FFmpeg
ffmetadec.c
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1 /*
2  * Metadata demuxer
3  * Copyright (c) 2010 Anton Khirnov
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 "libavutil/bprint.h"
23 #include "libavutil/mathematics.h"
24 #include "avformat.h"
25 #include "ffmeta.h"
26 #include "internal.h"
27 #include "libavutil/dict.h"
28 
29 static int probe(const AVProbeData *p)
30 {
31  if(!memcmp(p->buf, ID_STRING, strlen(ID_STRING)))
32  return AVPROBE_SCORE_MAX;
33  return 0;
34 }
35 
36 static int64_t read_line_to_bprint_escaped(AVIOContext *s, AVBPrint *bp)
37 {
38  int len, end;
39  int64_t read = 0;
40  char tmp[1024];
41  char c;
42  char prev = ' ';
43 
44  do {
45  len = 0;
46  do {
47  c = avio_r8(s);
48  end = prev != '\\' && (c == '\r' || c == '\n' || c == '\0');
49  if (!end)
50  tmp[len++] = c;
51  prev = c;
52  } while (!end && len < sizeof(tmp));
54  read += len;
55  } while (!end);
56 
57  if (c == '\r' && avio_r8(s) != '\n' && !avio_feof(s))
58  avio_skip(s, -1);
59 
60  if (!c && s->error)
61  return s->error;
62 
63  if (!c && !read && avio_feof(s))
64  return AVERROR_EOF;
65 
66  return read;
67 }
68 
69 static void get_bprint_line(AVIOContext *s, AVBPrint *bp)
70 {
71 
72  do {
73  av_bprint_clear(bp);
75  } while (!avio_feof(s) && (bp->str[0] == ';' || bp->str[0] == '#' || bp->str[0] == 0));
76 }
77 
78 static void get_line(AVIOContext *s, uint8_t *buf, int size)
79 {
80  do {
81  uint8_t c;
82  int i = 0;
83 
84  while ((c = avio_r8(s))) {
85  if (c == '\\') {
86  if (i < size - 1)
87  buf[i++] = c;
88  c = avio_r8(s);
89  } else if (c == '\n')
90  break;
91 
92  if (i < size - 1)
93  buf[i++] = c;
94  }
95  buf[i] = 0;
96  } while (!avio_feof(s) && (buf[0] == ';' || buf[0] == '#' || buf[0] == 0));
97 }
98 
100 {
101  uint8_t line[256];
102  int64_t start, end;
103  AVRational tb = {1, 1e9};
104  int ret;
105 
106  get_line(s->pb, line, sizeof(line));
107 
108  if (sscanf(line, "TIMEBASE=%d/%d", &tb.num, &tb.den))
109  get_line(s->pb, line, sizeof(line));
110  ret = sscanf(line, "START=%"SCNd64, &start);
111  if (ret <= 0) {
112  av_log(s, AV_LOG_ERROR, "Expected chapter start timestamp, found %s.\n", line);
113  start = (s->nb_chapters && s->chapters[s->nb_chapters - 1]->end != AV_NOPTS_VALUE) ?
114  s->chapters[s->nb_chapters - 1]->end : 0;
115  } else
116  get_line(s->pb, line, sizeof(line));
117 
118  ret = sscanf(line, "END=%"SCNd64, &end);
119  if (ret <= 0) {
120  av_log(s, AV_LOG_ERROR, "Expected chapter end timestamp, found %s.\n", line);
121  end = AV_NOPTS_VALUE;
122  }
123 
124  return avpriv_new_chapter(s, s->nb_chapters, tb, start, end, NULL);
125 }
126 
127 static uint8_t *unescape(const uint8_t *buf, int size)
128 {
129  uint8_t *ret = av_malloc(size + 1);
130  uint8_t *p1 = ret;
131  const uint8_t *p2 = buf;
132 
133  if (!ret)
134  return NULL;
135 
136  while (p2 < buf + size) {
137  if (*p2 == '\\')
138  p2++;
139  *p1++ = *p2++;
140  }
141  *p1 = 0;
142  return ret;
143 }
144 
145 static int read_tag(const uint8_t *line, AVDictionary **m)
146 {
147  uint8_t *key, *value;
148  const uint8_t *p = line;
149 
150  /* find first not escaped '=' */
151  while (1) {
152  if (*p == '=')
153  break;
154  else if (*p == '\\')
155  p++;
156 
157  if (*p++)
158  continue;
159 
160  return 0;
161  }
162 
163  if (!(key = unescape(line, p - line)))
164  return AVERROR(ENOMEM);
165  if (!(value = unescape(p + 1, strlen(p + 1)))) {
166  av_free(key);
167  return AVERROR(ENOMEM);
168  }
169 
171  return 0;
172 }
173 
175 {
176  AVDictionary **m = &s->metadata;
177  AVBPrint bp;
178 
180 
181  while(!avio_feof(s->pb)) {
182  get_bprint_line(s->pb, &bp);
183 
184  if (!memcmp(bp.str, ID_STREAM, strlen(ID_STREAM))) {
186 
187  if (!st)
188  goto nomem;
189 
192 
193  m = &st->metadata;
194  } else if (!memcmp(bp.str, ID_CHAPTER, strlen(ID_CHAPTER))) {
195  AVChapter *ch = read_chapter(s);
196 
197  if (!ch)
198  goto nomem;
199 
200  m = &ch->metadata;
201  } else
202  read_tag(bp.str, m);
203  }
204 
205  av_bprint_finalize(&bp, NULL);
206 
207  s->start_time = 0;
208  if (s->nb_chapters)
209  s->duration = av_rescale_q(s->chapters[s->nb_chapters - 1]->end,
210  s->chapters[s->nb_chapters - 1]->time_base,
212 
213  return 0;
214 nomem:
215  av_bprint_finalize(&bp, NULL);
216 
217  return AVERROR(ENOMEM);
218 }
219 
221 {
222  return AVERROR_EOF;
223 }
224 
226  .name = "ffmetadata",
227  .long_name = NULL_IF_CONFIG_SMALL("FFmpeg metadata in text"),
228  .read_probe = probe,
229  .read_header = read_header,
230  .read_packet = read_packet,
231 };
read_line_to_bprint_escaped
static int64_t read_line_to_bprint_escaped(AVIOContext *s, AVBPrint *bp)
Definition: ffmetadec.c:36
AV_BPRINT_SIZE_UNLIMITED
#define AV_BPRINT_SIZE_UNLIMITED
AVChapter::metadata
AVDictionary * metadata
Definition: avformat.h:1067
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
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4374
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
av_bprint_finalize
int av_bprint_finalize(AVBPrint *buf, char **ret_str)
Finalize a print buffer.
