FFmpeg: libavformat/aacdec.c Source File

FFmpeg
aacdec.c
Go to the documentation of this file.
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 "demux.h"
28 #include "internal.h"
29 #include "id3v1.h"
30 #include "id3v2.h"
31 #include "apetag.h"
32 
33  #define ADTS_HEADER_SIZE 7
34 
35  static int adts_aac_probe(const AVProbeData *p)
36 {
37  int max_frames = 0, first_frames = 0;
38  int fsize, frames;
39  const uint8_t *buf0 = p->buf;
40  const uint8_t *buf2;
41  const uint8_t *buf;
42  const uint8_t *end = buf0 + p->buf_size - 7;
43 
44  buf = buf0;
45 
46  for (; buf < end; buf = buf2 + 1) {
47  buf2 = buf;
48 
49  for (frames = 0; buf2 < end; frames++) {
50  uint32_t header = AV_RB16(buf2);
51  if ((header & 0xFFF6) != 0xFFF0) {
52  if (buf != buf0) {
53  // Found something that isn't an ADTS header, starting
54  // from a position other than the start of the buffer.
55  // Discard the count we've accumulated so far since it
56  // probably was a false positive.
57  frames = 0;
58  }
59  break;
60  }
61  fsize = (AV_RB32(buf2 + 3) >> 13) & 0x1FFF;
62  if (fsize < 7)
63  break;
64  fsize = FFMIN(fsize, end - buf2);
65  buf2 += fsize;
66  }
67  max_frames = FFMAX(max_frames, frames);
68  if (buf == buf0)
69  first_frames = frames;
70  }
71 
72  if (first_frames >= 3)
73  return AVPROBE_SCORE_EXTENSION + 1;
74  else if (max_frames > 100)
75  return AVPROBE_SCORE_EXTENSION;
76  else if (max_frames >= 3)
77  return AVPROBE_SCORE_EXTENSION / 2;
78  else if (first_frames >= 1)
79  return 1;
80  else
81  return 0;
82 }
83 
84  static int adts_aac_resync(AVFormatContext *s)
85 {
86  uint16_t state;
87  int64_t start_pos = avio_tell(s->pb);
88 
89  // skip data until an ADTS frame is found
90  state = avio_r8(s->pb);
91  while (!avio_feof(s->pb) &&
92  (avio_tell(s->pb) - start_pos) < s->probesize) {
93  state = (state << 8) | avio_r8(s->pb);
94  if ((state >> 4) != 0xFFF)
95  continue;
96  avio_seek(s->pb, -2, SEEK_CUR);
97  break;
98  }
99  if (s->pb->eof_reached)
100  return AVERROR_EOF;
101  if ((state >> 4) != 0xFFF)
102  return AVERROR_INVALIDDATA;
103 
104  return 0;
105 }
106 
107  static int adts_aac_read_header(AVFormatContext *s)
108 {
109  AVStream *st;
110  int ret;
111 
112  st = avformat_new_stream(s, NULL);
113  if (!st)
114  return AVERROR(ENOMEM);
115 
116  st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
117  st->codecpar->codec_id = AV_CODEC_ID_AAC;
118  ffstream(st)->need_parsing = AVSTREAM_PARSE_FULL_RAW;
119 
120  ff_id3v1_read(s);
121  if ((s->pb->seekable & AVIO_SEEKABLE_NORMAL) &&
122  !av_dict_count(s->metadata)) {
123  int64_t cur = avio_tell(s->pb);
124  ff_ape_parse_tag(s);
125  avio_seek(s->pb, cur, SEEK_SET);
126  }
127 
128  ret = adts_aac_resync(s);
129  if (ret < 0)
130  return ret;
131 
132  // LCM of all possible ADTS sample rates
133  avpriv_set_pts_info(st, 64, 1, 28224000);
134 
135  return 0;
136 }
137 
138  static int handle_id3(AVFormatContext *s, AVPacket *pkt)
139 {
140  AVDictionary *metadata = NULL;
141  FFIOContext pb;
142  ID3v2ExtraMeta *id3v2_extra_meta;
143  int ret;
144 
145  ret = av_append_packet(s->pb, pkt, ff_id3v2_tag_len(pkt->data) - pkt->size);
146  if (ret < 0)
147  return ret;
148 
149  ffio_init_read_context(&pb, pkt->data, pkt->size);
150  ff_id3v2_read_dict(&pb.pub, &metadata, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta);
151  if ((ret = ff_id3v2_parse_priv_dict(&metadata, id3v2_extra_meta)) < 0)
152  goto error;
153 
154  if (metadata) {
155  if ((ret = av_dict_copy(&s->metadata, metadata, 0)) < 0)
156  goto error;
157  s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;
158  }
159 
160 error:
161  av_packet_unref(pkt);
162  ff_id3v2_free_extra_meta(&id3v2_extra_meta);
163  av_dict_free(&metadata);
