FFmpeg  4.4.6
ac3.h
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1 /*
2  * Common code between the AC-3 encoder and decoder
3  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * Common code between the AC-3 encoder and decoder.
25  */
26 
27 #ifndef AVCODEC_AC3_H
28 #define AVCODEC_AC3_H
29 
30 #define EAC3_MAX_CHANNELS 16 /**< maximum number of channels in EAC3 */
31 #define AC3_MAX_CHANNELS 7 /**< maximum number of channels, including coupling channel */
32 #define CPL_CH 0 /**< coupling channel index */
33 
34 #define AC3_MAX_COEFS 256
35 #define AC3_BLOCK_SIZE 256
36 #define AC3_MAX_BLOCKS 6
37 #define AC3_FRAME_SIZE (AC3_MAX_BLOCKS * 256)
38 #define AC3_WINDOW_SIZE (AC3_BLOCK_SIZE * 2)
39 #define AC3_CRITICAL_BANDS 50
40 #define AC3_MAX_CPL_BANDS 18
41 
42 #include "libavutil/opt.h"
43 #include "avcodec.h"
44 #include "ac3tab.h"
45 
46 /* exponent encoding strategy */
47 #define EXP_REUSE 0
48 #define EXP_NEW 1
49 
50 #define EXP_D15 1
51 #define EXP_D25 2
52 #define EXP_D45 3
53 
54 #ifndef USE_FIXED
55 #define USE_FIXED 0
56 #endif
57 
58 #if USE_FIXED
59 
60 #define FFT_FLOAT 0
61 
62 #define FIXR(a) ((int)((a) * 0 + 0.5))
63 #define FIXR12(a) ((int)((a) * 4096 + 0.5))
64 #define FIXR15(a) ((int)((a) * 32768 + 0.5))
65 #define ROUND15(x) ((x) + 16384) >> 15
66 
67 #define AC3_RENAME(x) x ## _fixed
68 #define AC3_NORM(norm) (1<<24)/(norm)
69 #define AC3_MUL(a,b) ((((int64_t) (a)) * (b))>>12)
70 #define AC3_RANGE(x) ((x)|(((x)&128)<<1))
71 #define AC3_HEAVY_RANGE(x) ((x)<<1)
72 #define AC3_DYNAMIC_RANGE(x) (x)
73 #define AC3_SPX_BLEND(x) (x)
74 #define AC3_DYNAMIC_RANGE1 0
75 
76 typedef int INTFLOAT;
77 typedef unsigned int UINTFLOAT;
78 typedef int16_t SHORTFLOAT;
79 
80 #else /* USE_FIXED */
81 
82 #define FIXR(x) ((float)(x))
83 #define FIXR12(x) ((float)(x))
84 #define FIXR15(x) ((float)(x))
85 #define ROUND15(x) (x)
86 
87 #define AC3_RENAME(x) x
88 #define AC3_NORM(norm) (1.0f/(norm))
89 #define AC3_MUL(a,b) ((a) * (b))
90 #define AC3_RANGE(x) (dynamic_range_tab[(x)])
91 #define AC3_HEAVY_RANGE(x) (ff_ac3_heavy_dynamic_range_tab[(x)])
92 #define AC3_DYNAMIC_RANGE(x) (powf(x, s->drc_scale))
93 #define AC3_SPX_BLEND(x) (x)* (1.0f/32)
94 #define AC3_DYNAMIC_RANGE1 1.0f
95 
96 typedef float INTFLOAT;
97 typedef float UINTFLOAT;
98 typedef float SHORTFLOAT;
99 
100 #endif /* USE_FIXED */
101 
102 #define AC3_LEVEL(x) ROUND15((x) * FIXR15(M_SQRT1_2))
103 
104 /* pre-defined gain values */
105 #define LEVEL_PLUS_3DB M_SQRT2
106 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209
107 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145
108 #define LEVEL_MINUS_3DB M_SQRT1_2
109 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605
110 #define LEVEL_MINUS_6DB 0.5000000000000000
111 #define LEVEL_MINUS_9DB 0.3535533905932738
112 #define LEVEL_ZERO 0.0000000000000000
113 #define LEVEL_ONE 1.0000000000000000
114 
115 /** Delta bit allocation strategy */
116 typedef enum {
122 
123 /** Channel mode (audio coding mode) */
124 typedef enum {
134 
135 /** Dolby Surround mode */
136 typedef enum AC3DolbySurroundMode {
142 
143 /** Dolby Surround EX mode */
150 
151 /** Dolby Headphone mode */
152 typedef enum AC3DolbyHeadphoneMode {
158 
159 /** Preferred Stereo Downmix mode */
164  AC3_DMIXMOD_DPLII // reserved value in A/52, but used by encoders to indicate DPL2
166 
167 typedef struct AC3BitAllocParameters {
168  int sr_code;
169  int sr_shift;
173 
174 /**
175  * @struct AC3HeaderInfo
176  * Coded AC-3 header values up to the lfeon element, plus derived values.
