pvamrwbdecoder.cpp

实现3GPP的GSM中AMR语音的CODECS。

    {
        st->state >>=  1;
    }

    /* If this frame is the first speech frame after CNI period,
     * set the BFH state machine to an appropriate state depending
     * on whether there was DTX muting before start of speech or not
     * If there was DTX muting, the first speech frame is muted.
     * If there was no DTX muting, the first speech frame is not
     * muted. The BFH state machine starts from state 5, however, to
     * keep the audible noise resulting from a SID frame which is
     * erroneously interpreted as a good speech frame as small as
     * possible (the decoder output in this case is quickly muted)
     */

    if (st->dtx_decSt.dtxGlobalState == DTX)
    {
        st->state = 5;
        st->prev_bfi = 0;
    }
    else if (st->dtx_decSt.dtxGlobalState == DTX_MUTE)
    {
        st->state = 5;
        st->prev_bfi = 1;
    }

    if (newDTXState == SPEECH)
    {
        vad_flag = Serial_parm_1bit(&prms);

        if (bfi == 0)
        {
            if (vad_flag == 0)
            {
                st->vad_hist = add_int16(st->vad_hist, 1);
            }
            else
            {
                st->vad_hist = 0;
            }
        }
    }
    /*
     *  DTX-CNG
     */

    if (newDTXState != SPEECH)     /* CNG mode */
    {
        /* increase slightly energy of noise below 200 Hz */

        /* Convert ISFs to the cosine domain */
        Isf_isp(isf, ispnew, M);

        Isp_Az(ispnew, Aq, M, 1);

        pv_memcpy((void *)isf_tmp, (void *)st->isfold, M*sizeof(*isf_tmp));


        for (i_subfr = 0; i_subfr < L_FRAME; i_subfr += L_SUBFR)
        {
            j = i_subfr >> 6;

            for (i = 0; i < M; i++)
            {
                L_tmp = mul_16by16_to_int32(isf_tmp[i], sub_int16(32767, interpol_frac[j]));
                L_tmp = mac_16by16_to_int32(L_tmp, isf[i], interpol_frac[j]);
                HfIsf[i] = amr_wb_round(L_tmp);
            }

            synthesis_amr_wb(Aq,
                             &exc2[i_subfr],
                             0,
                             &synth16k[i_subfr *5/4],
                             (short) 1,
                             HfIsf,
                             nb_bits,
                             newDTXState,
                             st,
                             bfi,
                             ScratchMem);
        }

        /* reset speech coder memories */
        pvDecoder_AmrWb_Reset(st, 0);

        pv_memcpy((void *)st->isfold, (void *)isf, M*sizeof(*isf));

        st->prev_bfi = bfi;
        st->dtx_decSt.dtxGlobalState = newDTXState;

        return 0;
    }
    /*
     *  ACELP
     */

    /* copy coder memory state into working space (internal memory for DSP) */

    pv_memcpy((void *)old_exc, (void *)st->old_exc, (PIT_MAX + L_INTERPOL)*sizeof(*old_exc));

    exc = old_exc + PIT_MAX + L_INTERPOL;

    /* Decode the ISFs */

    if (nb_bits > NBBITS_7k)        /* all rates but 6.6 Kbps */
    {
        ind[0] = Serial_parm(8, &prms);     /* index of 1st ISP subvector */
        ind[1] = Serial_parm(8, &prms);     /* index of 2nd ISP subvector */
        ind[2] = Serial_parm(6, &prms);     /* index of 3rd ISP subvector */
        ind[3] = Serial_parm(7, &prms);     /* index of 4th ISP subvector */
        ind[4] = Serial_parm(7, &prms);     /* index of 5th ISP subvector */
        ind[5] = Serial_parm(5, &prms);     /* index of 6th ISP subvector */
        ind[6] = Serial_parm(5, &prms);     /* index of 7th ISP subvector */

        Dpisf_2s_46b(ind, isf, st->past_isfq, st->isfold, st->isf_buf, bfi, 1);
    }
    else
    {
        ind[0] = Serial_parm(8, &prms);
        ind[1] = Serial_parm(8, &prms);
        ind[2] = Serial_parm(14, &prms);
        ind[3] = ind[2] & 0x007F;
        ind[2] >>= 7;
        ind[4] = Serial_parm(6, &prms);

