www.pudn.com > ffmpeg_src2007.rar > ac3.h

/* 
 * Common code between AC3 encoder and decoder 
 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard. 
 * 
 * This library 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 of the License, or (at your option) any later version. 
 * 
 * This library 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 this library; if not, write to the Free Software 
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 
 */ 
 
/** 
 * @file ac3.h 
 * Common code between AC3 encoder and decoder. 
 */ 
 
#define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */ 
#define AC3_MAX_CHANNELS 6 /* including LFE channel */ 
 
#define NB_BLOCKS 6 /* number of PCM blocks inside an AC3 frame */ 
#define AC3_FRAME_SIZE (NB_BLOCKS * 256) 
 
/* exponent encoding strategy */ 
#define EXP_REUSE 0 
#define EXP_NEW   1 
 
#define EXP_D15   1 
#define EXP_D25   2 
#define EXP_D45   3 
 
typedef struct AC3BitAllocParameters { 
    int fscod; /* frequency */ 
    int halfratecod; 
    int sgain, sdecay, fdecay, dbknee, floor; 
    int cplfleak, cplsleak; 
} AC3BitAllocParameters; 
 
#if 0 
extern const uint16_t ac3_freqs[3]; 
extern const uint16_t ac3_bitratetab[19]; 
extern const int16_t ac3_window[256]; 
extern const uint8_t sdecaytab[4]; 
extern const uint8_t fdecaytab[4]; 
extern const uint16_t sgaintab[4]; 
extern const uint16_t dbkneetab[4]; 
extern const uint16_t floortab[8]; 
extern const uint16_t fgaintab[8]; 
#endif 
 
void ac3_common_init(void); 
void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap, 
                                   int8_t *exp, int start, int end, 
                                   int snroffset, int fgain, int is_lfe, 
                                   int deltbae,int deltnseg, 
                                   uint8_t *deltoffst, uint8_t *deltlen, uint8_t *deltba);