/*

  * Copyright (c) 2007 Bobby Bingham

  *
  * This file is part of FFmpeg.
  *
  * 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

  * scale video filter
  */
 

 #include <stdio.h>
 #include <string.h>
 

 #include "avfilter.h"

 #include "formats.h"

 #include "internal.h"

 #include "scale_eval.h"

 #include "video.h"

 #include "libavutil/avstring.h"

 #include "libavutil/eval.h"

 #include "libavutil/internal.h"

 #include "libavutil/mathematics.h"

 #include "libavutil/opt.h"

 #include "libavutil/parseutils.h"

 #include "libavutil/pixdesc.h"

 #include "libavutil/imgutils.h"

 #include "libavutil/avassert.h"

 #include "libswscale/swscale.h"
 

 static const char *const var_names[] = {
     "in_w",   "iw",
     "in_h",   "ih",
     "out_w",  "ow",
     "out_h",  "oh",
     "a",
     "sar",
     "dar",
     "hsub",
     "vsub",
     "ohsub",
     "ovsub",

     "n",
     "t",
     "pos",

     "main_w",
     "main_h",
     "main_a",
     "main_sar",
     "main_dar", "mdar",
     "main_hsub",
     "main_vsub",

     "main_n",
     "main_t",
     "main_pos",

     NULL
 };
 
 enum var_name {
     VAR_IN_W,   VAR_IW,
     VAR_IN_H,   VAR_IH,
     VAR_OUT_W,  VAR_OW,
     VAR_OUT_H,  VAR_OH,
     VAR_A,
     VAR_SAR,
     VAR_DAR,
     VAR_HSUB,
     VAR_VSUB,
     VAR_OHSUB,
     VAR_OVSUB,

     VAR_N,
     VAR_T,
     VAR_POS,

     VAR_S2R_MAIN_W,
     VAR_S2R_MAIN_H,
     VAR_S2R_MAIN_A,
     VAR_S2R_MAIN_SAR,
     VAR_S2R_MAIN_DAR, VAR_S2R_MDAR,
     VAR_S2R_MAIN_HSUB,
     VAR_S2R_MAIN_VSUB,

     VAR_S2R_MAIN_N,
     VAR_S2R_MAIN_T,
     VAR_S2R_MAIN_POS,

     VARS_NB

 };
 

 enum EvalMode {
     EVAL_MODE_INIT,
     EVAL_MODE_FRAME,
     EVAL_MODE_NB
 };
 

 typedef struct ScaleContext {

     const AVClass *class;

     struct SwsContext *sws;     ///< software scaler context

     struct SwsContext *isws[2]; ///< software scaler context for interlaced material

     AVDictionary *opts;

 
     /**
      * New dimensions. Special values are:
      *   0 = original width/height
      *  -1 = keep original aspect

      *  -N = try to keep aspect but make sure it is divisible by N

      */
     int w, h;

     char *size_str;

     unsigned int flags;         ///sws flags

     double param[2];            // sws params

 
     int hsub, vsub;             ///< chroma subsampling
     int slice_y;                ///< top of current output slice
     int input_is_pal;           ///< set to 1 if the input format is paletted

     int output_is_pal;          ///< set to 1 if the output format is paletted

     int interlaced;

     char *w_expr;               ///< width  expression string
     char *h_expr;               ///< height expression string

     AVExpr *w_pexpr;
     AVExpr *h_pexpr;

     double var_values[VARS_NB];

     char *flags_str;

 
     char *in_color_matrix;
     char *out_color_matrix;

 
     int in_range;
     int out_range;

 
     int out_h_chr_pos;
     int out_v_chr_pos;

     int in_h_chr_pos;
     int in_v_chr_pos;

 
     int force_original_aspect_ratio;

     int force_divisible_by;

 
     int nb_slices;

 
     int eval_mode;              ///< expression evaluation mode
 

 } ScaleContext;
 

 AVFilter ff_vf_scale2ref;
 

 static int config_props(AVFilterLink *outlink);
 

 static int check_exprs(AVFilterContext *ctx)
 {
     ScaleContext *scale = ctx->priv;
     unsigned vars_w[VARS_NB] = { 0 }, vars_h[VARS_NB] = { 0 };
 
     if (!scale->w_pexpr && !scale->h_pexpr)
         return AVERROR(EINVAL);
 
     if (scale->w_pexpr)
         av_expr_count_vars(scale->w_pexpr, vars_w, VARS_NB);
     if (scale->h_pexpr)
         av_expr_count_vars(scale->h_pexpr, vars_h, VARS_NB);
 
     if (vars_w[VAR_OUT_W] || vars_w[VAR_OW]) {
         av_log(ctx, AV_LOG_ERROR, "Width expression cannot be self-referencing: '%s'.\n", scale->w_expr);
         return AVERROR(EINVAL);
     }
 
     if (vars_h[VAR_OUT_H] || vars_h[VAR_OH]) {
         av_log(ctx, AV_LOG_ERROR, "Height expression cannot be self-referencing: '%s'.\n", scale->h_expr);
         return AVERROR(EINVAL);
     }
 
     if ((vars_w[VAR_OUT_H] || vars_w[VAR_OH]) &&
         (vars_h[VAR_OUT_W] || vars_h[VAR_OW])) {

         av_log(ctx, AV_LOG_WARNING, "Circular references detected for width '%s' and height '%s' - possibly invalid.\n", scale->w_expr, scale->h_expr);

