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 {
30 int first_frame_done;
31 } 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 */
aac_adtstoasc_filter(AVBitStreamFilterContext * bsfc,AVCodecContext * avctx,const char * args,uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size,int keyframe)37 static int aac_adtstoasc_filter(AVBitStreamFilterContext *bsfc,
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;
45 AACADTSHeaderInfo hdr;
46
47 AACBSFContext *ctx = bsfc->priv_data;
48
49 init_get_bits(&gb, buf, AAC_ADTS_HEADER_SIZE*8);
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 AVERROR_INVALIDDATA;
61 }
62
63 if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
64 avpriv_report_missing_feature(avctx,
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) {
78 avpriv_report_missing_feature(avctx,
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;
92 avctx->extradata = av_mallocz(avctx->extradata_size + FF_INPUT_BUFFER_PADDING_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
115 AVBitStreamFilter ff_aac_adtstoasc_bsf = {
116 .name = "aac_adtstoasc",
117 .priv_data_size = sizeof(AACBSFContext),
118 .filter = aac_adtstoasc_filter,
119 };
120