| 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 | }; |