sbr_hfgen.c

mpeg4 video codec mpeg4 video codec

        (QMF_RE(buffer[offset-1][bd]) * QMF_RE(buffer[offset-2][bd]) + QMF_IM(buffer[offset-1][bd]) * QMF_IM(buffer[offset-2][bd]));
    IM(ac->r12) = r01i -
        (QMF_IM(buffer[len+offset-1][bd]) * QMF_RE(buffer[len+offset-2][bd]) - QMF_RE(buffer[len+offset-1][bd]) * QMF_IM(buffer[len+offset-2][bd])) +
        (QMF_IM(buffer[offset-1][bd]) * QMF_RE(buffer[offset-2][bd]) - QMF_RE(buffer[offset-1][bd]) * QMF_IM(buffer[offset-2][bd]));
    RE(ac->r22) = r11r -
        (QMF_RE(buffer[len+offset-2][bd]) * QMF_RE(buffer[len+offset-2][bd]) + QMF_IM(buffer[len+offset-2][bd]) * QMF_IM(buffer[len+offset-2][bd])) +
        (QMF_RE(buffer[offset-2][bd]) * QMF_RE(buffer[offset-2][bd]) + QMF_IM(buffer[offset-2][bd]) * QMF_IM(buffer[offset-2][bd]));

    ac->det = RE(ac->r11) * RE(ac->r22) - rel * (RE(ac->r12) * RE(ac->r12) + IM(ac->r12) * IM(ac->r12));
}
#endif

/* calculate linear prediction coefficients using the covariance method */
static void calc_prediction_coef(sbr_info *sbr, qmf_t Xlow[MAX_NTSRHFG][32],
                                 complex_t *alpha_0, complex_t *alpha_1
#ifdef SBR_LOW_POWER
                                 , real_t *rxx
#endif
                                 )
{
    uint8_t k;
    real_t tmp;
    acorr_coef ac;

    for (k = 1; k < sbr->f_master[0]; k++)
    {
        auto_correlation(sbr, &ac, Xlow, k, sbr->numTimeSlotsRate + 6);

#ifdef SBR_LOW_POWER
        if (ac.det == 0)
        {
            RE(alpha_1[k]) = 0;
        } else {
            tmp = MUL_R(RE(ac.r01), RE(ac.r12)) - MUL_R(RE(ac.r02), RE(ac.r11));
            RE(alpha_1[k]) = SBR_DIV(tmp, ac.det);
        }

        if (RE(ac.r11) == 0)
        {
            RE(alpha_0[k]) = 0;
        } else {
            tmp = RE(ac.r01) + MUL_R(RE(alpha_1[k]), RE(ac.r12));
            RE(alpha_0[k]) = -SBR_DIV(tmp, RE(ac.r11));
        }

        if ((RE(alpha_0[k]) >= REAL_CONST(4)) || (RE(alpha_1[k]) >= REAL_CONST(4)))
        {
            RE(alpha_0[k]) = REAL_CONST(0);
            RE(alpha_1[k]) = REAL_CONST(0);
        }

        /* reflection coefficient */
        if (RE(ac.r11) == 0)
        {
            rxx[k] = REAL_CONST(0.0);
        } else {
            rxx[k] = -SBR_DIV(RE(ac.r01), RE(ac.r11));
            if (rxx[k] > REAL_CONST(1.0)) rxx[k] = REAL_CONST(1.0);
            if (rxx[k] < REAL_CONST(-1.0)) rxx[k] = REAL_CONST(-1.0);
        }
#else
        if (ac.det == 0)
        {
            RE(alpha_1[k]) = 0;
            IM(alpha_1[k]) = 0;
        } else {
            tmp = REAL_CONST(1.0) / ac.det;
            RE(alpha_1[k]) = (RE(ac.r01) * RE(ac.r12) - IM(ac.r01) * IM(ac.r12) - RE(ac.r02) * RE(ac.r11)) * tmp;
            IM(alpha_1[k]) = (IM(ac.r01) * RE(ac.r12) + RE(ac.r01) * IM(ac.r12) - IM(ac.r02) * RE(ac.r11)) * tmp;
        }

        if (RE(ac.r11) == 0)
        {
            RE(alpha_0[k]) = 0;
            IM(alpha_0[k]) = 0;
        } else {
            tmp = 1.0f / RE(ac.r11);
            RE(alpha_0[k]) = -(RE(ac.r01) + RE(alpha_1[k]) * RE(ac.r12) + IM(alpha_1[k]) * IM(ac.r12)) * tmp;
            IM(alpha_0[k]) = -(IM(ac.r01) + IM(alpha_1[k]) * RE(ac.r12) - RE(alpha_1[k]) * IM(ac.r12)) * tmp;
        }

        if ((RE(alpha_0[k])*RE(alpha_0[k]) + IM(alpha_0[k])*IM(alpha_0[k]) >= 16) ||
            (RE(alpha_1[k])*RE(alpha_1[k]) + IM(alpha_1[k])*IM(alpha_1[k]) >= 16))
        {
            RE(alpha_0[k]) = 0;
            IM(alpha_0[k]) = 0;
            RE(alpha_1[k]) = 0;
            IM(alpha_1[k]) = 0;
        }
#endif
    }
}

