3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2003 Michael Niedermayer
6 * This file is part of Libav.
8 * Libav 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.
13 * Libav 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.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with Libav; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #include "ac3_parser.h"
25 #include "aac_ac3_parser.h"
27 #include "libavutil/audioconvert.h"
30 #define AC3_HEADER_SIZE 7
33 static const uint8_t eac3_blocks[4] = {
38 int avpriv_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
42 memset(hdr, 0, sizeof(*hdr));
44 hdr->sync_word = get_bits(gbc, 16);
45 if(hdr->sync_word != 0x0B77)
46 return AAC_AC3_PARSE_ERROR_SYNC;
48 /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */
49 hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F;
50 if(hdr->bitstream_id > 16)
51 return AAC_AC3_PARSE_ERROR_BSID;
55 /* set default mix levels */
56 hdr->center_mix_level = 1; // -4.5dB
57 hdr->surround_mix_level = 1; // -6.0dB
59 if(hdr->bitstream_id <= 10) {
61 hdr->crc1 = get_bits(gbc, 16);
62 hdr->sr_code = get_bits(gbc, 2);
64 return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
66 frame_size_code = get_bits(gbc, 6);
67 if(frame_size_code > 37)
68 return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
70 skip_bits(gbc, 5); // skip bsid, already got it
72 hdr->bitstream_mode = get_bits(gbc, 3);
73 hdr->channel_mode = get_bits(gbc, 3);
75 if(hdr->channel_mode == AC3_CHMODE_STEREO) {
76 skip_bits(gbc, 2); // skip dsurmod
78 if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)
79 hdr->center_mix_level = get_bits(gbc, 2);
80 if(hdr->channel_mode & 4)
81 hdr->surround_mix_level = get_bits(gbc, 2);
83 hdr->lfe_on = get_bits1(gbc);
85 hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
86 hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
87 hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
88 hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
89 hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
90 hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;
95 hdr->frame_type = get_bits(gbc, 2);
96 if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)
97 return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
99 hdr->substreamid = get_bits(gbc, 3);
101 hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;
102 if(hdr->frame_size < AC3_HEADER_SIZE)
103 return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
105 hdr->sr_code = get_bits(gbc, 2);
106 if (hdr->sr_code == 3) {
107 int sr_code2 = get_bits(gbc, 2);
109 return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
110 hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
113 hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];
114 hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
118 hdr->channel_mode = get_bits(gbc, 3);
119 hdr->lfe_on = get_bits1(gbc);
121 hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /
122 (hdr->num_blocks * 256.0));
123 hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
125 hdr->channel_layout = ff_ac3_channel_layout_tab[hdr->channel_mode];
127 hdr->channel_layout |= AV_CH_LOW_FREQUENCY;
132 static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
133 int *need_next_header, int *new_frame_start)
139 } tmp = { av_be2ne64(state) };
143 init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
144 err = avpriv_ac3_parse_header(&gbc, &hdr);
149 hdr_info->sample_rate = hdr.sample_rate;
150 hdr_info->bit_rate = hdr.bit_rate;
151 hdr_info->channels = hdr.channels;
152 hdr_info->channel_layout = hdr.channel_layout;
153 hdr_info->samples = hdr.num_blocks * 256;
154 hdr_info->service_type = hdr.bitstream_mode;
155 if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
156 hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
157 if(hdr.bitstream_id>10)
158 hdr_info->codec_id = CODEC_ID_EAC3;
159 else if (hdr_info->codec_id == CODEC_ID_NONE)
160 hdr_info->codec_id = CODEC_ID_AC3;
162 *need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
163 *new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
164 return hdr.frame_size;
167 static av_cold int ac3_parse_init(AVCodecParserContext *s1)
169 AACAC3ParseContext *s = s1->priv_data;
170 s->header_size = AC3_HEADER_SIZE;
176 AVCodecParser ff_ac3_parser = {
177 .codec_ids = { CODEC_ID_AC3, CODEC_ID_EAC3 },
178 .priv_data_size = sizeof(AACAC3ParseContext),
179 .parser_init = ac3_parse_init,
180 .parser_parse = ff_aac_ac3_parse,
181 .parser_close = ff_parse_close,