/*

  * Copyright (c) 2008 vmrsss
  * Copyright (c) 2009 Stefano Sabatini

  *
  * 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 padding filter

  */
 

 #include <float.h>  /* DBL_MAX */
 

 #include "avfilter.h"

 #include "formats.h"

 #include "internal.h"

 #include "video.h"

 #include "libavutil/avstring.h"

 #include "libavutil/common.h"

 #include "libavutil/eval.h"

 #include "libavutil/pixdesc.h"

 #include "libavutil/colorspace.h"

 #include "libavutil/imgutils.h"
 #include "libavutil/parseutils.h"

 #include "libavutil/mathematics.h"

 #include "libavutil/opt.h"
 

 #include "drawutils.h"

 static const char *const var_names[] = {

     "in_w",   "iw",
     "in_h",   "ih",
     "out_w",  "ow",
     "out_h",  "oh",
     "x",
     "y",

     "a",

     "sar",

     "dar",

     "hsub",
     "vsub",
     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_X,
     VAR_Y,

     VAR_A,

     VAR_SAR,

     VAR_DAR,

     VAR_HSUB,
     VAR_VSUB,
     VARS_NB
 };
 

 static int query_formats(AVFilterContext *ctx)
 {

     return ff_set_common_formats(ctx, ff_draw_supported_pixel_formats(0));

 }
 

 enum EvalMode {
     EVAL_MODE_INIT,
     EVAL_MODE_FRAME,
     EVAL_MODE_NB
 };
 

 typedef struct PadContext {

     const AVClass *class;

     int w, h;               ///< output dimensions, a value of 0 will result in the input size
     int x, y;               ///< offsets of the input area with respect to the padded area
     int in_w, in_h;         ///< width and height for the padded input video, which has to be aligned to the chroma values in order to avoid chroma issues

     int inlink_w, inlink_h;

     AVRational aspect;

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

     uint8_t rgba_color[4];  ///< color for the padding area
     FFDrawContext draw;
     FFDrawColor color;

 
     int eval_mode;          ///< expression evaluation mode

 } PadContext;
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;

     PadContext *s = ctx->priv;

     AVRational adjusted_aspect = s->aspect;

     int ret;

     double var_values[VARS_NB], res;
     char *expr;

     ff_draw_init(&s->draw, inlink->format, 0);
     ff_draw_color(&s->draw, &s->color, s->rgba_color);

     var_values[VAR_IN_W]  = var_values[VAR_IW] = inlink->w;
     var_values[VAR_IN_H]  = var_values[VAR_IH] = inlink->h;
     var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
     var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;

     var_values[VAR_A]     = (double) inlink->w / inlink->h;

     var_values[VAR_SAR]   = inlink->sample_aspect_ratio.num ?

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

     var_values[VAR_DAR]   = var_values[VAR_A] * var_values[VAR_SAR];

     var_values[VAR_HSUB]  = 1 << s->draw.hsub_max;
     var_values[VAR_VSUB]  = 1 << s->draw.vsub_max;

 
     /* evaluate width and height */

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

                            var_names, var_values,
                            NULL, NULL, NULL, NULL, NULL, 0, ctx);

     s->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
     if ((ret = av_expr_parse_and_eval(&res, (expr = s->h_expr),

                                       var_names, var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto eval_fail;

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

     if (!s->h)
         var_values[VAR_OUT_H] = var_values[VAR_OH] = s->h = inlink->h;
 

     /* evaluate the width again, as it may depend on the evaluated output height */

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

                                       var_names, var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto eval_fail;

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

     if (!s->w)
         var_values[VAR_OUT_W] = var_values[VAR_OW] = s->w = inlink->w;

     if (adjusted_aspect.num && adjusted_aspect.den) {
         adjusted_aspect = av_div_q(adjusted_aspect, inlink->sample_aspect_ratio);
         if (s->h < av_rescale(s->w, adjusted_aspect.den, adjusted_aspect.num)) {
             s->h = var_values[VAR_OUT_H] = var_values[VAR_OH] = av_rescale(s->w, adjusted_aspect.den, adjusted_aspect.num);
         } else {
             s->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = av_rescale(s->h, adjusted_aspect.num, adjusted_aspect.den);
         }
     }
 