164 
165  return ret;
166 }
167 
168  static int adts_aac_read_packet(AVFormatContext *s, AVPacket *pkt)
169 {
170  int ret, fsize;
171 
172 retry:
173  ret = av_get_packet(s->pb, pkt, ADTS_HEADER_SIZE);
174  if (ret < 0)
175  return ret;
176 
177  if (ret < ADTS_HEADER_SIZE)
178  return AVERROR(EIO);
179 
180  if ((AV_RB16(pkt->data) >> 4) != 0xfff) {
181  // Parse all the ID3 headers between frames
182  int append = ID3v2_HEADER_SIZE - ADTS_HEADER_SIZE;
183 
184  av_assert2(append > 0);
185  ret = av_append_packet(s->pb, pkt, append);
186  if (ret != append)
187  return AVERROR(EIO);
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  ret = av_append_packet(s->pb, pkt, fsize - pkt->size);
204 
205  return ret;
206 }
207 
208  const FFInputFormat ff_aac_demuxer = {
209  .p.name = "aac",
210  .p.long_name = NULL_IF_CONFIG_SMALL("raw ADTS AAC (Advanced Audio Coding)"),
211  .p.flags = AVFMT_GENERIC_INDEX,
212  .p.extensions = "aac",
213  .p.mime_type = "audio/aac,audio/aacp,audio/x-aac",
214  .read_probe = adts_aac_probe,
215  .read_header = adts_aac_read_header,
216  .read_packet = adts_aac_read_packet,
217  .raw_codec_id = AV_CODEC_ID_AAC,
218 };
error
static void error(const char *err)
Definition: target_bsf_fuzzer.c:32
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: packet.c:429
AVERROR
Filter the word "frame" indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:51
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const struct AVCodec *c)
Add a new stream to a media file.
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
av_dict_count
int av_dict_count(const AVDictionary *m)
Get number of entries in dictionary.
Definition: dict.c:39
int64_t
long long int64_t
Definition: coverity.c:34
append
static uint8_t * append(uint8_t *buf, const uint8_t *src, int size)
Definition: mjpeg2jpeg.c:59
id3v2.h
apetag.h
AVPacket::data
uint8_t * data
Definition: packet.h:539
ff_id3v1_read
void ff_id3v1_read(AVFormatContext *s)
Read an ID3v1 tag.
Definition: id3v1.c:278
adts_aac_read_packet
static int adts_aac_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: aacdec.c:168
AVDictionary
Definition: dict.c:34
ffio_init_read_context
void ffio_init_read_context(FFIOContext *s, const uint8_t *buffer, int buffer_size)
Wrap a buffer in an AVIOContext for reading.
Definition: aviobuf.c:99
AVProbeData::buf_size
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:454
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
id3v1.h
FFIOContext
Definition: avio_internal.h:28
ff_ape_parse_tag
int64_t ff_ape_parse_tag(AVFormatContext *s)
Read and parse an APE tag.
Definition: apetag.c:110
avpriv_set_pts_info
void avpriv_set_pts_info(AVStream *st, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: avformat.c:860
ffstream
static av_always_inline FFStream * ffstream(AVStream *st)
Definition: internal.h:419
frames
if it could not because there are no more frames
Definition: filter_design.txt:266
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:494
AVFMT_GENERIC_INDEX
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:480
ADTS_HEADER_SIZE
#define ADTS_HEADER_SIZE
Definition: aacdec.c:33
avassert.h
pkt
AVPacket * pkt
Definition: movenc.c:60
adts_aac_read_header
static int adts_aac_read_header(AVFormatContext *s)
Definition: aacdec.c:107
ID3v2ExtraMeta
Definition: id3v2.h:84
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:198
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:553
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:453
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
fsize
static int64_t fsize(FILE *f)
Definition: audiomatch.c:29
FFStream::need_parsing
enum AVStreamParseType need_parsing
Definition: internal.h:386
AVFormatContext
Format I/O context.
