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avformat.h
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1 /*
2  * copyright (c) 2001 Fabrice Bellard
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVFORMAT_AVFORMAT_H
22 #define AVFORMAT_AVFORMAT_H
23 
24 /**
25  * @file
26  * @ingroup libavf
27  * Main libavformat public API header
28  */
29 
30 /**
31  * @defgroup libavf I/O and Muxing/Demuxing Library
32  * @{
33  *
34  * Libavformat (lavf) is a library for dealing with various media container
35  * formats. Its main two purposes are demuxing - i.e. splitting a media file
36  * into component streams, and the reverse process of muxing - writing supplied
37  * data in a specified container format. It also has an @ref lavf_io
38  * "I/O module" which supports a number of protocols for accessing the data (e.g.
39  * file, tcp, http and others). Before using lavf, you need to call
40  * av_register_all() to register all compiled muxers, demuxers and protocols.
41  * Unless you are absolutely sure you won't use libavformat's network
42  * capabilities, you should also call avformat_network_init().
43  *
44  * A supported input format is described by an AVInputFormat struct, conversely
45  * an output format is described by AVOutputFormat. You can iterate over all
46  * registered input/output formats using the av_iformat_next() /
47  * av_oformat_next() functions. The protocols layer is not part of the public
48  * API, so you can only get the names of supported protocols with the
49  * avio_enum_protocols() function.
50  *
51  * Main lavf structure used for both muxing and demuxing is AVFormatContext,
52  * which exports all information about the file being read or written. As with
53  * most Libavformat structures, its size is not part of public ABI, so it cannot be
54  * allocated on stack or directly with av_malloc(). To create an
55  * AVFormatContext, use avformat_alloc_context() (some functions, like
56  * avformat_open_input() might do that for you).
57  *
58  * Most importantly an AVFormatContext contains:
59  * @li the @ref AVFormatContext.iformat "input" or @ref AVFormatContext.oformat
60  * "output" format. It is either autodetected or set by user for input;
61  * always set by user for output.
62  * @li an @ref AVFormatContext.streams "array" of AVStreams, which describe all
63  * elementary streams stored in the file. AVStreams are typically referred to
64  * using their index in this array.
65  * @li an @ref AVFormatContext.pb "I/O context". It is either opened by lavf or
66  * set by user for input, always set by user for output (unless you are dealing
67  * with an AVFMT_NOFILE format).
68  *
69  * @section lavf_options Passing options to (de)muxers
70  * Lavf allows to configure muxers and demuxers using the @ref avoptions
71  * mechanism. Generic (format-independent) libavformat options are provided by
72  * AVFormatContext, they can be examined from a user program by calling
73  * av_opt_next() / av_opt_find() on an allocated AVFormatContext (or its AVClass
74  * from avformat_get_class()). Private (format-specific) options are provided by
75  * AVFormatContext.priv_data if and only if AVInputFormat.priv_class /
76  * AVOutputFormat.priv_class of the corresponding format struct is non-NULL.
77  * Further options may be provided by the @ref AVFormatContext.pb "I/O context",
78  * if its AVClass is non-NULL, and the protocols layer. See the discussion on
79  * nesting in @ref avoptions documentation to learn how to access those.
80  *
81  * @defgroup lavf_decoding Demuxing
82  * @{
83  * Demuxers read a media file and split it into chunks of data (@em packets). A
84  * @ref AVPacket "packet" contains one or more encoded frames which belongs to a
85  * single elementary stream. In the lavf API this process is represented by the
86  * avformat_open_input() function for opening a file, av_read_frame() for
87  * reading a single packet and finally avformat_close_input(), which does the
88  * cleanup.
89  *
90  * @section lavf_decoding_open Opening a media file
91  * The minimum information required to open a file is its URL or filename, which
92  * is passed to avformat_open_input(), as in the following code:
93  * @code
94  * const char *url = "in.mp3";
95  * AVFormatContext *s = NULL;
96  * int ret = avformat_open_input(&s, url, NULL, NULL);
97  * if (ret < 0)
98  * abort();
99  * @endcode
100  * The above code attempts to allocate an AVFormatContext, open the
101  * specified file (autodetecting the format) and read the header, exporting the
102  * information stored there into s. Some formats do not have a header or do not
103  * store enough information there, so it is recommended that you call the
104  * avformat_find_stream_info() function which tries to read and decode a few
105  * frames to find missing information.
