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 AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */
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)
71#define AC3_DYNAMIC_RANGE(x)    (x)
72#define AC3_SPX_BLEND(x)        (x)
73#define AC3_DYNAMIC_RANGE1      0
74
75#define INTFLOAT                int
76#define SHORTFLOAT              int16_t
77
78#else /* USE_FIXED */
79
80#define FIXR(x)                 ((float)(x))
81#define FIXR12(x)               ((float)(x))
82#define FIXR15(x)               ((float)(x))
83#define ROUND15(x)              (x)
84
85#define AC3_RENAME(x)           x
86#define AC3_NORM(norm)          (1.0f/(norm))
87#define AC3_MUL(a,b)            ((a) * (b))
88#define AC3_RANGE(x)            (dynamic_range_tab[(x)])
89#define AC3_DYNAMIC_RANGE(x)    (powf(x,  s->drc_scale))
90#define AC3_SPX_BLEND(x)        (x)* (1.0f/32)
91#define AC3_DYNAMIC_RANGE1      1.0f
92
93#define INTFLOAT                float
94#define SHORTFLOAT              float
95
96#endif /* USE_FIXED */
97
98#define AC3_LEVEL(x)            ROUND15((x) * FIXR15(0.7071067811865476))
99
100/* pre-defined gain values */
101#define LEVEL_PLUS_3DB          1.4142135623730950
102#define LEVEL_PLUS_1POINT5DB    1.1892071150027209
103#define LEVEL_MINUS_1POINT5DB   0.8408964152537145
104#define LEVEL_MINUS_3DB         0.7071067811865476
105#define LEVEL_MINUS_4POINT5DB   0.5946035575013605
106#define LEVEL_MINUS_6DB         0.5000000000000000
107#define LEVEL_MINUS_9DB         0.3535533905932738
108#define LEVEL_ZERO              0.0000000000000000
109#define LEVEL_ONE               1.0000000000000000
110
111/** Delta bit allocation strategy */
112typedef enum {
113    DBA_REUSE = 0,
114    DBA_NEW,
115    DBA_NONE,
116    DBA_RESERVED
117} AC3DeltaStrategy;
118
119/** Channel mode (audio coding mode) */
120typedef enum {
121    AC3_CHMODE_DUALMONO = 0,
122    AC3_CHMODE_MONO,
123    AC3_CHMODE_STEREO,
124    AC3_CHMODE_3F,
125    AC3_CHMODE_2F1R,
126    AC3_CHMODE_3F1R,
127    AC3_CHMODE_2F2R,
128    AC3_CHMODE_3F2R
129} AC3ChannelMode;
130
131/** Dolby Surround mode */
132typedef enum AC3DolbySurroundMode {
133    AC3_DSURMOD_NOTINDICATED = 0,
134    AC3_DSURMOD_OFF,
135    AC3_DSURMOD_ON,
136    AC3_DSURMOD_RESERVED
137} AC3DolbySurroundMode;
138
139/** Dolby Surround EX mode */
140typedef enum AC3DolbySurroundEXMode {
141    AC3_DSUREXMOD_NOTINDICATED = 0,
142    AC3_DSUREXMOD_OFF,
143    AC3_DSUREXMOD_ON,
144    AC3_DSUREXMOD_PLIIZ
145} AC3DolbySurroundEXMode;
146
147/** Dolby Headphone mode */
148typedef enum AC3DolbyHeadphoneMode {
149    AC3_DHEADPHONMOD_NOTINDICATED = 0,
150    AC3_DHEADPHONMOD_OFF,
151    AC3_DHEADPHONMOD_ON,
152    AC3_DHEADPHONMOD_RESERVED
153} AC3DolbyHeadphoneMode;
154
155/** Preferred Stereo Downmix mode */
156typedef enum AC3PreferredStereoDownmixMode {
157    AC3_DMIXMOD_NOTINDICATED = 0,
158    AC3_DMIXMOD_LTRT,
159    AC3_DMIXMOD_LORO,
160    AC3_DMIXMOD_DPLII // reserved value in A/52, but used by encoders to indicate DPL2
161} AC3PreferredStereoDownmixMode;
162
163typedef struct AC3BitAllocParameters {
164    int sr_code;
165    int sr_shift;
166    int slow_gain, slow_decay, fast_decay, db_per_bit, floor;
167    int cpl_fast_leak, cpl_slow_leak;
168} AC3BitAllocParameters;
169
170/**
171 * @struct AC3HeaderInfo
172 * Coded AC-3 header values up to the lfeon element, plus derived values.
