int ff_j2k_init_component(Jpeg2000Component *comp,

                          Jpeg2000CodingStyle *codsty,

                          Jpeg2000QuantStyle *qntsty,

                          int cbps, int dx, int dy,

                          AVCodecContext *avctx)

{

    uint8_t log2_band_prec_width, log2_band_prec_height;

    int reslevelno, bandno, gbandno = 0, ret, i, j, csize = 1;



    if (ret=ff_jpeg2000_dwt_init(&comp->dwt, comp->coord, codsty->nreslevels2decode-1, codsty->transform == FF_DWT53 ? FF_DWT53 : FF_DWT97_INT))

        return ret;

    for (i = 0; i < 2; i++)

        csize *= comp->coord[i][1] - comp->coord[i][0];



    comp->data = av_malloc_array(csize, sizeof(*comp->data));

    if (!comp->data)

        return AVERROR(ENOMEM);

    comp->reslevel = av_malloc_array(codsty->nreslevels, sizeof(*comp->reslevel));

    if (!comp->reslevel)

        return AVERROR(ENOMEM);

    /* LOOP on resolution levels */

    for (reslevelno = 0; reslevelno < codsty->nreslevels; reslevelno++) {

        int declvl = codsty->nreslevels - reslevelno;    // N_L -r see  ISO/IEC 15444-1:2002 B.5

        Jpeg2000ResLevel *reslevel = comp->reslevel + reslevelno;



        /* Compute borders for each resolution level.

         * Computation of trx_0, trx_1, try_0 and try_1.

         * see ISO/IEC 15444-1:2002 eq. B.5 and B-14 */

        for (i = 0; i < 2; i++)

            for (j = 0; j < 2; j++)

                reslevel->coord[i][j] =

                    ff_jpeg2000_ceildivpow2(comp->coord_o[i][j], declvl - 1);

        // update precincts size: 2^n value

        reslevel->log2_prec_width  = codsty->log2_prec_widths[reslevelno];

        reslevel->log2_prec_height = codsty->log2_prec_heights[reslevelno];



        /* Number of bands for each resolution level */

        if (reslevelno == 0)

            reslevel->nbands = 1;

        else

            reslevel->nbands = 3;



        /* Number of precincts wich span the tile for resolution level reslevelno

         * see B.6 in ISO/IEC 15444-1:2002 eq. B-16

         * num_precincts_x = |- trx_1 / 2 ^ log2_prec_width) -| - (trx_0 / 2 ^ log2_prec_width)

         * num_precincts_y = |- try_1 / 2 ^ log2_prec_width) -| - (try_0 / 2 ^ log2_prec_width)

         * for Dcinema profiles in JPEG 2000

         * num_precincts_x = |- trx_1 / 2 ^ log2_prec_width) -|

         * num_precincts_y = |- try_1 / 2 ^ log2_prec_width) -| */

        if (reslevel->coord[0][1] == reslevel->coord[0][0])

            reslevel->num_precincts_x = 0;

        else

            reslevel->num_precincts_x =

                ff_jpeg2000_ceildivpow2(reslevel->coord[0][1],

                                        reslevel->log2_prec_width) -

                (reslevel->coord[0][0] >> reslevel->log2_prec_width);



        if (reslevel->coord[1][1] == reslevel->coord[1][0])

            reslevel->num_precincts_y = 0;

        else

            reslevel->num_precincts_y =

                ff_jpeg2000_ceildivpow2(reslevel->coord[1][1],

                                        reslevel->log2_prec_height) -

                (reslevel->coord[1][0] >> reslevel->log2_prec_height);



        reslevel->band = av_malloc_array(reslevel->nbands, sizeof(*reslevel->band));

        if (!reslevel->band)

            return AVERROR(ENOMEM);



        for (bandno = 0; bandno < reslevel->nbands; bandno++, gbandno++) {

            Jpeg2000Band *band = reslevel->band + bandno;

            int cblkno, precno;

            int nb_precincts;



            /* TODO: Implementation of quantization step not finished,

             * see ISO/IEC 15444-1:2002 E.1 and A.6.4. */

            switch (qntsty->quantsty) {

                uint8_t gain;

                int numbps;

            case JPEG2000_QSTY_NONE:

                /* TODO: to verify. No quantization in this case */

                band->f_stepsize = 1;

                break;

            case JPEG2000_QSTY_SI:

                /*TODO: Compute formula to implement. */

                numbps = cbps +

                         lut_gain[codsty->transform][bandno + (reslevelno > 0)];

                band->f_stepsize = SHL(2048 + qntsty->mant[gbandno],

                                            2 + numbps - qntsty->expn[gbandno]);

                break;

            case JPEG2000_QSTY_SE:

                /* Exponent quantization step.

