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ffmpeg-4.2.2/libavcodec/opus_rc.h 4.21 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Copyright (c) 2012 Andrew D'Addesio
   * Copyright (c) 2013-2014 Mozilla Corporation
   * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@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 AVCODEC_OPUS_RC_H
  #define AVCODEC_OPUS_RC_H
  
  #include <stdint.h>
  #include "get_bits.h"
  
  #define OPUS_MAX_PACKET_SIZE 1275
  
  #define opus_ilog(i) (av_log2(i) + !!(i))
  
  typedef struct RawBitsContext {
      const uint8_t *position;
      uint32_t bytes;
      uint32_t cachelen;
      uint32_t cacheval;
  } RawBitsContext;
  
  typedef struct OpusRangeCoder {
      GetBitContext gb;
      RawBitsContext rb;
      uint32_t range;
      uint32_t value;
      uint32_t total_bits;
  
      /* Encoder */
      uint8_t buf[OPUS_MAX_PACKET_SIZE + 12]; /* memcpy vs (memmove + overreading) */
      uint8_t *rng_cur;                      /* Current range coded byte */
      int ext;                               /* Awaiting propagation */
      int rem;                               /* Carryout flag */
  
      /* Encoding stats */
      int waste;
  } OpusRangeCoder;
  
  /**
   * CELT: estimate bits of entropy that have thus far been consumed for the
   *       current CELT frame, to integer and fractional (1/8th bit) precision
   */
  static av_always_inline uint32_t opus_rc_tell(const OpusRangeCoder *rc)
  {
      return rc->total_bits - av_log2(rc->range) - 1;
  }
  
  static av_always_inline uint32_t opus_rc_tell_frac(const OpusRangeCoder *rc)
  {
      uint32_t i, total_bits, rcbuffer, range;
  
      total_bits = rc->total_bits << 3;
      rcbuffer   = av_log2(rc->range) + 1;
      range      = rc->range >> (rcbuffer-16);
  
      for (i = 0; i < 3; i++) {
          int bit;
          range = range * range >> 15;
          bit = range >> 16;
          rcbuffer = rcbuffer << 1 | bit;
          range >>= bit;
      }
  
      return total_bits - rcbuffer;
  }
  
  uint32_t ff_opus_rc_dec_cdf(OpusRangeCoder *rc, const uint16_t *cdf);
  void     ff_opus_rc_enc_cdf(OpusRangeCoder *rc, int val, const uint16_t *cdf);
  
  uint32_t ff_opus_rc_dec_log(OpusRangeCoder *rc, uint32_t bits);
  void     ff_opus_rc_enc_log(OpusRangeCoder *rc, int val, uint32_t bits);
  
  uint32_t ff_opus_rc_dec_uint_step(OpusRangeCoder *rc, int k0);
  void     ff_opus_rc_enc_uint_step(OpusRangeCoder *rc, uint32_t val, int k0);
  
  uint32_t ff_opus_rc_dec_uint_tri(OpusRangeCoder *rc, int qn);
  void     ff_opus_rc_enc_uint_tri(OpusRangeCoder *rc, uint32_t k, int qn);
  
  uint32_t ff_opus_rc_dec_uint(OpusRangeCoder *rc, uint32_t size);
  void     ff_opus_rc_enc_uint(OpusRangeCoder *rc, uint32_t val, uint32_t size);
  
  uint32_t ff_opus_rc_get_raw(OpusRangeCoder *rc, uint32_t count);
  void     ff_opus_rc_put_raw(OpusRangeCoder *rc, uint32_t val, uint32_t count);
  
  int      ff_opus_rc_dec_laplace(OpusRangeCoder *rc, uint32_t symbol, int decay);
  void     ff_opus_rc_enc_laplace(OpusRangeCoder *rc, int *value, uint32_t symbol, int decay);
  
  int      ff_opus_rc_dec_init(OpusRangeCoder *rc, const uint8_t *data, int size);
  void     ff_opus_rc_dec_raw_init(OpusRangeCoder *rc, const uint8_t *rightend, uint32_t bytes);
  
  void     ff_opus_rc_enc_end(OpusRangeCoder *rc, uint8_t *dst, int size);
  void     ff_opus_rc_enc_init(OpusRangeCoder *rc);
  
  #define OPUS_RC_CHECKPOINT_UPDATE(rc) \
      rc_rollback_bits = opus_rc_tell_frac(rc); \
      rc_rollback_ctx  = *rc
  
  #define OPUS_RC_CHECKPOINT_SPAWN(rc) \
      uint32_t rc_rollback_bits = opus_rc_tell_frac(rc); \
      OpusRangeCoder rc_rollback_ctx = *rc \
  
  #define OPUS_RC_CHECKPOINT_BITS(rc) \
      (opus_rc_tell_frac(rc) - rc_rollback_bits)
  
  #define OPUS_RC_CHECKPOINT_ROLLBACK(rc) \
      memcpy(rc, &rc_rollback_ctx, sizeof(OpusRangeCoder)); \
  
  #endif /* AVCODEC_OPUS_RC_H */