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ffmpeg-4.2.2/libavcodec/mpegaudio.h 2.02 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * copyright (c) 2001 Fabrice Bellard
   *
   * 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
   * mpeg audio declarations for both encoder and decoder.
   */
  
  #ifndef AVCODEC_MPEGAUDIO_H
  #define AVCODEC_MPEGAUDIO_H
  
  #ifndef USE_FLOATS
  #   define USE_FLOATS 0
  #endif
  
  #include <stdint.h>
  #include "libavutil/internal.h"
  
  /* max frame size, in samples */
  #define MPA_FRAME_SIZE 1152
  
  /* max compressed frame size */
  #define MPA_MAX_CODED_FRAME_SIZE 1792
  
  #define MPA_MAX_CHANNELS 2
  
  #define SBLIMIT 32 /* number of subbands */
  
  #define MPA_STEREO  0
  #define MPA_JSTEREO 1
  #define MPA_DUAL    2
  #define MPA_MONO    3
  
  #ifndef FRAC_BITS
  #define FRAC_BITS   23   /* fractional bits for sb_samples and dct */
  #define WFRAC_BITS  16   /* fractional bits for window */
  #endif
  
  #define IMDCT_SCALAR 1.759
  
  #define FRAC_ONE    (1 << FRAC_BITS)
  
  #define FIX(a)   ((int)((a) * FRAC_ONE))
  
  #if USE_FLOATS
  #   define INTFLOAT float
  #   define SUINTFLOAT float
  typedef float MPA_INT;
  typedef float OUT_INT;
  #elif FRAC_BITS <= 15
  #   define INTFLOAT int
  #   define SUINTFLOAT SUINT
  typedef int16_t MPA_INT;
  typedef int16_t OUT_INT;
  #else
  #   define INTFLOAT int
  #   define SUINTFLOAT SUINT
  typedef int32_t MPA_INT;
  typedef int16_t OUT_INT;
  #endif
  
  int ff_mpa_l2_select_table(int bitrate, int nb_channels, int freq, int lsf);
  
  #endif /* AVCODEC_MPEGAUDIO_H */