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1 | /* |
2 | * AC-3 parser | |
3 | * Copyright (c) 2003 Fabrice Bellard | |
4 | * Copyright (c) 2003 Michael Niedermayer | |
5 | * | |
6 | * This file is part of FFmpeg. | |
7 | * | |
8 | * FFmpeg is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * FFmpeg is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with FFmpeg; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
23 | #include "libavutil/channel_layout.h" | |
24 | #include "parser.h" | |
25 | #include "ac3_parser.h" | |
26 | #include "aac_ac3_parser.h" | |
27 | #include "get_bits.h" | |
28 | ||
29 | ||
30 | #define AC3_HEADER_SIZE 7 | |
31 | ||
32 | ||
33 | static const uint8_t eac3_blocks[4] = { | |
34 | 1, 2, 3, 6 | |
35 | }; | |
36 | ||
37 | /** | |
38 | * Table for center mix levels | |
39 | * reference: Section 5.4.2.4 cmixlev | |
40 | */ | |
41 | static const uint8_t center_levels[4] = { 4, 5, 6, 5 }; | |
42 | ||
43 | /** | |
44 | * Table for surround mix levels | |
45 | * reference: Section 5.4.2.5 surmixlev | |
46 | */ | |
47 | static const uint8_t surround_levels[4] = { 4, 6, 7, 6 }; | |
48 | ||
49 | ||
50 | int avpriv_ac3_parse_header2(GetBitContext *gbc, AC3HeaderInfo **phdr) | |
51 | { | |
52 | int frame_size_code; | |
53 | AC3HeaderInfo *hdr; | |
54 | ||
55 | if (!*phdr) | |
56 | *phdr = av_mallocz(sizeof(AC3HeaderInfo)); | |
57 | if (!*phdr) | |
58 | return AVERROR(ENOMEM); | |
59 | hdr = *phdr; | |
60 | ||
61 | memset(hdr, 0, sizeof(*hdr)); | |
62 | ||
63 | hdr->sync_word = get_bits(gbc, 16); | |
64 | if(hdr->sync_word != 0x0B77) | |
65 | return AAC_AC3_PARSE_ERROR_SYNC; | |
66 | ||
67 | /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */ | |
68 | hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F; | |
69 | if(hdr->bitstream_id > 16) | |
70 | return AAC_AC3_PARSE_ERROR_BSID; | |
71 | ||
72 | hdr->num_blocks = 6; | |
73 | ||
74 | /* set default mix levels */ | |
75 | hdr->center_mix_level = 5; // -4.5dB | |
76 | hdr->surround_mix_level = 6; // -6.0dB | |
77 | ||
78 | /* set default dolby surround mode */ | |
79 | hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED; | |
80 | ||
81 | if(hdr->bitstream_id <= 10) { | |
82 | /* Normal AC-3 */ | |
83 | hdr->crc1 = get_bits(gbc, 16); | |
84 | hdr->sr_code = get_bits(gbc, 2); | |
85 | if(hdr->sr_code == 3) | |
86 | return AAC_AC3_PARSE_ERROR_SAMPLE_RATE; | |
87 | ||
88 | frame_size_code = get_bits(gbc, 6); | |
89 | if(frame_size_code > 37) | |
90 | return AAC_AC3_PARSE_ERROR_FRAME_SIZE; | |
91 | ||
92 | skip_bits(gbc, 5); // skip bsid, already got it | |
93 | ||
94 | hdr->bitstream_mode = get_bits(gbc, 3); | |
95 | hdr->channel_mode = get_bits(gbc, 3); | |
96 | ||
97 | if(hdr->channel_mode == AC3_CHMODE_STEREO) { | |
98 | hdr->dolby_surround_mode = get_bits(gbc, 2); | |
99 | } else { | |
100 | if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO) | |
101 | hdr-> center_mix_level = center_levels[get_bits(gbc, 2)]; | |
102 | if(hdr->channel_mode & 4) | |
103 | hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)]; | |
104 | } | |
105 | hdr->lfe_on = get_bits1(gbc); | |
106 | ||
107 | hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8; | |
108 | hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift; | |
109 | hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift; | |
110 | hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on; | |
111 | hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2; | |
112 | hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT; | |
113 | hdr->substreamid = 0; | |
114 | } else { | |
115 | /* Enhanced AC-3 */ | |
116 | hdr->crc1 = 0; | |
117 | hdr->frame_type = get_bits(gbc, 2); | |
