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aac_adtstoasc_bsf.c
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1 /*
2  * MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration bitstream filter
3  * Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "avcodec.h"
23 #include "aacadtsdec.h"
24 #include "put_bits.h"
25 #include "get_bits.h"
26 #include "mpeg4audio.h"
27 #include "internal.h"
28 
29 typedef struct AACBSFContext {
32 
33 /**
34  * This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
35  * ADTS header and removes the ADTS header.
36  */
38  AVCodecContext *avctx, const char *args,
39  uint8_t **poutbuf, int *poutbuf_size,
40  const uint8_t *buf, int buf_size,
41  int keyframe)
42 {
43  GetBitContext gb;
44  PutBitContext pb;
46 
47  AACBSFContext *ctx = bsfc->priv_data;
48 
50 
51  *poutbuf = (uint8_t*) buf;
52  *poutbuf_size = buf_size;
53 
54  if (avctx->extradata)
55  if (show_bits(&gb, 12) != 0xfff)
56  return 0;
57 
58  if (avpriv_aac_parse_header(&gb, &hdr) < 0) {
59  av_log(avctx, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
60  return -1;
61  }
62 
63  if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
65  "Multiple RDBs per frame with CRC");
66  return AVERROR_PATCHWELCOME;
67  }
68 
69  buf += AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
70  buf_size -= AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
71 
72  if (!ctx->first_frame_done) {
73  int pce_size = 0;
74  uint8_t pce_data[MAX_PCE_SIZE];
75  if (!hdr.chan_config) {
76  init_get_bits(&gb, buf, buf_size * 8);
77  if (get_bits(&gb, 3) != 5) {
79  "PCE-based channel configuration "
80  "without PCE as first syntax "
81  "element");
82  return AVERROR_PATCHWELCOME;
83  }
84  init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
85  pce_size = avpriv_copy_pce_data(&pb, &gb)/8;
86  flush_put_bits(&pb);
87  buf_size -= get_bits_count(&gb)/8;
88  buf += get_bits_count(&gb)/8;
89  }
90  av_free(avctx->extradata);
91  avctx->extradata_size = 2 + pce_size;
93 
94  init_put_bits(&pb, avctx->extradata, avctx->extradata_size);
95  put_bits(&pb, 5, hdr.object_type);
96  put_bits(&pb, 4, hdr.sampling_index);
97  put_bits(&pb, 4, hdr.chan_config);
98  put_bits(&pb, 1, 0); //frame length - 1024 samples
99  put_bits(&pb, 1, 0); //does not depend on core coder
100  put_bits(&pb, 1, 0); //is not extension
101  flush_put_bits(&pb);
102  if (pce_size) {
103  memcpy(avctx->extradata + 2, pce_data, pce_size);
104  }
105 
106  ctx->first_frame_done = 1;
107  }
108 
109  *poutbuf = (uint8_t*) buf;
110  *poutbuf_size = buf_size;
111 
112  return 0;
113 }
114 
116  .name = "aac_adtstoasc",
117  .priv_data_size = sizeof(AACBSFContext),
119 };