adtsenc.c 3.9 KB

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  1. /*
  2. * ADTS muxer.
  3. * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
  4. * Mans Rullgard <mans@mansr.com>
  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 "libavcodec/bitstream.h"
  23. #include "libavcodec/internal.h"
  24. #include "avformat.h"
  25. #define ADTS_HEADER_SIZE 7
  26. typedef struct {
  27. int write_adts;
  28. int objecttype;
  29. int sample_rate_index;
  30. int channel_conf;
  31. } ADTSContext;
  32. static int decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
  33. {
  34. GetBitContext gb;
  35. init_get_bits(&gb, buf, size * 8);
  36. adts->objecttype = get_bits(&gb, 5) - 1;
  37. adts->sample_rate_index = get_bits(&gb, 4);
  38. adts->channel_conf = get_bits(&gb, 4);
  39. if (adts->objecttype > 3) {
  40. av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
  41. return -1;
  42. }
  43. if (adts->sample_rate_index == 15) {
  44. av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
  45. return -1;
  46. }
  47. if (adts->channel_conf == 0) {
  48. ff_log_missing_feature(s, "PCE based channel configuration", 0);
  49. return -1;
  50. }
  51. adts->write_adts = 1;
  52. return 0;
  53. }
  54. static int adts_write_header(AVFormatContext *s)
  55. {
  56. ADTSContext *adts = s->priv_data;
  57. AVCodecContext *avc = s->streams[0]->codec;
  58. if(avc->extradata_size > 0 &&
  59. decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
  60. return -1;
  61. return 0;
  62. }
  63. static int adts_write_frame_header(AVFormatContext *s, int size)
  64. {
  65. ADTSContext *ctx = s->priv_data;
  66. PutBitContext pb;
  67. uint8_t buf[ADTS_HEADER_SIZE];
  68. init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
  69. /* adts_fixed_header */
  70. put_bits(&pb, 12, 0xfff); /* syncword */
  71. put_bits(&pb, 1, 0); /* ID */
  72. put_bits(&pb, 2, 0); /* layer */
  73. put_bits(&pb, 1, 1); /* protection_absent */
  74. put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
  75. put_bits(&pb, 4, ctx->sample_rate_index);
  76. put_bits(&pb, 1, 0); /* private_bit */
  77. put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
  78. put_bits(&pb, 1, 0); /* original_copy */
  79. put_bits(&pb, 1, 0); /* home */
  80. /* adts_variable_header */
  81. put_bits(&pb, 1, 0); /* copyright_identification_bit */
  82. put_bits(&pb, 1, 0); /* copyright_identification_start */
  83. put_bits(&pb, 13, ADTS_HEADER_SIZE + size); /* aac_frame_length */
  84. put_bits(&pb, 11, 0x7ff); /* adts_buffer_fullness */
  85. put_bits(&pb, 2, 0); /* number_of_raw_data_blocks_in_frame */
  86. flush_put_bits(&pb);
  87. put_buffer(s->pb, buf, ADTS_HEADER_SIZE);
  88. return 0;
  89. }
  90. static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
  91. {
  92. ADTSContext *adts = s->priv_data;
  93. ByteIOContext *pb = s->pb;
  94. if (!pkt->size)
  95. return 0;
  96. if(adts->write_adts)
  97. adts_write_frame_header(s, pkt->size);
  98. put_buffer(pb, pkt->data, pkt->size);
  99. put_flush_packet(pb);
  100. return 0;
  101. }
  102. AVOutputFormat adts_muxer = {
  103. "adts",
  104. NULL_IF_CONFIG_SMALL("ADTS AAC"),
  105. "audio/aac",
  106. "aac",
  107. sizeof(ADTSContext),
  108. CODEC_ID_AAC,
  109. CODEC_ID_NONE,
  110. adts_write_header,
  111. adts_write_packet,
  112. };