118 | if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED) | |
119 | return AAC_AC3_PARSE_ERROR_FRAME_TYPE; | |
120 | ||
121 | hdr->substreamid = get_bits(gbc, 3); | |
122 | ||
123 | hdr->frame_size = (get_bits(gbc, 11) + 1) << 1; | |
124 | if(hdr->frame_size < AC3_HEADER_SIZE) | |
125 | return AAC_AC3_PARSE_ERROR_FRAME_SIZE; | |
126 | ||
127 | hdr->sr_code = get_bits(gbc, 2); | |
128 | if (hdr->sr_code == 3) { | |
129 | int sr_code2 = get_bits(gbc, 2); | |
130 | if(sr_code2 == 3) | |
131 | return AAC_AC3_PARSE_ERROR_SAMPLE_RATE; | |
132 | hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2; | |
133 | hdr->sr_shift = 1; | |
134 | } else { | |
135 | hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)]; | |
136 | hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code]; | |
137 | hdr->sr_shift = 0; | |
138 | } | |
139 | ||
140 | hdr->channel_mode = get_bits(gbc, 3); | |
141 | hdr->lfe_on = get_bits1(gbc); | |
142 | ||
143 | hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate / | |
144 | (hdr->num_blocks * 256.0)); | |
145 | hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on; | |
146 | } | |
147 | hdr->channel_layout = avpriv_ac3_channel_layout_tab[hdr->channel_mode]; | |
148 | if (hdr->lfe_on) | |
149 | hdr->channel_layout |= AV_CH_LOW_FREQUENCY; | |
150 | ||
151 | return 0; | |
152 | } | |
153 | ||
154 | int avpriv_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) | |
155 | { | |
156 | AC3HeaderInfo tmp, *ptmp = &tmp; | |
157 | int ret = avpriv_ac3_parse_header2(gbc, &ptmp); | |
158 | ||
159 | memcpy(hdr, ptmp, ((intptr_t)&tmp.channel_layout) - ((intptr_t)&tmp) + sizeof(uint64_t)); | |
160 | return ret; | |
161 | } | |
162 | ||
163 | static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info, | |
164 | int *need_next_header, int *new_frame_start) | |
165 | { | |
166 | int err; | |
167 | union { | |
168 | uint64_t u64; | |
169 | uint8_t u8[8 + FF_INPUT_BUFFER_PADDING_SIZE]; | |
170 | } tmp = { av_be2ne64(state) }; | |
171 | AC3HeaderInfo hdr, *phdr = &hdr; | |
172 | GetBitContext gbc; | |
173 | ||
174 | init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54); | |
175 | err = avpriv_ac3_parse_header2(&gbc, &phdr); | |
176 | ||
177 | if(err < 0) | |
178 | return 0; | |
179 | ||
180 | hdr_info->sample_rate = hdr.sample_rate; | |
181 | hdr_info->bit_rate = hdr.bit_rate; | |
182 | hdr_info->channels = hdr.channels; | |
183 | hdr_info->channel_layout = hdr.channel_layout; | |
184 | hdr_info->samples = hdr.num_blocks * 256; | |
185 | hdr_info->service_type = hdr.bitstream_mode; | |
186 | if (hdr.bitstream_mode == 0x7 && hdr.channels > 1) | |
187 | hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE; | |
188 | if(hdr.bitstream_id>10) | |
189 | hdr_info->codec_id = AV_CODEC_ID_EAC3; | |
190 | else if (hdr_info->codec_id == AV_CODEC_ID_NONE) | |
191 | hdr_info->codec_id = AV_CODEC_ID_AC3; | |
192 | ||
193 | *need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT); | |
194 | *new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT); | |
195 | return hdr.frame_size; | |
196 | } | |
197 | ||
198 | static av_cold int ac3_parse_init(AVCodecParserContext *s1) | |
199 | { | |
200 | AACAC3ParseContext *s = s1->priv_data; | |
201 | s->header_size = AC3_HEADER_SIZE; | |
202 | s->sync = ac3_sync; | |
203 | return 0; | |
204 | } | |
205 | ||
206 | ||
207 | AVCodecParser ff_ac3_parser = { | |
208 | .codec_ids = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 }, | |
209 | .priv_data_size = sizeof(AACAC3ParseContext), | |
210 | .parser_init = ac3_parse_init, | |
211 | .parser_parse = ff_aac_ac3_parse, | |
212 | .parser_close = ff_parse_close, | |
213 | }; |