/*
 * This file is part of FFmpeg.
 *
 * Copyright (C) 2011, 2012 Hyllian/Jararaca - sergiogdb@gmail.com
 *
 * Copyright (c) 2014 Arwa Arif <arwaarif1994@gmail.com>
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * XBR Filter is used for depixelization of image.
 * This is based on Hyllian's xBR shader.
 *
 * @see http://www.libretro.com/forums/viewtopic.php?f=6&t=134
 * @see https://github.com/yoyofr/iFBA/blob/master/fba_src/src/intf/video/scalers/xbr.cpp
 *
 * @todo add threading and FATE test
 */

#include "libavutil/opt.h"
#include "libavutil/avassert.h"
#include "libavutil/pixdesc.h"
#include "internal.h"

#define RGB_MASK      0x00FFFFFF
#define LB_MASK       0x00FEFEFE
#define RED_BLUE_MASK 0x00FF00FF
#define GREEN_MASK    0x0000FF00

typedef struct {
    const AVClass *class;
    int n;
    uint32_t rgbtoyuv[1<<24];
} XBRContext;

#define OFFSET(x) offsetof(XBRContext, x)
static const AVOption xbr_options[] = {
    { "n", "set scale factor", OFFSET(n), AV_OPT_TYPE_INT, {.i64 = 3}, 2, 4, },
    { NULL }
};

AVFILTER_DEFINE_CLASS(xbr);

static uint32_t pixel_diff(uint32_t x, uint32_t y, const uint32_t *r2y)
{
#define YMASK 0xff0000
#define UMASK 0x00ff00
#define VMASK 0x0000ff

    uint32_t yuv1 = r2y[x & 0xffffff];
    uint32_t yuv2 = r2y[y & 0xffffff];

    return (abs((yuv1 & YMASK) - (yuv2 & YMASK)) >> 16) +
           (abs((yuv1 & UMASK) - (yuv2 & UMASK)) >>  8) +
           abs((yuv1 & VMASK) - (yuv2 & VMASK));
}

#define ALPHA_BLEND_128_W(dst, src) dst = ((src & LB_MASK) >> 1) + ((dst & LB_MASK) >> 1)

#define ALPHA_BLEND_32_W(dst, src) \
    dst = ((RED_BLUE_MASK & ((dst & RED_BLUE_MASK) + ((((src & RED_BLUE_MASK) - \
          (dst & RED_BLUE_MASK))) >>3))) | (GREEN_MASK & ((dst & GREEN_MASK) + \
          ((((src & GREEN_MASK) - (dst & GREEN_MASK))) >>3))))

#define ALPHA_BLEND_64_W(dst, src) \
    dst = ((RED_BLUE_MASK & ((dst & RED_BLUE_MASK) + ((((src & RED_BLUE_MASK) - \
          (dst & RED_BLUE_MASK))) >>2))) | (GREEN_MASK & ((dst & GREEN_MASK) + \
          ((((src & GREEN_MASK) - (dst & GREEN_MASK))) >>2))))

#define ALPHA_BLEND_192_W(dst, src) \
    dst = ((RED_BLUE_MASK & ((dst & RED_BLUE_MASK) + ((((src & RED_BLUE_MASK) - \
          (dst & RED_BLUE_MASK)) * 3) >>2))) | (GREEN_MASK & ((dst & GREEN_MASK) + \
          ((((src & GREEN_MASK) - (dst & GREEN_MASK)) * 3) >>2))))

#define ALPHA_BLEND_224_W(dst, src) \
    dst = ((RED_BLUE_MASK & ((dst & RED_BLUE_MASK) + ((((src & RED_BLUE_MASK) - \
          (dst & RED_BLUE_MASK)) * 7) >>3))) | (GREEN_MASK & ((dst & GREEN_MASK) + \
          ((((src & GREEN_MASK) - (dst & GREEN_MASK)) * 7) >>3))))

