1 /*
2  * E-AC-3 encoder
3  * Copyright (c) 2011 Justin Ruggles <justin.ruggles@gmail.com>
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  * E-AC-3 encoder
25  */
26 
27 #define CONFIG_AC3ENC_FLOAT 1
28 
29 #include "libavutil/attributes.h"
30 #include "ac3enc.h"
31 #include "eac3enc.h"
32 #include "eac3_data.h"
33 
34 
35 #define AC3ENC_TYPE AC3ENC_TYPE_EAC3
36 #include "ac3enc_opts_template.c"
37 
38 static const AVClass eac3enc_class = {
39     .class_name = "E-AC-3 Encoder",
40     .item_name  = av_default_item_name,
41     .option     = ac3_options,
42     .version    = LIBAVUTIL_VERSION_INT,
43 };
44 
45 /**
46  * LUT for finding a matching frame exponent strategy index from a set of
47  * exponent strategies for a single channel across all 6 blocks.
48  */
49 static int8_t eac3_frame_expstr_index_tab[3][4][4][4][4][4];
50 
51 
ff_eac3_exponent_init(void)52 av_cold void ff_eac3_exponent_init(void)
53 {
54     int i;
55 
56     memset(eac3_frame_expstr_index_tab, -1, sizeof(eac3_frame_expstr_index_tab));
57     for (i = 0; i < 32; i++) {
58         eac3_frame_expstr_index_tab[ff_eac3_frm_expstr[i][0]-1]
59                                    [ff_eac3_frm_expstr[i][1]]
60                                    [ff_eac3_frm_expstr[i][2]]
61                                    [ff_eac3_frm_expstr[i][3]]
62                                    [ff_eac3_frm_expstr[i][4]]
63                                    [ff_eac3_frm_expstr[i][5]] = i;
64     }
65 }
66 
67 
ff_eac3_get_frame_exp_strategy(AC3EncodeContext * s)68 void ff_eac3_get_frame_exp_strategy(AC3EncodeContext *s)
69 {
70     int ch;
71 
72     if (s->num_blocks < 6) {
73         s->use_frame_exp_strategy = 0;
74         return;
75     }
76 
77     s->use_frame_exp_strategy = 1;
78     for (ch = !s->cpl_on; ch <= s->fbw_channels; ch++) {
79         int expstr = eac3_frame_expstr_index_tab[s->exp_strategy[ch][0]-1]
80                                                 [s->exp_strategy[ch][1]]
81                                                 [s->exp_strategy[ch][2]]
82                                                 [s->exp_strategy[ch][3]]
83                                                 [s->exp_strategy[ch][4]]
84                                                 [s->exp_strategy[ch][5]];
85         if (expstr < 0) {
86             s->use_frame_exp_strategy = 0;
87             break;
88         }
89         s->frame_exp_strategy[ch] = expstr;
90     }
91 }
92 
93 
94 
ff_eac3_set_cpl_states(AC3EncodeContext * s)95 void ff_eac3_set_cpl_states(AC3EncodeContext *s)
96 {
97     int ch, blk;
98     int first_cpl_coords[AC3_MAX_CHANNELS];
99 
100     /* set first cpl coords */
101     for (ch = 1; ch <= s->fbw_channels; ch++)
102         first_cpl_coords[ch] = 1;
103     for (blk = 0; blk < s->num_blocks; blk++) {
104         AC3Block *block = &s->blocks[blk];
105         for (ch = 1; ch <= s->fbw_channels; ch++) {
106             if (block->channel_in_cpl[ch]) {
107                 if (first_cpl_coords[ch]) {
108                     block->new_cpl_coords[ch] = 2;
109                     first_cpl_coords[ch]  = 0;
110                 }
111             } else {
112                 first_cpl_coords[ch] = 1;
113             }
114         }
115     }
116 
117     /* set first cpl leak */
118     for (blk = 0; blk < s->num_blocks; blk++) {
119         AC3Block *block = &s->blocks[blk];
120         if (block->cpl_in_use) {
121             block->new_cpl_leak = 2;
122             break;
123         }
124     }
125 }
126 
127 