#ifdef SBR_LOW_POWER
static void calc_aliasing_degree(sbr_info *sbr, real_t *rxx, real_t *deg)
{
    uint8_t k;

    rxx[0] = REAL_CONST(0.0);
    deg[1] = REAL_CONST(0.0);

    for (k = 2; k < sbr->k0; k++)
    {
        deg[k] = 0.0;

        if ((k % 2 == 0) && (rxx[k] < REAL_CONST(0.0)))
        {
            if (rxx[k-1] < 0.0)
            {
                deg[k] = REAL_CONST(1.0);

                if (rxx[k-2] > REAL_CONST(0.0))
                {
                    deg[k-1] = REAL_CONST(1.0) - MUL_R(rxx[k-1], rxx[k-1]);
                }
            } else if (rxx[k-2] > REAL_CONST(0.0)) {
                deg[k]   = REAL_CONST(1.0) - MUL_R(rxx[k-1], rxx[k-1]);
            }
        }

        if ((k % 2 == 1) && (rxx[k] > REAL_CONST(0.0)))
        {
            if (rxx[k-1] > REAL_CONST(0.0))
            {
                deg[k] = REAL_CONST(1.0);

                if (rxx[k-2] < REAL_CONST(0.0))
                {
                    deg[k-1] = REAL_CONST(1.0) - MUL_R(rxx[k-1], rxx[k-1]);
                }
            } else if (rxx[k-2] < REAL_CONST(0.0)) {
                deg[k] = REAL_CONST(1.0) - MUL_R(rxx[k-1], rxx[k-1]);
            }
        }
    }
}
#endif

/* FIXED POINT: bwArray = COEF */
static real_t mapNewBw(uint8_t invf_mode, uint8_t invf_mode_prev)
{
    switch (invf_mode)
    {
    case 1: /* LOW */
        if (invf_mode_prev == 0) /* NONE */
            return COEF_CONST(0.6);
        else
            return COEF_CONST(0.75);

    case 2: /* MID */
        return COEF_CONST(0.9);

    case 3: /* HIGH */
        return COEF_CONST(0.98);

    default: /* NONE */
        if (invf_mode_prev == 1) /* LOW */
            return COEF_CONST(0.6);
        else
            return COEF_CONST(0.0);
    }
}

/* FIXED POINT: bwArray = COEF */
static void calc_chirp_factors(sbr_info *sbr, uint8_t ch)
{
    uint8_t i;

    for (i = 0; i < sbr->N_Q; i++)
    {
        sbr->bwArray[ch][i] = mapNewBw(sbr->bs_invf_mode[ch][i], sbr->bs_invf_mode_prev[ch][i]);

        if (sbr->bwArray[ch][i] < sbr->bwArray_prev[ch][i])
            sbr->bwArray[ch][i] = MUL_F(sbr->bwArray[ch][i], FRAC_CONST(0.75)) + MUL_F(sbr->bwArray_prev[ch][i], FRAC_CONST(0.25));
        else
            sbr->bwArray[ch][i] = MUL_F(sbr->bwArray[ch][i], FRAC_CONST(0.90625)) + MUL_F(sbr->bwArray_prev[ch][i], FRAC_CONST(0.09375));

        if (sbr->bwArray[ch][i] < COEF_CONST(0.015625))
            sbr->bwArray[ch][i] = COEF_CONST(0.0);

        if (sbr->bwArray[ch][i] >= COEF_CONST(0.99609375))
            sbr->bwArray[ch][i] = COEF_CONST(0.99609375);

        sbr->bwArray_prev[ch][i] = sbr->bwArray[ch][i];
        sbr->bs_invf_mode_prev[ch][i] = sbr->bs_invf_mode[ch][i];
    }
}

static void patch_construction(sbr_info *sbr)
{
    uint8_t i, k;
    uint8_t odd, sb;
    uint8_t msb = sbr->k0;
    uint8_t usb = sbr->kx;
    uint8_t goalSbTab[] = { 21, 23, 43, 46, 64, 85, 93, 128, 0, 0, 0 };
    /* (uint8_t)(2.048e6/sbr->sample_rate + 0.5); */
    uint8_t goalSb = goalSbTab[get_sr_index(sbr->sample_rate)];

    sbr->noPatches = 0;

    if (goalSb < (sbr->kx + sbr->M))
    {
        for (i = 0, k = 0; sbr->f_master[i] < goalSb; i++)
            k = i+1;
    } else {
        k = sbr->N_master;
    }

    do
    {
        uint8_t j = k + 1;

        do
        {
            j--;

            sb = sbr->f_master[j];
            odd = (sb - 2 + sbr->k0) % 2;
        } while (sb > (sbr->k0 - 1 + msb - odd));

        sbr->patchNoSubbands[sbr->noPatches] = max(sb - usb, 0);
        sbr->patchStartSubband[sbr->noPatches] = sbr->k0 - odd -
            sbr->patchNoSubbands[sbr->noPatches];

        if (sbr->patchNoSubbands[sbr->noPatches] > 0)
        {
            usb = sb;
            msb = sb;
            sbr->noPatches++;
        } else {
            msb = sbr->kx;
        }

        if (sbr->f_master[k] - sb < 3)
            k = sbr->N_master;
    } while (sb != (sbr->kx + sbr->M));

    if ((sbr->patchNoSubbands[sbr->noPatches-1] < 3) && (sbr->noPatches > 1))
    {
        sbr->noPatches--;
    }

    sbr->noPatches = min(sbr->noPatches, 5);
}

#endif