#define LEFT_UP_2_2X(N3, N2, N1, PIXEL)\
    ALPHA_BLEND_224_W(E[N3], PIXEL); \
    ALPHA_BLEND_64_W( E[N2], PIXEL); \
    E[N1] = E[N2]; \

#define LEFT_2_2X(N3, N2, PIXEL)\
    ALPHA_BLEND_192_W(E[N3], PIXEL); \
    ALPHA_BLEND_64_W( E[N2], PIXEL); \

#define UP_2_2X(N3, N1, PIXEL)\
    ALPHA_BLEND_192_W(E[N3], PIXEL); \
    ALPHA_BLEND_64_W( E[N1], PIXEL); \

#define DIA_2X(N3, PIXEL)\
    ALPHA_BLEND_128_W(E[N3], PIXEL); \

#define df(A, B) pixel_diff(A, B, r2y)

#define eq(A, B)\
    (df(A, B) < 155)\

#define FILTRO(PE, PI, PH, PF, PG, PC, PD, PB, PA, G5, C4, G0, D0, C1, B1, F4, I4, H5, I5, A0, A1, N0, N1, N2, N3) do { \
     unsigned ex = (PE!=PH && PE!=PF); \
     if ( ex )\
     {\
          unsigned e = (df(PE,PC)+df(PE,PG)+df(PI,H5)+df(PI,F4))+(df(PH,PF)<<2); \
          unsigned i = (df(PH,PD)+df(PH,I5)+df(PF,I4)+df(PF,PB))+(df(PE,PI)<<2); \
          if ((e<i)  && ( !eq(PF,PB) && !eq(PH,PD) || eq(PE,PI) && (!eq(PF,I4) && !eq(PH,I5)) || eq(PE,PG) || eq(PE,PC)) )\
          {\
              unsigned ke = df(PF,PG); \
              unsigned ki = df(PH,PC); \
              unsigned ex2 = (PE!=PC && PB!=PC); \
              unsigned ex3 = (PE!=PG && PD!=PG); \
              unsigned px = (df(PE,PF) <= df(PE,PH)) ? PF : PH; \
              if ( ((ke<<1)<=ki) && ex3 && (ke>=(ki<<1)) && ex2 ) \
              {\
                     LEFT_UP_2_2X(N3, N2, N1, px)\
              }\
              else if ( ((ke<<1)<=ki) && ex3 ) \
              {\
                     LEFT_2_2X(N3, N2, px);\
              }\
              else if ( (ke>=(ki<<1)) && ex2 ) \
              {\
                     UP_2_2X(N3, N1, px);\
              }\
              else \
              {\
                     DIA_2X(N3, px);\
              }\
          }\
          else if (e<=i)\
          {\
               ALPHA_BLEND_128_W( E[N3], ((df(PE,PF) <= df(PE,PH)) ? PF : PH)); \
          }\
     }\
} while (0)

static void xbr2x(AVFrame * input, AVFrame * output, const uint32_t * r2y)
{
    int x,y;
    int next_line = output->linesize[0]>>2;

    for (y = 0; y < input->height; y++) {

        uint32_t pprev;
        uint32_t pprev2;

        uint32_t * E = (uint32_t *)(output->data[0] + y * output->linesize[0] * 2);

        /* middle. Offset of -8 is given */
        uint32_t * sa2 = (uint32_t *)(input->data[0] + y * input->linesize[0] - 8);
        /* up one */
        uint32_t * sa1 = sa2 - (input->linesize[0]>>2);
        /* up two */
        uint32_t * sa0 = sa1 - (input->linesize[0]>>2);
        /* down one */
        uint32_t * sa3 = sa2 + (input->linesize[0]>>2);
        /* down two */
        uint32_t * sa4 = sa3 + (input->linesize[0]>>2);

        if (y <= 1) {
            sa0 = sa1;
            if (y == 0) {
                sa0 = sa1 = sa2;
            }
        }