ff_eac3_output_frame_header(AC3EncodeContext * s)128 void ff_eac3_output_frame_header(AC3EncodeContext *s)
129 {
130     int blk, ch;
131     AC3EncOptions *opt = &s->options;
132 
133     put_bits(&s->pb, 16, 0x0b77);                   /* sync word */
134 
135     /* BSI header */
136     put_bits(&s->pb,  2, 0);                        /* stream type = independent */
137     put_bits(&s->pb,  3, 0);                        /* substream id = 0 */
138     put_bits(&s->pb, 11, (s->frame_size / 2) - 1);  /* frame size */
139     if (s->bit_alloc.sr_shift) {
140         put_bits(&s->pb, 2, 0x3);                   /* fscod2 */
141         put_bits(&s->pb, 2, s->bit_alloc.sr_code);  /* sample rate code */
142     } else {
143         put_bits(&s->pb, 2, s->bit_alloc.sr_code);  /* sample rate code */
144         put_bits(&s->pb, 2, s->num_blks_code);      /* number of blocks */
145     }
146     put_bits(&s->pb, 3, s->channel_mode);           /* audio coding mode */
147     put_bits(&s->pb, 1, s->lfe_on);                 /* LFE channel indicator */
148     put_bits(&s->pb, 5, s->bitstream_id);           /* bitstream id (EAC3=16) */
149     put_bits(&s->pb, 5, -opt->dialogue_level);      /* dialogue normalization level */
150     put_bits(&s->pb, 1, 0);                         /* no compression gain */
151     /* mixing metadata*/
152     put_bits(&s->pb, 1, opt->eac3_mixing_metadata);
153     if (opt->eac3_mixing_metadata) {
154         if (s->channel_mode > AC3_CHMODE_STEREO)
155             put_bits(&s->pb, 2, opt->preferred_stereo_downmix);
156         if (s->has_center) {
157             put_bits(&s->pb, 3, s->ltrt_center_mix_level);
158             put_bits(&s->pb, 3, s->loro_center_mix_level);
159         }
160         if (s->has_surround) {
161             put_bits(&s->pb, 3, s->ltrt_surround_mix_level);
162             put_bits(&s->pb, 3, s->loro_surround_mix_level);
163         }
164         if (s->lfe_on)
165             put_bits(&s->pb, 1, 0);
166         put_bits(&s->pb, 1, 0);                     /* no program scale */
167         put_bits(&s->pb, 1, 0);                     /* no ext program scale */
168         put_bits(&s->pb, 2, 0);                     /* no mixing parameters */
169         if (s->channel_mode < AC3_CHMODE_STEREO)
170             put_bits(&s->pb, 1, 0);                 /* no pan info */
171         put_bits(&s->pb, 1, 0);                     /* no frame mix config info */
172     }
173     /* info metadata*/
174     put_bits(&s->pb, 1, opt->eac3_info_metadata);
175     if (opt->eac3_info_metadata) {
176         put_bits(&s->pb, 3, s->bitstream_mode);
177         put_bits(&s->pb, 1, opt->copyright);
178         put_bits(&s->pb, 1, opt->original);
179         if (s->channel_mode == AC3_CHMODE_STEREO) {
180             put_bits(&s->pb, 2, opt->dolby_surround_mode);
181             put_bits(&s->pb, 2, opt->dolby_headphone_mode);
182         }
183         if (s->channel_mode >= AC3_CHMODE_2F2R)
184             put_bits(&s->pb, 2, opt->dolby_surround_ex_mode);
185         put_bits(&s->pb, 1, opt->audio_production_info);
186         if (opt->audio_production_info) {
187             put_bits(&s->pb, 5, opt->mixing_level - 80);
188             put_bits(&s->pb, 2, opt->room_type);
189             put_bits(&s->pb, 1, opt->ad_converter_type);
190         }
191         put_bits(&s->pb, 1, 0);
192     }
193     if (s->num_blocks != 6)
194         put_bits(&s->pb, 1, !(s->avctx->frame_number % 6)); /* converter sync flag */
195     put_bits(&s->pb, 1, 0);                         /* no additional bit stream info */
196 
197     /* frame header */
