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ffmpeg-4.2.2/libavcodec/lossless_videoencdsp.c 3.1 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 "config.h"
  #include "libavutil/attributes.h"
  #include "lossless_videoencdsp.h"
  #include "mathops.h"
  
  // 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
  #define pb_7f (~0UL / 255 * 0x7f)
  #define pb_80 (~0UL / 255 * 0x80)
  
  static void diff_bytes_c(uint8_t *dst, const uint8_t *src1, const uint8_t *src2, intptr_t w)
  {
      long i;
  
  #if !HAVE_FAST_UNALIGNED
      if (((long)src1 | (long)src2) & (sizeof(long) - 1)) {
          for (i = 0; i + 7 < w; i += 8) {
              dst[i + 0] = src1[i + 0] - src2[i + 0];
              dst[i + 1] = src1[i + 1] - src2[i + 1];
              dst[i + 2] = src1[i + 2] - src2[i + 2];
              dst[i + 3] = src1[i + 3] - src2[i + 3];
              dst[i + 4] = src1[i + 4] - src2[i + 4];
              dst[i + 5] = src1[i + 5] - src2[i + 5];
              dst[i + 6] = src1[i + 6] - src2[i + 6];
              dst[i + 7] = src1[i + 7] - src2[i + 7];
          }
      } else
  #endif
      for (i = 0; i <= w - (int) sizeof(long); i += sizeof(long)) {
          long a = *(long *) (src1 + i);
          long b = *(long *) (src2 + i);
          *(long *) (dst + i) = ((a | pb_80) - (b & pb_7f)) ^
                                ((a ^ b ^ pb_80) & pb_80);
      }
      for (; i < w; i++)
          dst[i + 0] = src1[i + 0] - src2[i + 0];
  }
  
  static void sub_median_pred_c(uint8_t *dst, const uint8_t *src1,
                                const uint8_t *src2, intptr_t w,
                                int *left, int *left_top)
  {
      int i;
      uint8_t l, lt;
  
      l  = *left;
      lt = *left_top;
  
      for (i = 0; i < w; i++) {
          const int pred = mid_pred(l, src1[i], (l + src1[i] - lt) & 0xFF);
          lt     = src1[i];
          l      = src2[i];
          dst[i] = l - pred;
      }
  
      *left     = l;
      *left_top = lt;
  }
  
  static void sub_left_predict_c(uint8_t *dst, uint8_t *src,
                                 ptrdiff_t stride, ptrdiff_t width, int height)
  {
      int i, j;
      uint8_t prev = 0x80; /* Set the initial value */
      for (j = 0; j < height; j++) {
          for (i = 0; i < width; i++) {
              *dst++ = src[i] - prev;
              prev   = src[i];
          }
          src += stride;
      }
  }
  
  av_cold void ff_llvidencdsp_init(LLVidEncDSPContext *c)
  {
      c->diff_bytes      = diff_bytes_c;
      c->sub_median_pred = sub_median_pred_c;
      c->sub_left_predict = sub_left_predict_c;
  
      if (ARCH_X86)
          ff_llvidencdsp_init_x86(c);
  }