        if (y >= input->height - 2) {
            sa4 = sa3;
            if (y == input->height - 1) {
                sa4 = sa3 = sa2;
            }
        }

        pprev = pprev2 = 2;

        for (x = 0; x < input->width; x++) {
            uint32_t B1 = sa0[2];
            uint32_t PB = sa1[2];
            uint32_t PE = sa2[2];
            uint32_t PH = sa3[2];
            uint32_t H5 = sa4[2];

            uint32_t A1 = sa0[pprev];
            uint32_t PA = sa1[pprev];
            uint32_t PD = sa2[pprev];
            uint32_t PG = sa3[pprev];
            uint32_t G5 = sa4[pprev];

            uint32_t A0 = sa1[pprev2];
            uint32_t D0 = sa2[pprev2];
            uint32_t G0 = sa3[pprev2];

            uint32_t C1 = 0;
            uint32_t PC = 0;
            uint32_t PF = 0;
            uint32_t PI = 0;
            uint32_t I5 = 0;

            uint32_t C4 = 0;
            uint32_t F4 = 0;
            uint32_t I4 = 0;

            if (x >= input->width - 2) {
                if (x == input->width - 1) {
                    C1 = sa0[2];
                    PC = sa1[2];
                    PF = sa2[2];
                    PI = sa3[2];
                    I5 = sa4[2];

                    C4 = sa1[2];
                    F4 = sa2[2];
                    I4 = sa3[2];
                } else {
                    C1 = sa0[3];
                    PC = sa1[3];
                    PF = sa2[3];
                    PI = sa3[3];
                    I5 = sa4[3];

                    C4 = sa1[3];
                    F4 = sa2[3];
                    I4 = sa3[3];
                }
            } else {
                C1 = sa0[3];
                PC = sa1[3];
                PF = sa2[3];
                PI = sa3[3];
                I5 = sa4[3];

                C4 = sa1[4];
                F4 = sa2[4];
                I4 = sa3[4];
            }

            E[0] = E[1] = E[next_line] = E[next_line + 1] = PE; // 0, 1, 2, 3

            FILTRO(PE, PI, PH, PF, PG, PC, PD, PB, PA, G5, C4, G0, D0, C1, B1, F4, I4, H5, I5, A0, A1, 0, 1, next_line, next_line+1);
            FILTRO(PE, PC, PF, PB, PI, PA, PH, PD, PG, I4, A1, I5, H5, A0, D0, B1, C1, F4, C4, G5, G0, next_line, 0, next_line+1, 1);
            FILTRO(PE, PA, PB, PD, PC, PG, PF, PH, PI, C1, G0, C4, F4, G5, H5, D0, A0, B1, A1, I4, I5, next_line+1, next_line, 1, 0);
            FILTRO(PE, PG, PD, PH, PA, PI, PB, PF, PC, A0, I5, A1, B1, I4, F4, H5, G5, D0, G0, C1, C4, 1, next_line+1, 0, next_line);

            sa0 += 1;
            sa1 += 1;
            sa2 += 1;
            sa3 += 1;
            sa4 += 1;

            E += 2;

            if (pprev2){
                pprev2--;
                pprev = 1;
            }
        }
    }
}
#undef FILTRO

#define LEFT_UP_2_3X(N7, N5, N6, N2, N8, PIXEL)\
    ALPHA_BLEND_192_W(E[N7], PIXEL); \
    ALPHA_BLEND_64_W( E[N6], PIXEL); \
    E[N5] = E[N7]; \
    E[N2] = E[N6]; \
    E[N8] =  PIXEL;\

#define LEFT_2_3X(N7, N5, N6, N8, PIXEL)\
    ALPHA_BLEND_192_W(E[N7], PIXEL); \
    ALPHA_BLEND_64_W( E[N5], PIXEL); \
    ALPHA_BLEND_64_W( E[N6], PIXEL); \
    E[N8] =  PIXEL;\

