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ffmpeg-4.2.2/libavfilter/vf_vflip.c 3.2 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * 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 vertical flip filter
   */
  
  #include "libavutil/internal.h"
  #include "libavutil/opt.h"
  #include "libavutil/pixdesc.h"
  #include "avfilter.h"
  #include "internal.h"
  #include "video.h"
  
  typedef struct FlipContext {
      const AVClass *class;
      int vsub;   ///< vertical chroma subsampling
  } FlipContext;
  
  static const AVOption vflip_options[] = {
      { NULL }
  };
  
  AVFILTER_DEFINE_CLASS(vflip);
  
  static int config_input(AVFilterLink *link)
  {
      FlipContext *flip = link->dst->priv;
      const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
  
      flip->vsub = desc->log2_chroma_h;
  
      return 0;
  }
  
  static AVFrame *get_video_buffer(AVFilterLink *link, int w, int h)
  {
      FlipContext *flip = link->dst->priv;
      AVFrame *frame;
      int i;
  
      frame = ff_get_video_buffer(link->dst->outputs[0], w, h);
      if (!frame)
          return NULL;
  
      for (i = 0; i < 4; i ++) {
          int vsub = i == 1 || i == 2 ? flip->vsub : 0;
          int height = AV_CEIL_RSHIFT(h, vsub);
  
          if (frame->data[i]) {
              frame->data[i] += (height - 1) * frame->linesize[i];
              frame->linesize[i] = -frame->linesize[i];
          }
      }
  
      return frame;
  }
  
  static int filter_frame(AVFilterLink *link, AVFrame *frame)
  {
      FlipContext *flip = link->dst->priv;
      int i;
  
      for (i = 0; i < 4; i ++) {
          int vsub = i == 1 || i == 2 ? flip->vsub : 0;
          int height = AV_CEIL_RSHIFT(link->h, vsub);
  
          if (frame->data[i]) {
              frame->data[i] += (height - 1) * frame->linesize[i];
              frame->linesize[i] = -frame->linesize[i];
          }
      }
  
      return ff_filter_frame(link->dst->outputs[0], frame);
  }
  static const AVFilterPad avfilter_vf_vflip_inputs[] = {
      {
          .name             = "default",
          .type             = AVMEDIA_TYPE_VIDEO,
          .get_video_buffer = get_video_buffer,
          .filter_frame     = filter_frame,
          .config_props     = config_input,
      },
      { NULL }
  };
  
  static const AVFilterPad avfilter_vf_vflip_outputs[] = {
      {
          .name = "default",
          .type = AVMEDIA_TYPE_VIDEO,
      },
      { NULL }
  };
  
  AVFilter ff_vf_vflip = {
      .name        = "vflip",
      .description = NULL_IF_CONFIG_SMALL("Flip the input video vertically."),
      .priv_size   = sizeof(FlipContext),
      .priv_class  = &vflip_class,
      .inputs      = avfilter_vf_vflip_inputs,
      .outputs     = avfilter_vf_vflip_outputs,
      .flags       = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
  };