Globally rename the header inclusion guard names.
[libav.git] / libavcodec / ac3.h
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 ac3.h
24 * Common code between the AC-3 encoder and decoder.
25 */
26
27 #ifndef AVCODEC_AC3_H
28 #define AVCODEC_AC3_H
29
30 #include "ac3tab.h"
31
32 #define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */
33 #define AC3_MAX_CHANNELS 6 /* including LFE channel */
34
35 #define NB_BLOCKS 6 /* number of PCM blocks inside an AC-3 frame */
36 #define AC3_FRAME_SIZE (NB_BLOCKS * 256)
37
38 /* exponent encoding strategy */
39 #define EXP_REUSE 0
40 #define EXP_NEW 1
41
42 #define EXP_D15 1
43 #define EXP_D25 2
44 #define EXP_D45 3
45
46 /** Delta bit allocation strategy */
47 typedef enum {
48 DBA_REUSE = 0,
49 DBA_NEW,
50 DBA_NONE,
51 DBA_RESERVED
52 } AC3DeltaStrategy;
53
54 /** Channel mode (audio coding mode) */
55 typedef enum {
56 AC3_CHMODE_DUALMONO = 0,
57 AC3_CHMODE_MONO,
58 AC3_CHMODE_STEREO,
59 AC3_CHMODE_3F,
60 AC3_CHMODE_2F1R,
61 AC3_CHMODE_3F1R,
62 AC3_CHMODE_2F2R,
63 AC3_CHMODE_3F2R
64 } AC3ChannelMode;
65
66 typedef struct AC3BitAllocParameters {
67 int sr_code;
68 int sr_shift;
69 int slow_gain, slow_decay, fast_decay, db_per_bit, floor;
70 int cpl_fast_leak, cpl_slow_leak;
71 } AC3BitAllocParameters;
72
73 /**
74 * @struct AC3HeaderInfo
75 * Coded AC-3 header values up to the lfeon element, plus derived values.
76 */
77 typedef struct {
78 /** @defgroup coded Coded elements
79 * @{
80 */
81 uint16_t sync_word;
82 uint16_t crc1;
83 uint8_t sr_code;
84 uint8_t bitstream_id;
85 uint8_t channel_mode;
86 uint8_t lfe_on;
87 uint8_t frame_type;
88 int substreamid; ///< substream identification
89 int center_mix_level; ///< Center mix level index
90 int surround_mix_level; ///< Surround mix level index
91 uint16_t channel_map;
92 int num_blocks; ///< number of audio blocks
93 /** @} */
94
95 /** @defgroup derived Derived values
96 * @{
97 */
98 uint8_t sr_shift;
99 uint16_t sample_rate;
100 uint32_t bit_rate;
101 uint8_t channels;
102 uint16_t frame_size;
103 /** @} */
104 } AC3HeaderInfo;
105
106 typedef enum {
107 EAC3_FRAME_TYPE_INDEPENDENT = 0,
108 EAC3_FRAME_TYPE_DEPENDENT,
109 EAC3_FRAME_TYPE_AC3_CONVERT,
110 EAC3_FRAME_TYPE_RESERVED
111 } EAC3FrameType;
112
113 void ac3_common_init(void);
114
115 /**
116 * Calculates the log power-spectral density of the input signal.
117 * This gives a rough estimate of signal power in the frequency domain by using
118 * the spectral envelope (exponents). The psd is also separately grouped
119 * into critical bands for use in the calculating the masking curve.
120 * 128 units in psd = -6 dB. The dbknee parameter in AC3BitAllocParameters
121 * determines the reference level.
122 *
123 * @param[in] exp frequency coefficient exponents
124 * @param[in] start starting bin location
125 * @param[in] end ending bin location
126 * @param[out] psd signal power for each frequency bin
127 * @param[out] band_psd signal power for each critical band
128 */
129 void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
130 int16_t *band_psd);
131
132 /**
133 * Calculates the masking curve.
134 * First, the excitation is calculated using parameters in \p s and the signal
135 * power in each critical band. The excitation is compared with a predefined
136 * hearing threshold table to produce the masking curve. If delta bit
137 * allocation information is provided, it is used for adjusting the masking
138 * curve, usually to give a closer match to a better psychoacoustic model.
139 *
140 * @param[in] s adjustable bit allocation parameters
141 * @param[in] band_psd signal power for each critical band
142 * @param[in] start starting bin location
143 * @param[in] end ending bin location
144 * @param[in] fast_gain fast gain (estimated signal-to-mask ratio)
145 * @param[in] is_lfe whether or not the channel being processed is the LFE
146 * @param[in] dba_mode delta bit allocation mode (none, reuse, or new)
147 * @param[in] dba_nsegs number of delta segments
148 * @param[in] dba_offsets location offsets for each segment
149 * @param[in] dba_lengths length of each segment
150 * @param[in] dba_values delta bit allocation for each segment
151 * @param[out] mask calculated masking curve
152 */
153 void ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
154 int start, int end, int fast_gain, int is_lfe,
155 int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
156 uint8_t *dba_lengths, uint8_t *dba_values,
157 int16_t *mask);
158
159 /**
160 * Calculates bit allocation pointers.
161 * The SNR is the difference between the masking curve and the signal. AC-3
162 * uses this value for each frequency bin to allocate bits. The \p snroffset
163 * parameter is a global adjustment to the SNR for all bins.
164 *
165 * @param[in] mask masking curve
166 * @param[in] psd signal power for each frequency bin
167 * @param[in] start starting bin location
168 * @param[in] end ending bin location
169 * @param[in] snr_offset SNR adjustment
170 * @param[in] floor noise floor
171 * @param[in] bap_tab look-up table for bit allocation pointers
172 * @param[out] bap bit allocation pointers
173 */
174 void ff_ac3_bit_alloc_calc_bap(int16_t *mask, int16_t *psd, int start, int end,
175 int snr_offset, int floor,
176 const uint8_t *bap_tab, uint8_t *bap);
177
178 void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap,
179 int8_t *exp, int start, int end,
180 int snr_offset, int fast_gain, int is_lfe,
181 int dba_mode, int dba_nsegs,
182 uint8_t *dba_offsets, uint8_t *dba_lengths,
183 uint8_t *dba_values);
184
185 #endif /* AVCODEC_AC3_H */