     }
 
     if (ctx->filter != &ff_vf_scale2ref &&
         (vars_w[VAR_S2R_MAIN_W]    || vars_h[VAR_S2R_MAIN_W]    ||
          vars_w[VAR_S2R_MAIN_H]    || vars_h[VAR_S2R_MAIN_H]    ||
          vars_w[VAR_S2R_MAIN_A]    || vars_h[VAR_S2R_MAIN_A]    ||
          vars_w[VAR_S2R_MAIN_SAR]  || vars_h[VAR_S2R_MAIN_SAR]  ||
          vars_w[VAR_S2R_MAIN_DAR]  || vars_h[VAR_S2R_MAIN_DAR]  ||
          vars_w[VAR_S2R_MDAR]      || vars_h[VAR_S2R_MDAR]      ||
          vars_w[VAR_S2R_MAIN_HSUB] || vars_h[VAR_S2R_MAIN_HSUB] ||

          vars_w[VAR_S2R_MAIN_VSUB] || vars_h[VAR_S2R_MAIN_VSUB] ||
          vars_w[VAR_S2R_MAIN_N]    || vars_h[VAR_S2R_MAIN_N]    ||
          vars_w[VAR_S2R_MAIN_T]    || vars_h[VAR_S2R_MAIN_T]    ||
          vars_w[VAR_S2R_MAIN_POS]  || vars_h[VAR_S2R_MAIN_POS]) ) {

         av_log(ctx, AV_LOG_ERROR, "Expressions with scale2ref variables are not valid in scale filter.\n");
         return AVERROR(EINVAL);
     }
 

     if (scale->eval_mode == EVAL_MODE_INIT &&
         (vars_w[VAR_N]            || vars_h[VAR_N]           ||
          vars_w[VAR_T]            || vars_h[VAR_T]           ||
          vars_w[VAR_POS]          || vars_h[VAR_POS]         ||
          vars_w[VAR_S2R_MAIN_N]   || vars_h[VAR_S2R_MAIN_N]  ||
          vars_w[VAR_S2R_MAIN_T]   || vars_h[VAR_S2R_MAIN_T]  ||
          vars_w[VAR_S2R_MAIN_POS] || vars_h[VAR_S2R_MAIN_POS]) ) {
         av_log(ctx, AV_LOG_ERROR, "Expressions with frame variables 'n', 't', 'pos' are not valid in init eval_mode.\n");
         return AVERROR(EINVAL);
     }
 

     return 0;
 }
 

 static int scale_parse_expr(AVFilterContext *ctx, char *str_expr, AVExpr **pexpr_ptr, const char *var, const char *args)
 {
     ScaleContext *scale = ctx->priv;
     int ret, is_inited = 0;
     char *old_str_expr = NULL;
     AVExpr *old_pexpr = NULL;
 
     if (str_expr) {
         old_str_expr = av_strdup(str_expr);
         if (!old_str_expr)
             return AVERROR(ENOMEM);
         av_opt_set(scale, var, args, 0);
     }
 
     if (*pexpr_ptr) {
         old_pexpr = *pexpr_ptr;
         *pexpr_ptr = NULL;
         is_inited = 1;
     }
 

     ret = av_expr_parse(pexpr_ptr, args, var_names,

                         NULL, NULL, NULL, NULL, 0, ctx);
     if (ret < 0) {
         av_log(ctx, AV_LOG_ERROR, "Cannot parse expression for %s: '%s'\n", var, args);
         goto revert;
     }
 

     ret = check_exprs(ctx);
     if (ret < 0)
         goto revert;
 

     if (is_inited && (ret = config_props(ctx->outputs[0])) < 0)
         goto revert;
 
     av_expr_free(old_pexpr);
     old_pexpr = NULL;
     av_freep(&old_str_expr);
 
     return 0;
 
 revert:
     av_expr_free(*pexpr_ptr);
     *pexpr_ptr = NULL;
     if (old_str_expr) {
         av_opt_set(scale, var, old_str_expr, 0);
         av_free(old_str_expr);
     }
     if (old_pexpr)
         *pexpr_ptr = old_pexpr;
 
     return ret;
 }
 

 static av_cold int init_dict(AVFilterContext *ctx, AVDictionary **opts)

 {
     ScaleContext *scale = ctx->priv;

     int ret;
 

     if (scale->size_str && (scale->w_expr || scale->h_expr)) {
         av_log(ctx, AV_LOG_ERROR,
                "Size and width/height expressions cannot be set at the same time.\n");
             return AVERROR(EINVAL);
     }
 

     if (scale->w_expr && !scale->h_expr)
         FFSWAP(char *, scale->w_expr, scale->size_str);
 

     if (scale->size_str) {
         char buf[32];
         if ((ret = av_parse_video_size(&scale->w, &scale->h, scale->size_str)) < 0) {
             av_log(ctx, AV_LOG_ERROR,
                    "Invalid size '%s'\n", scale->size_str);
             return ret;
         }
         snprintf(buf, sizeof(buf)-1, "%d", scale->w);
         av_opt_set(scale, "w", buf, 0);
         snprintf(buf, sizeof(buf)-1, "%d", scale->h);
         av_opt_set(scale, "h", buf, 0);
     }
     if (!scale->w_expr)
         av_opt_set(scale, "w", "iw", 0);
     if (!scale->h_expr)
         av_opt_set(scale, "h", "ih", 0);
 

     ret = scale_parse_expr(ctx, NULL, &scale->w_pexpr, "width", scale->w_expr);
     if (ret < 0)
         return ret;
 
     ret = scale_parse_expr(ctx, NULL, &scale->h_pexpr, "height", scale->h_expr);
     if (ret < 0)
         return ret;
 

     av_log(ctx, AV_LOG_VERBOSE, "w:%s h:%s flags:'%s' interl:%d\n",
            scale->w_expr, scale->h_expr, (char *)av_x_if_null(scale->flags_str, ""), scale->interlaced);

     scale->flags = 0;

     if (scale->flags_str) {
         const AVClass *class = sws_get_class();
         const AVOption    *o = av_opt_find(&class, "sws_flags", NULL, 0,
                                            AV_OPT_SEARCH_FAKE_OBJ);
         int ret = av_opt_eval_flags(&class, o, scale->flags_str, &scale->flags);
         if (ret < 0)
             return ret;