Definition: bprint.c:235
av_bprint_init
void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
Definition: bprint.c:69
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:55
AV_TIME_BASE_Q
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:260
tmp
static uint8_t tmp[11]
Definition: aes_ctr.c:27
AV_CODEC_ID_FFMETADATA
@ AV_CODEC_ID_FFMETADATA
Dummy codec for streams containing only metadata information.
Definition: codec_id.h:567
mathematics.h
AVDictionary
Definition: dict.c:30
av_bprint_append_data
void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size)
Append data to a print buffer.
Definition: bprint.c:158
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:31
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:453
AVChapter
Definition: avformat.h:1063
ID_CHAPTER
#define ID_CHAPTER
Definition: ffmeta.h:26
AV_DICT_DONT_STRDUP_VAL
#define AV_DICT_DONT_STRDUP_VAL
Take ownership of a value that's been allocated with av_malloc() or another memory allocation functio...
Definition: dict.h:74
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:181
AVInputFormat
Definition: avformat.h:616
s
#define s(width, name)
Definition: cbs_vp9.c:257
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:621
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
read_header
static int read_header(AVFormatContext *s)
Definition: ffmetadec.c:174
ff_ffmetadata_demuxer
const AVInputFormat ff_ffmetadata_demuxer
Definition: ffmetadec.c:225
av_rescale_q
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
key
const char * key
Definition: hwcontext_opencl.c:168
AVMEDIA_TYPE_DATA
@ AVMEDIA_TYPE_DATA
Opaque data information usually continuous.
Definition: avutil.h:203
read_packet
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: ffmetadec.c:220
AVFormatContext
Format I/O context.
Definition: avformat.h:1106
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:979
NULL
#define NULL
Definition: coverity.c:32
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
AVStream::metadata
AVDictionary * metadata
Definition: avformat.h:890
get_line
static void get_line(AVIOContext *s, uint8_t *buf, int size)
Definition: ffmetadec.c:78
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
AVIOContext
Bytestream IO Context.
Definition: avio.h:161
unescape
static uint8_t * unescape(const uint8_t *buf, int size)
Definition: ffmetadec.c:127
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:117
size
int size
Definition: twinvq_data.h:10344
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
avio_r8
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:607
line
Definition: graph2dot.c:48
bprint.h
i
int i
Definition: input.c:407
read_chapter
static AVChapter * read_chapter(AVFormatContext *s)
Definition: ffmetadec.c:99
read_tag
static int read_tag(const uint8_t *line, AVDictionary **m)
Definition: ffmetadec.c:145
value
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default value
Definition: writing_filters.txt:86
tb
#define tb
Definition: regdef.h:68
len
int len
Definition: vorbis_enc_data.h:452
avpriv_new_chapter
AVChapter * avpriv_new_chapter(AVFormatContext *s, int64_t id, AVRational time_base, int64_t start, int64_t end, const char *title)
Add a new chapter.
Definition: utils.c:4487
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:832
get_bprint_line
static void get_bprint_line(AVIOContext *s, AVBPrint *bp)
Definition: ffmetadec.c:69
avformat.h
dict.h
ID_STREAM
#define ID_STREAM
Definition: ffmeta.h:27
av_bprint_clear
void av_bprint_clear(AVBPrint *buf)
Reset the string to "" but keep internal allocated data.
Definition: bprint.c:227
probe
static int probe(const AVProbeData *p)
Definition: ffmetadec.c:29
ffmeta.h
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:327
av_free
#define av_free(p)
Definition: tableprint_vlc.h:34
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
AVPacket
This structure stores compressed data.
Definition: packet.h:342
av_dict_set
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:70
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
line
The official guide to swscale for confused that consecutive non overlapping rectangles of slice_bottom special converter These generally are unscaled converters of common like for each output line the vertical scaler pulls lines from a ring buffer When the ring buffer does not contain the wanted line
Definition: swscale.txt:40
AV_DICT_DONT_STRDUP_KEY
#define AV_DICT_DONT_STRDUP_KEY
Take ownership of a key that's been allocated with av_malloc() or another memory allocation function.
Definition: dict.h:72
ID_STRING
#define ID_STRING
Definition: ffmeta.h:25
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:354