/*

  * 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

  * video crop filter
  */
 

 #include <stdio.h>
 

 #include "avfilter.h"

 #include "formats.h"

 #include "internal.h"

 #include "video.h"

 #include "libavutil/eval.h"
 #include "libavutil/avstring.h"

 #include "libavutil/internal.h"

 #include "libavutil/libm.h"

 #include "libavutil/imgutils.h"

 #include "libavutil/mathematics.h"

 #include "libavutil/opt.h"

 static const char *const var_names[] = {

     "in_w", "iw",   ///< width  of the input video
     "in_h", "ih",   ///< height of the input video
     "out_w", "ow",  ///< width  of the cropped video
     "out_h", "oh",  ///< height of the cropped video

     "a",
     "sar",
     "dar",
     "hsub",
     "vsub",

     "x",
     "y",
     "n",            ///< number of frame
     "pos",          ///< position in the file
     "t",            ///< timestamp expressed in seconds
     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_X,
     VAR_Y,
     VAR_N,

     VAR_POS,

     VAR_T,
     VAR_VARS_NB

 };
 

 typedef struct CropContext {

     const AVClass *class;

     int  x;             ///< x offset of the non-cropped area with respect to the input area
     int  y;             ///< y offset of the non-cropped area with respect to the input area
     int  w;             ///< width of the cropped area
     int  h;             ///< height of the cropped area
 

     AVRational out_sar; ///< output sample aspect ratio
     int keep_aspect;    ///< keep display aspect ratio when cropping

     int exact;          ///< exact cropping, for subsampled formats

     int max_step[4];    ///< max pixel step for each plane, expressed as a number of bytes

     int hsub, vsub;     ///< chroma subsampling

     char *x_expr, *y_expr, *w_expr, *h_expr;

     AVExpr *x_pexpr, *y_pexpr;  /* parsed expressions for x and y */

     double var_values[VAR_VARS_NB];

 } CropContext;
 
 static int query_formats(AVFilterContext *ctx)
 {

     AVFilterFormats *formats = NULL;

     int fmt, ret;

     for (fmt = 0; av_pix_fmt_desc_get(fmt); fmt++) {

         const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(fmt);
         if (!(desc->flags & (AV_PIX_FMT_FLAG_HWACCEL | AV_PIX_FMT_FLAG_BITSTREAM)) &&

             !((desc->log2_chroma_w || desc->log2_chroma_h) && !(desc->flags & AV_PIX_FMT_FLAG_PLANAR)) &&
             (ret = ff_add_format(&formats, fmt)) < 0)
             return ret;

     }
 

     return ff_set_common_formats(ctx, formats);

 }
 

 static av_cold void uninit(AVFilterContext *ctx)
 {

     CropContext *s = ctx->priv;

     av_expr_free(s->x_pexpr);
     s->x_pexpr = NULL;
     av_expr_free(s->y_pexpr);
     s->y_pexpr = NULL;

 }
 
 static inline int normalize_double(int *n, double d)
 {
     int ret = 0;
 
     if (isnan(d)) {
         ret = AVERROR(EINVAL);
     } else if (d > INT_MAX || d < INT_MIN) {
         *n = d > INT_MAX ? INT_MAX : INT_MIN;
         ret = AVERROR(EINVAL);
     } else

         *n = lrint(d);

 
     return ret;
 }
 

 static int config_input(AVFilterLink *link)
 {
     AVFilterContext *ctx = link->dst;

     CropContext *s = ctx->priv;

     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(link->format);

     int ret;
     const char *expr;
     double res;
 

     s->var_values[VAR_IN_W]  = s->var_values[VAR_IW] = ctx->inputs[0]->w;
     s->var_values[VAR_IN_H]  = s->var_values[VAR_IH] = ctx->inputs[0]->h;

     s->var_values[VAR_A]     = (float) link->w / link->h;
     s->var_values[VAR_SAR]   = link->sample_aspect_ratio.num ? av_q2d(link->sample_aspect_ratio) : 1;
     s->var_values[VAR_DAR]   = s->var_values[VAR_A] * s->var_values[VAR_SAR];
     s->var_values[VAR_HSUB]  = 1<<pix_desc->log2_chroma_w;
     s->var_values[VAR_VSUB]  = 1<<pix_desc->log2_chroma_h;

