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 "adts_header.h"
23 #include "adts_parser.h"
24 #include "bsf.h"
25 #include "bsf_internal.h"
26 #include "put_bits.h"
27 #include "get_bits.h"
28 #include "mpeg4audio.h"
29
30 typedef struct AACBSFContext {
31 int first_frame_done;
32 } AACBSFContext;
33
34 /**
35 * This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
36 * ADTS header and removes the ADTS header.
37 */
aac_adtstoasc_filter(AVBSFContext * bsfc,AVPacket * pkt)38 static int aac_adtstoasc_filter(AVBSFContext *bsfc, AVPacket *pkt)
39 {
40 AACBSFContext *ctx = bsfc->priv_data;
41
42 GetBitContext gb;
43 PutBitContext pb;
44 AACADTSHeaderInfo hdr;
45 int ret;
46
47 ret = ff_bsf_get_packet_ref(bsfc, pkt);
48 if (ret < 0)
49 return ret;
50
51 if (bsfc->par_in->extradata && pkt->size >= 2 && (AV_RB16(pkt->data) >> 4) != 0xfff)
52 return 0;
53
54 if (pkt->size < AV_AAC_ADTS_HEADER_SIZE)
55 goto packet_too_small;
56
57 init_get_bits(&gb, pkt->data, AV_AAC_ADTS_HEADER_SIZE * 8);
58
59 if (ff_adts_header_parse(&gb, &hdr) < 0) {
60 av_log(bsfc, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
61 ret = AVERROR_INVALIDDATA;
62 goto fail;
63 }
64
65 if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
66 avpriv_report_missing_feature(bsfc,
67 "Multiple RDBs per frame with CRC");
68 ret = AVERROR_PATCHWELCOME;
69 goto fail;
70 }
71
72 pkt->size -= AV_AAC_ADTS_HEADER_SIZE + 2 * !hdr.crc_absent;
73 if (pkt->size <= 0)
74 goto packet_too_small;
75 pkt->data += AV_AAC_ADTS_HEADER_SIZE + 2 * !hdr.crc_absent;
76
77 if (!ctx->first_frame_done) {
78 int pce_size = 0;
79 uint8_t pce_data[MAX_PCE_SIZE];
80 uint8_t *extradata;
81
82 if (!hdr.chan_config) {
83 init_get_bits(&gb, pkt->data, pkt->size * 8);
84 if (get_bits(&gb, 3) != 5) {
85 avpriv_report_missing_feature(bsfc,
86 "PCE-based channel configuration "
87 "without PCE as first syntax "
88 "element");
89 ret = AVERROR_PATCHWELCOME;
90 goto fail;
91 }
92 init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
93 pce_size = ff_copy_pce_data(&pb, &gb) / 8;
94 flush_put_bits(&pb);
95 pkt->size -= get_bits_count(&gb)/8;
96 pkt->data += get_bits_count(&gb)/8;
97 }
98
99 extradata = av_packet_new_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
100 2 + pce_size);
101 if (!extradata) {
102 ret = AVERROR(ENOMEM);
103 goto fail;
104 }
105
106 init_put_bits(&pb, extradata, 2 + pce_size);
107 put_bits(&pb, 5, hdr.object_type);
108 put_bits(&pb, 4, hdr.sampling_index);
109 put_bits(&pb, 4, hdr.chan_config);
110 put_bits(&pb, 1, 0); //frame length - 1024 samples
111 put_bits(&pb, 1, 0); //does not depend on core coder
112 put_bits(&pb, 1, 0); //is not extension
113 flush_put_bits(&pb);
114 if (pce_size) {
115 memcpy(extradata + 2, pce_data, pce_size);
116 }
117
118 ctx->first_frame_done = 1;
119 }
120
121 return 0;
122
123 packet_too_small:
124 av_log(bsfc, AV_LOG_ERROR, "Input packet too small\n");
125 ret = AVERROR_INVALIDDATA;
126 fail:
127 av_packet_unref(pkt);
128 return ret;
129 }
130
aac_adtstoasc_init(AVBSFContext * ctx)131 static int aac_adtstoasc_init(AVBSFContext *ctx)
132 {
133 /* Validate the extradata if the stream is already MPEG-4 AudioSpecificConfig */
134 if (ctx->par_in->extradata) {
135 MPEG4AudioConfig mp4ac;
136 int ret = avpriv_mpeg4audio_get_config2(&mp4ac, ctx->par_in->extradata,
137 ctx->par_in->extradata_size, 1, ctx);
138 if (ret < 0) {
139 av_log(ctx, AV_LOG_ERROR, "Error parsing AudioSpecificConfig extradata!\n");
140 return ret;
141 }
142 }
143
144 return 0;
145 }
146
147 static const enum AVCodecID codec_ids[] = {
148 AV_CODEC_ID_AAC, AV_CODEC_ID_NONE,
149 };
150
151 const FFBitStreamFilter ff_aac_adtstoasc_bsf = {
152 .p.name = "aac_adtstoasc",
153 .p.codec_ids = codec_ids,
154 .priv_data_size = sizeof(AACBSFContext),
155 .init = aac_adtstoasc_init,
156 .filter = aac_adtstoasc_filter,
157 };
158