libavcodec/ac3.h

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/*
 * Common code between the AC-3 encoder and decoder
 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
 *
 * 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_AC3_H
#define AVCODEC_AC3_H

#include "ac3tab.h"

#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 AC-3 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 enum {
    DBA_REUSE = 0,
    DBA_NEW,
    DBA_NONE,
    DBA_RESERVED
} AC3DeltaStrategy;

typedef enum {
    AC3_CHMODE_DUALMONO = 0,
    AC3_CHMODE_MONO,
    AC3_CHMODE_STEREO,
    AC3_CHMODE_3F,
    AC3_CHMODE_2F1R,
    AC3_CHMODE_3F1R,
    AC3_CHMODE_2F2R,
    AC3_CHMODE_3F2R
} AC3ChannelMode;

typedef struct AC3BitAllocParameters {
    int sr_code;
    int sr_shift;
    int slow_gain, slow_decay, fast_decay, db_per_bit, floor;
    int cpl_fast_leak, cpl_slow_leak;
} AC3BitAllocParameters;

typedef struct {
    uint16_t sync_word;
    uint16_t crc1;
    uint8_t sr_code;
    uint8_t bitstream_id;
    uint8_t channel_mode;
    uint8_t lfe_on;
    uint8_t frame_type;
    int substreamid;                        
    int center_mix_level;                   
    int surround_mix_level;                 
    uint16_t channel_map;
    int num_blocks;                         

    uint8_t sr_shift;
    uint16_t sample_rate;
    uint32_t bit_rate;
    uint8_t channels;
    uint16_t frame_size;
} AC3HeaderInfo;

typedef enum {
    EAC3_FRAME_TYPE_INDEPENDENT = 0,
    EAC3_FRAME_TYPE_DEPENDENT,
    EAC3_FRAME_TYPE_AC3_CONVERT,
    EAC3_FRAME_TYPE_RESERVED
} EAC3FrameType;

void ac3_common_init(void);

void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
                               int16_t *band_psd);

int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
                               int start, int end, int fast_gain, int is_lfe,
                               int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
                               uint8_t *dba_lengths, uint8_t *dba_values,
                               int16_t *mask);

void ff_ac3_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);

void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap,
                                   int8_t *exp, int start, int end,
                                   int snr_offset, int fast_gain, int is_lfe,
                                   int dba_mode, int dba_nsegs,
                                   uint8_t *dba_offsets, uint8_t *dba_lengths,
                                   uint8_t *dba_values);

#endif /* AVCODEC_AC3_H */

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