106  *
107  * In some cases you might want to preallocate an AVFormatContext yourself with
108  * avformat_alloc_context() and do some tweaking on it before passing it to
109  * avformat_open_input(). One such case is when you want to use custom functions
110  * for reading input data instead of lavf internal I/O layer.
111  * To do that, create your own AVIOContext with avio_alloc_context(), passing
112  * your reading callbacks to it. Then set the @em pb field of your
113  * AVFormatContext to newly created AVIOContext.
114  *
115  * Since the format of the opened file is in general not known until after
116  * avformat_open_input() has returned, it is not possible to set demuxer private
117  * options on a preallocated context. Instead, the options should be passed to
118  * avformat_open_input() wrapped in an AVDictionary:
119  * @code
120  * AVDictionary *options = NULL;
121  * av_dict_set(&options, "video_size", "640x480", 0);
122  * av_dict_set(&options, "pixel_format", "rgb24", 0);
123  *
124  * if (avformat_open_input(&s, url, NULL, &options) < 0)
125  * abort();
126  * av_dict_free(&options);
127  * @endcode
128  * This code passes the private options 'video_size' and 'pixel_format' to the
129  * demuxer. They would be necessary for e.g. the rawvideo demuxer, since it
130  * cannot know how to interpret raw video data otherwise. If the format turns
131  * out to be something different than raw video, those options will not be
132  * recognized by the demuxer and therefore will not be applied. Such unrecognized
133  * options are then returned in the options dictionary (recognized options are
134  * consumed). The calling program can handle such unrecognized options as it
135  * wishes, e.g.
136  * @code
137  * AVDictionaryEntry *e;
138  * if (e = av_dict_get(options, "", NULL, AV_DICT_IGNORE_SUFFIX)) {
139  * fprintf(stderr, "Option %s not recognized by the demuxer.\n", e->key);
140  * abort();
141  * }
142  * @endcode
143  *
144  * After you have finished reading the file, you must close it with
145  * avformat_close_input(). It will free everything associated with the file.
146  *
147  * @section lavf_decoding_read Reading from an opened file
148  * Reading data from an opened AVFormatContext is done by repeatedly calling
149  * av_read_frame() on it. Each call, if successful, will return an AVPacket
150  * containing encoded data for one AVStream, identified by
151  * AVPacket.stream_index. This packet may be passed straight into the libavcodec
152  * decoding functions avcodec_decode_video2(), avcodec_decode_audio4() or
153  * avcodec_decode_subtitle2() if the caller wishes to decode the data.
154  *
155  * AVPacket.pts, AVPacket.dts and AVPacket.duration timing information will be
156  * set if known. They may also be unset (i.e. AV_NOPTS_VALUE for
157  * pts/dts, 0 for duration) if the stream does not provide them. The timing
158  * information will be in AVStream.time_base units, i.e. it has to be
159  * multiplied by the timebase to convert them to seconds.
160  *
161  * If AVPacket.buf is set on the returned packet, then the packet is
162  * allocated dynamically and the user may keep it indefinitely.
163  * Otherwise, if AVPacket.buf is NULL, the packet data is backed by a
164  * static storage somewhere inside the demuxer and the packet is only valid
165  * until the next av_read_frame() call or closing the file. If the caller
166  * requires a longer lifetime, av_dup_packet() will make an av_malloc()ed copy
167  * of it.
168  * In both cases, the packet must be freed with av_free_packet() when it is no
169  * longer needed.