177  */
178 typedef struct AC3HeaderInfo {
179  /** @name Coded elements
180  * @{
181  */
182  uint16_t sync_word;
183  uint16_t crc1;
190  int substreamid; ///< substream identification
191  int center_mix_level; ///< Center mix level index
192  int surround_mix_level; ///< Surround mix level index
193  uint16_t channel_map;
194  int num_blocks; ///< number of audio blocks
196  /** @} */
197 
198  /** @name Derived values
199  * @{
200  */
202  uint16_t sample_rate;
203  uint32_t bit_rate;
205  uint16_t frame_size;
206  uint64_t channel_layout;
207  /** @} */
208 } AC3HeaderInfo;
209 
210 typedef enum {
216 
218 
219 /**
220  * Calculate the log power-spectral density of the input signal.
221  * This gives a rough estimate of signal power in the frequency domain by using
222  * the spectral envelope (exponents). The psd is also separately grouped
223  * into critical bands for use in the calculating the masking curve.
224  * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters
225  * determines the reference level.
226  *
227  * @param[in] exp frequency coefficient exponents
228  * @param[in] start starting bin location
229  * @param[in] end ending bin location
230  * @param[out] psd signal power for each frequency bin
231  * @param[out] band_psd signal power for each critical band
232  */
233 void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
234  int16_t *band_psd);
235 
236 /**
237  * Calculate the masking curve.
238  * First, the excitation is calculated using parameters in s and the signal
239  * power in each critical band. The excitation is compared with a predefined
240  * hearing threshold table to produce the masking curve. If delta bit
241  * allocation information is provided, it is used for adjusting the masking
242  * curve, usually to give a closer match to a better psychoacoustic model.
243  *
244  * @param[in] s adjustable bit allocation parameters
245  * @param[in] band_psd signal power for each critical band
246  * @param[in] start starting bin location
247  * @param[in] end ending bin location
248  * @param[in] fast_gain fast gain (estimated signal-to-mask ratio)
249  * @param[in] is_lfe whether or not the channel being processed is the LFE
250  * @param[in] dba_mode delta bit allocation mode (none, reuse, or new)
251  * @param[in] dba_nsegs number of delta segments
252  * @param[in] dba_offsets location offsets for each segment
253  * @param[in] dba_lengths length of each segment
254  * @param[in] dba_values delta bit allocation for each segment
255  * @param[out] mask calculated masking curve
256  * @return returns 0 for success, non-zero for error
257  */
258 int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
259  int start, int end, int fast_gain, int is_lfe,
260  int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
261  uint8_t *dba_lengths, uint8_t *dba_values,
262  int16_t *mask);
263 
264 #endif /* AVCODEC_AC3_H */
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)
Calculate the masking curve.
Definition: ac3.c:118
AC3DolbyHeadphoneMode
Dolby Headphone mode.
Definition: ac3.h:152
@ AC3_DHEADPHONMOD_RESERVED
Definition: ac3.h:156
@ AC3_DHEADPHONMOD_NOTINDICATED
Definition: ac3.h:153
@ AC3_DHEADPHONMOD_ON
Definition: ac3.h:155
@ AC3_DHEADPHONMOD_OFF
Definition: ac3.h:154
float SHORTFLOAT
Definition: ac3.h:98
AC3DolbySurroundEXMode
Dolby Surround EX mode.
