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ffmpeg-4.2.2/libavcodec/h261.c 2.66 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * H.261 common code
   * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
   * Copyright (c) 2004 Maarten Daniels
   *
   * 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
   * H.261 codec
   */
  
  #include "avcodec.h"
  #include "h261.h"
  
  #define IS_FIL(a)    ((a) & MB_TYPE_H261_FIL)
  
  uint8_t ff_h261_rl_table_store[2][2 * MAX_RUN + MAX_LEVEL + 3];
  
  static void h261_loop_filter(uint8_t *src, int stride)
  {
      int x, y, xy, yz;
      int temp[64];
  
      for (x = 0; x < 8; x++) {
          temp[x]         = 4 * src[x];
          temp[x + 7 * 8] = 4 * src[x + 7 * stride];
      }
      for (y = 1; y < 7; y++) {
          for (x = 0; x < 8; x++) {
              xy       = y * stride + x;
              yz       = y * 8      + x;
              temp[yz] = src[xy - stride] + 2 * src[xy] + src[xy + stride];
          }
      }
  
      for (y = 0; y < 8; y++) {
          src[y * stride]     = (temp[y * 8]     + 2) >> 2;
          src[y * stride + 7] = (temp[y * 8 + 7] + 2) >> 2;
          for (x = 1; x < 7; x++) {
              xy      = y * stride + x;
              yz      = y * 8      + x;
              src[xy] = (temp[yz - 1] + 2 * temp[yz] + temp[yz + 1] + 8) >> 4;
          }
      }
  }
  
  void ff_h261_loop_filter(MpegEncContext *s)
  {
      H261Context *h       = (H261Context *)s;
      const int linesize   = s->linesize;
      const int uvlinesize = s->uvlinesize;
      uint8_t *dest_y      = s->dest[0];
      uint8_t *dest_cb     = s->dest[1];
      uint8_t *dest_cr     = s->dest[2];
  
      if (!(IS_FIL(h->mtype)))
          return;
  
      h261_loop_filter(dest_y,                    linesize);
      h261_loop_filter(dest_y + 8,                linesize);
      h261_loop_filter(dest_y + 8 * linesize,     linesize);
      h261_loop_filter(dest_y + 8 * linesize + 8, linesize);
      h261_loop_filter(dest_cb, uvlinesize);
      h261_loop_filter(dest_cr, uvlinesize);
  }
  
  av_cold void ff_h261_common_init(void)
  {
      static int done = 0;
  
      if (done)
          return;
  
      ff_rl_init(&ff_h261_rl_tcoeff, ff_h261_rl_table_store);
      done = 1;
  }