#define UP_2_3X(N5, N7, N2, N8, PIXEL)\
    ALPHA_BLEND_192_W(E[N5], PIXEL); \
    ALPHA_BLEND_64_W( E[N7], PIXEL); \
    ALPHA_BLEND_64_W( E[N2], PIXEL); \
    E[N8] =  PIXEL;\

#define DIA_3X(N8, N5, N7, PIXEL)\
    ALPHA_BLEND_224_W(E[N8], PIXEL); \
    ALPHA_BLEND_32_W(E[N5], PIXEL); \
    ALPHA_BLEND_32_W(E[N7], PIXEL); \

#define FILTRO(PE, PI, PH, PF, PG, PC, PD, PB, PA, G5, C4, G0, D0, C1, B1, F4, I4, H5, I5, A0, A1, N0, N1, N2, N3, N4, N5, N6, N7, N8) do { \
     unsigned ex = (PE!=PH && PE!=PF); \
     if ( ex )\
     {\
          unsigned e = (df(PE,PC)+df(PE,PG)+df(PI,H5)+df(PI,F4))+(df(PH,PF)<<2); \
          unsigned i = (df(PH,PD)+df(PH,I5)+df(PF,I4)+df(PF,PB))+(df(PE,PI)<<2); \
          if ((e<i)  && ( !eq(PF,PB) && !eq(PF,PC) || !eq(PH,PD) && !eq(PH,PG) || eq(PE,PI) && (!eq(PF,F4) && !eq(PF,I4) || !eq(PH,H5) && !eq(PH,I5)) || eq(PE,PG) || eq(PE,PC)) )\
          {\
              unsigned ke = df(PF,PG); \
              unsigned ki = df(PH,PC); \
              unsigned ex2 = (PE!=PC && PB!=PC); \
              unsigned ex3 = (PE!=PG && PD!=PG); \
              unsigned px = (df(PE,PF) <= df(PE,PH)) ? PF : PH; \
              if ( ((ke<<1)<=ki) && ex3 && (ke>=(ki<<1)) && ex2 ) \
              {\
                     LEFT_UP_2_3X(N7, N5, N6, N2, N8, px)\
              }\
              else if ( ((ke<<1)<=ki) && ex3 ) \
              {\
                     LEFT_2_3X(N7, N5, N6, N8, px);\
              }\
              else if ( (ke>=(ki<<1)) && ex2 ) \
              {\
                     UP_2_3X(N5, N7, N2, N8, px);\
              }\
              else \
              {\
                     DIA_3X(N8, N5, N7, px);\
              }\
          }\
          else if (e<=i)\
          {\
               ALPHA_BLEND_128_W( E[N8], ((df(PE,PF) <= df(PE,PH)) ? PF : PH)); \
          }\
     }\
} while (0)

static void xbr3x(AVFrame *input, AVFrame *output, const uint32_t *r2y)
{
    const int nl = output->linesize[0]>>2;
    const int nl1 = nl + nl;
    uint32_t pprev;
    uint32_t pprev2;

    int x,y;

    for (y = 0; y < input->height; y++) {

        uint32_t * E = (uint32_t *)(output->data[0] + y * output->linesize[0] * 3);

        /* middle. Offset of -8 is given */
        uint32_t * sa2 = (uint32_t *)(input->data[0] + y * input->linesize[0] - 8);
        /* up one */
        uint32_t * sa1 = sa2 - (input->linesize[0]>>2);
        /* up two */
        uint32_t * sa0 = sa1 - (input->linesize[0]>>2);
        /* down one */
        uint32_t * sa3 = sa2 + (input->linesize[0]>>2);
        /* down two */
        uint32_t * sa4 = sa3 + (input->linesize[0]>>2);

        if (y <= 1){
            sa0 = sa1;
            if (y == 0){
                sa0 = sa1 = sa2;
            }
        }