     s->var_values[VAR_X]     = NAN;
     s->var_values[VAR_Y]     = NAN;
     s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = NAN;
     s->var_values[VAR_OUT_H] = s->var_values[VAR_OH] = NAN;
     s->var_values[VAR_N]     = 0;
     s->var_values[VAR_T]     = NAN;

     s->var_values[VAR_POS]   = NAN;

 
     av_image_fill_max_pixsteps(s->max_step, NULL, pix_desc);
     s->hsub = pix_desc->log2_chroma_w;
     s->vsub = pix_desc->log2_chroma_h;
 

     if ((ret = av_expr_parse_and_eval(&res, (expr = s->w_expr),

                                       var_names, s->var_values,

                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto fail_expr;

     s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = res;

     if ((ret = av_expr_parse_and_eval(&res, (expr = s->h_expr),

                                       var_names, s->var_values,

                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto fail_expr;

     s->var_values[VAR_OUT_H] = s->var_values[VAR_OH] = res;

     /* evaluate again ow as it may depend on oh */

     if ((ret = av_expr_parse_and_eval(&res, (expr = s->w_expr),

                                       var_names, s->var_values,

                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto fail_expr;
 

     s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = res;
     if (normalize_double(&s->w, s->var_values[VAR_OUT_W]) < 0 ||
         normalize_double(&s->h, s->var_values[VAR_OUT_H]) < 0) {

         av_log(ctx, AV_LOG_ERROR,
                "Too big value or invalid expression for out_w/ow or out_h/oh. "
                "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",

                s->w_expr, s->h_expr);

         return AVERROR(EINVAL);
     }

 
     if (!s->exact) {
         s->w &= ~((1 << s->hsub) - 1);
         s->h &= ~((1 << s->vsub) - 1);
     }

     av_expr_free(s->x_pexpr);
     av_expr_free(s->y_pexpr);
     s->x_pexpr = s->y_pexpr = NULL;

     if ((ret = av_expr_parse(&s->x_pexpr, s->x_expr, var_names,

                              NULL, NULL, NULL, NULL, 0, ctx)) < 0 ||

         (ret = av_expr_parse(&s->y_pexpr, s->y_expr, var_names,

                              NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         return AVERROR(EINVAL);

     if (s->keep_aspect) {

         AVRational dar = av_mul_q(link->sample_aspect_ratio,
                                   (AVRational){ link->w, link->h });

         av_reduce(&s->out_sar.num, &s->out_sar.den,
                   dar.num * s->h, dar.den * s->w, INT_MAX);

     } else

         s->out_sar = link->sample_aspect_ratio;

     av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d sar:%d/%d -> w:%d h:%d sar:%d/%d\n",

            link->w, link->h, link->sample_aspect_ratio.num, link->sample_aspect_ratio.den,

            s->w, s->h, s->out_sar.num, s->out_sar.den);

     if (s->w <= 0 || s->h <= 0 ||
         s->w > link->w || s->h > link->h) {

         av_log(ctx, AV_LOG_ERROR,

                "Invalid too big or non positive size for width '%d' or height '%d'\n",

                s->w, s->h);

         return AVERROR(EINVAL);

     }
 

     /* set default, required in the case the first computed value for x/y is NAN */

     s->x = (link->w - s->w) / 2;
     s->y = (link->h - s->h) / 2;

     if (!s->exact) {
         s->x &= ~((1 << s->hsub) - 1);
         s->y &= ~((1 << s->vsub) - 1);
     }

     return 0;

 
 fail_expr:
     av_log(NULL, AV_LOG_ERROR, "Error when evaluating the expression '%s'\n", expr);
     return ret;

 }
 
 static int config_output(AVFilterLink *link)
 {

     CropContext *s = link->src->priv;

     link->w = s->w;
     link->h = s->h;

     link->sample_aspect_ratio = s->out_sar;

 
     return 0;
 }
 

 static int filter_frame(AVFilterLink *link, AVFrame *frame)

 {

     AVFilterContext *ctx = link->dst;

     CropContext *s = ctx->priv;

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

     int i;
 

     frame->width  = s->w;
     frame->height = s->h;

     s->var_values[VAR_N] = link->frame_count_out;

     s->var_values[VAR_T] = frame->pts == AV_NOPTS_VALUE ?

