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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) {
64  av_log_missing_feature(avctx, "Multiple RDBs per frame with CRC", 0);
65  return AVERROR_PATCHWELCOME;
66  }
67 
68  buf += AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
69  buf_size -= AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
70 
71  if (!ctx->first_frame_done) {
72  int pce_size = 0;
73  uint8_t pce_data[MAX_PCE_SIZE];
74  if (!hdr.chan_config) {
75  init_get_bits(&gb, buf, buf_size * 8);
76  if (get_bits(&gb, 3) != 5) {
77  av_log_missing_feature(avctx, "PCE based channel configuration, where the PCE is not the first syntax element", 0);
78  return AVERROR_PATCHWELCOME;
79  }
80  init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
81  pce_size = avpriv_copy_pce_data(&pb, &gb)/8;
82  flush_put_bits(&pb);
83  buf_size -= get_bits_count(&gb)/8;
84  buf += get_bits_count(&gb)/8;
85  }
86  avctx->extradata_size = 2 + pce_size;
88 
89  init_put_bits(&pb, avctx->extradata, avctx->extradata_size);
90  put_bits(&pb, 5, hdr.object_type);
91  put_bits(&pb, 4, hdr.sampling_index);
92  put_bits(&pb, 4, hdr.chan_config);
93  put_bits(&pb, 1, 0); //frame length - 1024 samples
94  put_bits(&pb, 1, 0); //does not depend on core coder
95  put_bits(&pb, 1, 0); //is not extension
96  flush_put_bits(&pb);
97  if (pce_size) {
98  memcpy(avctx->extradata + 2, pce_data, pce_size);
99  }
100 
101  ctx->first_frame_done = 1;
102  }
103 
104  *poutbuf = (uint8_t*) buf;
105  *poutbuf_size = buf_size;
106 
107  return 0;
108 }
109 
111  "aac_adtstoasc",
112  sizeof(AACBSFContext),
114 };