     /* evaluate x and y */

     av_expr_parse_and_eval(&res, (expr = s->x_expr),

                            var_names, var_values,
                            NULL, NULL, NULL, NULL, NULL, 0, ctx);

     s->x = var_values[VAR_X] = res;
     if ((ret = av_expr_parse_and_eval(&res, (expr = s->y_expr),

                                       var_names, var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto eval_fail;

     s->y = var_values[VAR_Y] = res;

     /* evaluate x again, as it may depend on the evaluated y value */

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

                                       var_names, var_values,
                                       NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
         goto eval_fail;

     s->x = var_values[VAR_X] = res;

     if (s->x < 0 || s->x + inlink->w > s->w)
         s->x = var_values[VAR_X] = (s->w - inlink->w) / 2;
     if (s->y < 0 || s->y + inlink->h > s->h)
         s->y = var_values[VAR_Y] = (s->h - inlink->h) / 2;
 

     /* sanity check params */

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

         av_log(ctx, AV_LOG_ERROR, "Negative values are not acceptable.\n");
         return AVERROR(EINVAL);
     }
 

     s->w    = ff_draw_round_to_sub(&s->draw, 0, -1, s->w);
     s->h    = ff_draw_round_to_sub(&s->draw, 1, -1, s->h);
     s->x    = ff_draw_round_to_sub(&s->draw, 0, -1, s->x);
     s->y    = ff_draw_round_to_sub(&s->draw, 1, -1, s->y);
     s->in_w = ff_draw_round_to_sub(&s->draw, 0, -1, inlink->w);
     s->in_h = ff_draw_round_to_sub(&s->draw, 1, -1, inlink->h);

     s->inlink_w = inlink->w;
     s->inlink_h = inlink->h;

     av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d -> w:%d h:%d x:%d y:%d color:0x%02X%02X%02X%02X\n",

            inlink->w, inlink->h, s->w, s->h, s->x, s->y,

            s->rgba_color[0], s->rgba_color[1], s->rgba_color[2], s->rgba_color[3]);

     if (s->x <  0 || s->y <  0                      ||
         s->w <= 0 || s->h <= 0                      ||
         (unsigned)s->x + (unsigned)inlink->w > s->w ||
         (unsigned)s->y + (unsigned)inlink->h > s->h) {

         av_log(ctx, AV_LOG_ERROR,
                "Input area %d:%d:%d:%d not within the padded area 0:0:%d:%d or zero-sized\n",

                s->x, s->y, s->x + inlink->w, s->y + inlink->h, s->w, s->h);

         return AVERROR(EINVAL);

     }
 
     return 0;

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

 }
 
 static int config_output(AVFilterLink *outlink)
 {

     PadContext *s = outlink->src->priv;

     outlink->w = s->w;
     outlink->h = s->h;

     return 0;
 }
 

 static AVFrame *get_video_buffer(AVFilterLink *inlink, int w, int h)

 {

     PadContext *s = inlink->dst->priv;

     AVFrame *frame;

     int plane;

     if (s->inlink_w <= 0)
         return NULL;
 
     frame = ff_get_video_buffer(inlink->dst->outputs[0],
                                 w + (s->w - s->in_w),
                                 h + (s->h - s->in_h) + (s->x > 0));
 

     if (!frame)

         return NULL;
 

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

     for (plane = 0; plane < 4 && frame->data[plane] && frame->linesize[plane]; plane++) {

         int hsub = s->draw.hsub[plane];
         int vsub = s->draw.vsub[plane];
         frame->data[plane] += (s->x >> hsub) * s->draw.pixelstep[plane] +
                               (s->y >> vsub) * frame->linesize[plane];