         NAN : frame->pts * av_q2d(link->time_base);

     s->var_values[VAR_POS] = frame->pkt_pos == -1 ?
         NAN : frame->pkt_pos;

     s->var_values[VAR_X] = av_expr_eval(s->x_pexpr, s->var_values, NULL);
     s->var_values[VAR_Y] = av_expr_eval(s->y_pexpr, s->var_values, NULL);

     /* It is necessary if x is expressed from y  */

     s->var_values[VAR_X] = av_expr_eval(s->x_pexpr, s->var_values, NULL);
 
     normalize_double(&s->x, s->var_values[VAR_X]);
     normalize_double(&s->y, s->var_values[VAR_Y]);
 
     if (s->x < 0)
         s->x = 0;
     if (s->y < 0)
         s->y = 0;
     if ((unsigned)s->x + (unsigned)s->w > link->w)
         s->x = link->w - s->w;
     if ((unsigned)s->y + (unsigned)s->h > link->h)
         s->y = link->h - s->h;

     if (!s->exact) {
         s->x &= ~((1 << s->hsub) - 1);
         s->y &= ~((1 << s->vsub) - 1);
     }

     av_log(ctx, AV_LOG_TRACE, "n:%d t:%f pos:%f x:%d y:%d x+w:%d y+h:%d\n",

             (int)s->var_values[VAR_N], s->var_values[VAR_T], s->var_values[VAR_POS],
             s->x, s->y, s->x+s->w, s->y+s->h);

     frame->data[0] += s->y * frame->linesize[0];
     frame->data[0] += s->x * s->max_step[0];

     if (!(desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & FF_PSEUDOPAL)) {

         for (i = 1; i < 3; i ++) {

             if (frame->data[i]) {

                 frame->data[i] += (s->y >> s->vsub) * frame->linesize[i];
                 frame->data[i] += (s->x * s->max_step[i]) >> s->hsub;

             }
         }
     }
 
     /* alpha plane */

     if (frame->data[3]) {

         frame->data[3] += s->y * frame->linesize[3];
         frame->data[3] += s->x * s->max_step[3];

     }
 

     return ff_filter_frame(link->dst->outputs[0], frame);

 }
 

 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
                            char *res, int res_len, int flags)
 {
     CropContext *s = ctx->priv;
     int ret;
 
     if (   !strcmp(cmd, "out_w")  || !strcmp(cmd, "w")
         || !strcmp(cmd, "out_h")  || !strcmp(cmd, "h")
         || !strcmp(cmd, "x")      || !strcmp(cmd, "y")) {
 
         int old_x = s->x;
         int old_y = s->y;
         int old_w = s->w;
         int old_h = s->h;
 
         AVFilterLink *outlink = ctx->outputs[0];
         AVFilterLink *inlink  = ctx->inputs[0];
 
         av_opt_set(s, cmd, args, 0);
 
         if ((ret = config_input(inlink)) < 0) {
             s->x = old_x;
             s->y = old_y;
             s->w = old_w;
             s->h = old_h;
             return ret;
         }
 
         ret = config_output(outlink);
 
     } else
         ret = AVERROR(ENOSYS);
 
     return ret;
 }
 

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

 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption crop_options[] = {
     { "out_w",       "set the width crop area expression",   OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "w",           "set the width crop area expression",   OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "out_h",       "set the height crop area expression",  OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "h",           "set the height crop area expression",  OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "x",           "set the x crop area expression",       OFFSET(x_expr), AV_OPT_TYPE_STRING, {.str = "(in_w-out_w)/2"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "y",           "set the y crop area expression",       OFFSET(y_expr), AV_OPT_TYPE_STRING, {.str = "(in_h-out_h)/2"}, CHAR_MIN, CHAR_MAX, FLAGS },

     { "keep_aspect", "keep aspect ratio",                    OFFSET(keep_aspect), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },

     { "exact",       "do exact cropping",                    OFFSET(exact),  AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },

     { NULL }

 };
 

 AVFILTER_DEFINE_CLASS(crop);

 static const AVFilterPad avfilter_vf_crop_inputs[] = {
     {

         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
         .config_props = config_input,

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

 AVFilter ff_vf_crop = {

     .name            = "crop",
     .description     = NULL_IF_CONFIG_SMALL("Crop the input video."),
     .priv_size       = sizeof(CropContext),
     .priv_class      = &crop_class,
     .query_formats   = query_formats,
     .uninit          = uninit,
     .inputs          = avfilter_vf_crop_inputs,
     .outputs         = avfilter_vf_crop_outputs,
     .process_command = process_command,

 };