/*

  * 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
  */
 

 /* #define DEBUG */
 

 #include "avfilter.h"

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

 #include "libavutil/imgutils.h"

 static const char *var_names[] = {
     "E",
     "PHI",
     "PI",
     "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
     "x",
     "y",
     "n",            ///< number of frame
     "pos",          ///< position in the file
     "t",            ///< timestamp expressed in seconds
     NULL
 };
 
 enum var_name {

     VAR_E,
     VAR_PHI,
     VAR_PI,
     VAR_IN_W,  VAR_IW,
     VAR_IN_H,  VAR_IH,
     VAR_OUT_W, VAR_OW,
     VAR_OUT_H, VAR_OH,
     VAR_X,
     VAR_Y,
     VAR_N,
     VAR_POS,
     VAR_T,
     VAR_VARS_NB

 };
 

 typedef struct {
     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
 

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

     int hsub, vsub;     ///< chroma subsampling

     char x_expr[256], y_expr[256], ow_expr[256], oh_expr[256];
     AVExpr *x_pexpr, *y_pexpr;  /* parsed expressions for x and y */

     double var_values[VAR_VARS_NB];

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

     static const enum PixelFormat pix_fmts[] = {

         PIX_FMT_RGB48BE,      PIX_FMT_RGB48LE,

         PIX_FMT_BGR48BE,      PIX_FMT_BGR48LE,

         PIX_FMT_ARGB,         PIX_FMT_RGBA,
         PIX_FMT_ABGR,         PIX_FMT_BGRA,
         PIX_FMT_RGB24,        PIX_FMT_BGR24,
         PIX_FMT_RGB565BE,     PIX_FMT_RGB565LE,
         PIX_FMT_RGB555BE,     PIX_FMT_RGB555LE,
         PIX_FMT_BGR565BE,     PIX_FMT_BGR565LE,
         PIX_FMT_BGR555BE,     PIX_FMT_BGR555LE,
         PIX_FMT_GRAY16BE,     PIX_FMT_GRAY16LE,
         PIX_FMT_YUV420P16LE,  PIX_FMT_YUV420P16BE,
         PIX_FMT_YUV422P16LE,  PIX_FMT_YUV422P16BE,
         PIX_FMT_YUV444P16LE,  PIX_FMT_YUV444P16BE,
         PIX_FMT_YUV444P,      PIX_FMT_YUV422P,
         PIX_FMT_YUV420P,      PIX_FMT_YUV411P,
         PIX_FMT_YUV410P,      PIX_FMT_YUV440P,
         PIX_FMT_YUVJ444P,     PIX_FMT_YUVJ422P,
         PIX_FMT_YUVJ420P,     PIX_FMT_YUVJ440P,
         PIX_FMT_YUVA420P,
         PIX_FMT_RGB8,         PIX_FMT_BGR8,
         PIX_FMT_RGB4_BYTE,    PIX_FMT_BGR4_BYTE,
         PIX_FMT_PAL8,         PIX_FMT_GRAY8,
         PIX_FMT_NONE
     };
 

     avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));

 
     return 0;
 }
 
 static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
 {
     CropContext *crop = ctx->priv;
 

     av_strlcpy(crop->ow_expr, "iw", sizeof(crop->ow_expr));
     av_strlcpy(crop->oh_expr, "ih", sizeof(crop->oh_expr));
     av_strlcpy(crop->x_expr, "(in_w-out_w)/2", sizeof(crop->x_expr));
     av_strlcpy(crop->y_expr, "(in_h-out_h)/2", sizeof(crop->y_expr));
 

     if (args)

         sscanf(args, "%255[^:]:%255[^:]:%255[^:]:%255[^:]", crop->ow_expr, crop->oh_expr, crop->x_expr, crop->y_expr);

 
     return 0;
 }
 

 static av_cold void uninit(AVFilterContext *ctx)
 {
     CropContext *crop = ctx->priv;
 

     av_expr_free(crop->x_pexpr); crop->x_pexpr = NULL;
     av_expr_free(crop->y_pexpr); crop->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 = round(d);
 
     return ret;
 }
 

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

     const AVPixFmtDescriptor *pix_desc = &av_pix_fmt_descriptors[link->format];

     int ret;
     const char *expr;
     double res;
 

     crop->var_values[VAR_E]     = M_E;
     crop->var_values[VAR_PHI]   = M_PHI;
     crop->var_values[VAR_PI]    = M_PI;
     crop->var_values[VAR_IN_W]  = crop->var_values[VAR_IW] = ctx->inputs[0]->w;
     crop->var_values[VAR_IN_H]  = crop->var_values[VAR_IH] = ctx->inputs[0]->h;
     crop->var_values[VAR_X]     = NAN;
     crop->var_values[VAR_Y]     = NAN;
     crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = NAN;
     crop->var_values[VAR_OUT_H] = crop->var_values[VAR_OH] = NAN;
     crop->var_values[VAR_N]     = 0;
     crop->var_values[VAR_T]     = NAN;
     crop->var_values[VAR_POS]   = NAN;

     av_image_fill_max_pixsteps(crop->max_step, NULL, pix_desc);

     crop->hsub = av_pix_fmt_descriptors[link->format].log2_chroma_w;
     crop->vsub = av_pix_fmt_descriptors[link->format].log2_chroma_h;

     if ((ret = av_expr_parse_and_eval(&res, (expr = crop->ow_expr),

                                       var_names, crop->var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;