     }
 

     return frame;

 }
 

 /* check whether each plane in this buffer can be padded without copying */
 static int buffer_needs_copy(PadContext *s, AVFrame *frame, AVBufferRef *buf)

 {

     int planes[4] = { -1, -1, -1, -1}, *p = planes;
     int i, j;

     /* get all planes in this buffer */
     for (i = 0; i < FF_ARRAY_ELEMS(planes) && frame->data[i]; i++) {
         if (av_frame_get_plane_buffer(frame, i) == buf)
             *p++ = i;
     }

     /* for each plane in this buffer, check that it can be padded without
      * going over buffer bounds or other planes */
     for (i = 0; i < FF_ARRAY_ELEMS(planes) && planes[i] >= 0; i++) {

         int hsub = s->draw.hsub[planes[i]];
         int vsub = s->draw.vsub[planes[i]];

 
         uint8_t *start = frame->data[planes[i]];

         uint8_t *end   = start + (frame->height >> vsub) *

                                  frame->linesize[planes[i]];
 
         /* amount of free space needed before the start and after the end
          * of the plane */

         ptrdiff_t req_start = (s->x >> hsub) * s->draw.pixelstep[planes[i]] +

                               (s->y >> vsub) * frame->linesize[planes[i]];
         ptrdiff_t req_end   = ((s->w - s->x - frame->width) >> hsub) *

                               s->draw.pixelstep[planes[i]] +

                               ((s->h - s->y - frame->height) >> vsub) * frame->linesize[planes[i]];

         if (frame->linesize[planes[i]] < (s->w >> hsub) * s->draw.pixelstep[planes[i]])

             return 1;
         if (start - buf->data < req_start ||
             (buf->data + buf->size) - end < req_end)
             return 1;
 

         for (j = 0; j < FF_ARRAY_ELEMS(planes) && planes[j] >= 0; j++) {

             int vsub1 = s->draw.vsub[planes[j]];

             uint8_t *start1 = frame->data[planes[j]];

             uint8_t *end1   = start1 + (frame->height >> vsub1) *

                                        frame->linesize[planes[j]];
             if (i == j)
                 continue;
 

             if (FFSIGN(start - end1) != FFSIGN(start - end1 - req_start) ||
                 FFSIGN(end - start1) != FFSIGN(end - start1 + req_end))

                 return 1;
         }
     }

     return 0;
 }

 static int frame_needs_copy(PadContext *s, AVFrame *frame)
 {
     int i;

     if (!av_frame_is_writable(frame))

         return 1;

     for (i = 0; i < 4 && frame->buf[i]; i++)

         if (buffer_needs_copy(s, frame, frame->buf[i]))
             return 1;

     return 0;
 }
 

 static int filter_frame(AVFilterLink *inlink, AVFrame *in)

 {

     PadContext *s = inlink->dst->priv;

     AVFilterLink *outlink = inlink->dst->outputs[0];

     AVFrame *out;

     int needs_copy;
     if(s->eval_mode == EVAL_MODE_FRAME && (
            in->width  != s->inlink_w
         || in->height != s->inlink_h
         || in->format != outlink->format
         || in->sample_aspect_ratio.den != outlink->sample_aspect_ratio.den || in->sample_aspect_ratio.num != outlink->sample_aspect_ratio.num)) {
         int ret;
 
         inlink->dst->inputs[0]->format = in->format;
         inlink->dst->inputs[0]->w      = in->width;
         inlink->dst->inputs[0]->h      = in->height;
 
         inlink->dst->inputs[0]->sample_aspect_ratio.den = in->sample_aspect_ratio.den;
         inlink->dst->inputs[0]->sample_aspect_ratio.num = in->sample_aspect_ratio.num;
 
 
         if ((ret = config_input(inlink)) < 0) {
             s->inlink_w = -1;
             return ret;
         }
         if ((ret = config_output(outlink)) < 0) {
             s->inlink_w = -1;
             return ret;
         }
     }
 
     needs_copy = frame_needs_copy(s, in);

     if (needs_copy) {

         av_log(inlink->dst, AV_LOG_DEBUG, "Direct padding impossible allocating new frame\n");

         out = ff_get_video_buffer(inlink->dst->outputs[0],

                                   FFMAX(inlink->w, s->w),
                                   FFMAX(inlink->h, s->h));

         if (!out) {

             av_frame_free(&in);

             return AVERROR(ENOMEM);