                 * Formula:

                 * delta_b = 2 ^ (R_b - expn_b) * (1 + (mant_b / 2 ^ 11))

                 * R_b = R_I + log2 (gain_b )

                 * see ISO/IEC 15444-1:2002 E.1.1 eqn. E-3 and E-4 */

                /* TODO/WARN: value of log2 (gain_b ) not taken into account

                 * but it works (compared to OpenJPEG). Why?

                 * Further investigation needed. */

                gain      = cbps;

                band->f_stepsize  = pow(2.0, gain - qntsty->expn[gbandno]);

                band->f_stepsize *= (qntsty->mant[gbandno] / 2048.0 + 1.0);

                break;

            default:

                band->f_stepsize = 0;

                av_log(avctx, AV_LOG_ERROR, "Unknown quantization format\n");

                break;

            }

            /* FIXME: In openjepg code stespize = stepsize * 0.5. Why?

             * If not set output of entropic decoder is not correct. */

            if (!av_codec_is_encoder(avctx->codec))

                band->f_stepsize *= 0.5;



            band->i_stepsize = band->f_stepsize * (1 << 16);



            /* computation of tbx_0, tbx_1, tby_0, tby_1

             * see ISO/IEC 15444-1:2002 B.5 eq. B-15 and tbl B.1

             * codeblock width and height is computed for

             * DCI JPEG 2000 codeblock_width = codeblock_width = 32 = 2 ^ 5 */

            if (reslevelno == 0) {

                /* for reslevelno = 0, only one band, x0_b = y0_b = 0 */

                for (i = 0; i < 2; i++)

                    for (j = 0; j < 2; j++)

                        band->coord[i][j] =

                            ff_jpeg2000_ceildivpow2(comp->coord_o[i][j] - comp->coord_o[i][0],

                                                    declvl - 1);

                log2_band_prec_width  = reslevel->log2_prec_width;

                log2_band_prec_height = reslevel->log2_prec_height;

                /* see ISO/IEC 15444-1:2002 eq. B-17 and eq. B-15 */

                band->log2_cblk_width  = FFMIN(codsty->log2_cblk_width,

                                               reslevel->log2_prec_width);

                band->log2_cblk_height = FFMIN(codsty->log2_cblk_height,

                                               reslevel->log2_prec_height);

            } else {

                /* 3 bands x0_b = 1 y0_b = 0; x0_b = 0 y0_b = 1; x0_b = y0_b = 1 */

                /* x0_b and y0_b are computed with ((bandno + 1 >> i) & 1) */

                for (i = 0; i < 2; i++)

                    for (j = 0; j < 2; j++)

                        /* Formula example for tbx_0 = ceildiv((tcx_0 - 2 ^ (declvl - 1) * x0_b) / declvl) */

                        band->coord[i][j] =

                            ff_jpeg2000_ceildivpow2(comp->coord_o[i][j] - comp->coord_o[i][0] -

                                                    (((bandno + 1 >> i) & 1) << declvl - 1),

                                                    declvl);

                /* TODO: Manage case of 3 band offsets here or

                 * in coding/decoding function? */



                /* see ISO/IEC 15444-1:2002 eq. B-17 and eq. B-15 */

                band->log2_cblk_width  = FFMIN(codsty->log2_cblk_width,

                                               reslevel->log2_prec_width - 1);

                band->log2_cblk_height = FFMIN(codsty->log2_cblk_height,

                                               reslevel->log2_prec_height - 1);



                log2_band_prec_width  = reslevel->log2_prec_width  - 1;

                log2_band_prec_height = reslevel->log2_prec_height - 1;

            }



            for (j = 0; j < 2; j++)

                band->coord[0][j] = ff_jpeg2000_ceildiv(band->coord[0][j], dx);

            for (j = 0; j < 2; j++)

                band->coord[1][j] = ff_jpeg2000_ceildiv(band->coord[1][j], dy);



            band->prec = av_malloc_array(reslevel->num_precincts_x *

                                         reslevel->num_precincts_y,

                                         sizeof(*band->prec));

            if (!band->prec)

                return AVERROR(ENOMEM);



            nb_precincts = reslevel->num_precincts_x * reslevel->num_precincts_y;



            for (precno = 0; precno < nb_precincts; precno++) {

                Jpeg2000Prec *prec = band->prec + precno;



