libavcodec/ac3_parser.c

   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 "config.h"
  24 #include "config_components.h"
  25
  26 #include "libavutil/channel_layout.h"
  27 #include "parser.h"
  28 #include "ac3defs.h"
  29 #include "ac3tab.h"
  30 #include "ac3_parser.h"
  31 #include "ac3_parser_internal.h"
  32 #include "aac_ac3_parser.h"
  33 #include "get_bits.h"
  34
  35
  36 #define AC3_HEADER_SIZE 7
  37
  38 #if CONFIG_AC3_PARSER
  39
  40 static const uint8_t eac3_blocks[4] = {
  41     1, 2, 3, 6
  42 };
  43
  44 /**
  45  * Table for center mix levels
  46  * reference: Section 5.4.2.4 cmixlev
  47  */
  48 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
  49
  50 /**
  51  * Table for surround mix levels
  52  * reference: Section 5.4.2.5 surmixlev
  53  */
  54 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
  55
  56
  57 int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
  58 {
  59     int frame_size_code;
  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     hdr->ac3_bit_rate_code = -1;
  74
  75     /* set default mix levels */
  76     hdr->center_mix_level   = 5;  // -4.5dB
  77     hdr->surround_mix_level = 6;  // -6.0dB
  78
  79     /* set default dolby surround mode */
  80     hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED;
  81
  82     if(hdr->bitstream_id <= 10) {
  83         /* Normal AC-3 */
  84         hdr->crc1 = get_bits(gbc, 16);
  85         hdr->sr_code = get_bits(gbc, 2);
  86         if(hdr->sr_code == 3)
  87             return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
  88
  89         frame_size_code = get_bits(gbc, 6);
  90         if(frame_size_code > 37)
  91             return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
  92
  93         hdr->ac3_bit_rate_code = (frame_size_code >> 1);
  94
  95         skip_bits(gbc, 5); // skip bsid, already got it
  96
  97         hdr->bitstream_mode = get_bits(gbc, 3);
  98         hdr->channel_mode = get_bits(gbc, 3);
  99
 100         if(hdr->channel_mode == AC3_CHMODE_STEREO) {
 101             hdr->dolby_surround_mode = get_bits(gbc, 2);
 102         } else {
 103             if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)
 104                 hdr->  center_mix_level =   center_levels[get_bits(gbc, 2)];
 105             if(hdr->channel_mode & 4)
 106                 hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)];
 107         }
 108         hdr->lfe_on = get_bits1(gbc);
 109
 110         hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
 111         hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
 112         hdr->bit_rate = (ff_ac3_bitrate_tab[hdr->ac3_bit_rate_code] * 1000) >> hdr->sr_shift;
 113         hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
 114         hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
 115         hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;
 116         hdr->substreamid = 0;
 117     } else {
 118         /* Enhanced AC-3 */
 119         hdr->crc1 = 0;
 120         hdr->frame_type = get_bits(gbc, 2);
 121         if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)
 122             return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
 123
 124         hdr->substreamid = get_bits(gbc, 3);
 125
 126         hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;
 127         if(hdr->frame_size < AC3_HEADER_SIZE)
 128             return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
 129
 130         hdr->sr_code = get_bits(gbc, 2);
 131         if (hdr->sr_code == 3) {
 132             int sr_code2 = get_bits(gbc, 2);
 133             if(sr_code2 == 3)
 134                 return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
 135             hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
 136             hdr->sr_shift = 1;
 137         } else {
 138             hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];
 139             hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
 140             hdr->sr_shift = 0;
 141         }
 142
 143         hdr->channel_mode = get_bits(gbc, 3);
 144         hdr->lfe_on = get_bits1(gbc);
 145
 146         hdr->bit_rate = 8LL * hdr->frame_size * hdr->sample_rate /
 147                         (hdr->num_blocks * 256);
 148         hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
 149     }
 150     hdr->channel_layout = ff_ac3_channel_layout_tab[hdr->channel_mode];
 151     if (hdr->lfe_on)
 152         hdr->channel_layout |= AV_CH_LOW_FREQUENCY;
 153
 154     return 0;
 155 }
 156
 157 // TODO: Better way to pass AC3HeaderInfo fields to mov muxer.