170  *
171  * @section lavf_decoding_seek Seeking
172  * @}
173  *
174  * @defgroup lavf_encoding Muxing
175  * @{
176  * @}
177  *
178  * @defgroup lavf_io I/O Read/Write
179  * @{
180  * @}
181  *
182  * @defgroup lavf_codec Demuxers
183  * @{
184  * @defgroup lavf_codec_native Native Demuxers
185  * @{
186  * @}
187  * @defgroup lavf_codec_wrappers External library wrappers
188  * @{
189  * @}
190  * @}
191  * @defgroup lavf_protos I/O Protocols
192  * @{
193  * @}
194  * @defgroup lavf_internal Internal
195  * @{
196  * @}
197  * @}
198  *
199  */
200 
201 #include <time.h>
202 #include <stdio.h> /* FILE */
203 #include "libavcodec/avcodec.h"
204 #include "libavutil/dict.h"
205 #include "libavutil/log.h"
206 
207 #include "avio.h"
208 #include "libavformat/version.h"
209 
210 struct AVFormatContext;
211 
212 
213 /**
214  * @defgroup metadata_api Public Metadata API
215  * @{
216  * @ingroup libavf
217  * The metadata API allows libavformat to export metadata tags to a client
218  * application when demuxing. Conversely it allows a client application to
219  * set metadata when muxing.
220  *
221  * Metadata is exported or set as pairs of key/value strings in the 'metadata'
222  * fields of the AVFormatContext, AVStream, AVChapter and AVProgram structs
223  * using the @ref lavu_dict "AVDictionary" API. Like all strings in FFmpeg,
224  * metadata is assumed to be UTF-8 encoded Unicode. Note that metadata
225  * exported by demuxers isn't checked to be valid UTF-8 in most cases.
226  *
227  * Important concepts to keep in mind:
228  * - Keys are unique; there can never be 2 tags with the same key. This is
229  * also meant semantically, i.e., a demuxer should not knowingly produce
230  * several keys that are literally different but semantically identical.
231  * E.g., key=Author5, key=Author6. In this example, all authors must be
232  * placed in the same tag.
233  * - Metadata is flat, not hierarchical; there are no subtags. If you
234  * want to store, e.g., the email address of the child of producer Alice
235  * and actor Bob, that could have key=alice_and_bobs_childs_email_address.
236  * - Several modifiers can be applied to the tag name. This is done by
237  * appending a dash character ('-') and the modifier name in the order
238  * they appear in the list below -- e.g. foo-eng-sort, not foo-sort-eng.
239  * - language -- a tag whose value is localized for a particular language
240  * is appended with the ISO 639-2/B 3-letter language code.
241  * For example: Author-ger=Michael, Author-eng=Mike
242  * The original/default language is in the unqualified "Author" tag.
243  * A demuxer should set a default if it sets any translated tag.
244  * - sorting -- a modified version of a tag that should be used for
245  * sorting will have '-sort' appended. E.g. artist="The Beatles",
246  * artist-sort="Beatles, The".
247  *
248  * - Demuxers attempt to export metadata in a generic format, however tags
249  * with no generic equivalents are left as they are stored in the container.
250  * Follows a list of generic tag names:
251  *
252  @verbatim
253  album -- name of the set this work belongs to
254  album_artist -- main creator of the set/album, if different from artist.
255  e.g. "Various Artists" for compilation albums.
256  artist -- main creator of the work
257  comment -- any additional description of the file.
258  composer -- who composed the work, if different from artist.
259  copyright -- name of copyright holder.
260  creation_time-- date when the file was created, preferably in ISO 8601.
261  date -- date when the work was created, preferably in ISO 8601.
262  disc -- number of a subset, e.g. disc in a multi-disc collection.
263  encoder -- name/settings of the software/hardware that produced the file.
264  encoded_by -- person/group who created the file.
265  filename -- original name of the file.
266  genre -- <self-evident>.
267  language -- main language in which the work is performed, preferably
268  in ISO 639-2 format. Multiple languages can be specified by
269  separating them with commas.
270  performer -- artist who performed the work, if different from artist.
271  E.g for "Also sprach Zarathustra", artist would be "Richard
272  Strauss" and performer "London Philharmonic Orchestra".
273  publisher -- name of the label/publisher.
274  service_name -- name of the service in broadcasting (channel name).
275  service_provider -- name of the service provider in broadcasting.
276  title -- name of the work.
277  track -- number of this work in the set, can be in form current/total.
278  variant_bitrate -- the total bitrate of the bitrate variant that the current stream is part of
279  @endverbatim
280  *
281  * Look in the examples section for an application example how to use the Metadata API.
282  *
283  * @}
284  */
285 
286 /* packet functions */
287 
288 
289 /**
290  * Allocate and read the payload of a packet and initialize its
291  * fields with default values.
