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ffmpeg-4.2.2/libavfilter/vf_field.c 3.52 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Copyright (c) 2003 Rich Felker
   * Copyright (c) 2012 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
   * field filter, based on libmpcodecs/vf_field.c by Rich Felker
   */
  
  #include "libavutil/opt.h"
  #include "libavutil/pixdesc.h"
  #include "avfilter.h"
  #include "internal.h"
  
  enum FieldType { FIELD_TYPE_TOP = 0, FIELD_TYPE_BOTTOM };
  
  typedef struct FieldContext {
      const AVClass *class;
      int type;                   ///< FieldType
      int nb_planes;              ///< number of planes of the current format
  } FieldContext;
  
  #define OFFSET(x) offsetof(FieldContext, x)
  #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
  
  static const AVOption field_options[] = {
      {"type", "set field type (top or bottom)", OFFSET(type), AV_OPT_TYPE_INT, {.i64=FIELD_TYPE_TOP}, 0, 1, FLAGS, "field_type" },
      {"top",    "select top field",    0, AV_OPT_TYPE_CONST, {.i64=FIELD_TYPE_TOP},    INT_MIN, INT_MAX, FLAGS, "field_type"},
      {"bottom", "select bottom field", 0, AV_OPT_TYPE_CONST, {.i64=FIELD_TYPE_BOTTOM}, INT_MIN, INT_MAX, FLAGS, "field_type"},
      {NULL}
  };
  
  AVFILTER_DEFINE_CLASS(field);
  
  static int config_props_output(AVFilterLink *outlink)
  {
      AVFilterContext *ctx = outlink->src;
      FieldContext *field = ctx->priv;
      AVFilterLink *inlink = ctx->inputs[0];
  
      field->nb_planes = av_pix_fmt_count_planes(outlink->format);
  
      outlink->w = inlink->w;
      outlink->h = (inlink->h + (field->type == FIELD_TYPE_TOP)) / 2;
  
      av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d type:%s -> w:%d h:%d\n",
             inlink->w, inlink->h, field->type == FIELD_TYPE_BOTTOM ? "bottom" : "top",
             outlink->w, outlink->h);
      return 0;
  }
  
  static int filter_frame(AVFilterLink *inlink, AVFrame *inpicref)
  {
      FieldContext *field = inlink->dst->priv;
      AVFilterLink *outlink = inlink->dst->outputs[0];
      int i;
  
      inpicref->height = outlink->h;
      inpicref->interlaced_frame = 0;
  
      for (i = 0; i < field->nb_planes; i++) {
          if (field->type == FIELD_TYPE_BOTTOM)
              inpicref->data[i] = inpicref->data[i] + inpicref->linesize[i];
          inpicref->linesize[i] = 2 * inpicref->linesize[i];
      }
      return ff_filter_frame(outlink, inpicref);
  }
  
  static const AVFilterPad field_inputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
          .filter_frame = filter_frame,
      },
      { NULL }
  };
  
  static const AVFilterPad field_outputs[] = {
      {
          .name         = "default",
          .type         = AVMEDIA_TYPE_VIDEO,
          .config_props = config_props_output,
      },
      { NULL }
  };
  
  AVFilter ff_vf_field = {
      .name        = "field",
      .description = NULL_IF_CONFIG_SMALL("Extract a field from the input video."),
      .priv_size   = sizeof(FieldContext),
      .inputs      = field_inputs,
      .outputs     = field_outputs,
      .priv_class  = &field_class,
  };