FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
format.c
Go to the documentation of this file.
1 /*
2  * Format register and lookup
3  * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
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/atomic.h"
23 #include "libavutil/avstring.h"
24 #include "libavutil/bprint.h"
25 #include "libavutil/opt.h"
26 
27 #include "avio_internal.h"
28 #include "avformat.h"
29 #include "id3v2.h"
30 #include "internal.h"
31 
32 
33 /**
34  * @file
35  * Format register and lookup
36  */
37 /** head of registered input format linked list */
39 /** head of registered output format linked list */
41 
44 
46 {
47  if (f)
48  return f->next;
49  else
50  return first_iformat;
51 }
52 
54 {
55  if (f)
56  return f->next;
57  else
58  return first_oformat;
59 }
60 
62 {
64 
65  format->next = NULL;
66  while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format))
67  p = &(*p)->next;
68  last_iformat = &format->next;
69 }
70 
72 {
74 
75  format->next = NULL;
76  while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format))
77  p = &(*p)->next;
78  last_oformat = &format->next;
79 }
80 
81 int av_match_ext(const char *filename, const char *extensions)
82 {
83  const char *ext;
84 
85  if (!filename)
86  return 0;
87 
88  ext = strrchr(filename, '.');
89  if (ext)
90  return av_match_name(ext + 1, extensions);
91  return 0;
92 }
93 
94 AVOutputFormat *av_guess_format(const char *short_name, const char *filename,
95  const char *mime_type)
96 {
97  AVOutputFormat *fmt = NULL, *fmt_found;
98  int score_max, score;
99 
100  /* specific test for image sequences */
101 #if CONFIG_IMAGE2_MUXER
102  if (!short_name && filename &&
103  av_filename_number_test(filename) &&
105  return av_guess_format("image2", NULL, NULL);
106  }
107 #endif
108  /* Find the proper file type. */
109  fmt_found = NULL;
110  score_max = 0;
111  while ((fmt = av_oformat_next(fmt))) {
112  score = 0;
113  if (fmt->name && short_name && av_match_name(short_name, fmt->name))
114  score += 100;
115  if (fmt->mime_type && mime_type && !strcmp(fmt->mime_type, mime_type))
116  score += 10;
117  if (filename && fmt->extensions &&
118  av_match_ext(filename, fmt->extensions)) {
119  score += 5;
120  }
121  if (score > score_max) {
122  score_max = score;
123  fmt_found = fmt;
124  }
125  }
126  return fmt_found;
127 }
128 
129 enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
130  const char *filename, const char *mime_type,
131  enum AVMediaType type)
132 {
133  if (av_match_name("segment", fmt->name) || av_match_name("ssegment", fmt->name)) {
134  AVOutputFormat *fmt2 = av_guess_format(NULL, filename, NULL);
135  if (fmt2)
136  fmt = fmt2;
137  }
138 
139  if (type == AVMEDIA_TYPE_VIDEO) {
141 
142 #if CONFIG_IMAGE2_MUXER
143  if (!strcmp(fmt->name, "image2") || !strcmp(fmt->name, "image2pipe")) {
144  codec_id = ff_guess_image2_codec(filename);
145  }
146 #endif
147  if (codec_id == AV_CODEC_ID_NONE)
148  codec_id = fmt->video_codec;
149  return codec_id;
150  } else if (type == AVMEDIA_TYPE_AUDIO)
151  return fmt->audio_codec;
152  else if (type == AVMEDIA_TYPE_SUBTITLE)
153  return fmt->subtitle_codec;
154  else if (type == AVMEDIA_TYPE_DATA)
155  return fmt->data_codec;
156  else
157  return AV_CODEC_ID_NONE;
158 }
159 
160 AVInputFormat *av_find_input_format(const char *short_name)
161 {
163  while ((fmt = av_iformat_next(fmt)))
164  if (av_match_name(short_name, fmt->name))
165  return fmt;
166  return NULL;
167 }
168 
170  int *score_ret)
171 {
172  AVProbeData lpd = *pd;
173  AVInputFormat *fmt1 = NULL, *fmt;
174  int score, nodat = 0, score_max = 0;
175  const static uint8_t zerobuffer[AVPROBE_PADDING_SIZE];
176 
177  if (!lpd.buf)
178  lpd.buf = zerobuffer;
179 