        if (y >= input->height - 2){
            sa4 = sa3;
            if (y == input->height - 1){
                sa4 = sa3 = sa2;
            }
        }

        pprev = pprev2 = 2;

        for (x = 0; x < input->width; x++){
            uint32_t B1 = sa0[2];
            uint32_t PB = sa1[2];
            uint32_t PE = sa2[2];
            uint32_t PH = sa3[2];
            uint32_t H5 = sa4[2];

            uint32_t A1 = sa0[pprev];
            uint32_t PA = sa1[pprev];
            uint32_t PD = sa2[pprev];
            uint32_t PG = sa3[pprev];
            uint32_t G5 = sa4[pprev];

            uint32_t A0 = sa1[pprev2];
            uint32_t D0 = sa2[pprev2];
            uint32_t G0 = sa3[pprev2];

            uint32_t C1 = 0;
            uint32_t PC = 0;
            uint32_t PF = 0;
            uint32_t PI = 0;
            uint32_t I5 = 0;

            uint32_t C4 = 0;
            uint32_t F4 = 0;
            uint32_t I4 = 0;

            if (x >= input->width - 2){
                if (x == input->width - 1){
                    C1 = sa0[2];
                    PC = sa1[2];
                    PF = sa2[2];
                    PI = sa3[2];
                    I5 = sa4[2];

                    C4 = sa1[2];
                    F4 = sa2[2];
                    I4 = sa3[2];
                } else {
                    C1 = sa0[3];
                    PC = sa1[3];
                    PF = sa2[3];
                    PI = sa3[3];
                    I5 = sa4[3];

                    C4 = sa1[3];
                    F4 = sa2[3];
                    I4 = sa3[3];
                }
            } else {
                C1 = sa0[3];
                PC = sa1[3];
                PF = sa2[3];
                PI = sa3[3];
                I5 = sa4[3];

                C4 = sa1[4];
                F4 = sa2[4];
                I4 = sa3[4];
            }

            E[0]   = E[1]     = E[2]     = PE;
            E[nl]  = E[nl+1]  = E[nl+2]  = PE; // 3, 4, 5
            E[nl1] = E[nl1+1] = E[nl1+2] = PE; // 6, 7, 8

            FILTRO(PE, PI, PH, PF, PG, PC, PD, PB, PA, G5, C4, G0, D0, C1, B1, F4, I4, H5, I5, A0, A1, 0, 1, 2, nl, nl+1, nl+2, nl1, nl1+1, nl1+2);
            FILTRO(PE, PC, PF, PB, PI, PA, PH, PD, PG, I4, A1, I5, H5, A0, D0, B1, C1, F4, C4, G5, G0, nl1, nl, 0, nl1+1, nl+1, 1, nl1+2, nl+2, 2);
            FILTRO(PE, PA, PB, PD, PC, PG, PF, PH, PI, C1, G0, C4, F4, G5, H5, D0, A0, B1, A1, I4, I5, nl1+2, nl1+1, nl1, nl+2, nl+1, nl, 2, 1, 0);
            FILTRO(PE, PG, PD, PH, PA, PI, PB, PF, PC, A0, I5, A1, B1, I4, F4, H5, G5, D0, G0, C1, C4, 2, nl+2, nl1+2, 1, nl+1, nl1+1, 0, nl, nl1);

            sa0 += 1;
            sa1 += 1;
            sa2 += 1;
            sa3 += 1;
            sa4 += 1;

            E += 3;

            if (pprev2){
                pprev2--;
                pprev = 1;
            }
        }
    }
}
#undef FILTRO

#define LEFT_UP_2(N15, N14, N11, N13, N12, N10, N7, N3, PIXEL)\
    ALPHA_BLEND_192_W(E[N13], PIXEL); \
    ALPHA_BLEND_64_W( E[N12], PIXEL); \
    E[N15] = E[N14] = E[N11] = PIXEL; \
    E[N10] = E[N3] = E[N12]; \
    E[N7]  = E[N13]; \

