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ffmpeg-4.2.2/libavcodec/mdct_fixed.c 2.11 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
   */
  
  #define FFT_FLOAT 0
  #define FFT_FIXED_32 0
  #include "mdct_template.c"
  
  /* same as ff_mdct_calcw_c with double-width unscaled output */
  void ff_mdct_calcw_c(FFTContext *s, FFTDouble *out, const FFTSample *input)
  {
      int i, j, n, n8, n4, n2, n3;
      FFTDouble re, im;
      const uint16_t *revtab = s->revtab;
      const FFTSample *tcos = s->tcos;
      const FFTSample *tsin = s->tsin;
      FFTComplex *x = s->tmp_buf;
      FFTDComplex *o = (FFTDComplex *)out;
  
      n = 1 << s->mdct_bits;
      n2 = n >> 1;
      n4 = n >> 2;
      n8 = n >> 3;
      n3 = 3 * n4;
  
      /* pre rotation */
      for(i=0;i<n8;i++) {
          re = RSCALE(-input[2*i+n3], - input[n3-1-2*i]);
          im = RSCALE(-input[n4+2*i], + input[n4-1-2*i]);
          j = revtab[i];
          CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
  
          re = RSCALE( input[2*i]   , - input[n2-1-2*i]);
          im = RSCALE(-input[n2+2*i], - input[ n-1-2*i]);
          j = revtab[n8 + i];
          CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
      }
  
      s->fft_calc(s, x);
  
      /* post rotation */
      for(i=0;i<n8;i++) {
          FFTDouble r0, i0, r1, i1;
          CMULL(i1, r0, x[n8-i-1].re, x[n8-i-1].im, -tsin[n8-i-1], -tcos[n8-i-1]);
          CMULL(i0, r1, x[n8+i  ].re, x[n8+i  ].im, -tsin[n8+i  ], -tcos[n8+i  ]);
          o[n8-i-1].re = r0;
          o[n8-i-1].im = i0;
          o[n8+i  ].re = r1;
          o[n8+i  ].im = i1;
      }
  }