198     if (s->num_blocks == 6) {
199     put_bits(&s->pb, 1, !s->use_frame_exp_strategy);/* exponent strategy syntax */
200     put_bits(&s->pb, 1, 0);                         /* aht enabled = no */
201     }
202     put_bits(&s->pb, 2, 0);                         /* snr offset strategy = 1 */
203     put_bits(&s->pb, 1, 0);                         /* transient pre-noise processing enabled = no */
204     put_bits(&s->pb, 1, 0);                         /* block switch syntax enabled = no */
205     put_bits(&s->pb, 1, 0);                         /* dither flag syntax enabled = no */
206     put_bits(&s->pb, 1, 0);                         /* bit allocation model syntax enabled = no */
207     put_bits(&s->pb, 1, 0);                         /* fast gain codes enabled = no */
208     put_bits(&s->pb, 1, 0);                         /* dba syntax enabled = no */
209     put_bits(&s->pb, 1, 0);                         /* skip field syntax enabled = no */
210     put_bits(&s->pb, 1, 0);                         /* spx enabled = no */
211     /* coupling strategy use flags */
212     if (s->channel_mode > AC3_CHMODE_MONO) {
213         put_bits(&s->pb, 1, s->blocks[0].cpl_in_use);
214         for (blk = 1; blk < s->num_blocks; blk++) {
215             AC3Block *block = &s->blocks[blk];
216             put_bits(&s->pb, 1, block->new_cpl_strategy);
217             if (block->new_cpl_strategy)
218                 put_bits(&s->pb, 1, block->cpl_in_use);
219         }
220     }
221     /* exponent strategy */
222     if (s->use_frame_exp_strategy) {
223         for (ch = !s->cpl_on; ch <= s->fbw_channels; ch++)
224             put_bits(&s->pb, 5, s->frame_exp_strategy[ch]);
225     } else {
226         for (blk = 0; blk < s->num_blocks; blk++)
227             for (ch = !s->blocks[blk].cpl_in_use; ch <= s->fbw_channels; ch++)
228                 put_bits(&s->pb, 2, s->exp_strategy[ch][blk]);
229     }
230     if (s->lfe_on) {
231         for (blk = 0; blk < s->num_blocks; blk++)
232             put_bits(&s->pb, 1, s->exp_strategy[s->lfe_channel][blk]);
233     }
234     /* E-AC-3 to AC-3 converter exponent strategy (not optional when num blocks == 6) */
235     if (s->num_blocks != 6) {
236         put_bits(&s->pb, 1, 0);
237     } else {
238     for (ch = 1; ch <= s->fbw_channels; ch++) {
239         if (s->use_frame_exp_strategy)
240             put_bits(&s->pb, 5, s->frame_exp_strategy[ch]);
241         else
242             put_bits(&s->pb, 5, 0);
243     }
244     }
245     /* snr offsets */
246     put_bits(&s->pb, 6, s->coarse_snr_offset);
247     put_bits(&s->pb, 4, s->fine_snr_offset[1]);
248     /* block start info */
249     if (s->num_blocks > 1)
250         put_bits(&s->pb, 1, 0);
251 }
252 
253 
254 AVCodec ff_eac3_encoder = {
255     .name            = "eac3",
256     .long_name       = NULL_IF_CONFIG_SMALL("ATSC A/52 E-AC-3"),
257     .type            = AVMEDIA_TYPE_AUDIO,
258     .id              = AV_CODEC_ID_EAC3,
259     .priv_data_size  = sizeof(AC3EncodeContext),
260     .init            = ff_ac3_float_encode_init,
261     .encode2         = ff_ac3_float_encode_frame,
262     .close           = ff_ac3_encode_close,
263     .sample_fmts     = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_FLTP,
264                                                       AV_SAMPLE_FMT_NONE },
265     .priv_class      = &eac3enc_class,
266     .supported_samplerates = ff_ac3_sample_rate_tab,
267     .channel_layouts = ff_ac3_channel_layouts,
268     .defaults        = ac3_defaults,
269     .caps_internal   = FF_CODEC_CAP_INIT_CLEANUP,
270 };
271