1 /*
2 * raw ADTS AAC demuxer
3 * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
4 * Copyright (c) 2009 Robert Swain ( rob opendot cl )
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
23 #include "libavutil/avassert.h"
24 #include "libavutil/intreadwrite.h"
25 #include "avformat.h"
26 #include "avio_internal.h"
27 #include "internal.h"
28 #include "id3v1.h"
29 #include "id3v2.h"
30 #include "apetag.h"
31
32 #define ADTS_HEADER_SIZE 7
33
adts_aac_probe(const AVProbeData * p)34 static int adts_aac_probe(const AVProbeData *p)
35 {
36 int max_frames = 0, first_frames = 0;
37 int fsize, frames;
38 const uint8_t *buf0 = p->buf;
39 const uint8_t *buf2;
40 const uint8_t *buf;
41 const uint8_t *end = buf0 + p->buf_size - 7;
42
43 buf = buf0;
44
45 for (; buf < end; buf = buf2 + 1) {
46 buf2 = buf;
47
48 for (frames = 0; buf2 < end; frames++) {
49 uint32_t header = AV_RB16(buf2);
50 if ((header & 0xFFF6) != 0xFFF0) {
51 if (buf != buf0) {
52 // Found something that isn't an ADTS header, starting
53 // from a position other than the start of the buffer.
54 // Discard the count we've accumulated so far since it
55 // probably was a false positive.
56 frames = 0;
57 }
58 break;
59 }
60 fsize = (AV_RB32(buf2 + 3) >> 13) & 0x1FFF;
61 if (fsize < 7)
62 break;
63 fsize = FFMIN(fsize, end - buf2);
64 buf2 += fsize;
65 }
66 max_frames = FFMAX(max_frames, frames);
67 if (buf == buf0)
68 first_frames = frames;
69 }
70
71 if (first_frames >= 3)
72 return AVPROBE_SCORE_EXTENSION + 1;
73 else if (max_frames > 100)
74 return AVPROBE_SCORE_EXTENSION;
75 else if (max_frames >= 3)
76 return AVPROBE_SCORE_EXTENSION / 2;
77 else if (first_frames >= 1)
78 return 1;
79 else
80 return 0;
81 }
82
adts_aac_resync(AVFormatContext * s)83 static int adts_aac_resync(AVFormatContext *s)
84 {
85 uint16_t state;
86
87 // skip data until an ADTS frame is found
88 state = avio_r8(s->pb);
89 while (!avio_feof(s->pb) && avio_tell(s->pb) < s->probesize) {
90 state = (state << 8) | avio_r8(s->pb);
91 if ((state >> 4) != 0xFFF)
92 continue;
93 avio_seek(s->pb, -2, SEEK_CUR);
94 break;
95 }
96 if (s->pb->eof_reached)
97 return AVERROR_EOF;
98 if ((state >> 4) != 0xFFF)
99 return AVERROR_INVALIDDATA;
100
101 return 0;
102 }
103
adts_aac_read_header(AVFormatContext * s)104 static int adts_aac_read_header(AVFormatContext *s)
105 {
106 AVStream *st;
107 int ret;
108
109 st = avformat_new_stream(s, NULL);
110 if (!st)
111 return AVERROR(ENOMEM);
112
113 st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
114 st->codecpar->codec_id = s->iformat->raw_codec_id;
115 st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
116
117 ff_id3v1_read(s);
118 if ((s->pb->seekable & AVIO_SEEKABLE_NORMAL) &&
119 !av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX)) {
120 int64_t cur = avio_tell(s->pb);
121 ff_ape_parse_tag(s);
122 avio_seek(s->pb, cur, SEEK_SET);
123 }
124
125 ret = adts_aac_resync(s);
126 if (ret < 0)
127 return ret;
128
129 // LCM of all possible ADTS sample rates
130 avpriv_set_pts_info(st, 64, 1, 28224000);
131
132 return 0;
133 }
134
handle_id3(AVFormatContext * s,AVPacket * pkt)135 static int handle_id3(AVFormatContext *s, AVPacket *pkt)
136 {
137 AVDictionary *metadata = NULL;
138 AVIOContext ioctx;
139 ID3v2ExtraMeta *id3v2_extra_meta = NULL;
140 int ret;
141
142 ret = av_append_packet(s->pb, pkt, ff_id3v2_tag_len(pkt->data) - pkt->size);
143 if (ret < 0) {
144 return ret;
145 }
146
147 ffio_init_context(&ioctx, pkt->data, pkt->size, 0, NULL, NULL, NULL, NULL);
148 ff_id3v2_read_dict(&ioctx, &metadata, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta);
149 if ((ret = ff_id3v2_parse_priv_dict(&metadata, id3v2_extra_meta)) < 0)
150 goto error;
151
152 if (metadata) {
153 if ((ret = av_dict_copy(&s->metadata, metadata, 0)) < 0)
154 goto error;
155 s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;
156 }
157
158 error:
159 av_packet_unref(pkt);
160 ff_id3v2_free_extra_meta(&id3v2_extra_meta);
161 av_dict_free(&metadata);
162
163 return ret;
164 }
165
adts_aac_read_packet(AVFormatContext * s,AVPacket * pkt)166 static int adts_aac_read_packet(AVFormatContext *s, AVPacket *pkt)
167 {
168 int ret, fsize;
169
170 retry:
171 ret = av_get_packet(s->pb, pkt, ADTS_HEADER_SIZE);
172 if (ret < 0)
173 return ret;
174
175 if (ret < ADTS_HEADER_SIZE) {
176 return AVERROR(EIO);
177 }
178
179 if ((AV_RB16(pkt->data) >> 4) != 0xfff) {
180 // Parse all the ID3 headers between frames
181 int append = ID3v2_HEADER_SIZE - ADTS_HEADER_SIZE;
182
183 av_assert2(append > 0);
184 ret = av_append_packet(s->pb, pkt, append);
185 if (ret != append) {
186 return AVERROR(EIO);
187 }
188 if (!ff_id3v2_match(pkt->data, ID3v2_DEFAULT_MAGIC)) {
189 av_packet_unref(pkt);
190 ret = adts_aac_resync(s);
191 } else
192 ret = handle_id3(s, pkt);
193 if (ret < 0)
194 return ret;
195
196 goto retry;
197 }
198
199 fsize = (AV_RB32(pkt->data + 3) >> 13) & 0x1FFF;
200 if (fsize < ADTS_HEADER_SIZE) {
201 return AVERROR_INVALIDDATA;
202 }
203
204 ret = av_append_packet(s->pb, pkt, fsize - pkt->size);
205
206 return ret;
207 }
208
209 AVInputFormat ff_aac_demuxer = {
210 .name = "aac",
211 .long_name = NULL_IF_CONFIG_SMALL("raw ADTS AAC (Advanced Audio Coding)"),
212 .read_probe = adts_aac_probe,
213 .read_header = adts_aac_read_header,
214 .read_packet = adts_aac_read_packet,
215 .flags = AVFMT_GENERIC_INDEX,
216 .extensions = "aac",
217 .mime_type = "audio/aac,audio/aacp,audio/x-aac",
218 .raw_codec_id = AV_CODEC_ID_AAC,
219 };
220