static int mjpeg_decode_scan(MJpegDecodeContext *s, int nb_components, int Ah, int Al){
    int i, mb_x, mb_y;
    uint8_t* data[MAX_COMPONENTS];
    int linesize[MAX_COMPONENTS];

    if(s->flipped && s->avctx->flags & CODEC_FLAG_EMU_EDGE) {
        av_log(s->avctx, AV_LOG_ERROR, "Can not flip image with CODEC_FLAG_EMU_EDGE set!\n");
        s->flipped = 0;
    }
    for(i=0; i < nb_components; i++) {
        int c = s->comp_index[i];
        data[c] = s->picture.data[c];
        linesize[c]=s->linesize[c];
        s->coefs_finished[c] |= 1;
        if(s->flipped) {
            //picture should be flipped upside-down for this codec
            data[c] += (linesize[c] * (s->v_scount[i] * (8 * s->mb_height -((s->height/s->v_max)&7)) - 1 ));
            linesize[c] *= -1;
        }
    }

    for(mb_y = 0; mb_y < s->mb_height; mb_y++) {
        for(mb_x = 0; mb_x < s->mb_width; mb_x++) {
            if (s->restart_interval && !s->restart_count)
                s->restart_count = s->restart_interval;

            for(i=0;i<nb_components;i++) {
                uint8_t *ptr;
                int n, h, v, x, y, c, j;
                n = s->nb_blocks[i];
                c = s->comp_index[i];
                h = s->h_scount[i];
                v = s->v_scount[i];
                x = 0;
                y = 0;
                for(j=0;j<n;j++) {
                    ptr = data[c] +
                        (((linesize[c] * (v * mb_y + y) * 8) +
                        (h * mb_x + x) * 8) >> s->avctx->lowres);
                    if(s->interlaced && s->bottom_field)
                        ptr += linesize[c] >> 1;
                    if(!s->progressive) {
                        s->dsp.clear_block(s->block);
                        if(decode_block(s, s->block, i,
                                     s->dc_index[i], s->ac_index[i],
                                     s->quant_matrixes[ s->quant_index[c] ]) < 0) {
                            av_log(s->avctx, AV_LOG_ERROR, "error y=%d x=%d\n", mb_y, mb_x);
                            return -1;
                        }
                        s->dsp.idct_put(ptr, linesize[c], s->block);
                    } else {
                        int block_idx = s->block_stride[c] * (v * mb_y + y) + (h * mb_x + x);
                        DCTELEM *block = s->blocks[c][block_idx];
                        if(Ah)
                            block[0] += get_bits1(&s->gb) * s->quant_matrixes[ s->quant_index[c] ][0] << Al;
                        else if(decode_dc_progressive(s, block, i, s->dc_index[i], s->quant_matrixes[ s->quant_index[c] ], Al) < 0) {
                            av_log(s->avctx, AV_LOG_ERROR, "error y=%d x=%d\n", mb_y, mb_x);
                            return -1;
                        }
                    }
//                    av_log(s->avctx, AV_LOG_DEBUG, "mb: %d %d processed\n", mb_y, mb_x);
//av_log(NULL, AV_LOG_DEBUG, "%d %d %d %d %d %d %d %d \n", mb_x, mb_y, x, y, c, s->bottom_field, (v * mb_y + y) * 8, (h * mb_x + x) * 8);
                    if (++x == h) {
                        x = 0;
                        y++;
                    }
                }
            }

            if (s->restart_interval && !--s->restart_count) {
                align_get_bits(&s->gb);
                skip_bits(&s->gb, 16); /* skip RSTn */
                for (i=0; i<nb_components; i++) /* reset dc */
                    s->last_dc[i] = 1024;
            }
        }
    }
    return 0;
}