     }

     scale->opts = *opts;
     *opts = NULL;

 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     ScaleContext *scale = ctx->priv;

     av_expr_free(scale->w_pexpr);
     av_expr_free(scale->h_pexpr);
     scale->w_pexpr = scale->h_pexpr = NULL;

     sws_freeContext(scale->sws);

     sws_freeContext(scale->isws[0]);
     sws_freeContext(scale->isws[1]);

     scale->sws = NULL;

     av_dict_free(&scale->opts);

 }
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats *formats;

     enum AVPixelFormat pix_fmt;

     int ret;

 
     if (ctx->inputs[0]) {

         const AVPixFmtDescriptor *desc = NULL;

         formats = NULL;

         while ((desc = av_pix_fmt_desc_next(desc))) {
             pix_fmt = av_pix_fmt_desc_get_id(desc);

             if ((sws_isSupportedInput(pix_fmt) ||
                  sws_isSupportedEndiannessConversion(pix_fmt))

                 && (ret = ff_add_format(&formats, pix_fmt)) < 0) {

                 return ret;
             }

         }

         if ((ret = ff_formats_ref(formats, &ctx->inputs[0]->out_formats)) < 0)
             return ret;

     }
     if (ctx->outputs[0]) {

         const AVPixFmtDescriptor *desc = NULL;

         formats = NULL;

         while ((desc = av_pix_fmt_desc_next(desc))) {
             pix_fmt = av_pix_fmt_desc_get_id(desc);

             if ((sws_isSupportedOutput(pix_fmt) || pix_fmt == AV_PIX_FMT_PAL8 ||

                  sws_isSupportedEndiannessConversion(pix_fmt))

                 && (ret = ff_add_format(&formats, pix_fmt)) < 0) {

                 return ret;
             }

         }

         if ((ret = ff_formats_ref(formats, &ctx->outputs[0]->in_formats)) < 0)
             return ret;

     }
 
     return 0;
 }
 

 static const int *parse_yuv_type(const char *s, enum AVColorSpace colorspace)
 {
     if (!s)
         s = "bt601";
 
     if (s && strstr(s, "bt709")) {
         colorspace = AVCOL_SPC_BT709;
     } else if (s && strstr(s, "fcc")) {
         colorspace = AVCOL_SPC_FCC;
     } else if (s && strstr(s, "smpte240m")) {
         colorspace = AVCOL_SPC_SMPTE240M;
     } else if (s && (strstr(s, "bt601") || strstr(s, "bt470") || strstr(s, "smpte170m"))) {
         colorspace = AVCOL_SPC_BT470BG;

     } else if (s && strstr(s, "bt2020")) {
         colorspace = AVCOL_SPC_BT2020_NCL;

     }
 

     if (colorspace < 1 || colorspace > 10 || colorspace == 8) {

         colorspace = AVCOL_SPC_BT470BG;
     }
 

     return sws_getCoefficients(colorspace);

 }
 

 static int scale_eval_dimensions(AVFilterContext *ctx)
 {
     ScaleContext *scale = ctx->priv;
     const char scale2ref = ctx->filter == &ff_vf_scale2ref;
     const AVFilterLink *inlink = scale2ref ? ctx->inputs[1] : ctx->inputs[0];
     const AVFilterLink *outlink = ctx->outputs[0];
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     const AVPixFmtDescriptor *out_desc = av_pix_fmt_desc_get(outlink->format);
     char *expr;
     int eval_w, eval_h;
     int ret;
     double res;
     const AVPixFmtDescriptor *main_desc;
     const AVFilterLink *main_link;
 
     if (scale2ref) {
         main_link = ctx->inputs[0];
         main_desc = av_pix_fmt_desc_get(main_link->format);
     }
 
     scale->var_values[VAR_IN_W]  = scale->var_values[VAR_IW] = inlink->w;
     scale->var_values[VAR_IN_H]  = scale->var_values[VAR_IH] = inlink->h;
     scale->var_values[VAR_OUT_W] = scale->var_values[VAR_OW] = NAN;
     scale->var_values[VAR_OUT_H] = scale->var_values[VAR_OH] = NAN;
     scale->var_values[VAR_A]     = (double) inlink->w / inlink->h;
     scale->var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?
         (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
     scale->var_values[VAR_DAR]   = scale->var_values[VAR_A] * scale->var_values[VAR_SAR];
     scale->var_values[VAR_HSUB]  = 1 << desc->log2_chroma_w;
     scale->var_values[VAR_VSUB]  = 1 << desc->log2_chroma_h;
     scale->var_values[VAR_OHSUB] = 1 << out_desc->log2_chroma_w;
     scale->var_values[VAR_OVSUB] = 1 << out_desc->log2_chroma_h;
 
     if (scale2ref) {

         scale->var_values[VAR_S2R_MAIN_W] = main_link->w;
         scale->var_values[VAR_S2R_MAIN_H] = main_link->h;
         scale->var_values[VAR_S2R_MAIN_A] = (double) main_link->w / main_link->h;
         scale->var_values[VAR_S2R_MAIN_SAR] = main_link->sample_aspect_ratio.num ?