         }

         av_frame_copy_props(out, in);
     } else {
         int i;

         out = in;

         for (i = 0; i < 4 && out->data[i] && out->linesize[i]; i++) {

             int hsub = s->draw.hsub[i];
             int vsub = s->draw.vsub[i];
             out->data[i] -= (s->x >> hsub) * s->draw.pixelstep[i] +

                             (s->y >> vsub) * out->linesize[i];

         }
     }

     /* top bar */

     if (s->y) {

         ff_fill_rectangle(&s->draw, &s->color,

                           out->data, out->linesize,

                           0, 0, s->w, s->y);

     }
 

     /* bottom bar */

     if (s->h > s->y + s->in_h) {

         ff_fill_rectangle(&s->draw, &s->color,

                           out->data, out->linesize,

                           0, s->y + s->in_h, s->w, s->h - s->y - s->in_h);

     }
 
     /* left border */

     ff_fill_rectangle(&s->draw, &s->color, out->data, out->linesize,
                       0, s->y, s->x, in->height);

     if (needs_copy) {

         ff_copy_rectangle2(&s->draw,

                           out->data, out->linesize, in->data, in->linesize,

                           s->x, s->y, 0, 0, in->width, in->height);

     }
 

     /* right border */

     ff_fill_rectangle(&s->draw, &s->color, out->data, out->linesize,

                       s->x + s->in_w, s->y, s->w - s->x - s->in_w,

                       in->height);
 

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

     if (in != out)
         av_frame_free(&in);

     return ff_filter_frame(inlink->dst->outputs[0], out);

 }
 

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

 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption pad_options[] = {
     { "width",  "set the pad area width expression",       OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "w",      "set the pad area width expression",       OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "height", "set the pad area height expression",      OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "h",      "set the pad area height expression",      OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "x",      "set the x offset expression for the input image position", OFFSET(x_expr), AV_OPT_TYPE_STRING, {.str = "0"}, CHAR_MIN, CHAR_MAX, FLAGS },
     { "y",      "set the y offset expression for the input image position", OFFSET(y_expr), AV_OPT_TYPE_STRING, {.str = "0"}, CHAR_MIN, CHAR_MAX, FLAGS },

     { "color",  "set the color of the padded area border", OFFSET(rgba_color), AV_OPT_TYPE_COLOR, {.str = "black"}, .flags = 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" },

     { "aspect",  "pad to fit an aspect instead of a resolution", OFFSET(aspect), AV_OPT_TYPE_RATIONAL, {.dbl = 0}, 0, DBL_MAX, FLAGS },

     { NULL }

 };
 

 AVFILTER_DEFINE_CLASS(pad);

 static const AVFilterPad avfilter_vf_pad_inputs[] = {
     {
         .name             = "default",
         .type             = AVMEDIA_TYPE_VIDEO,
         .config_props     = config_input,
         .get_video_buffer = get_video_buffer,

         .filter_frame     = filter_frame,

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

 AVFilter ff_vf_pad = {

     .name          = "pad",

     .description   = NULL_IF_CONFIG_SMALL("Pad the input video."),

     .priv_size     = sizeof(PadContext),

     .priv_class    = &pad_class,

     .query_formats = query_formats,

     .inputs        = avfilter_vf_pad_inputs,
     .outputs       = avfilter_vf_pad_outputs,

 };