 158 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
 159                             size_t size)
 160 {
 161     GetBitContext gb;
 162     AC3HeaderInfo *hdr;
 163     int err;
 164
 165     if (!*phdr)
 166         *phdr = av_mallocz(sizeof(AC3HeaderInfo));
 167     if (!*phdr)
 168         return AVERROR(ENOMEM);
 169     hdr = *phdr;
 170
 171     err = init_get_bits8(&gb, buf, size);
 172     if (err < 0)
 173         return AVERROR_INVALIDDATA;
 174     err = ff_ac3_parse_header(&gb, hdr);
 175     if (err < 0)
 176         return AVERROR_INVALIDDATA;
 177
 178     return get_bits_count(&gb);
 179 }
 180
 181 int av_ac3_parse_header(const uint8_t *buf, size_t size,
 182                         uint8_t *bitstream_id, uint16_t *frame_size)
 183 {
 184     GetBitContext gb;
 185     AC3HeaderInfo hdr;
 186     int err;
 187
 188     err = init_get_bits8(&gb, buf, size);
 189     if (err < 0)
 190         return AVERROR_INVALIDDATA;
 191     err = ff_ac3_parse_header(&gb, &hdr);
 192     if (err < 0)
 193         return AVERROR_INVALIDDATA;
 194
 195     *bitstream_id = hdr.bitstream_id;
 196     *frame_size   = hdr.frame_size;
 197
 198     return 0;
 199 }
 200
 201 static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
 202         int *need_next_header, int *new_frame_start)
 203 {
 204     int err;
 205     union {
 206         uint64_t u64;
 207         uint8_t  u8[8 + AV_INPUT_BUFFER_PADDING_SIZE];
 208     } tmp = { av_be2ne64(state) };
 209     AC3HeaderInfo hdr;
 210     GetBitContext gbc;
 211
 212     if (tmp.u8[1] == 0x77 && tmp.u8[2] == 0x0b) {
 213         FFSWAP(uint8_t, tmp.u8[1], tmp.u8[2]);
 214         FFSWAP(uint8_t, tmp.u8[3], tmp.u8[4]);
 215         FFSWAP(uint8_t, tmp.u8[5], tmp.u8[6]);
 216     }
 217
 218     init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
 219     err = ff_ac3_parse_header(&gbc, &hdr);
 220
 221     if(err < 0)
 222         return 0;
 223
 224     hdr_info->sample_rate = hdr.sample_rate;
 225     hdr_info->bit_rate = hdr.bit_rate;
 226     hdr_info->channels = hdr.channels;
 227     hdr_info->channel_layout = hdr.channel_layout;
 228     hdr_info->samples = hdr.num_blocks * 256;
 229     hdr_info->service_type = hdr.bitstream_mode;
 230     if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
 231         hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
 232     if(hdr.bitstream_id>10)
 233         hdr_info->codec_id = AV_CODEC_ID_EAC3;
 234     else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
 235         hdr_info->codec_id = AV_CODEC_ID_AC3;
 236
 237     *new_frame_start  = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
 238     *need_next_header = *new_frame_start || (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
 239     return hdr.frame_size;
 240 }
 241
 242 static av_cold int ac3_parse_init(AVCodecParserContext *s1)
 243 {
 244     AACAC3ParseContext *s = s1->priv_data;
 245     s->header_size = AC3_HEADER_SIZE;
 246     s->sync = ac3_sync;
 247     return 0;
 248 }
 249
 250
 251 const AVCodecParser ff_ac3_parser = {
 252     .codec_ids      = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 },
 253     .priv_data_size = sizeof(AACAC3ParseContext),
 254     .parser_init    = ac3_parse_init,
 255     .parser_parse   = ff_aac_ac3_parse,
 256     .parser_close   = ff_parse_close,
 257 };
 258
 259 #else
 260
 261 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
 262                             size_t size)
 263 {
 264     return AVERROR(ENOSYS);
 265 }
 266
 267 int av_ac3_parse_header(const uint8_t *buf, size_t size,
 268                         uint8_t *bitstream_id, uint16_t *frame_size)
 269 {
 270     return AVERROR(ENOSYS);
 271 }
 272 #endif