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ffmpeg-4.2.2/libavcodec/opusdsp.c 1.8 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 "opusdsp.h"
  
  static void postfilter_c(float *data, int period, float *gains, int len)
  {
      const float g0 = gains[0];
      const float g1 = gains[1];
      const float g2 = gains[2];
  
      float x4 = data[-period - 2];
      float x3 = data[-period - 1];
      float x2 = data[-period + 0];
      float x1 = data[-period + 1];
  
      for (int i = 0; i < len; i++) {
          float x0 = data[i - period + 2];
          data[i] += g0 * x2        +
                     g1 * (x1 + x3) +
                     g2 * (x0 + x4);
          x4 = x3;
          x3 = x2;
          x2 = x1;
          x1 = x0;
      }
  }
  
  static float deemphasis_c(float *y, float *x, float coeff, int len)
  {
      float state = coeff;
  
      for (int i = 0; i < len; i++) {
          const float tmp = x[i] + state;
          state = tmp * CELT_EMPH_COEFF;
          y[i] = tmp;
      }
  
      return state;
  }
  
  av_cold void ff_opus_dsp_init(OpusDSP *ctx)
  {
      ctx->postfilter = postfilter_c;
      ctx->deemphasis = deemphasis_c;
  
      if (ARCH_X86)
          ff_opus_dsp_init_x86(ctx);
  
      if (ARCH_AARCH64)
          ff_opus_dsp_init_aarch64(ctx);
  }