             (double) main_link->sample_aspect_ratio.num / main_link->sample_aspect_ratio.den : 1;

         scale->var_values[VAR_S2R_MAIN_DAR] = scale->var_values[VAR_S2R_MDAR] =
             scale->var_values[VAR_S2R_MAIN_A] * scale->var_values[VAR_S2R_MAIN_SAR];
         scale->var_values[VAR_S2R_MAIN_HSUB] = 1 << main_desc->log2_chroma_w;
         scale->var_values[VAR_S2R_MAIN_VSUB] = 1 << main_desc->log2_chroma_h;

     }
 
     res = av_expr_eval(scale->w_pexpr, scale->var_values, NULL);
     eval_w = scale->var_values[VAR_OUT_W] = scale->var_values[VAR_OW] = (int) res == 0 ? inlink->w : (int) res;
 
     res = av_expr_eval(scale->h_pexpr, scale->var_values, NULL);
     if (isnan(res)) {
         expr = scale->h_expr;
         ret = AVERROR(EINVAL);
         goto fail;
     }
     eval_h = scale->var_values[VAR_OUT_H] = scale->var_values[VAR_OH] = (int) res == 0 ? inlink->h : (int) res;
 
     res = av_expr_eval(scale->w_pexpr, scale->var_values, NULL);
     if (isnan(res)) {
         expr = scale->w_expr;
         ret = AVERROR(EINVAL);
         goto fail;
     }
     eval_w = scale->var_values[VAR_OUT_W] = scale->var_values[VAR_OW] = (int) res == 0 ? inlink->w : (int) res;
 
     scale->w = eval_w;
     scale->h = eval_h;
 
     return 0;
 
 fail:
     av_log(ctx, AV_LOG_ERROR,
            "Error when evaluating the expression '%s'.\n", expr);
     return ret;
 }
 

 static int config_props(AVFilterLink *outlink)
 {
     AVFilterContext *ctx = outlink->src;

     AVFilterLink *inlink0 = outlink->src->inputs[0];
     AVFilterLink *inlink  = ctx->filter == &ff_vf_scale2ref ?
                             outlink->src->inputs[1] :
                             outlink->src->inputs[0];

     enum AVPixelFormat outfmt = outlink->format;

     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);

     ScaleContext *scale = ctx->priv;

     int ret;

     if ((ret = scale_eval_dimensions(ctx)) < 0)

         goto fail;

     ff_scale_adjust_dimensions(inlink, &scale->w, &scale->h,

                                scale->force_original_aspect_ratio,
                                scale->force_divisible_by);

     if (scale->w > INT_MAX ||
         scale->h > INT_MAX ||
         (scale->h * inlink->w) > INT_MAX ||
         (scale->w * inlink->h) > INT_MAX)

         av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");
 

     outlink->w = scale->w;
     outlink->h = scale->h;

 
     /* TODO: make algorithm configurable */
 

     scale->input_is_pal = desc->flags & AV_PIX_FMT_FLAG_PAL;

     if (outfmt == AV_PIX_FMT_PAL8) outfmt = AV_PIX_FMT_BGR8;

     scale->output_is_pal = av_pix_fmt_desc_get(outfmt)->flags & AV_PIX_FMT_FLAG_PAL ||

                            av_pix_fmt_desc_get(outfmt)->flags & FF_PSEUDOPAL;

     if (scale->sws)

         sws_freeContext(scale->sws);

     if (scale->isws[0])
         sws_freeContext(scale->isws[0]);
     if (scale->isws[1])
         sws_freeContext(scale->isws[1]);
     scale->isws[0] = scale->isws[1] = scale->sws = NULL;

     if (inlink0->w == outlink->w &&
         inlink0->h == outlink->h &&

         !scale->out_color_matrix &&

         scale->in_range == scale->out_range &&

         inlink0->format == outlink->format)

         ;

     else {

         struct SwsContext **swscs[3] = {&scale->sws, &scale->isws[0], &scale->isws[1]};
         int i;
 
         for (i = 0; i < 3; i++) {

             int in_v_chr_pos = scale->in_v_chr_pos, out_v_chr_pos = scale->out_v_chr_pos;

             struct SwsContext **s = swscs[i];
             *s = sws_alloc_context();
             if (!*s)
                 return AVERROR(ENOMEM);
 

             av_opt_set_int(*s, "srcw", inlink0 ->w, 0);
             av_opt_set_int(*s, "srch", inlink0 ->h >> !!i, 0);
             av_opt_set_int(*s, "src_format", inlink0->format, 0);

             av_opt_set_int(*s, "dstw", outlink->w, 0);
             av_opt_set_int(*s, "dsth", outlink->h >> !!i, 0);
             av_opt_set_int(*s, "dst_format", outfmt, 0);
             av_opt_set_int(*s, "sws_flags", scale->flags, 0);

             av_opt_set_int(*s, "param0", scale->param[0], 0);
             av_opt_set_int(*s, "param1", scale->param[1], 0);

             if (scale->in_range != AVCOL_RANGE_UNSPECIFIED)
                 av_opt_set_int(*s, "src_range",
                                scale->in_range == AVCOL_RANGE_JPEG, 0);
             if (scale->out_range != AVCOL_RANGE_UNSPECIFIED)
                 av_opt_set_int(*s, "dst_range",
                                scale->out_range == AVCOL_RANGE_JPEG, 0);

             if (scale->opts) {
                 AVDictionaryEntry *e = NULL;
                 while ((e = av_dict_get(scale->opts, "", e, AV_DICT_IGNORE_SUFFIX))) {
                     if ((ret = av_opt_set(*s, e->key, e->value, 0)) < 0)
                         return ret;
                 }
             }

             /* Override YUV420P default settings to have the correct (MPEG-2) chroma positions

