if ((mode <= MR74) || (mode == MR102))
        {
            /* read and decode pitch and code gain */
            index = *parm++;                 /* index of gain(s) */

            if (bfi == 0)
            {
                Dec_gain(
                    &(st->pred_state),
                    mode,
                    index,
                    code,
                    evenSubfr,
                    &gain_pit,
                    &gain_code,
                    pOverflow);
            }
            else
            {
                ec_gain_pitch(
                    &(st->ec_gain_p_st),
                    st->state,
                    &gain_pit,
                    pOverflow);

                ec_gain_code(
                    &(st->ec_gain_c_st),
                    &(st->pred_state),
                    st->state,
                    &gain_code,
                    pOverflow);
            }

            ec_gain_pitch_update(
                &(st->ec_gain_p_st),
                bfi,
                st->prev_bf,
                &gain_pit,
                pOverflow);

            ec_gain_code_update(
                &(st->ec_gain_c_st),
                bfi,
                st->prev_bf,
                &gain_code,
                pOverflow);

            pit_sharp = gain_pit;

            if (pit_sharp > SHARPMAX)
            {
                pit_sharp = SHARPMAX;
            }

            if (mode == MR102)
            {
                if (st->old_T0 > (L_SUBFR + 5))
                {
                    if (pit_sharp < 0)
                    {
                        pit_sharp = ~((~pit_sharp) >> 2);
                    }
                    else
                    {
                        pit_sharp = pit_sharp >> 2;
                    }
                }
            }
        }
        else
        {
            /* read and decode pitch gain */
            index = *parm++;                 /* index of gain(s) */

            if (mode == MR795)
            {
                /* decode pitch gain */
                if (bfi != 0)
                {
                    ec_gain_pitch(
                        &(st->ec_gain_p_st),
                        st->state,
                        &gain_pit,
                        pOverflow);
                }
                else
                {
                    gain_pit = d_gain_pitch(mode, index);
                }
                ec_gain_pitch_update(
                    &(st->ec_gain_p_st),
                    bfi,
                    st->prev_bf,
                    &gain_pit,
                    pOverflow);

                /* read and decode code gain */
                index = *parm++;

                if (bfi == 0)
                {
                    d_gain_code(
                        &(st->pred_state),
                        mode,
                        index,
                        code,
                        &gain_code,
                        pOverflow);
                }
                else
                {
                    ec_gain_code(
                        &(st->ec_gain_c_st),
                        &(st->pred_state),
                        st->state,
                        &gain_code,
                        pOverflow);
                }

                ec_gain_code_update(
                    &(st->ec_gain_c_st),
                    bfi,
                    st->prev_bf,
                    &gain_code,
                    pOverflow);

                pit_sharp = gain_pit;

                if (pit_sharp > SHARPMAX)
                {
                    pit_sharp = SHARPMAX;
                }
            }
            else
            { /* MR122 */

                if (bfi == 0)
                {
                    d_gain_code(
                        &(st->pred_state),
                        mode,
                        index,
                        code,
                        &gain_code,
                        pOverflow);
                }
                else
                {
                    ec_gain_code(
                        &(st->ec_gain_c_st),
                        &(st->pred_state),
                        st->state,
                        &gain_code,
                        pOverflow);
                }

                ec_gain_code_update(
                    &(st->ec_gain_c_st),
                    bfi,
                    st->prev_bf,
                    &gain_code,
                    pOverflow);

                pit_sharp = gain_pit;
            }
        }

        /* store pitch sharpening for next subframe             */
        /* (for modes which use the previous pitch gain for     */
        /* pitch sharpening in the search phase)                */
        /* do not update sharpening in even subframes for MR475 */
        if ((mode != MR475) || (evenSubfr == 0))
        {
            st->sharp = gain_pit;

            if (st->sharp > SHARPMAX)
            {
                st->sharp = SHARPMAX;
            }
        }

        pit_sharp = shl(pit_sharp, 1, pOverflow);

        if (pit_sharp > 16384)
        {
            for (i = 0; i < L_SUBFR; i++)
            {
                temp = mult(st->exc[i], pit_sharp, pOverflow);
                L_temp = L_mult(temp, gain_pit, pOverflow);

                if (mode == MR122)
                {
                    if (L_temp < 0)
                    {
                        L_temp = ~((~L_temp) >> 1);
                    }
                    else
                    {
                        L_temp = L_temp >> 1;
                    }
                }
                *(excp + i) = pv_round(L_temp, pOverflow);
            }
        }

        /*-------------------------------------------------------*
         * - Store list of LTP gains needed in the source        *
         *   characteristic detector (SCD)                       *
         *-------------------------------------------------------*/

        if (bfi == 0)
        {
            for (i = 0; i < 8; i++)
            {
                st->ltpGainHistory[i] = st->ltpGainHistory[i+1];
            }
            st->ltpGainHistory[8] = gain_pit;
        }

        /*-------------------------------------------------------*
        * - Limit gain_pit if in background noise and BFI       *
        *   for MR475, MR515, MR59                              *
        *-------------------------------------------------------*/


        if ((st->prev_bf != 0 || bfi != 0) && st->inBackgroundNoise != 0 &&
                ((mode == MR475) || (mode == MR515) || (mode == MR59)))
        {

            if (gain_pit > 12288)    /* if (gain_pit > 0.75) in Q14*/
            {