/*
  * Copyright (c) 2011 Mark Himsley
  *
  * 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 field order filter, heavily influenced by vf_pad.c
  */
 

 #include "libavutil/opt.h"

 #include "libavutil/imgutils.h"

 #include "libavutil/internal.h"

 #include "libavutil/opt.h"

 #include "libavutil/pixdesc.h"
 #include "avfilter.h"

 #include "formats.h"

 #include "internal.h"

 #include "video.h"

 typedef struct {
     const AVClass *class;

     int dst_tff;               ///< output bff/tff

     int          line_size[4]; ///< bytes of pixel data per line for each plane
 } FieldOrderContext;
 
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats  *formats;

     enum AVPixelFormat pix_fmt;

     int              ret;
 
     /** accept any input pixel format that is not hardware accelerated, not
      *  a bitstream format, and does not have vertically sub-sampled chroma */
     if (ctx->inputs[0]) {
         formats = NULL;

         for (pix_fmt = 0; pix_fmt < AV_PIX_FMT_NB; pix_fmt++) {
             const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);

             if (!(desc->flags & AV_PIX_FMT_FLAG_HWACCEL ||
                   desc->flags & AV_PIX_FMT_FLAG_BITSTREAM) &&

                 desc->nb_components && !desc->log2_chroma_h &&
                 (ret = ff_add_format(&formats, pix_fmt)) < 0) {

                 ff_formats_unref(&formats);

                 return ret;
             }

         }

         ff_formats_ref(formats, &ctx->inputs[0]->out_formats);
         ff_formats_ref(formats, &ctx->outputs[0]->in_formats);

     }
 
     return 0;
 }
 
 static int config_input(AVFilterLink *inlink)
 {

     AVFilterContext   *ctx = inlink->dst;
     FieldOrderContext *s   = ctx->priv;

     int               plane;
 
     /** full an array with the number of bytes that the video
      *  data occupies per line for each plane of the input video */
     for (plane = 0; plane < 4; plane++) {

         s->line_size[plane] = av_image_get_linesize(inlink->format, inlink->w,
                                                     plane);

     }
 
     return 0;
 }
 

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

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

     return ff_get_video_buffer(outlink, w, h);

 }
 

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

 {

     AVFilterContext   *ctx     = inlink->dst;
     FieldOrderContext *s       = ctx->priv;
     AVFilterLink      *outlink = ctx->outputs[0];
     int h, plane, line_step, line_size, line;
     uint8_t *data;

     if (!frame->interlaced_frame ||
         frame->top_field_first == s->dst_tff)

         return ff_filter_frame(outlink, frame);

     av_dlog(ctx,
             "picture will move %s one line\n",
             s->dst_tff ? "up" : "down");

     h = frame->height;

     for (plane = 0; plane < 4 && frame->data[plane]; plane++) {
         line_step = frame->linesize[plane];
         line_size = s->line_size[plane];
         data = frame->data[plane];
         if (s->dst_tff) {
             /** Move every line up one line, working from
              *  the top to the bottom of the frame.
              *  The original top line is lost.
              *  The new last line is created as a copy of the
              *  penultimate line from that field. */
             for (line = 0; line < h; line++) {

                 if (1 + line < frame->height) {

                     memcpy(data, data + line_step, line_size);
                 } else {
                     memcpy(data, data - line_step - line_step, line_size);

                 }

                 data += line_step;
             }
         } else {
             /** Move every line down one line, working from
              *  the bottom to the top of the frame.
              *  The original bottom line is lost.
              *  The new first line is created as a copy of the
              *  second line from that field. */
             data += (h - 1) * line_step;
             for (line = h - 1; line >= 0 ; line--) {
                 if (line > 0) {
                     memcpy(data, data - line_step, line_size);
                 } else {
                     memcpy(data, data + line_step + line_step, line_size);

                 }

                 data -= line_step;

             }
         }

     }

     frame->top_field_first = s->dst_tff;

     return ff_filter_frame(outlink, frame);

 }
 

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

 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption fieldorder_options[] = {

     { "order", "output field order", OFFSET(dst_tff), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, FLAGS, "order" },

         { "bff", "bottom field first", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, .flags=FLAGS, .unit = "order" },
         { "tff", "top field first",    0, AV_OPT_TYPE_CONST, { .i64 = 1 }, .flags=FLAGS, .unit = "order" },

     { NULL },
 };
 

 AVFILTER_DEFINE_CLASS(fieldorder);

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

         .filter_frame     = filter_frame,

         .needs_writable   = 1,

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

 AVFilter avfilter_vf_fieldorder = {
     .name          = "fieldorder",
     .description   = NULL_IF_CONFIG_SMALL("Set the field order."),
     .priv_size     = sizeof(FieldOrderContext),

     .priv_class    = &fieldorder_class,

     .query_formats = query_formats,

     .inputs        = avfilter_vf_fieldorder_inputs,
     .outputs       = avfilter_vf_fieldorder_outputs,

 };