#define LEFT_2(N15, N14, N11, N13, N12, N10, PIXEL)\
    ALPHA_BLEND_192_W(E[N11], PIXEL); \
    ALPHA_BLEND_192_W(E[N13], PIXEL); \
    ALPHA_BLEND_64_W( E[N10], PIXEL); \
    ALPHA_BLEND_64_W( E[N12], PIXEL); \
    E[N14] = PIXEL; \
    E[N15] = PIXEL; \

#define UP_2(N15, N14, N11, N3, N7, N10, PIXEL)\
    ALPHA_BLEND_192_W(E[N14], PIXEL); \
    ALPHA_BLEND_192_W(E[N7 ], PIXEL); \
    ALPHA_BLEND_64_W( E[N10], PIXEL); \
    ALPHA_BLEND_64_W( E[N3 ], PIXEL); \
    E[N11] = PIXEL; \
    E[N15] = PIXEL; \

#define DIA(N15, N14, N11, PIXEL)\
    ALPHA_BLEND_128_W(E[N11], PIXEL); \
    ALPHA_BLEND_128_W(E[N14], PIXEL); \
    E[N15] = PIXEL; \

#define FILTRO(PE, PI, PH, PF, PG, PC, PD, PB, PA, G5, C4, G0, D0, C1, B1, F4, I4, H5, I5, A0, A1, N15, N14, N11, N3, N7, N10, N13, N12, N9, N6, N2, N1, N5, N8, N4, N0) do { \
     unsigned ex   = (PE!=PH && PE!=PF); \
     if ( ex )\
     {\
          unsigned e = (df(PE,PC)+df(PE,PG)+df(PI,H5)+df(PI,F4))+(df(PH,PF)<<2); \
          unsigned i = (df(PH,PD)+df(PH,I5)+df(PF,I4)+df(PF,PB))+(df(PE,PI)<<2); \
          if ((e<i)  && ( !eq(PF,PB) && !eq(PH,PD) || eq(PE,PI) && (!eq(PF,I4) && !eq(PH,I5)) || eq(PE,PG) || eq(PE,PC)) )\
          {\
              unsigned ke = df(PF,PG); \
              unsigned ki = df(PH,PC); \
              unsigned ex2 = (PE!=PC && PB!=PC); \
              unsigned ex3 = (PE!=PG && PD!=PG); \
              unsigned px = (df(PE,PF) <= df(PE,PH)) ? PF : PH; \
              if ( ((ke<<1)<=ki) && ex3 && (ke>=(ki<<1)) && ex2 ) \
              {\
                     LEFT_UP_2(N15, N14, N11, N13, N12, N10, N7, N3, px)\
              }\
              else if ( ((ke<<1)<=ki) && ex3 ) \
              {\
                     LEFT_2(N15, N14, N11, N13, N12, N10, px)\
              }\
              else if ( (ke>=(ki<<1)) && ex2 ) \
              {\
                     UP_2(N15, N14, N11, N3, N7, N10, px)\
              }\
              else \
              {\
                     DIA(N15, N14, N11, px)\
              }\
          }\
          else if (e<=i)\
          {\
               ALPHA_BLEND_128_W( E[N15], ((df(PE,PF) <= df(PE,PH)) ? PF : PH)); \
          }\
     }\
} while (0)

static void xbr4x(AVFrame *input, AVFrame *output, const uint32_t *r2y)
{

    const int nl = output->linesize[0]>>2;
    const int nl1 = nl + nl;
    const int nl2 = nl1 + nl;
    uint32_t pprev;
    uint32_t pprev2;

    int x, y;

    for (y = 0; y < input->height; y++) {

        uint32_t * E = (uint32_t *)(output->data[0] + y * output->linesize[0] * 4);