              * MPEG-2 chroma positions are used by convention
              * XXX: support other 4:2:0 pixel formats */

             if (inlink0->format == AV_PIX_FMT_YUV420P && scale->in_v_chr_pos == -513) {

                 in_v_chr_pos = (i == 0) ? 128 : (i == 1) ? 64 : 192;

             }
 

             if (outlink->format == AV_PIX_FMT_YUV420P && scale->out_v_chr_pos == -513) {

                 out_v_chr_pos = (i == 0) ? 128 : (i == 1) ? 64 : 192;

             }
 

             av_opt_set_int(*s, "src_h_chr_pos", scale->in_h_chr_pos, 0);

             av_opt_set_int(*s, "src_v_chr_pos", in_v_chr_pos, 0);

             av_opt_set_int(*s, "dst_h_chr_pos", scale->out_h_chr_pos, 0);

             av_opt_set_int(*s, "dst_v_chr_pos", out_v_chr_pos, 0);

             if ((ret = sws_init_context(*s, NULL, NULL)) < 0)
                 return ret;

             if (!scale->interlaced)
                 break;

         }

     }

     if (inlink0->sample_aspect_ratio.num){
         outlink->sample_aspect_ratio = av_mul_q((AVRational){outlink->h * inlink0->w, outlink->w * inlink0->h}, inlink0->sample_aspect_ratio);

     } else

         outlink->sample_aspect_ratio = inlink0->sample_aspect_ratio;

     av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d fmt:%s sar:%d/%d -> w:%d h:%d fmt:%s sar:%d/%d flags:0x%0x\n",

            inlink ->w, inlink ->h, av_get_pix_fmt_name( inlink->format),

            inlink->sample_aspect_ratio.num, inlink->sample_aspect_ratio.den,

            outlink->w, outlink->h, av_get_pix_fmt_name(outlink->format),

            outlink->sample_aspect_ratio.num, outlink->sample_aspect_ratio.den,
            scale->flags);

     return 0;

 
 fail:
     return ret;

 }
 

 static int config_props_ref(AVFilterLink *outlink)
 {
     AVFilterLink *inlink = outlink->src->inputs[1];
 
     outlink->w = inlink->w;
     outlink->h = inlink->h;
     outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;

     outlink->time_base = inlink->time_base;

     outlink->frame_rate = inlink->frame_rate;

 
     return 0;
 }
 

 static int request_frame(AVFilterLink *outlink)
 {
     return ff_request_frame(outlink->src->inputs[0]);
 }
 
 static int request_frame_ref(AVFilterLink *outlink)
 {
     return ff_request_frame(outlink->src->inputs[1]);
 }
 

 static int scale_slice(AVFilterLink *link, AVFrame *out_buf, AVFrame *cur_pic, struct SwsContext *sws, int y, int h, int mul, int field)

 {
     ScaleContext *scale = link->dst->priv;

     const uint8_t *in[4];
     uint8_t *out[4];

     int in_stride[4],out_stride[4];
     int i;
 

     for (i=0; i<4; i++) {

         int vsub= ((i+1)&2) ? scale->vsub : 0;
          in_stride[i] = cur_pic->linesize[i] * mul;
         out_stride[i] = out_buf->linesize[i] * mul;
          in[i] = cur_pic->data[i] + ((y>>vsub)+field) * cur_pic->linesize[i];
         out[i] = out_buf->data[i] +            field  * out_buf->linesize[i];
     }

     if (scale->input_is_pal)

          in[1] = cur_pic->data[1];

     if (scale->output_is_pal)

         out[1] = out_buf->data[1];
 
     return sws_scale(sws, in, in_stride, y/mul, h,
                          out,out_stride);
 }
 

 #define TS2T(ts, tb) ((ts) == AV_NOPTS_VALUE ? NAN : (double)(ts) * av_q2d(tb))
 

 static int scale_frame(AVFilterLink *link, AVFrame *in, AVFrame **frame_out)

 {

     AVFilterContext *ctx = link->dst;
     ScaleContext *scale = ctx->priv;
     AVFilterLink *outlink = ctx->outputs[0];

     AVFrame *out;

     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
     char buf[32];

     int in_range;

     int frame_changed;

     *frame_out = NULL;

     if (in->colorspace == AVCOL_SPC_YCGCO)

         av_log(link->dst, AV_LOG_WARNING, "Detected unsupported YCgCo colorspace.\n");
 

     frame_changed = in->width  != link->w ||
                     in->height != link->h ||
                     in->format != link->format ||
                     in->sample_aspect_ratio.den != link->sample_aspect_ratio.den ||
                     in->sample_aspect_ratio.num != link->sample_aspect_ratio.num;
 

     if (scale->eval_mode == EVAL_MODE_FRAME || frame_changed) {

         int ret;

         unsigned vars_w[VARS_NB] = { 0 }, vars_h[VARS_NB] = { 0 };
 
         av_expr_count_vars(scale->w_pexpr, vars_w, VARS_NB);
         av_expr_count_vars(scale->h_pexpr, vars_h, VARS_NB);
 
         if (scale->eval_mode == EVAL_MODE_FRAME &&
             !frame_changed &&
             ctx->filter != &ff_vf_scale2ref &&
             !(vars_w[VAR_N] || vars_w[VAR_T] || vars_w[VAR_POS]) &&
             !(vars_h[VAR_N] || vars_h[VAR_T] || vars_h[VAR_POS]) &&
             scale->w && scale->h)
             goto scale;

 
         if (scale->eval_mode == EVAL_MODE_INIT) {
             snprintf(buf, sizeof(buf)-1, "%d", outlink->w);
             av_opt_set(scale, "w", buf, 0);
             snprintf(buf, sizeof(buf)-1, "%d", outlink->h);
             av_opt_set(scale, "h", buf, 0);

 
             ret = scale_parse_expr(ctx, NULL, &scale->w_pexpr, "width", scale->w_expr);
             if (ret < 0)
                 return ret;
 
             ret = scale_parse_expr(ctx, NULL, &scale->h_pexpr, "height", scale->h_expr);
             if (ret < 0)
                 return ret;