Definition: avformat.h:1287
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:771
NULL
#define NULL
Definition: coverity.c:32
ff_aac_demuxer
const FFInputFormat ff_aac_demuxer
Definition: aacdec.c:208
adts_aac_probe
static int adts_aac_probe(const AVProbeData *p)
Definition: aacdec.c:35
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:451
ID3v2_HEADER_SIZE
#define ID3v2_HEADER_SIZE
Definition: id3v2.h:30
AVPROBE_SCORE_EXTENSION
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:461
AV_CODEC_ID_AAC
@ AV_CODEC_ID_AAC
Definition: codec_id.h:442
AVPacket::size
int size
Definition: packet.h:540
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:94
FFIOContext::pub
AVIOContext pub
Definition: avio_internal.h:29
ID3v2_DEFAULT_MAGIC
#define ID3v2_DEFAULT_MAGIC
Default magic bytes for ID3v2 header: "ID3".
Definition: id3v2.h:35
AV_RB32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:96
FFInputFormat::p
AVInputFormat p
The public AVInputFormat.
Definition: demux.h:41
header
static const uint8_t header[24]
Definition: sdr2.c:68
avio_r8
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:603
av_dict_free
void av_dict_free(AVDictionary **pm)
Free all the memory allocated for an AVDictionary struct and all keys and values.
Definition: dict.c:223
av_assert2
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
Definition: avassert.h:67
avio_internal.h
ff_id3v2_read_dict
void ff_id3v2_read_dict(AVIOContext *pb, AVDictionary **metadata, const char *magic, ID3v2ExtraMeta **extra_meta)
Read an ID3v2 tag into specified dictionary and retrieve supported extra metadata.
Definition: id3v2.c:1134
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
demux.h
av_get_packet
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
Allocate and read the payload of a packet and initialize its fields with default values.
Definition: utils.c:91
ff_id3v2_tag_len
int ff_id3v2_tag_len(const uint8_t *buf)
Get the length of an ID3v2 tag.
Definition: id3v2.c:158
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:748
avio_seek
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:231
av_append_packet
int av_append_packet(AVIOContext *s, AVPacket *pkt, int size)
Read data and append it to the current content of the AVPacket.
Definition: utils.c:107
handle_id3
static int handle_id3(AVFormatContext *s, AVPacket *pkt)
Definition: aacdec.c:138
avformat.h
adts_aac_resync
static int adts_aac_resync(AVFormatContext *s)
Definition: aacdec.c:84
AVIO_SEEKABLE_NORMAL
#define AVIO_SEEKABLE_NORMAL
Seeking works like for a local file.
Definition: avio.h:41
AVSTREAM_PARSE_FULL_RAW
@ AVSTREAM_PARSE_FULL_RAW
full parsing and repack with timestamp and position generation by parser for raw this assumes that ea...
Definition: avformat.h:597
state
static struct @454 state
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:55
AVPacket
This structure stores compressed data.
Definition: packet.h:516
av_dict_copy
int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags)
Copy entries from one AVDictionary struct into another.
Definition: dict.c:237
ff_id3v2_free_extra_meta
void ff_id3v2_free_extra_meta(ID3v2ExtraMeta **extra_meta)
Free memory allocated parsing special (non-text) metadata.
Definition: id3v2.c:1146
FFInputFormat
Definition: demux.h:37
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
ff_id3v2_parse_priv_dict
int ff_id3v2_parse_priv_dict(AVDictionary **metadata, ID3v2ExtraMeta *extra_meta)
Parse PRIV tags into a dictionary.
Definition: id3v2.c:1218
AVFMT_EVENT_FLAG_METADATA_UPDATED
#define AVFMT_EVENT_FLAG_METADATA_UPDATED
Definition: avformat.h:1664
ff_id3v2_match
int ff_id3v2_match(const uint8_t *buf, const char *magic)
Detect ID3v2 Header.
Definition: id3v2.c:145
AV_RB16
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:98
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:346
Generated on Fri Aug 22 2025 13:58:05 for FFmpeg by   doxygen 1.8.17

AltStyle によって変換されたページ (->オリジナル) /