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  1. /*
  2. * Audio and Video frame extraction
  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. #include "parser.h"
  23. #include "aac_ac3_parser.h"
  24. #include "bitstream.h"
  25. #include "mpeg4audio.h"
  26. #define AAC_HEADER_SIZE 7
  27. static int aac_sync(uint64_t state, AACAC3ParseContext *hdr_info)
  28. {
  29. GetBitContext bits;
  30. int size, rdb, ch, sr;
  31. uint64_t tmp = be2me_64(state);
  32. init_get_bits(&bits, ((uint8_t *)&tmp)+8-AAC_HEADER_SIZE, AAC_HEADER_SIZE * 8);
  33. if(get_bits(&bits, 12) != 0xfff)
  34. return 0;
  35. skip_bits1(&bits); /* id */
  36. skip_bits(&bits, 2); /* layer */
  37. skip_bits1(&bits); /* protection_absent */
  38. skip_bits(&bits, 2); /* profile_objecttype */
  39. sr = get_bits(&bits, 4); /* sample_frequency_index */
  40. if(!ff_mpeg4audio_sample_rates[sr])
  41. return 0;
  42. skip_bits1(&bits); /* private_bit */
  43. ch = get_bits(&bits, 3); /* channel_configuration */
  44. if(!ff_mpeg4audio_channels[ch])
  45. return 0;
  46. skip_bits1(&bits); /* original/copy */
  47. skip_bits1(&bits); /* home */
  48. /* adts_variable_header */
  49. skip_bits1(&bits); /* copyright_identification_bit */
  50. skip_bits1(&bits); /* copyright_identification_start */
  51. size = get_bits(&bits, 13); /* aac_frame_length */
  52. if(size < AAC_HEADER_SIZE)
  53. return 0;
  54. skip_bits(&bits, 11); /* adts_buffer_fullness */
  55. rdb = get_bits(&bits, 2); /* number_of_raw_data_blocks_in_frame */
  56. hdr_info->channels = ff_mpeg4audio_channels[ch];
  57. hdr_info->sample_rate = ff_mpeg4audio_sample_rates[sr];
  58. hdr_info->samples = (rdb + 1) * 1024;
  59. hdr_info->bit_rate = size * 8 * hdr_info->sample_rate / hdr_info->samples;
  60. return size;
  61. }
  62. static av_cold int aac_parse_init(AVCodecParserContext *s1)
  63. {
  64. AACAC3ParseContext *s = s1->priv_data;
  65. s->header_size = AAC_HEADER_SIZE;
  66. s->sync = aac_sync;
  67. return 0;
  68. }
  69. AVCodecParser aac_parser = {
  70. { CODEC_ID_AAC },
  71. sizeof(AACAC3ParseContext),
  72. aac_parse_init,
  73. ff_aac_ac3_parse,
  74. NULL,
  75. };