        Dpisf_2s_36b(ind, isf, st->past_isfq, st->isfold, st->isf_buf, bfi, 1);
    }

    /* Convert ISFs to the cosine domain */

    Isf_isp(isf, ispnew, M);

    if (st->first_frame != 0)
    {
        st->first_frame = 0;
        pv_memcpy((void *)st->ispold, (void *)ispnew, M*sizeof(*ispnew));

    }
    /* Find the interpolated ISPs and convert to a[] for all subframes */
    interpolate_isp(st->ispold, ispnew, interpol_frac, Aq);

    /* update ispold[] for the next frame */
    pv_memcpy((void *)st->ispold, (void *)ispnew, M*sizeof(*ispnew));

    /* Check stability on isf : distance between old isf and current isf */

    L_tmp = 0;
    for (i = 0; i < M - 1; i++)
    {
        tmp = sub_int16(isf[i], st->isfold[i]);
        L_tmp = mac_16by16_to_int32(L_tmp, tmp, tmp);
    }
    tmp = extract_h(shl_int32(L_tmp, 8));
    tmp = mult_int16(tmp, 26214);                /* tmp = L_tmp*0.8/256 */

    tmp = 20480 - tmp;                 /* 1.25 - tmp */
    stab_fac = shl_int16(tmp, 1);                /* Q14 -> Q15 with saturation */

    if (stab_fac < 0)
    {
        stab_fac = 0;
    }
    pv_memcpy((void *)isf_tmp, (void *)st->isfold, M*sizeof(*isf_tmp));

    pv_memcpy((void *)st->isfold, (void *)isf, M*sizeof(*isf));

    /*
     *          Loop for every subframe in the analysis frame
     *
     * The subframe size is L_SUBFR and the loop is repeated L_FRAME/L_SUBFR
     *  times
     *     - decode the pitch delay and filter mode
     *     - decode algebraic code
     *     - decode pitch and codebook gains
     *     - find voicing factor and tilt of code for next subframe.
     *     - find the excitation and compute synthesis speech
     */

    p_Aq = Aq;                                /* pointer to interpolated LPC parameters */


    /*
     *   Sub process next 3 subframes
     */


    for (i_subfr = 0; i_subfr < L_FRAME; i_subfr += L_SUBFR)
    {
        pit_flag = i_subfr;


        if ((i_subfr == 2*L_SUBFR) && (nb_bits > NBBITS_7k))
        {
            pit_flag = 0;        /* set to 0 for 3rd subframe, <=> is not 6.6 kbps */
        }
        /*-------------------------------------------------*
         * - Decode pitch lag                              *
         * Lag indeces received also in case of BFI,       *
         * so that the parameter pointer stays in sync.    *
         *-------------------------------------------------*/

        if (pit_flag == 0)
        {

            if (nb_bits <= NBBITS_9k)
            {
                index = Serial_parm(8, &prms);

                if (index < (PIT_FR1_8b - PIT_MIN) * 2)
                {
                    T0 = PIT_MIN + (index >> 1);
                    T0_frac = sub_int16(index, shl_int16(sub_int16(T0, PIT_MIN), 1));
                    T0_frac = shl_int16(T0_frac, 1);
                }
                else
                {
                    T0 = add_int16(index, PIT_FR1_8b - ((PIT_FR1_8b - PIT_MIN) * 2));
                    T0_frac = 0;
                }
            }
            else
            {
                index = Serial_parm(9, &prms);

                if (index < (PIT_FR2 - PIT_MIN) * 4)
                {
                    T0 = PIT_MIN + (index >> 2);
                    T0_frac = sub_int16(index, shl_int16(sub_int16(T0, PIT_MIN), 2));
                }
                else if (index < (((PIT_FR2 - PIT_MIN) << 2) + ((PIT_FR1_9b - PIT_FR2) << 1)))
                {
                    index -= (PIT_FR2 - PIT_MIN) << 2;
                    T0 = PIT_FR2 + (index >> 1);
                    T0_frac = sub_int16(index, shl_int16(sub_int16(T0, PIT_FR2), 1));
                    T0_frac = shl_int16(T0_frac, 1);
                }
                else
                {
                    T0 = add_int16(index, (PIT_FR1_9b - ((PIT_FR2 - PIT_MIN) * 4) - ((PIT_FR1_9b - PIT_FR2) * 2)));
                    T0_frac = 0;
                }
            }

