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ffmpeg-4.2.2/libavresample/dither.h 3.07 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Copyright (c) 2012 Justin Ruggles <justin.ruggles@gmail.com>
   *
   * 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
   */
  
  #ifndef AVRESAMPLE_DITHER_H
  #define AVRESAMPLE_DITHER_H
  
  #include "avresample.h"
  #include "audio_data.h"
  
  typedef struct DitherContext DitherContext;
  
  typedef struct DitherDSPContext {
      /**
       * Convert samples from flt to s16 with added dither noise.
       *
       * @param dst    destination float array, range -0.5 to 0.5
       * @param src    source int array, range INT_MIN to INT_MAX.
       * @param dither float dither noise array
       * @param len    number of samples
       */
      void (*quantize)(int16_t *dst, const float *src, float *dither, int len);
  
      int ptr_align;      ///< src and dst constraints for quantize()
      int samples_align;  ///< len constraints for quantize()
  
      /**
       * Convert dither noise from int to float with triangular distribution.
       *
       * @param dst  destination float array, range -0.5 to 0.5
       *             constraints: 32-byte aligned
       * @param src0 source int array, range INT_MIN to INT_MAX.
       *             the array size is len * 2
       *             constraints: 32-byte aligned
       * @param len  number of output noise samples
       *             constraints: multiple of 16
       */
      void (*dither_int_to_float)(float *dst, int *src0, int len);
  } DitherDSPContext;
  
  /**
   * Allocate and initialize a DitherContext.
   *
   * The parameters in the AVAudioResampleContext are used to initialize the
   * DitherContext.
   *
   * @param avr  AVAudioResampleContext
   * @return     newly-allocated DitherContext
   */
  DitherContext *ff_dither_alloc(AVAudioResampleContext *avr,
                                 enum AVSampleFormat out_fmt,
                                 enum AVSampleFormat in_fmt,
                                 int channels, int sample_rate, int apply_map);
  
  /**
   * Free a DitherContext.
   *
   * @param c  DitherContext
   */
  void ff_dither_free(DitherContext **c);
  
  /**
   * Convert audio sample format with dithering.
   *
   * @param c    DitherContext
   * @param dst  destination audio data
   * @param src  source audio data
   * @return     0 if ok, negative AVERROR code on failure
   */
  int ff_convert_dither(DitherContext *c, AudioData *dst, AudioData *src);
  
  /* arch-specific initialization functions */
  
  void ff_dither_init_x86(DitherDSPContext *ddsp,
                          enum AVResampleDitherMethod method);
  
  #endif /* AVRESAMPLE_DITHER_H */