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ffmpeg-4.2.2/libavcodec/h263dsp.c 3.36 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * 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
   */
  
  #include <stdint.h>
  
  #include "libavutil/attributes.h"
  #include "libavutil/common.h"
  #include "config.h"
  #include "h263dsp.h"
  
  const uint8_t ff_h263_loop_filter_strength[32] = {
      0, 1, 1, 2, 2, 3, 3,  4,  4,  4,  5,  5,  6,  6,  7, 7,
      7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12
  };
  
  static void h263_h_loop_filter_c(uint8_t *src, int stride, int qscale)
  {
      int y;
      const int strength = ff_h263_loop_filter_strength[qscale];
  
      for (y = 0; y < 8; y++) {
          int d1, d2, ad1;
          int p0 = src[y * stride - 2];
          int p1 = src[y * stride - 1];
          int p2 = src[y * stride + 0];
          int p3 = src[y * stride + 1];
          int d  = (p0 - p3 + 4 * (p2 - p1)) / 8;
  
          if (d < -2 * strength)
              d1 = 0;
          else if (d < -strength)
              d1 = -2 * strength - d;
          else if (d < strength)
              d1 = d;
          else if (d < 2 * strength)
              d1 = 2 * strength - d;
          else
              d1 = 0;
  
          p1 += d1;
          p2 -= d1;
          if (p1 & 256)
              p1 = ~(p1 >> 31);
          if (p2 & 256)
              p2 = ~(p2 >> 31);
  
          src[y * stride - 1] = p1;
          src[y * stride + 0] = p2;
  
          ad1 = FFABS(d1) >> 1;
  
          d2 = av_clip((p0 - p3) / 4, -ad1, ad1);
  
          src[y * stride - 2] = p0 - d2;
          src[y * stride + 1] = p3 + d2;
      }
  }
  
  static void h263_v_loop_filter_c(uint8_t *src, int stride, int qscale)
  {
      int x;
      const int strength = ff_h263_loop_filter_strength[qscale];
  
      for (x = 0; x < 8; x++) {
          int d1, d2, ad1;
          int p0 = src[x - 2 * stride];
          int p1 = src[x - 1 * stride];
          int p2 = src[x + 0 * stride];
          int p3 = src[x + 1 * stride];
          int d  = (p0 - p3 + 4 * (p2 - p1)) / 8;
  
          if (d < -2 * strength)
              d1 = 0;
          else if (d < -strength)
              d1 = -2 * strength - d;
          else if (d < strength)
              d1 = d;
          else if (d < 2 * strength)
              d1 = 2 * strength - d;
          else
              d1 = 0;
  
          p1 += d1;
          p2 -= d1;
          if (p1 & 256)
              p1 = ~(p1 >> 31);
          if (p2 & 256)
              p2 = ~(p2 >> 31);
  
          src[x - 1 * stride] = p1;
          src[x + 0 * stride] = p2;
  
          ad1 = FFABS(d1) >> 1;
  
          d2 = av_clip((p0 - p3) / 4, -ad1, ad1);
  
          src[x - 2 * stride] = p0 - d2;
          src[x + stride]     = p3 + d2;
      }
  }
  
  av_cold void ff_h263dsp_init(H263DSPContext *ctx)
  {
      ctx->h263_h_loop_filter = h263_h_loop_filter_c;
      ctx->h263_v_loop_filter = h263_v_loop_filter_c;
  
      if (ARCH_X86)
          ff_h263dsp_init_x86(ctx);
      if (ARCH_MIPS)
          ff_h263dsp_init_mips(ctx);
  }