         }

         if (ctx->filter == &ff_vf_scale2ref) {
             scale->var_values[VAR_S2R_MAIN_N] = link->frame_count_out;
             scale->var_values[VAR_S2R_MAIN_T] = TS2T(in->pts, link->time_base);
             scale->var_values[VAR_S2R_MAIN_POS] = in->pkt_pos == -1 ? NAN : in->pkt_pos;
         } else {
             scale->var_values[VAR_N] = link->frame_count_out;
             scale->var_values[VAR_T] = TS2T(in->pts, link->time_base);
             scale->var_values[VAR_POS] = in->pkt_pos == -1 ? NAN : in->pkt_pos;
         }
 

         link->dst->inputs[0]->format = in->format;

         link->dst->inputs[0]->w      = in->width;
         link->dst->inputs[0]->h      = in->height;

         link->dst->inputs[0]->sample_aspect_ratio.den = in->sample_aspect_ratio.den;
         link->dst->inputs[0]->sample_aspect_ratio.num = in->sample_aspect_ratio.num;
 

         if ((ret = config_props(outlink)) < 0)
             return ret;

     }
 

 scale:

     if (!scale->sws) {
         *frame_out = in;
         return 0;
     }

 
     scale->hsub = desc->log2_chroma_w;
     scale->vsub = desc->log2_chroma_h;
 

     out = ff_get_video_buffer(outlink, outlink->w, outlink->h);

     if (!out) {

         av_frame_free(&in);

         return AVERROR(ENOMEM);
     }

     *frame_out = out;

     av_frame_copy_props(out, in);
     out->width  = outlink->w;
     out->height = outlink->h;

     if (scale->output_is_pal)

         avpriv_set_systematic_pal2((uint32_t*)out->data[1], outlink->format == AV_PIX_FMT_PAL8 ? AV_PIX_FMT_BGR8 : outlink->format);
 

     in_range = in->color_range;

     if (   scale->in_color_matrix
         || scale->out_color_matrix
         || scale-> in_range != AVCOL_RANGE_UNSPECIFIED

         || in_range != AVCOL_RANGE_UNSPECIFIED

         || scale->out_range != AVCOL_RANGE_UNSPECIFIED) {
         int in_full, out_full, brightness, contrast, saturation;
         const int *inv_table, *table;
 
         sws_getColorspaceDetails(scale->sws, (int **)&inv_table, &in_full,
                                  (int **)&table, &out_full,
                                  &brightness, &contrast, &saturation);
 
         if (scale->in_color_matrix)

             inv_table = parse_yuv_type(scale->in_color_matrix, in->colorspace);

         if (scale->out_color_matrix)
             table     = parse_yuv_type(scale->out_color_matrix, AVCOL_SPC_UNSPECIFIED);

         else if (scale->in_color_matrix)
             table = inv_table;

         if (scale-> in_range != AVCOL_RANGE_UNSPECIFIED)
             in_full  = (scale-> in_range == AVCOL_RANGE_JPEG);

         else if (in_range != AVCOL_RANGE_UNSPECIFIED)
             in_full  = (in_range == AVCOL_RANGE_JPEG);

         if (scale->out_range != AVCOL_RANGE_UNSPECIFIED)
             out_full = (scale->out_range == AVCOL_RANGE_JPEG);
 

         sws_setColorspaceDetails(scale->sws, inv_table, in_full,
                                  table, out_full,
                                  brightness, contrast, saturation);
         if (scale->isws[0])

             sws_setColorspaceDetails(scale->isws[0], inv_table, in_full,
                                      table, out_full,
                                      brightness, contrast, saturation);

         if (scale->isws[1])

             sws_setColorspaceDetails(scale->isws[1], inv_table, in_full,
                                      table, out_full,
                                      brightness, contrast, saturation);

         out->color_range = out_full ? AVCOL_RANGE_JPEG : AVCOL_RANGE_MPEG;

     }
 

     av_reduce(&out->sample_aspect_ratio.num, &out->sample_aspect_ratio.den,
               (int64_t)in->sample_aspect_ratio.num * outlink->h * link->w,
               (int64_t)in->sample_aspect_ratio.den * outlink->w * link->h,

               INT_MAX);

     if (scale->interlaced>0 || (scale->interlaced<0 && in->interlaced_frame)) {

         scale_slice(link, out, in, scale->isws[0], 0, (link->h+1)/2, 2, 0);
         scale_slice(link, out, in, scale->isws[1], 0,  link->h   /2, 2, 1);

     } else if (scale->nb_slices) {

         int i, slice_h, slice_start, slice_end = 0;
         const int nb_slices = FFMIN(scale->nb_slices, link->h);
         for (i = 0; i < nb_slices; i++) {
             slice_start = slice_end;
             slice_end   = (link->h * (i+1)) / nb_slices;
             slice_h     = slice_end - slice_start;
             scale_slice(link, out, in, scale->sws, slice_start, slice_h, 1, 0);
         }

     } else {

         scale_slice(link, out, in, scale->sws, 0, link->h, 1, 0);

     }

     av_frame_free(&in);

     return 0;
 }
 
 static int filter_frame(AVFilterLink *link, AVFrame *in)
 {
     AVFilterContext *ctx = link->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     AVFrame *out;
     int ret;
 
     ret = scale_frame(link, in, &out);
     if (out)
         return ff_filter_frame(outlink, out);
 
     return ret;

