int ff_mjpeg_decode_sos(MJpegDecodeContext *s, const uint8_t *mb_bitmask,
                        int mb_bitmask_size, const AVFrame *reference)
{
    int len, nb_components, i, h, v, predictor, point_transform;
    int index, id, ret;
    const int block_size = s->lossless ? 1 : 8;
    int ilv, prev_shift;
    if (!s->got_picture) {
        av_log(s->avctx, AV_LOG_WARNING,
                "Can not process SOS before SOF, skipping\n");
        return -1;
    av_assert0(s->picture_ptr->data[0]);
    /* XXX: verify len field validity */
    len = get_bits(&s->gb, 16);
    nb_components = get_bits(&s->gb, 8);
    if (nb_components == 0 || nb_components > MAX_COMPONENTS) {
        avpriv_report_missing_feature(s->avctx,
                                      "decode_sos: nb_components (%d)",
                                      nb_components);
        return AVERROR_PATCHWELCOME;
    if (len != 6 + 2 * nb_components) {
        av_log(s->avctx, AV_LOG_ERROR, "decode_sos: invalid len (%d)\n", len);
    for (i = 0; i < nb_components; i++) {
        id = get_bits(&s->gb, 8) - 1;
        av_log(s->avctx, AV_LOG_DEBUG, "component: %d\n", id);
        /* find component index */
        for (index = 0; index < s->nb_components; index++)
            if (id == s->component_id[index])
                break;
        if (index == s->nb_components) {
            av_log(s->avctx, AV_LOG_ERROR,
                   "decode_sos: index(%d) out of components\n", index);
        /* Metasoft MJPEG codec has Cb and Cr swapped */
        if (s->avctx->codec_tag == MKTAG('M', 'T', 'S', 'J')
            && nb_components == 3 && s->nb_components == 3 && i)
            index = 3 - i;
        s->quant_sindex[i] = s->quant_index[index];
        s->nb_blocks[i] = s->h_count[index] * s->v_count[index];
        s->h_scount[i]  = s->h_count[index];
        s->v_scount[i]  = s->v_count[index];
        if(nb_components == 3 && s->nb_components == 3 && s->avctx->pix_fmt == AV_PIX_FMT_GBR24P)
            index = (i+2)%3;
        if(nb_components == 1 && s->nb_components == 3 && s->avctx->pix_fmt == AV_PIX_FMT_GBR24P)
            index = (index+2)%3;
        s->comp_index[i] = index;
        s->dc_index[i] = get_bits(&s->gb, 4);
        s->ac_index[i] = get_bits(&s->gb, 4);
        if (s->dc_index[i] <  0 || s->ac_index[i] < 0 ||
            s->dc_index[i] >= 4 || s->ac_index[i] >= 4)
            goto out_of_range;
        if (!s->vlcs[0][s->dc_index[i]].table || !(s->progressive ? s->vlcs[2][s->ac_index[0]].table : s->vlcs[1][s->ac_index[i]].table))
            goto out_of_range;
    predictor = get_bits(&s->gb, 8);       /* JPEG Ss / lossless JPEG predictor /JPEG-LS NEAR */
    ilv = get_bits(&s->gb, 8);             /* JPEG Se / JPEG-LS ILV */
    if(s->avctx->codec_tag != AV_RL32("CJPG")){
        prev_shift      = get_bits(&s->gb, 4); /* Ah */
        point_transform = get_bits(&s->gb, 4); /* Al */
    }else
        prev_shift = point_transform = 0;
    if (nb_components > 1) {
        /* interleaved stream */
        s->mb_width  = (s->width  + s->h_max * block_size - 1) / (s->h_max * block_size);
        s->mb_height = (s->height + s->v_max * block_size - 1) / (s->v_max * block_size);
    } else if (!s->ls) { /* skip this for JPEG-LS */
        h = s->h_max / s->h_scount[0];
        v = s->v_max / s->v_scount[0];
        s->mb_width     = (s->width  + h * block_size - 1) / (h * block_size);
        s->mb_height    = (s->height + v * block_size - 1) / (v * block_size);
        s->nb_blocks[0] = 1;
        s->h_scount[0]  = 1;
        s->v_scount[0]  = 1;
    if (s->avctx->debug & FF_DEBUG_PICT_INFO)
        av_log(s->avctx, AV_LOG_DEBUG, "%s %s p:%d >>:%d ilv:%d bits:%d skip:%d %s comp:%d\n",
               s->lossless ? "lossless" : "sequential DCT", s->rgb ? "RGB" : "",
               predictor, point_transform, ilv, s->bits, s->mjpb_skiptosod,
               s->pegasus_rct ? "PRCT" : (s->rct ? "RCT" : ""), nb_components);
    /* mjpeg-b can have padding bytes between sos and image data, skip them */
    for (i = s->mjpb_skiptosod; i > 0; i--)
        skip_bits(&s->gb, 8);
next_field:
    for (i = 0; i < nb_components; i++)
        s->last_dc[i] = (4 << s->bits);
    if (s->lossless) {
        av_assert0(s->picture_ptr == s->picture);
        if (CONFIG_JPEGLS_DECODER && s->ls) {
//            for () {
//            reset_ls_coding_parameters(s, 0);
            if ((ret = ff_jpegls_decode_picture(s, predictor,
                                                point_transform, ilv)) < 0)
                return ret;
        } else {
            if (s->rgb) {
                if ((ret = ljpeg_decode_rgb_scan(s, nb_components, predictor, point_transform)) < 0)
                    return ret;
            } else {
                if ((ret = ljpeg_decode_yuv_scan(s, predictor,
                                                 point_transform,
                                                 nb_components)) < 0)
                    return ret;
    } else {
        if (s->progressive && predictor) {
            av_assert0(s->picture_ptr == s->picture);
            if ((ret = mjpeg_decode_scan_progressive_ac(s, predictor,
                                                        ilv, prev_shift,
                                                        point_transform)) < 0)
                return ret;
        } else {
            if ((ret = mjpeg_decode_scan(s, nb_components,
                                         prev_shift, point_transform,
                                         mb_bitmask, mb_bitmask_size, reference)) < 0)
                return ret;
    if (s->interlaced &&
        get_bits_left(&s->gb) > 32 &&
        show_bits(&s->gb, 8) == 0xFF) {
        GetBitContext bak = s->gb;
        align_get_bits(&bak);
        if (show_bits(&bak, 16) == 0xFFD1) {
            av_log(s->avctx, AV_LOG_DEBUG, "AVRn interlaced picture marker found\n");
            s->gb = bak;
            skip_bits(&s->gb, 16);
            s->bottom_field ^= 1;
            goto next_field;
    emms_c();
    return 0;
 out_of_range:
    av_log(s->avctx, AV_LOG_ERROR, "decode_sos: ac/dc index out of range\n");