Definition: ac3.h:144
@ AC3_DSUREXMOD_ON
Definition: ac3.h:147
@ AC3_DSUREXMOD_PLIIZ
Definition: ac3.h:148
@ AC3_DSUREXMOD_OFF
Definition: ac3.h:146
@ AC3_DSUREXMOD_NOTINDICATED
Definition: ac3.h:145
float INTFLOAT
Definition: ac3.h:96
void ff_ac3_common_init(void)
AC3ChannelMode
Channel mode (audio coding mode)
Definition: ac3.h:124
@ AC3_CHMODE_MONO
Definition: ac3.h:126
@ AC3_CHMODE_STEREO
Definition: ac3.h:127
@ AC3_CHMODE_2F1R
Definition: ac3.h:129
@ AC3_CHMODE_DUALMONO
Definition: ac3.h:125
@ AC3_CHMODE_3F
Definition: ac3.h:128
@ AC3_CHMODE_3F1R
Definition: ac3.h:130
@ AC3_CHMODE_2F2R
Definition: ac3.h:131
@ AC3_CHMODE_3F2R
Definition: ac3.h:132
void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, int16_t *band_psd)
Calculate the log power-spectral density of the input signal.
Definition: ac3.c:92
EAC3FrameType
Definition: ac3.h:210
@ EAC3_FRAME_TYPE_DEPENDENT
Definition: ac3.h:212
@ EAC3_FRAME_TYPE_INDEPENDENT
Definition: ac3.h:211
@ EAC3_FRAME_TYPE_RESERVED
Definition: ac3.h:214
@ EAC3_FRAME_TYPE_AC3_CONVERT
Definition: ac3.h:213
AC3DeltaStrategy
Delta bit allocation strategy.
Definition: ac3.h:116
@ DBA_RESERVED
Definition: ac3.h:120
@ DBA_NEW
Definition: ac3.h:118
@ DBA_REUSE
Definition: ac3.h:117
@ DBA_NONE
Definition: ac3.h:119
float UINTFLOAT
Definition: ac3.h:97
AC3PreferredStereoDownmixMode
Preferred Stereo Downmix mode.
Definition: ac3.h:160
@ AC3_DMIXMOD_DPLII
Definition: ac3.h:164
@ AC3_DMIXMOD_NOTINDICATED
Definition: ac3.h:161
@ AC3_DMIXMOD_LTRT
Definition: ac3.h:162
@ AC3_DMIXMOD_LORO
Definition: ac3.h:163
AC3DolbySurroundMode
Dolby Surround mode.
Definition: ac3.h:136
@ AC3_DSURMOD_RESERVED
Definition: ac3.h:140
@ AC3_DSURMOD_OFF
Definition: ac3.h:138
@ AC3_DSURMOD_NOTINDICATED
Definition: ac3.h:137
@ AC3_DSURMOD_ON
Definition: ac3.h:139
uint8_t
Libavcodec external API header.
#define s(width, name)
Definition: cbs_vp9.c:257
int8_t exp
Definition: eval.c:72
static const uint16_t mask[17]
Definition: lzw.c:38
AVOptions.
Coded AC-3 header values up to the lfeon element, plus derived values.
Definition: ac3.h:178
uint8_t sr_shift
Definition: ac3.h:201
uint8_t bitstream_mode
Definition: ac3.h:186
uint16_t crc1
Definition: ac3.h:183
int dolby_surround_mode
Definition: ac3.h:195
uint8_t bitstream_id
Definition: ac3.h:185
int center_mix_level
Center mix level index.
Definition: ac3.h:191
uint8_t channels
Definition: ac3.h:204
uint8_t channel_mode
Definition: ac3.h:187
int substreamid
substream identification
Definition: ac3.h:190
int num_blocks
number of audio blocks
Definition: ac3.h:194
int surround_mix_level
Surround mix level index.
Definition: ac3.h:192
uint16_t sample_rate
Definition: ac3.h:202
uint8_t frame_type
Definition: ac3.h:189
uint16_t channel_map
Definition: ac3.h:193
uint16_t sync_word
Definition: ac3.h:182
uint16_t frame_size
Definition: ac3.h:205
uint8_t sr_code
Definition: ac3.h:184
uint32_t bit_rate
Definition: ac3.h:203
uint8_t lfe_on
Definition: ac3.h:188
uint64_t channel_layout
Definition: ac3.h:206