 }
 

 static int filter_frame_ref(AVFilterLink *link, AVFrame *in)
 {

     ScaleContext *scale = link->dst->priv;

     AVFilterLink *outlink = link->dst->outputs[1];

     int frame_changed;
 
     frame_changed = in->width  != link->w ||
                     in->height != link->h ||
                     in->format != link->format ||
                     in->sample_aspect_ratio.den != link->sample_aspect_ratio.den ||
                     in->sample_aspect_ratio.num != link->sample_aspect_ratio.num;
 
     if (frame_changed) {
         link->format = in->format;
         link->w = in->width;
         link->h = in->height;
         link->sample_aspect_ratio.num = in->sample_aspect_ratio.num;
         link->sample_aspect_ratio.den = in->sample_aspect_ratio.den;
 
         config_props_ref(outlink);
     }

     if (scale->eval_mode == EVAL_MODE_FRAME) {
         scale->var_values[VAR_N] = link->frame_count_out;
         scale->var_values[VAR_T] = TS2T(in->pts, link->time_base);
         scale->var_values[VAR_POS] = in->pkt_pos == -1 ? NAN : in->pkt_pos;
     }
 

     return ff_filter_frame(outlink, in);
 }
 

 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
                            char *res, int res_len, int flags)
 {
     ScaleContext *scale = ctx->priv;

     char *str_expr;
     AVExpr **pexpr_ptr;
     int ret, w, h;

     w = !strcmp(cmd, "width")  || !strcmp(cmd, "w");
     h = !strcmp(cmd, "height")  || !strcmp(cmd, "h");

     if (w || h) {
         str_expr = w ? scale->w_expr : scale->h_expr;
         pexpr_ptr = w ? &scale->w_pexpr : &scale->h_pexpr;

         ret = scale_parse_expr(ctx, str_expr, pexpr_ptr, cmd, args);

     } else
         ret = AVERROR(ENOSYS);
 

     if (ret < 0)
         av_log(ctx, AV_LOG_ERROR, "Failed to process command. Continuing with existing parameters.\n");
 

     return ret;
 }
 

 static const AVClass *child_class_next(const AVClass *prev)
 {
     return prev ? NULL : sws_get_class();
 }
 

 #define OFFSET(x) offsetof(ScaleContext, x)

 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

 #define TFLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM

 
 static const AVOption scale_options[] = {

     { "w",     "Output video width",          OFFSET(w_expr),    AV_OPT_TYPE_STRING,        .flags = TFLAGS },
     { "width", "Output video width",          OFFSET(w_expr),    AV_OPT_TYPE_STRING,        .flags = TFLAGS },
     { "h",     "Output video height",         OFFSET(h_expr),    AV_OPT_TYPE_STRING,        .flags = TFLAGS },
     { "height","Output video height",         OFFSET(h_expr),    AV_OPT_TYPE_STRING,        .flags = TFLAGS },

     { "flags", "Flags to pass to libswscale", OFFSET(flags_str), AV_OPT_TYPE_STRING, { .str = "bilinear" }, .flags = FLAGS },

     { "interl", "set interlacing", OFFSET(interlaced), AV_OPT_TYPE_BOOL, {.i64 = 0 }, -1, 1, FLAGS },

     { "size",   "set video size",          OFFSET(size_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, FLAGS },
     { "s",      "set video size",          OFFSET(size_str), AV_OPT_TYPE_STRING, {.str = NULL}, 0, FLAGS },

     {  "in_color_matrix", "set input YCbCr type",   OFFSET(in_color_matrix),  AV_OPT_TYPE_STRING, { .str = "auto" }, .flags = FLAGS, "color" },
     { "out_color_matrix", "set output YCbCr type",  OFFSET(out_color_matrix), AV_OPT_TYPE_STRING, { .str = NULL }, .flags = FLAGS,  "color"},
         { "auto",        NULL, 0, AV_OPT_TYPE_CONST, { .str = "auto" },      0, 0, FLAGS, "color" },
         { "bt601",       NULL, 0, AV_OPT_TYPE_CONST, { .str = "bt601" },     0, 0, FLAGS, "color" },
         { "bt470",       NULL, 0, AV_OPT_TYPE_CONST, { .str = "bt470" },     0, 0, FLAGS, "color" },
         { "smpte170m",   NULL, 0, AV_OPT_TYPE_CONST, { .str = "smpte170m" }, 0, 0, FLAGS, "color" },
         { "bt709",       NULL, 0, AV_OPT_TYPE_CONST, { .str = "bt709" },     0, 0, FLAGS, "color" },
         { "fcc",         NULL, 0, AV_OPT_TYPE_CONST, { .str = "fcc" },       0, 0, FLAGS, "color" },
         { "smpte240m",   NULL, 0, AV_OPT_TYPE_CONST, { .str = "smpte240m" }, 0, 0, FLAGS, "color" },
         { "bt2020",      NULL, 0, AV_OPT_TYPE_CONST, { .str = "bt2020" },    0, 0, FLAGS, "color" },

     {  "in_range", "set input color range",  OFFSET( in_range), AV_OPT_TYPE_INT, {.i64 = AVCOL_RANGE_UNSPECIFIED }, 0, 2, FLAGS, "range" },
     { "out_range", "set output color range", OFFSET(out_range), AV_OPT_TYPE_INT, {.i64 = AVCOL_RANGE_UNSPECIFIED }, 0, 2, FLAGS, "range" },
     { "auto",   NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_UNSPECIFIED }, 0, 0, FLAGS, "range" },

     { "unknown", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_UNSPECIFIED }, 0, 0, FLAGS, "range" },

