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libavcodec/ac3.h

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00001 /*
00002  * Common code between the AC-3 encoder and decoder
00003  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00027 #ifndef AVCODEC_AC3_H
00028 #define AVCODEC_AC3_H
00029 
00030 #include "ac3tab.h"
00031 
00032 #define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */
00033 #define AC3_MAX_CHANNELS 6 /* including LFE channel */
00034 
00035 #define NB_BLOCKS 6 /* number of PCM blocks inside an AC-3 frame */
00036 #define AC3_FRAME_SIZE (NB_BLOCKS * 256)
00037 
00038 /* exponent encoding strategy */
00039 #define EXP_REUSE 0
00040 #define EXP_NEW   1
00041 
00042 #define EXP_D15   1
00043 #define EXP_D25   2
00044 #define EXP_D45   3
00045 
00047 typedef enum {
00048     DBA_REUSE = 0,
00049     DBA_NEW,
00050     DBA_NONE,
00051     DBA_RESERVED
00052 } AC3DeltaStrategy;
00053 
00055 typedef enum {
00056     AC3_CHMODE_DUALMONO = 0,
00057     AC3_CHMODE_MONO,
00058     AC3_CHMODE_STEREO,
00059     AC3_CHMODE_3F,
00060     AC3_CHMODE_2F1R,
00061     AC3_CHMODE_3F1R,
00062     AC3_CHMODE_2F2R,
00063     AC3_CHMODE_3F2R
00064 } AC3ChannelMode;
00065 
00066 typedef struct AC3BitAllocParameters {
00067     int sr_code;
00068     int sr_shift;
00069     int slow_gain, slow_decay, fast_decay, db_per_bit, floor;
00070     int cpl_fast_leak, cpl_slow_leak;
00071 } AC3BitAllocParameters;
00072 
00077 typedef struct {
00081     uint16_t sync_word;
00082     uint16_t crc1;
00083     uint8_t sr_code;
00084     uint8_t bitstream_id;
00085     uint8_t channel_mode;
00086     uint8_t lfe_on;
00087     uint8_t frame_type;
00088     int substreamid;                        
00089     int center_mix_level;                   
00090     int surround_mix_level;                 
00091     uint16_t channel_map;
00092     int num_blocks;                         
00093 
00098     uint8_t sr_shift;
00099     uint16_t sample_rate;
00100     uint32_t bit_rate;
00101     uint8_t channels;
00102     uint16_t frame_size;
00103     int64_t channel_layout;
00105 } AC3HeaderInfo;
00106 
00107 typedef enum {
00108     EAC3_FRAME_TYPE_INDEPENDENT = 0,
00109     EAC3_FRAME_TYPE_DEPENDENT,
00110     EAC3_FRAME_TYPE_AC3_CONVERT,
00111     EAC3_FRAME_TYPE_RESERVED
00112 } EAC3FrameType;
00113 
00114 void ac3_common_init(void);
00115 
00130 void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
00131                                int16_t *band_psd);
00132 
00155 int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
00156                                int start, int end, int fast_gain, int is_lfe,
00157                                int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
00158                                uint8_t *dba_lengths, uint8_t *dba_values,
00159                                int16_t *mask);
00160 
00176 void ff_ac3_bit_alloc_calc_bap(int16_t *mask, int16_t *psd, int start, int end,
00177                                int snr_offset, int floor,
00178                                const uint8_t *bap_tab, uint8_t *bap);
00179 
00180 void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap,
00181                                    int8_t *exp, int start, int end,
00182                                    int snr_offset, int fast_gain, int is_lfe,
00183                                    int dba_mode, int dba_nsegs,
00184                                    uint8_t *dba_offsets, uint8_t *dba_lengths,
00185                                    uint8_t *dba_values);
00186 
00187 #endif /* AVCODEC_AC3_H */

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