180  if (lpd.buf_size > 10 && ff_id3v2_match(lpd.buf, ID3v2_DEFAULT_MAGIC)) {
181  int id3len = ff_id3v2_tag_len(lpd.buf);
182  if (lpd.buf_size > id3len + 16) {
183  lpd.buf += id3len;
184  lpd.buf_size -= id3len;
185  } else if (id3len >= PROBE_BUF_MAX) {
186  nodat = 2;
187  } else
188  nodat = 1;
189  }
190 
191  fmt = NULL;
192  while ((fmt1 = av_iformat_next(fmt1))) {
193  if (!is_opened == !(fmt1->flags & AVFMT_NOFILE) && strcmp(fmt1->name, "image2"))
194  continue;
195  score = 0;
196  if (fmt1->read_probe) {
197  score = fmt1->read_probe(&lpd);
198  if (score)
199  av_log(NULL, AV_LOG_TRACE, "Probing %s score:%d size:%d\n", fmt1->name, score, lpd.buf_size);
200  if (fmt1->extensions && av_match_ext(lpd.filename, fmt1->extensions)) {
201  if (nodat == 0) score = FFMAX(score, 1);
202  else if (nodat == 1) score = FFMAX(score, AVPROBE_SCORE_EXTENSION / 2 - 1);
203  else score = FFMAX(score, AVPROBE_SCORE_EXTENSION);
204  }
205  } else if (fmt1->extensions) {
206  if (av_match_ext(lpd.filename, fmt1->extensions))
207  score = AVPROBE_SCORE_EXTENSION;
208  }
209  if (av_match_name(lpd.mime_type, fmt1->mime_type))
210  score = FFMAX(score, AVPROBE_SCORE_MIME);
211  if (score > score_max) {
212  score_max = score;
213  fmt = fmt1;
214  } else if (score == score_max)
215  fmt = NULL;
216  }
217  if (nodat == 1)
218  score_max = FFMIN(AVPROBE_SCORE_EXTENSION / 2 - 1, score_max);
219  *score_ret = score_max;
220 
221  return fmt;
222 }
223 
224 AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max)
225 {
226  int score_ret;
227  AVInputFormat *fmt = av_probe_input_format3(pd, is_opened, &score_ret);
228  if (score_ret > *score_max) {
229  *score_max = score_ret;
230  return fmt;
231  } else
232  return NULL;
233 }
234 
236 {
237  int score = 0;
238  return av_probe_input_format2(pd, is_opened, &score);
239 }
240 
242  const char *filename, void *logctx,
243  unsigned int offset, unsigned int max_probe_size)
244 {
245  AVProbeData pd = { filename ? filename : "" };
246  uint8_t *buf = NULL;
247  int ret = 0, probe_size, buf_offset = 0;
248  int score = 0;
249  int ret2;
250 
251  if (!max_probe_size)
252  max_probe_size = PROBE_BUF_MAX;
253  else if (max_probe_size < PROBE_BUF_MIN) {
254  av_log(logctx, AV_LOG_ERROR,
255  "Specified probe size value %u cannot be < %u\n", max_probe_size, PROBE_BUF_MIN);
256  return AVERROR(EINVAL);
257  }
258 
259  if (offset >= max_probe_size)
260  return AVERROR(EINVAL);
261 
262  if (pb->av_class) {
263  uint8_t *mime_type_opt = NULL;
264  av_opt_get(pb, "mime_type", AV_OPT_SEARCH_CHILDREN, &mime_type_opt);
265  pd.mime_type = (const char *)mime_type_opt;
266  }
267 #if 0
268  if (!*fmt && pb->av_class && av_opt_get(pb, "mime_type", AV_OPT_SEARCH_CHILDREN, &mime_type) >= 0 && mime_type) {
269  if (!av_strcasecmp(mime_type, "audio/aacp")) {
270  *fmt = av_find_input_format("aac");
271  }
272  av_freep(&mime_type);
273  }
274 #endif
275 
276  for (probe_size = PROBE_BUF_MIN; probe_size <= max_probe_size && !*fmt;
277  probe_size = FFMIN(probe_size << 1,
278  FFMAX(max_probe_size, probe_size + 1))) {
279  score = probe_size < max_probe_size ? AVPROBE_SCORE_RETRY : 0;
280 
281  /* Read probe data. */
282  if ((ret = av_reallocp(&buf, probe_size + AVPROBE_PADDING_SIZE)) < 0)
283  goto fail;
284  if ((ret = avio_read(pb, buf + buf_offset,
285  probe_size - buf_offset)) < 0) {
286  /* Fail if error was not end of file, otherwise, lower score. */
287  if (ret != AVERROR_EOF)
288  goto fail;
289 
290  score = 0;
291  ret = 0; /* error was end of file, nothing read */
292  }
293  buf_offset += ret;
294  if (buf_offset < offset)
295  continue;
296  pd.buf_size = buf_offset - offset;
297  pd.buf = &buf[offset];
298 
299  memset(pd.buf + pd.buf_size, 0, AVPROBE_PADDING_SIZE);
300 
301  /* Guess file format. */
