text: /*
   * Copyright (c) 2019 Xuewei Meng
   *
   * 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
   * Filter implementing image derain filter using deep convolutional networks.
   * http://openaccess.thecvf.com/content_ECCV_2018/html/Xia_Li_Recurrent_Squeeze-and-Excitation_Context_ECCV_2018_paper.html
   */
  
  #include "libavformat/avio.h"
  #include "libavutil/opt.h"
  #include "avfilter.h"
  #include "dnn_filter_common.h"
  #include "formats.h"
  #include "internal.h"
  
  typedef struct DRContext {
      const AVClass *class;
      DnnContext dnnctx;
      int                filter_type;
  } DRContext;
  
  #define OFFSET(x) offsetof(DRContext, x)
  #define FLAGS AV_OPT_FLAG_FILTERING_PARAM | AV_OPT_FLAG_VIDEO_PARAM
  static const AVOption derain_options[] = {
      { "filter_type", "filter type(derain/dehaze)",  OFFSET(filter_type),    AV_OPT_TYPE_INT,    { .i64 = 0 },    0, 1, FLAGS, "type" },
      { "derain",      "derain filter flag",          0,                      AV_OPT_TYPE_CONST,  { .i64 = 0 },    0, 0, FLAGS, "type" },
      { "dehaze",      "dehaze filter flag",          0,                      AV_OPT_TYPE_CONST,  { .i64 = 1 },    0, 0, FLAGS, "type" },
      { "dnn_backend", "DNN backend",                 OFFSET(dnnctx.backend_type),   AV_OPT_TYPE_INT,    { .i64 = 0 },    0, 1, FLAGS, "backend" },
      { "native",      "native backend flag",         0,                      AV_OPT_TYPE_CONST,  { .i64 = 0 },    0, 0, FLAGS, "backend" },
  #if (CONFIG_LIBTENSORFLOW == 1)
      { "tensorflow",  "tensorflow backend flag",     0,                      AV_OPT_TYPE_CONST,  { .i64 = 1 },    0, 0, FLAGS, "backend" },
  #endif
      { "model",       "path to model file",          OFFSET(dnnctx.model_filename),   AV_OPT_TYPE_STRING,    { .str = NULL }, 0, 0, FLAGS },
      { "input",       "input name of the model",     OFFSET(dnnctx.model_inputname),  AV_OPT_TYPE_STRING,    { .str = "x" },  0, 0, FLAGS },
      { "output",      "output name of the model",    OFFSET(dnnctx.model_outputname), AV_OPT_TYPE_STRING,    { .str = "y" },  0, 0, FLAGS },
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(derain);
  
  static int query_formats(AVFilterContext *ctx)
  {
      AVFilterFormats *formats;
      const enum AVPixelFormat pixel_fmts[] = {
          AV_PIX_FMT_RGB24,
          AV_PIX_FMT_NONE
      };
  
      formats = ff_make_format_list(pixel_fmts);
  
      return ff_set_common_formats(ctx, formats);
  }
  
  static int filter_frame(AVFilterLink *inlink, AVFrame *in)
  {
      AVFilterContext *ctx  = inlink->dst;
      AVFilterLink *outlink = ctx->outputs[0];
      DRContext *dr_context = ctx->priv;
      DNNReturnType dnn_result;
      AVFrame *out;
  
      out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
      if (!out) {
          av_log(ctx, AV_LOG_ERROR, "could not allocate memory for output frame\n");
          av_frame_free(&in);
          return AVERROR(ENOMEM);
      }
      av_frame_copy_props(out, in);
  
      dnn_result = ff_dnn_execute_model(&dr_context->dnnctx, in, out);
      if (dnn_result != DNN_SUCCESS){
          av_log(ctx, AV_LOG_ERROR, "failed to execute model\n");
          av_frame_free(&in);
          return AVERROR(EIO);
      }
  
      av_frame_free(&in);
  
      return ff_filter_frame(outlink, out);
  }
  
  static av_cold int init(AVFilterContext *ctx)
  {
      DRContext *dr_context = ctx->priv;
      return ff_dnn_init(&dr_context->dnnctx, DFT_PROCESS_FRAME, ctx);
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      DRContext *dr_context = ctx->priv;
      ff_dnn_uninit(&dr_context->dnnctx);
  }
  
  static const AVFilterPad derain_inputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
          .filter_frame = filter_frame,
      },
      { NULL }
  };
  
  static const AVFilterPad derain_outputs[] = {
      {
          .name = "default",
          .type = AVMEDIA_TYPE_VIDEO,
      },
      { NULL }
  };
  
  AVFilter ff_vf_derain = {
      .name          = "derain",
      .description   = NULL_IF_CONFIG_SMALL("Apply derain filter to the input."),
      .priv_size     = sizeof(DRContext),
      .init          = init,
      .uninit        = uninit,
      .query_formats = query_formats,
      .inputs        = derain_inputs,
      .outputs       = derain_outputs,
      .priv_class    = &derain_class,
      .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
  };
  