                /* TODO: Explain formula for JPEG200 DCINEMA. */

                /* TODO: Verify with previous count of codeblocks per band */



                /* Compute P_x0 */

                prec->coord[0][0] = (precno % reslevel->num_precincts_x) *

                                    (1 << log2_band_prec_width);

                prec->coord[0][0] = FFMAX(prec->coord[0][0], band->coord[0][0]);



                /* Compute P_y0 */

                prec->coord[1][0] = (precno / reslevel->num_precincts_x) *

                                    (1 << log2_band_prec_height);

                prec->coord[1][0] = FFMAX(prec->coord[1][0], band->coord[1][0]);



                /* Compute P_x1 */

                prec->coord[0][1] = prec->coord[0][0] +

                                    (1 << log2_band_prec_width);

                prec->coord[0][1] = FFMIN(prec->coord[0][1], band->coord[0][1]);



                /* Compute P_y1 */

                prec->coord[1][1] = prec->coord[1][0] +

                                    (1 << log2_band_prec_height);

                prec->coord[1][1] = FFMIN(prec->coord[1][1], band->coord[1][1]);



                prec->nb_codeblocks_width =

                    ff_jpeg2000_ceildivpow2(prec->coord[0][1] -

                                            prec->coord[0][0],

                                            band->log2_cblk_width);

                prec->nb_codeblocks_height =

                    ff_jpeg2000_ceildivpow2(prec->coord[1][1] -

                                            prec->coord[1][0],

                                            band->log2_cblk_height);



                /* Tag trees initialization */

                prec->cblkincl =

                    ff_j2k_tag_tree_init(prec->nb_codeblocks_width,

                                              prec->nb_codeblocks_height);

                if (!prec->cblkincl)

                    return AVERROR(ENOMEM);



                prec->zerobits =

                    ff_j2k_tag_tree_init(prec->nb_codeblocks_width,

                                              prec->nb_codeblocks_height);

                if (!prec->zerobits)

                    return AVERROR(ENOMEM);



                prec->cblk = av_malloc_array(prec->nb_codeblocks_width *

                                             prec->nb_codeblocks_height,

                                             sizeof(*prec->cblk));

                if (!prec->cblk)

                    return AVERROR(ENOMEM);

                for (cblkno = 0; cblkno < prec->nb_codeblocks_width * prec->nb_codeblocks_height; cblkno++) {

                    Jpeg2000Cblk *cblk = prec->cblk + cblkno;

                    uint16_t Cx0, Cy0;



                    /* Compute coordinates of codeblocks */

                    /* Compute Cx0*/

                    Cx0 = (prec->coord[0][0] >> band->log2_cblk_width) << band->log2_cblk_width;

                    Cx0 = Cx0 + ((cblkno % prec->nb_codeblocks_width)  << band->log2_cblk_width);

                    cblk->coord[0][0] = FFMAX(Cx0, prec->coord[0][0]);



                    /* Compute Cy0*/

                    Cy0 = (prec->coord[1][0] >> band->log2_cblk_height) << band->log2_cblk_height;

                    Cy0 = Cy0 + ((cblkno / prec->nb_codeblocks_width)   << band->log2_cblk_height);

                    cblk->coord[1][0] = FFMAX(Cy0, prec->coord[1][0]);



                    /* Compute Cx1 */

                    cblk->coord[0][1] = FFMIN(Cx0 + (1 << band->log2_cblk_width),

                                              prec->coord[0][1]);



                    /* Compute Cy1 */

                    cblk->coord[1][1] = FFMIN(Cy0 + (1 << band->log2_cblk_height),

                                              prec->coord[1][1]);



                    if((bandno + !!reslevelno) & 1) {

                        cblk->coord[0][0] += comp->reslevel[reslevelno-1].coord[0][1] - comp->reslevel[reslevelno-1].coord[0][0];

                        cblk->coord[0][1] += comp->reslevel[reslevelno-1].coord[0][1] - comp->reslevel[reslevelno-1].coord[0][0];

                    }

                    if((bandno + !!reslevelno) & 2) {

                        cblk->coord[1][0] += comp->reslevel[reslevelno-1].coord[1][1] - comp->reslevel[reslevelno-1].coord[1][0];

                        cblk->coord[1][1] += comp->reslevel[reslevelno-1].coord[1][1] - comp->reslevel[reslevelno-1].coord[1][0];

                    }



                    cblk->zero      = 0;

                    cblk->lblock    = 3;

                    cblk->length    = 0;

                    cblk->lengthinc = 0;

                    cblk->npasses   = 0;

                }

            }

        }

    }

    return 0;

}