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

     if ((ret = av_expr_parse_and_eval(&res, (expr = crop->oh_expr),

                                       var_names, crop->var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;

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

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

     if ((ret = av_expr_parse_and_eval(&res, (expr = crop->ow_expr),

                                       var_names, crop->var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0) goto fail_expr;

     crop->var_values[VAR_OUT_W] = crop->var_values[VAR_OW] = res;
     if (normalize_double(&crop->w, crop->var_values[VAR_OUT_W]) < 0 ||
         normalize_double(&crop->h, crop->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",
                crop->ow_expr, crop->oh_expr);
         return AVERROR(EINVAL);
     }
     crop->w &= ~((1 << crop->hsub) - 1);
     crop->h &= ~((1 << crop->vsub) - 1);

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

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

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

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

     av_log(ctx, AV_LOG_INFO, "w:%d h:%d -> w:%d h:%d\n",

            link->w, link->h, crop->w, crop->h);

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

         av_log(ctx, AV_LOG_ERROR,

                "Invalid too big or non positive size for width '%d' or height '%d'\n",
                crop->w, crop->h);

         return AVERROR(EINVAL);

     }
 

     /* set default, required in the case the first computed value for x/y is NAN */
     crop->x = (link->w - crop->w) / 2;
     crop->y = (link->h - crop->h) / 2;
     crop->x &= ~((1 << crop->hsub) - 1);
     crop->y &= ~((1 << crop->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 *crop = link->src->priv;
 
     link->w = crop->w;
     link->h = crop->h;
 
     return 0;
 }
 

 static void start_frame(AVFilterLink *link, AVFilterBufferRef *picref)

 {

     AVFilterContext *ctx = link->dst;
     CropContext *crop = ctx->priv;

     AVFilterBufferRef *ref2;

     int i;
 

     ref2 = avfilter_ref_buffer(picref, ~0);

     ref2->video->w = crop->w;
     ref2->video->h = crop->h;

     crop->var_values[VAR_T] = picref->pts == AV_NOPTS_VALUE ?
         NAN : picref->pts * av_q2d(link->time_base);

     crop->var_values[VAR_POS] = picref->pos == -1 ? NAN : picref->pos;

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

     normalize_double(&crop->x, crop->var_values[VAR_X]);
     normalize_double(&crop->y, crop->var_values[VAR_Y]);

 
     if (crop->x < 0) crop->x = 0;
     if (crop->y < 0) crop->y = 0;
     if ((unsigned)crop->x + (unsigned)crop->w > link->w) crop->x = link->w - crop->w;
     if ((unsigned)crop->y + (unsigned)crop->h > link->h) crop->y = link->h - crop->h;
     crop->x &= ~((1 << crop->hsub) - 1);
     crop->y &= ~((1 << crop->vsub) - 1);
 

     av_dlog(ctx, "n:%d t:%f x:%d y:%d x+w:%d y+h:%d\n",
             (int)crop->var_values[VAR_N], crop->var_values[VAR_T], crop->x,
             crop->y, crop->x+crop->w, crop->y+crop->h);

     ref2->data[0] += crop->y * ref2->linesize[0];

     ref2->data[0] += crop->x * crop->max_step[0];

     if (!(av_pix_fmt_descriptors[link->format].flags & PIX_FMT_PAL)) {

         for (i = 1; i < 3; i ++) {
             if (ref2->data[i]) {
                 ref2->data[i] += (crop->y >> crop->vsub) * ref2->linesize[i];

                 ref2->data[i] += (crop->x * crop->max_step[i]) >> crop->hsub;

             }
         }
     }
 
     /* alpha plane */
     if (ref2->data[3]) {
         ref2->data[3] += crop->y * ref2->linesize[3];

         ref2->data[3] += crop->x * crop->max_step[3];

     }
 
     avfilter_start_frame(link->dst->outputs[0], ref2);
 }
 

 static void draw_slice(AVFilterLink *link, int y, int h, int slice_dir)

 {
     AVFilterContext *ctx = link->dst;
     CropContext *crop = ctx->priv;
 
     if (y >= crop->y + crop->h || y + h <= crop->y)
         return;
 
     if (y < crop->y) {
         h -= crop->y - y;
         y  = crop->y;
     }
     if (y + h > crop->y + crop->h)
         h = crop->y + crop->h - y;
 

     avfilter_draw_slice(ctx->outputs[0], y - crop->y, h, slice_dir);

 }
 

 static void end_frame(AVFilterLink *link)
 {
     CropContext *crop = link->dst->priv;
 

     crop->var_values[VAR_N] += 1.0;

     avfilter_unref_buffer(link->cur_buf);

     avfilter_end_frame(link->dst->outputs[0]);
 }
 

 AVFilter avfilter_vf_crop = {
     .name      = "crop",

     .description = NULL_IF_CONFIG_SMALL("Crop the input video to width:height:x:y."),

     .priv_size = sizeof(CropContext),
 
     .query_formats = query_formats,
     .init          = init,

     .uninit        = uninit,

 
     .inputs    = (AVFilterPad[]) {{ .name             = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO,

                                     .start_frame      = start_frame,
                                     .draw_slice       = draw_slice,

                                     .end_frame        = end_frame,

                                     .get_video_buffer = avfilter_null_get_video_buffer,

                                     .config_props     = config_input, },
                                   { .name = NULL}},
     .outputs   = (AVFilterPad[]) {{ .name             = "default",

                                     .type             = AVMEDIA_TYPE_VIDEO,

                                     .config_props     = config_output, },
                                   { .name = NULL}},
 };