        /* middle. Offset of -8 is given */
        uint32_t * sa2 = (uint32_t *)(input->data[0] + y * input->linesize[0] - 8);
        /* up one */
        uint32_t * sa1 = sa2 - (input->linesize[0]>>2);
        /* up two */
        uint32_t * sa0 = sa1 - (input->linesize[0]>>2);
        /* down one */
        uint32_t * sa3 = sa2 + (input->linesize[0]>>2);
        /* down two */
        uint32_t * sa4 = sa3 + (input->linesize[0]>>2);

        if (y <= 1) {
            sa0 = sa1;
            if (y == 0) {
                sa0 = sa1 = sa2;
            }
        }

        if (y >= input->height - 2) {
            sa4 = sa3;
            if (y == input->height - 1) {
                sa4 = sa3 = sa2;
            }
        }

        pprev = pprev2 = 2;

        for (x = 0; x < input->width; x++) {
            uint32_t B1 = sa0[2];
            uint32_t PB = sa1[2];
            uint32_t PE = sa2[2];
            uint32_t PH = sa3[2];
            uint32_t H5 = sa4[2];

            uint32_t A1 = sa0[pprev];
            uint32_t PA = sa1[pprev];
            uint32_t PD = sa2[pprev];
            uint32_t PG = sa3[pprev];
            uint32_t G5 = sa4[pprev];

            uint32_t A0 = sa1[pprev2];
            uint32_t D0 = sa2[pprev2];
            uint32_t G0 = sa3[pprev2];

            uint32_t C1 = 0;
            uint32_t PC = 0;
            uint32_t PF = 0;
            uint32_t PI = 0;
            uint32_t I5 = 0;

            uint32_t C4 = 0;
            uint32_t F4 = 0;
            uint32_t I4 = 0;

            if (x >= input->width - 2) {
                if (x == input->width - 1) {
                    C1 = sa0[2];
                    PC = sa1[2];
                    PF = sa2[2];
                    PI = sa3[2];
                    I5 = sa4[2];

                    C4 = sa1[2];
                    F4 = sa2[2];
                    I4 = sa3[2];
                } else {
                    C1 = sa0[3];
                    PC = sa1[3];
                    PF = sa2[3];
                    PI = sa3[3];
                    I5 = sa4[3];

                    C4 = sa1[3];
                    F4 = sa2[3];
                    I4 = sa3[3];
                }
            } else {
                C1 = sa0[3];
                PC = sa1[3];
                PF = sa2[3];
                PI = sa3[3];
                I5 = sa4[3];

                C4 = sa1[4];
                F4 = sa2[4];
                I4 = sa3[4];
            }

            E[0]   = E[1]     = E[2]     = E[3]     = PE;
            E[nl]  = E[nl+1]  = E[nl+2]  = E[nl+3]  = PE; //  4,  5,  6,  7
            E[nl1] = E[nl1+1] = E[nl1+2] = E[nl1+3] = PE; //  8,  9, 10, 11
            E[nl2] = E[nl2+1] = E[nl2+2] = E[nl2+3] = PE; // 12, 13, 14, 15

            FILTRO(PE, PI, PH, PF, PG, PC, PD, PB, PA, G5, C4, G0, D0, C1, B1, F4, I4, H5, I5, A0, A1, nl2+3, nl2+2, nl1+3,  3,  nl+3, nl1+2, nl2+1, nl2,  nl1+1,  nl+2, 2,  1, nl+1, nl1, nl, 0);
            FILTRO(PE, PC, PF, PB, PI, PA, PH, PD, PG, I4, A1, I5, H5, A0, D0, B1, C1, F4, C4, G5, G0,  3,  nl+3,  2,  0,  1,  nl+2, nl1+3, nl2+3, nl1+2,  nl+1, nl,  nl1, nl1+1,nl2+2,nl2+1,nl2);
            FILTRO(PE, PA, PB, PD, PC, PG, PF, PH, PI, C1, G0, C4, F4, G5, H5, D0, A0, B1, A1, I4, I5,  0,  1,  nl, nl2,  nl1,  nl+1,  2,  3,  nl+2,  nl1+1, nl2+1,nl2+2,nl1+2, nl+3,nl1+3,nl2+3);
            FILTRO(PE, PG, PD, PH, PA, PI, PB, PF, PC, A0, I5, A1, B1, I4, F4, H5, G5, D0, G0, C1, C4, nl2,  nl1, nl2+1, nl2+3, nl2+2,  nl1+1,  nl,  0,  nl+1, nl1+2, nl1+3, nl+3, nl+2, 1, 2, 3);