     { "full",   NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_JPEG}, 0, 0, FLAGS, "range" },

     { "limited",NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_MPEG}, 0, 0, FLAGS, "range" },

     { "jpeg",   NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_JPEG}, 0, 0, FLAGS, "range" },
     { "mpeg",   NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_MPEG}, 0, 0, FLAGS, "range" },

     { "tv",     NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_MPEG}, 0, 0, FLAGS, "range" },
     { "pc",     NULL, 0, AV_OPT_TYPE_CONST, {.i64 = AVCOL_RANGE_JPEG}, 0, 0, FLAGS, "range" },

     { "in_v_chr_pos",   "input vertical chroma position in luma grid/256"  ,   OFFSET(in_v_chr_pos),  AV_OPT_TYPE_INT, { .i64 = -513}, -513, 512, FLAGS },
     { "in_h_chr_pos",   "input horizontal chroma position in luma grid/256",   OFFSET(in_h_chr_pos),  AV_OPT_TYPE_INT, { .i64 = -513}, -513, 512, FLAGS },
     { "out_v_chr_pos",   "output vertical chroma position in luma grid/256"  , OFFSET(out_v_chr_pos), AV_OPT_TYPE_INT, { .i64 = -513}, -513, 512, FLAGS },
     { "out_h_chr_pos",   "output horizontal chroma position in luma grid/256", OFFSET(out_h_chr_pos), AV_OPT_TYPE_INT, { .i64 = -513}, -513, 512, FLAGS },

     { "force_original_aspect_ratio", "decrease or increase w/h if necessary to keep the original AR", OFFSET(force_original_aspect_ratio), AV_OPT_TYPE_INT, { .i64 = 0}, 0, 2, FLAGS, "force_oar" },
     { "disable",  NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 0 }, 0, 0, FLAGS, "force_oar" },
     { "decrease", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 1 }, 0, 0, FLAGS, "force_oar" },
     { "increase", NULL, 0, AV_OPT_TYPE_CONST, {.i64 = 2 }, 0, 0, FLAGS, "force_oar" },

     { "force_divisible_by", "enforce that the output resolution is divisible by a defined integer when force_original_aspect_ratio is used", OFFSET(force_divisible_by), AV_OPT_TYPE_INT, { .i64 = 1}, 1, 256, FLAGS },

     { "param0", "Scaler param 0",             OFFSET(param[0]),  AV_OPT_TYPE_DOUBLE, { .dbl = SWS_PARAM_DEFAULT  }, INT_MIN, INT_MAX, FLAGS },
     { "param1", "Scaler param 1",             OFFSET(param[1]),  AV_OPT_TYPE_DOUBLE, { .dbl = SWS_PARAM_DEFAULT  }, INT_MIN, INT_MAX, FLAGS },

     { "nb_slices", "set the number of slices (debug purpose only)", OFFSET(nb_slices), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },

     { "eval", "specify when to evaluate expressions", OFFSET(eval_mode), AV_OPT_TYPE_INT, {.i64 = EVAL_MODE_INIT}, 0, EVAL_MODE_NB-1, FLAGS, "eval" },
          { "init",  "eval expressions once during initialization", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_INIT},  .flags = FLAGS, .unit = "eval" },
          { "frame", "eval expressions during initialization and per-frame", 0, AV_OPT_TYPE_CONST, {.i64=EVAL_MODE_FRAME}, .flags = FLAGS, .unit = "eval" },

     { NULL }

 };
 

 static const AVClass scale_class = {
     .class_name       = "scale",
     .item_name        = av_default_item_name,
     .option           = scale_options,
     .version          = LIBAVUTIL_VERSION_INT,

     .category         = AV_CLASS_CATEGORY_FILTER,

     .child_class_next = child_class_next,
 };

 static const AVFilterPad avfilter_vf_scale_inputs[] = {
     {

         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,

         .filter_frame = filter_frame,

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

 AVFilter ff_vf_scale = {

     .name            = "scale",
     .description     = NULL_IF_CONFIG_SMALL("Scale the input video size and/or convert the image format."),
     .init_dict       = init_dict,
     .uninit          = uninit,
     .query_formats   = query_formats,
     .priv_size       = sizeof(ScaleContext),
     .priv_class      = &scale_class,
     .inputs          = avfilter_vf_scale_inputs,
     .outputs         = avfilter_vf_scale_outputs,
     .process_command = process_command,

 };

 
 static const AVClass scale2ref_class = {
     .class_name       = "scale2ref",
     .item_name        = av_default_item_name,
     .option           = scale_options,
     .version          = LIBAVUTIL_VERSION_INT,
     .category         = AV_CLASS_CATEGORY_FILTER,
     .child_class_next = child_class_next,
 };
 
 static const AVFilterPad avfilter_vf_scale2ref_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
     },
     {
         .name         = "ref",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame_ref,
     },
     { NULL }
 };
 
 static const AVFilterPad avfilter_vf_scale2ref_outputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_props,

         .request_frame= request_frame,

     },
     {
         .name         = "ref",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_props_ref,

         .request_frame= request_frame_ref,

     },
     { NULL }
 };
 
 AVFilter ff_vf_scale2ref = {
     .name            = "scale2ref",
     .description     = NULL_IF_CONFIG_SMALL("Scale the input video size and/or convert the image format to the given reference."),
     .init_dict       = init_dict,
     .uninit          = uninit,
     .query_formats   = query_formats,
     .priv_size       = sizeof(ScaleContext),
     .priv_class      = &scale2ref_class,
     .inputs          = avfilter_vf_scale2ref_inputs,
     .outputs         = avfilter_vf_scale2ref_outputs,
     .process_command = process_command,
 };