292  *
293  * @param pkt packet
294  * @param size desired payload size
295  * @return >0 (read size) if OK, AVERROR_xxx otherwise
296  */
298 
299 
300 /**
301  * Read data and append it to the current content of the AVPacket.
302  * If pkt->size is 0 this is identical to av_get_packet.
303  * Note that this uses av_grow_packet and thus involves a realloc
304  * which is inefficient. Thus this function should only be used
305  * when there is no reasonable way to know (an upper bound of)
306  * the final size.
307  *
308  * @param pkt packet
309  * @param size amount of data to read
310  * @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data
311  * will not be lost even if an error occurs.
312  */
314 
315 /*************************************************/
316 /* fractional numbers for exact pts handling */
317 
318 /**
319  * The exact value of the fractional number is: 'val + num / den'.
320  * num is assumed to be 0 <= num < den.
321  */
322 typedef struct AVFrac {
323  int64_t val, num, den;
324 } AVFrac;
325 
326 /*************************************************/
327 /* input/output formats */
328 
329 struct AVCodecTag;
330 
331 /**
332  * This structure contains the data a format has to probe a file.
333  */
334 typedef struct AVProbeData {
335  const char *filename;
336  unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
337  int buf_size; /**< Size of buf except extra allocated bytes */
338 } AVProbeData;
339 
340 #define AVPROBE_SCORE_RETRY (AVPROBE_SCORE_MAX/4)
341 #define AVPROBE_SCORE_EXTENSION 50 ///< score for file extension
342 #define AVPROBE_SCORE_MAX 100 ///< maximum score
343 
344 #define AVPROBE_PADDING_SIZE 32 ///< extra allocated bytes at the end of the probe buffer
345 
346 /// Demuxer will use avio_open, no opened file should be provided by the caller.
347 #define AVFMT_NOFILE 0x0001
348 #define AVFMT_NEEDNUMBER 0x0002 /**< Needs '%d' in filename. */
349 #define AVFMT_SHOW_IDS 0x0008 /**< Show format stream IDs numbers. */
350 #define AVFMT_RAWPICTURE 0x0020 /**< Format wants AVPicture structure for
351  raw picture data. */
352 #define AVFMT_GLOBALHEADER 0x0040 /**< Format wants global header. */
353 #define AVFMT_NOTIMESTAMPS 0x0080 /**< Format does not need / have any timestamps. */
354 #define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */
355 #define AVFMT_TS_DISCONT 0x0200 /**< Format allows timestamp discontinuities. Note, muxers always require valid (monotone) timestamps */
356 #define AVFMT_VARIABLE_FPS 0x0400 /**< Format allows variable fps. */
357 #define AVFMT_NODIMENSIONS 0x0800 /**< Format does not need width/height */
358 #define AVFMT_NOSTREAMS 0x1000 /**< Format does not require any streams */
359 #define AVFMT_NOBINSEARCH 0x2000 /**< Format does not allow to fall back on binary search via read_timestamp */
360 #define AVFMT_NOGENSEARCH 0x4000 /**< Format does not allow to fall back on generic search */
361 #define AVFMT_NO_BYTE_SEEK 0x8000 /**< Format does not allow seeking by bytes */
362 #define AVFMT_ALLOW_FLUSH 0x10000 /**< Format allows flushing. If not set, the muxer will not receive a NULL packet in the write_packet function. */
363 #if LIBAVFORMAT_VERSION_MAJOR <= 54
364 #define AVFMT_TS_NONSTRICT 0x8020000 //we try to be compatible to the ABIs of ffmpeg and major forks
365 #else
366 #define AVFMT_TS_NONSTRICT 0x20000
367 #endif
368  /**< Format does not require strictly
369  increasing timestamps, but they must
370  still be monotonic */
371 #define AVFMT_TS_NEGATIVE 0x40000 /**< Format allows muxing negative
372  timestamps. If not set the timestamp
373  will be shifted in av_write_frame and
374  av_interleaved_write_frame so they
375  start from 0.