173 */
174typedef struct AC3HeaderInfo {
175    /** @name Coded elements
176     * @{
177     */
178    uint16_t sync_word;
179    uint16_t crc1;
180    uint8_t sr_code;
181    uint8_t bitstream_id;
182    uint8_t bitstream_mode;
183    uint8_t channel_mode;
184    uint8_t lfe_on;
185    uint8_t frame_type;
186    int substreamid;                        ///< substream identification
187    int center_mix_level;                   ///< Center mix level index
188    int surround_mix_level;                 ///< Surround mix level index
189    uint16_t channel_map;
190    int num_blocks;                         ///< number of audio blocks
191#if AV_HAVE_INCOMPATIBLE_LIBAV_ABI
192    int dolby_surround_mode;
193#endif
194    /** @} */
195
196    /** @name Derived values
197     * @{
198     */
199    uint8_t sr_shift;
200    uint16_t sample_rate;
201    uint32_t bit_rate;
202    uint8_t channels;
203    uint16_t frame_size;
204    uint64_t channel_layout;
205    /** @} */
206#if !AV_HAVE_INCOMPATIBLE_LIBAV_ABI
207    int dolby_surround_mode;
208#endif
209} AC3HeaderInfo;
210
211typedef enum {
212    EAC3_FRAME_TYPE_INDEPENDENT = 0,
213    EAC3_FRAME_TYPE_DEPENDENT,
214    EAC3_FRAME_TYPE_AC3_CONVERT,
215    EAC3_FRAME_TYPE_RESERVED
216} EAC3FrameType;
217
218void ff_ac3_common_init(void);
219
220/**
221 * Calculate the log power-spectral density of the input signal.
222 * This gives a rough estimate of signal power in the frequency domain by using
223 * the spectral envelope (exponents).  The psd is also separately grouped
224 * into critical bands for use in the calculating the masking curve.
225 * 128 units in psd = -6 dB.  The dbknee parameter in AC3BitAllocParameters
226 * determines the reference level.
227 *
228 * @param[in]  exp        frequency coefficient exponents
229 * @param[in]  start      starting bin location
230 * @param[in]  end        ending bin location
231 * @param[out] psd        signal power for each frequency bin
232 * @param[out] band_psd   signal power for each critical band
233 */
234void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
235                               int16_t *band_psd);
236
237/**
238 * Calculate the masking curve.
239 * First, the excitation is calculated using parameters in s and the signal
240 * power in each critical band.  The excitation is compared with a predefined
241 * hearing threshold table to produce the masking curve.  If delta bit
242 * allocation information is provided, it is used for adjusting the masking
243 * curve, usually to give a closer match to a better psychoacoustic model.
244 *
245 * @param[in]  s            adjustable bit allocation parameters
246 * @param[in]  band_psd     signal power for each critical band
247 * @param[in]  start        starting bin location
248 * @param[in]  end          ending bin location
249 * @param[in]  fast_gain    fast gain (estimated signal-to-mask ratio)
250 * @param[in]  is_lfe       whether or not the channel being processed is the LFE
251 * @param[in]  dba_mode     delta bit allocation mode (none, reuse, or new)
252 * @param[in]  dba_nsegs    number of delta segments
253 * @param[in]  dba_offsets  location offsets for each segment
254 * @param[in]  dba_lengths  length of each segment
255 * @param[in]  dba_values   delta bit allocation for each segment
256 * @param[out] mask         calculated masking curve
257 * @return returns 0 for success, non-zero for error
258 */
259int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
260                               int start, int end, int fast_gain, int is_lfe,
261                               int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
262                               uint8_t *dba_lengths, uint8_t *dba_values,
263                               int16_t *mask);
264
265#endif /* AVCODEC_AC3_H */
266