302  *fmt = av_probe_input_format2(&pd, 1, &score);
303  if (*fmt) {
304  /* This can only be true in the last iteration. */
305  if (score <= AVPROBE_SCORE_RETRY) {
306  av_log(logctx, AV_LOG_WARNING,
307  "Format %s detected only with low score of %d, "
308  "misdetection possible!\n", (*fmt)->name, score);
309  } else
310  av_log(logctx, AV_LOG_DEBUG,
311  "Format %s probed with size=%d and score=%d\n",
312  (*fmt)->name, probe_size, score);
313 #if 0
314  FILE *f = fopen("probestat.tmp", "ab");
315  fprintf(f, "probe_size:%d format:%s score:%d filename:%s\n", probe_size, (*fmt)->name, score, filename);
316  fclose(f);
317 #endif
318  }
319  }
320 
321  if (!*fmt)
322  ret = AVERROR_INVALIDDATA;
323 
324 fail:
325  /* Rewind. Reuse probe buffer to avoid seeking. */
326  ret2 = ffio_rewind_with_probe_data(pb, &buf, buf_offset);
327  if (ret >= 0)
328  ret = ret2;
329 
330  av_freep(&pd.mime_type);
331  return ret < 0 ? ret : score;
332 }
333 
335  const char *filename, void *logctx,
336  unsigned int offset, unsigned int max_probe_size)
337 {
338  int ret = av_probe_input_buffer2(pb, fmt, filename, logctx, offset, max_probe_size);
339  return ret < 0 ? ret : 0;
340 }
#define NULL
Definition: coverity.c:32
Bytestream IO Context.
Definition: avio.h:111
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
static AVInputFormat ** last_iformat
Definition: format.c:42
const char * fmt
Definition: avisynth_c.h:632
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
const char * filename
Definition: avformat.h:449
int ffio_rewind_with_probe_data(AVIOContext *s, unsigned char **buf, int buf_size)
Rewind the AVIOContext using the specified buffer containing the first buf_size bytes of the file...
Definition: aviobuf.c:865
static AVOutputFormat ** last_oformat
Definition: format.c:43
int av_probe_input_buffer2(AVIOContext *pb, AVInputFormat **fmt, const char *filename, void *logctx, unsigned int offset, unsigned int max_probe_size)
Probe a bytestream to determine the input format.
Definition: format.c:241
enum AVCodecID video_codec
default video codec
Definition: avformat.h:524
#define ID3v2_DEFAULT_MAGIC
Default magic bytes for ID3v2 header: "ID3".
Definition: id3v2.h:35
#define AVPROBE_PADDING_SIZE
extra allocated bytes at the end of the probe buffer
Definition: avformat.h:462
AVInputFormat * av_probe_input_format3(AVProbeData *pd, int is_opened, int *score_ret)
Guess the file format.
Definition: format.c:169
#define PROBE_BUF_MAX
Definition: internal.h:32
uint8_t
Opaque data information usually continuous.
Definition: avutil.h:196
AVOptions.
int flags
Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS, AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH, AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK, AVFMT_SEEK_TO_PTS.
Definition: avformat.h:642
#define AV_LOG_TRACE
Extremely verbose debugging, useful for libav* development.
Definition: log.h:204
#define AVPROBE_SCORE_MIME
score for file mime type
Definition: avformat.h:459
const AVClass * av_class
A class for private options.
Definition: avio.h:124
int av_reallocp(void *ptr, size_t size)
Allocate or reallocate a block of memory.
Definition: mem.c:185
#define AVERROR_EOF
End of file.
Definition: error.h:55
int av_match_ext(const char *filename, const char *extensions)
Return a positive value if the given filename has one of the given extensions, 0 otherwise.
Definition: format.c:81
#define av_log(a,...)
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:537
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: avcodec.h:102
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#define avpriv_atomic_ptr_cas
Definition: atomic_gcc.h:60
int(* read_probe)(AVProbeData *)
Tell if a given file has a chance of being parsed as this format.
