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ffmpeg-4.2.2/libavcodec/avdct.h 2.51 KB
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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
   */
  
  #ifndef AVCODEC_AVDCT_H
  #define AVCODEC_AVDCT_H
  
  #include "libavutil/opt.h"
  
  /**
   * AVDCT context.
   * @note function pointers can be NULL if the specific features have been
   *       disabled at build time.
   */
  typedef struct AVDCT {
      const AVClass *av_class;
  
      void (*idct)(int16_t *block /* align 16 */);
  
      /**
       * IDCT input permutation.
       * Several optimized IDCTs need a permutated input (relative to the
       * normal order of the reference IDCT).
       * This permutation must be performed before the idct_put/add.
       * Note, normally this can be merged with the zigzag/alternate scan<br>
       * An example to avoid confusion:
       * - (->decode coeffs -> zigzag reorder -> dequant -> reference IDCT -> ...)
       * - (x -> reference DCT -> reference IDCT -> x)
       * - (x -> reference DCT -> simple_mmx_perm = idct_permutation
       *    -> simple_idct_mmx -> x)
       * - (-> decode coeffs -> zigzag reorder -> simple_mmx_perm -> dequant
       *    -> simple_idct_mmx -> ...)
       */
      uint8_t idct_permutation[64];
  
      void (*fdct)(int16_t *block /* align 16 */);
  
  
      /**
       * DCT algorithm.
       * must use AVOptions to set this field.
       */
      int dct_algo;
  
      /**
       * IDCT algorithm.
       * must use AVOptions to set this field.
       */
      int idct_algo;
  
      void (*get_pixels)(int16_t *block /* align 16 */,
                         const uint8_t *pixels /* align 8 */,
                         ptrdiff_t line_size);
  
      int bits_per_sample;
  } AVDCT;
  
  /**
   * Allocates a AVDCT context.
   * This needs to be initialized with avcodec_dct_init() after optionally
   * configuring it with AVOptions.
   *
   * To free it use av_free()
   */
  AVDCT *avcodec_dct_alloc(void);
  int avcodec_dct_init(AVDCT *);
  
  const AVClass *avcodec_dct_get_class(void);
  
  #endif /* AVCODEC_AVDCT_H */