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3rdparty/ffmpeg-4.4.4/libavcodec/ac3dsp.h 4.77 KB
09c2d08c   Hu Chunming   arm交付版
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  /*
   * AC-3 DSP functions
   * Copyright (c) 2011 Justin Ruggles
   *
   * 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_AC3DSP_H
  #define AVCODEC_AC3DSP_H
  
  #include <stdint.h>
  
  /**
   * Number of mantissa bits written for each bap value.
   * bap values with fractional bits are set to 0 and are calculated separately.
   */
  extern const uint16_t ff_ac3_bap_bits[16];
  
  typedef struct AC3DSPContext {
      /**
       * Set each encoded exponent in a block to the minimum of itself and the
       * exponents in the same frequency bin of up to 5 following blocks.
       * @param exp   pointer to the start of the current block of exponents.
       *              constraints: align 16
       * @param num_reuse_blocks  number of blocks that will reuse exponents from the current block.
       *                          constraints: range 0 to 5
       * @param nb_coefs  number of frequency coefficients.
       */
      void (*ac3_exponent_min)(uint8_t *exp, int num_reuse_blocks, int nb_coefs);
  
      /**
       * Convert an array of float in range [-1.0,1.0] to int32_t with range
       * [-(1<<24),(1<<24)]
       *
       * @param dst destination array of int32_t.
       *            constraints: 16-byte aligned
       * @param src source array of float.
       *            constraints: 16-byte aligned
       * @param len number of elements to convert.
       *            constraints: multiple of 32 greater than zero
       */
      void (*float_to_fixed24)(int32_t *dst, const float *src, unsigned int len);
  
      /**
       * Calculate bit allocation pointers.
       * The SNR is the difference between the masking curve and the signal.  AC-3
       * uses this value for each frequency bin to allocate bits.  The snroffset
       * parameter is a global adjustment to the SNR for all bins.
       *
       * @param[in]  mask       masking curve
       * @param[in]  psd        signal power for each frequency bin
       * @param[in]  start      starting bin location
       * @param[in]  end        ending bin location
       * @param[in]  snr_offset SNR adjustment
       * @param[in]  floor      noise floor
       * @param[in]  bap_tab    look-up table for bit allocation pointers
       * @param[out] bap        bit allocation pointers
       */
      void (*bit_alloc_calc_bap)(int16_t *mask, int16_t *psd, int start, int end,
                                 int snr_offset, int floor,
                                 const uint8_t *bap_tab, uint8_t *bap);
  
      /**
       * Update bap counts using the supplied array of bap.
       *
       * @param[out] mant_cnt   bap counts for 1 block
       * @param[in]  bap        array of bap, pointing to start coef bin
       * @param[in]  len        number of elements to process
       */
      void (*update_bap_counts)(uint16_t mant_cnt[16], uint8_t *bap, int len);
  
      /**
       * Calculate the number of bits needed to encode a set of mantissas.
       *
       * @param[in] mant_cnt    bap counts for all blocks
       * @return                mantissa bit count
       */
      int (*compute_mantissa_size)(uint16_t mant_cnt[6][16]);
  
      void (*extract_exponents)(uint8_t *exp, int32_t *coef, int nb_coefs);
  
      void (*sum_square_butterfly_int32)(int64_t sum[4], const int32_t *coef0,
                                         const int32_t *coef1, int len);
  
      void (*sum_square_butterfly_float)(float sum[4], const float *coef0,
                                         const float *coef1, int len);
  
      int out_channels;
      int in_channels;
      void (*downmix)(float **samples, float **matrix, int len);
      void (*downmix_fixed)(int32_t **samples, int16_t **matrix, int len);
  } AC3DSPContext;
  
  void ff_ac3dsp_init    (AC3DSPContext *c, int bit_exact);
  void ff_ac3dsp_init_arm(AC3DSPContext *c, int bit_exact);
  void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact);
  void ff_ac3dsp_init_mips(AC3DSPContext *c, int bit_exact);
  
  void ff_ac3dsp_downmix(AC3DSPContext *c, float **samples, float **matrix,
                         int out_ch, int in_ch, int len);
  void ff_ac3dsp_downmix_fixed(AC3DSPContext *c, int32_t **samples, int16_t **matrix,
                               int out_ch, int in_ch, int len);
  
  void ff_ac3dsp_set_downmix_x86(AC3DSPContext *c);
  
  #endif /* AVCODEC_AC3DSP_H */