376  The user or muxer can override this through
377  AVFormatContext.avoid_negative_ts
378  */
379 
380 #define AVFMT_SEEK_TO_PTS 0x4000000 /**< Seeking is based on PTS */
381 
382 /**
383  * @addtogroup lavf_encoding
384  * @{
385  */
386 typedef struct AVOutputFormat {
387  const char *name;
388  /**
389  * Descriptive name for the format, meant to be more human-readable
390  * than name. You should use the NULL_IF_CONFIG_SMALL() macro
391  * to define it.
392  */
393  const char *long_name;
394  const char *mime_type;
395  const char *extensions; /**< comma-separated filename extensions */
396  /* output support */
397  enum AVCodecID audio_codec; /**< default audio codec */
398  enum AVCodecID video_codec; /**< default video codec */
399  enum AVCodecID subtitle_codec; /**< default subtitle codec */
400  /**
401  * can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_RAWPICTURE,
402  * AVFMT_GLOBALHEADER, AVFMT_NOTIMESTAMPS, AVFMT_VARIABLE_FPS,
403  * AVFMT_NODIMENSIONS, AVFMT_NOSTREAMS, AVFMT_ALLOW_FLUSH,
404  * AVFMT_TS_NONSTRICT
405  */
406  int flags;
407 
408  /**
409  * List of supported codec_id-codec_tag pairs, ordered by "better
410  * choice first". The arrays are all terminated by AV_CODEC_ID_NONE.
411  */
412  const struct AVCodecTag * const *codec_tag;
413 
414 
415  const AVClass *priv_class; ///< AVClass for the private context
416 
417  /*****************************************************************
418  * No fields below this line are part of the public API. They
419  * may not be used outside of libavformat and can be changed and
420  * removed at will.
421  * New public fields should be added right above.
422  *****************************************************************
423  */
425  /**
426  * size of private data so that it can be allocated in the wrapper
427  */
429 
430  int (*write_header)(struct AVFormatContext *);
431  /**
432  * Write a packet. If AVFMT_ALLOW_FLUSH is set in flags,
433  * pkt can be NULL in order to flush data buffered in the muxer.
434  * When flushing, return 0 if there still is more data to flush,
435  * or 1 if everything was flushed and there is no more buffered
436  * data.
437  */
439  int (*write_trailer)(struct AVFormatContext *);
440  /**
441  * Currently only used to set pixel format if not YUV420P.
442  */
444  AVPacket *in, int flush);
445  /**
446  * Test if the given codec can be stored in this container.
447  *
448  * @return 1 if the codec is supported, 0 if it is not.
449  * A negative number if unknown.
450  * MKTAG('A', 'P', 'I', 'C') if the codec is only supported as AV_DISPOSITION_ATTACHED_PIC
451  */
452  int (*query_codec)(enum AVCodecID id, int std_compliance);
453 
454  void (*get_output_timestamp)(struct AVFormatContext *s, int stream,
455  int64_t *dts, int64_t *wall);
457 /**
458  * @}
459  */
460 
461 /**
462  * @addtogroup lavf_decoding
463  * @{
464  */
465 typedef struct AVInputFormat {
466  /**
467  * A comma separated list of short names for the format. New names
468  * may be appended with a minor bump.
469  */
470  const char *name;
471 
472  /**
473  * Descriptive name for the format, meant to be more human-readable
474  * than name. You should use the NULL_IF_CONFIG_SMALL() macro
475  * to define it.
476  */
477  const char *long_name;
478 
479  /**
480  * Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS,
481  * AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH,
482  * AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK, AVFMT_SEEK_TO_PTS.
483  */
484  int flags;
485 
486  /**
487  * If extensions are defined, then no probe is done. You should
488  * usually not use extension format guessing because it is not
489  * reliable enough
490  */
491  const char *extensions;
492 
493  const struct AVCodecTag * const *codec_tag;
494 
495  const AVClass *priv_class; ///< AVClass for the private context
496 
497  /*****************************************************************
498  * No fields below this line are part of the public API. They
499  * may not be used outside of libavformat and can be changed and
500  * removed at will.
501  * New public fields should be added right above.
502  *****************************************************************
503  */
505 
506  /**
507  * Raw demuxers store their codec ID here.
508  */
510 
511  /**
512  * Size of private data so that it can be allocated in the wrapper.