            /* find T0_min and T0_max for subframe 2 and 4 */

            T0_min = T0 - 8;

            if (T0_min < PIT_MIN)
            {
                T0_min = PIT_MIN;
            }
            T0_max = T0_min + 15;

            if (T0_max > PIT_MAX)
            {
                T0_max = PIT_MAX;
                T0_min = PIT_MAX - 15;
            }
        }
        else
        {                                  /* if subframe 2 or 4 */

            if (nb_bits <= NBBITS_9k)
            {
                index = Serial_parm(5, &prms);

                T0 = T0_min + (index >> 1);
                T0_frac = sub_int16(index, shl_int16(T0 - T0_min, 1));
                T0_frac = shl_int16(T0_frac, 1);
            }
            else
            {
                index = Serial_parm(6, &prms);

                T0 = T0_min + (index >> 2);
                T0_frac = sub_int16(index, shl_int16(T0 - T0_min, 2));
            }
        }

        /* check BFI after pitch lag decoding */

        if (bfi != 0)                      /* if frame erasure */
        {
            lagconceal(&(st->dec_gain[17]), st->lag_hist, &T0, &(st->old_T0), &(st->seed3), unusable_frame);
            T0_frac = 0;
        }
        /*
         *  Find the pitch gain, the interpolation filter
         *  and the adaptive codebook vector.
         */

        Pred_lt4(&exc[i_subfr], T0, T0_frac, L_SUBFR + 1);


        if (unusable_frame)
        {
            select = 1;
        }
        else
        {

            if (nb_bits <= NBBITS_9k)
            {
                select = 0;
            }
            else
            {
                select = Serial_parm_1bit(&prms);
            }
        }


        if (select == 0)
        {
            /* find pitch excitation with lp filter */
            for (i = 0; i < L_SUBFR; i++)
            {
                L_tmp  = ((int32) exc[i-1+i_subfr] + exc[i+1+i_subfr]);
                L_tmp *= 5898;
                L_tmp += ((int32) exc[i+i_subfr] * 20972);

                code[i] = amr_wb_round(L_tmp << 1);
            }
            pv_memcpy((void *)&exc[i_subfr], (void *)code, L_SUBFR*sizeof(*code));

        }
        /*
         * Decode innovative codebook.
         * Add the fixed-gain pitch contribution to code[].
         */

        if (unusable_frame != 0)
        {
            /* the innovative code doesn't need to be scaled (see Q_gain2) */
            for (i = 0; i < L_SUBFR; i++)
            {
                code[i] = noise_gen_amrwb(&(st->seed)) >> 3;
            }
        }
        else if (nb_bits <= NBBITS_7k)
        {
            ind[0] = Serial_parm(12, &prms);
            dec_acelp_2p_in_64(ind[0], code);
        }
        else if (nb_bits <= NBBITS_9k)
        {
            for (i = 0; i < 4; i++)
            {
                ind[i] = Serial_parm(5, &prms);
            }
            dec_acelp_4p_in_64(ind, 20, code);
        }
        else if (nb_bits <= NBBITS_12k)
        {
            for (i = 0; i < 4; i++)
            {
                ind[i] = Serial_parm(9, &prms);
            }
            dec_acelp_4p_in_64(ind, 36, code);
        }
        else if (nb_bits <= NBBITS_14k)
        {
            ind[0] = Serial_parm(13, &prms);
            ind[1] = Serial_parm(13, &prms);
            ind[2] = Serial_parm(9, &prms);
            ind[3] = Serial_parm(9, &prms);
            dec_acelp_4p_in_64(ind, 44, code);
        }
        else if (nb_bits <= NBBITS_16k)
        {
            for (i = 0; i < 4; i++)
            {
                ind[i] = Serial_parm(13, &prms);
            }
            dec_acelp_4p_in_64(ind, 52, code);
        }
        else if (nb_bits <= NBBITS_18k)
        {
            for (i = 0; i < 4; i++)
            {
                ind[i] = Serial_parm(2, &prms);
            }
            for (i = 4; i < 8; i++)
            {