Definition: avformat.h:686
static AVOutputFormat * first_oformat
head of registered output format linked list
Definition: format.c:40
#define AVERROR(e)
Definition: error.h:43
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
int av_match_name(const char *name, const char *names)
Match instances of a name in a comma-separated list of names.
Definition: avstring.c:342
enum AVCodecID codec_id
Definition: mov_chan.c:433
static const uint8_t offset[127][2]
Definition: vf_spp.c:92
#define FFMAX(a, b)
Definition: common.h:64
AVInputFormat * av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max)
Guess the file format.
Definition: format.c:224
const char * mime_type
mime_type, when known.
Definition: avformat.h:452
int buf_size
Size of buf except extra allocated bytes.
Definition: avformat.h:451
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:450
AVInputFormat * av_find_input_format(const char *short_name)
Find AVInputFormat based on the short name of the input format.
Definition: format.c:160
#define FFMIN(a, b)
Definition: common.h:66
int av_strcasecmp(const char *a, const char *b)
Locale-independent case-insensitive compare.
Definition: avstring.c:213
#define AV_OPT_SEARCH_CHILDREN
Search in possible children of the given object first.
Definition: opt.h:602
enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name, const char *filename, const char *mime_type, enum AVMediaType type)
Guess the codec ID based upon muxer and filename.
Definition: format.c:129
ret
Definition: avfilter.c:974
int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt, const char *filename, void *logctx, unsigned int offset, unsigned int max_probe_size)
Like av_probe_input_buffer2() but returns 0 on success.
Definition: format.c:334
const char * name
Definition: avformat.h:513
AVOutputFormat * av_guess_format(const char *short_name, const char *filename, const char *mime_type)
Return the output format in the list of registered output formats which best matches the provided par...
Definition: format.c:94
#define AVPROBE_SCORE_RETRY
Definition: avformat.h:455
void av_register_input_format(AVInputFormat *format)
Definition: format.c:61
AVOutputFormat * av_oformat_next(const AVOutputFormat *f)
If f is NULL, returns the first registered output format, if f is non-NULL, returns the next register...
Definition: format.c:53
#define PROBE_BUF_MIN
size of probe buffer, for guessing file type from file contents
Definition: internal.h:31
void av_register_output_format(AVOutputFormat *format)
Definition: format.c:71
struct AVOutputFormat * next
Definition: avformat.h:550
int av_filename_number_test(const char *filename)
Check whether filename actually is a numbered sequence generator.
Definition: utils.c:258
void * buf
Definition: avisynth_c.h:553
GLint GLenum type
Definition: opengl_enc.c:105
enum AVCodecID subtitle_codec
default subtitle codec
Definition: avformat.h:525
AVMediaType
Definition: avutil.h:192
#define AVPROBE_SCORE_EXTENSION
score for file extension
Definition: avformat.h:458
This structure contains the data a format has to probe a file.
Definition: avformat.h:448
const char * mime_type
Comma-separated list of mime types.
Definition: avformat.h:660
const char * extensions
If extensions are defined, then no probe is done.
Definition: avformat.h:649
Main libavformat public API header.
static AVInputFormat * first_iformat
head of registered input format linked list
Definition: format.c:38
#define AVFMT_NOFILE
Demuxer will use avio_open, no opened file should be provided by the caller.
Definition: avformat.h:465
int ff_id3v2_match(const uint8_t *buf, const char *magic)
Detect ID3v2 Header.
Definition: id3v2.c:141
enum AVCodecID data_codec
default data codec
Definition: avformat.h:613
enum AVCodecID ff_guess_image2_codec(const char *filename)
Definition: img2.c:103
int av_opt_get(void *obj, const char *name, int search_flags, uint8_t **out_val)
Definition: opt.c:689
enum AVCodecID audio_codec
default audio codec
Definition: avformat.h:523
int ff_id3v2_tag_len(const uint8_t *buf)
Get the length of an ID3v2 tag.
Definition: id3v2.c:154
#define av_freep(p)
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:628
struct AVInputFormat * next
Definition: avformat.h:669
const char * extensions
comma-separated filename extensions
Definition: avformat.h:521
AVInputFormat * av_probe_input_format(AVProbeData *pd, int is_opened)
Guess the file format.
Definition: format.c:235
const char * mime_type
Definition: avformat.h:520
AVInputFormat * av_iformat_next(const AVInputFormat *f)
If f is NULL, returns the first registered input format, if f is non-NULL, returns the next registere...
Definition: format.c:45