            sa0 += 1;
            sa1 += 1;
            sa2 += 1;
            sa3 += 1;
            sa4 += 1;

            E += 4;

            if (pprev2){
                pprev2--;
                pprev = 1;
            }
        }
    }
}
#undef FILTRO

static int config_output(AVFilterLink *outlink)
{
    AVFilterContext *ctx = outlink->src;
    XBRContext *xbr = ctx->priv;
    AVFilterLink *inlink = ctx->inputs[0];

    outlink->w = inlink->w * xbr->n;
    outlink->h = inlink->h * xbr->n;
    return 0;
}

static int query_formats(AVFilterContext *ctx)
{
    static const enum AVPixelFormat pix_fmts[] = {
        AV_PIX_FMT_0RGB32, AV_PIX_FMT_NONE,
    };

    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
    return 0;
}

static int filter_frame(AVFilterLink *inlink, AVFrame *in)
{
    AVFilterContext *ctx = inlink->dst;
    AVFilterLink *outlink = ctx->outputs[0];
    XBRContext *xbr = ctx->priv;
    const uint32_t *r2y = xbr->rgbtoyuv;

    AVFrame *out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
    if (!out) {
        av_frame_free(&in);
        return AVERROR(ENOMEM);
    }

    av_frame_copy_props(out, in);
    if (xbr->n == 4)
        xbr4x(in, out, r2y);
    else if (xbr->n == 3)
        xbr3x(in, out, r2y);
    else
        xbr2x(in, out, r2y);

    out->width  = outlink->w;
    out->height = outlink->h;

    av_frame_free(&in);
    return ff_filter_frame(outlink, out);
}

static int init(AVFilterContext *ctx)
{
    XBRContext *xbr = ctx->priv;
    uint32_t c;
    int bg, rg, g;

    for (bg = -255; bg < 256; bg++) {
        for (rg = -255; rg < 256; rg++) {
            const uint32_t u = (uint32_t)((-169*rg + 500*bg)/1000) + 128;
            const uint32_t v = (uint32_t)(( 500*rg -  81*bg)/1000) + 128;
            int startg = FFMAX3(-bg, -rg, 0);
            int endg = FFMIN3(255-bg, 255-rg, 255);
            uint32_t y = (uint32_t)(( 299*rg + 1000*startg + 114*bg)/1000);
            c = bg + (rg<<16) + 0x010101 * startg;
            for (g = startg; g <= endg; g++) {
                xbr->rgbtoyuv[c] = ((y++) << 16) + (u << 8) + v;
                c+= 0x010101;
            }
        }
    }

    return 0;
}

static const AVFilterPad xbr_inputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .filter_frame = filter_frame,
    },
    { NULL }
};

static const AVFilterPad xbr_outputs[] = {
    {
        .name         = "default",
        .type         = AVMEDIA_TYPE_VIDEO,
        .config_props = config_output,
    },
    { NULL }
};

AVFilter ff_vf_xbr = {
    .name          = "xbr",
    .description   = NULL_IF_CONFIG_SMALL("Scale the input using xBR algorithm."),
    .inputs        = xbr_inputs,
    .outputs       = xbr_outputs,
    .query_formats = query_formats,
    .priv_size     = sizeof(XBRContext),
    .priv_class    = &xbr_class,
    .init          = init,
};