513  */
515 
516  /**
517  * Tell if a given file has a chance of being parsed as this format.
518  * The buffer provided is guaranteed to be AVPROBE_PADDING_SIZE bytes
519  * big so you do not have to check for that unless you need more.
520  */
522 
523  /**
524  * Read the format header and initialize the AVFormatContext
525  * structure. Return 0 if OK. Only used in raw format right
526  * now. 'avformat_new_stream' should be called to create new streams.
527  */
528  int (*read_header)(struct AVFormatContext *);
529 
530  /**
531  * Read one packet and put it in 'pkt'. pts and flags are also
532  * set. 'avformat_new_stream' can be called only if the flag
533  * AVFMTCTX_NOHEADER is used and only in the calling thread (not in a
534  * background thread).
535  * @return 0 on success, < 0 on error.
536  * When returning an error, pkt must not have been allocated
537  * or must be freed before returning
538  */
540 
541  /**
542  * Close the stream. The AVFormatContext and AVStreams are not
543  * freed by this function
544  */
545  int (*read_close)(struct AVFormatContext *);
546 
547  /**
548  * Seek to a given timestamp relative to the frames in
549  * stream component stream_index.
550  * @param stream_index Must not be -1.
551  * @param flags Selects which direction should be preferred if no exact
552  * match is available.
553  * @return >= 0 on success (but not necessarily the new offset)
554  */
555  int (*read_seek)(struct AVFormatContext *,
556  int stream_index, int64_t timestamp, int flags);
557 
558  /**
559  * Get the next timestamp in stream[stream_index].time_base units.
560  * @return the timestamp or AV_NOPTS_VALUE if an error occurred
561  */
562  int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,
563  int64_t *pos, int64_t pos_limit);
564 
565  /**
566  * Start/resume playing - only meaningful if using a network-based format
567  * (RTSP).
568  */
569  int (*read_play)(struct AVFormatContext *);
570 
571  /**
572  * Pause playing - only meaningful if using a network-based format
573  * (RTSP).
574  */
575  int (*read_pause)(struct AVFormatContext *);
576 
577  /**
578  * Seek to timestamp ts.
579  * Seeking will be done so that the point from which all active streams
580  * can be presented successfully will be closest to ts and within min/max_ts.
581  * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
582  */
583  int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
584 } AVInputFormat;
585 /**
586  * @}
587  */
588 
591  AVSTREAM_PARSE_FULL, /**< full parsing and repack */
592  AVSTREAM_PARSE_HEADERS, /**< Only parse headers, do not repack. */
593  AVSTREAM_PARSE_TIMESTAMPS, /**< full parsing and interpolation of timestamps for frames not starting on a packet boundary */
594  AVSTREAM_PARSE_FULL_ONCE, /**< full parsing and repack of the first frame only, only implemented for H.264 currently */
595  AVSTREAM_PARSE_FULL_RAW=MKTAG(0,'R','A','W'), /**< full parsing and repack with timestamp and position generation by parser for raw
596  this assumes that each packet in the file contains no demuxer level headers and
597  just codec level data, otherwise position generation would fail */
598 };
599 
600 typedef struct AVIndexEntry {
601  int64_t pos;
602  int64_t timestamp; /**<
603  * Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are available
604  * when seeking to this entry. That means preferable PTS on keyframe based formats.
605  * But demuxers can choose to store a different timestamp, if it is more convenient for the implementation or nothing better
606  * is known
607  */
608 #define AVINDEX_KEYFRAME 0x0001
609  int flags:2;
610  int size:30; //Yeah, trying to keep the size of this small to reduce memory requirements (it is 24 vs. 32 bytes due to possible 8-byte alignment).
611  int min_distance; /**< Minimum distance between this and the previous keyframe, used to avoid unneeded searching. */
612 } AVIndexEntry;
613 
614 #define AV_DISPOSITION_DEFAULT 0x0001
615 #define AV_DISPOSITION_DUB 0x0002
616 #define AV_DISPOSITION_ORIGINAL 0x0004
617 #define AV_DISPOSITION_COMMENT 0x0008
618 #define AV_DISPOSITION_LYRICS 0x0010
619 #define AV_DISPOSITION_KARAOKE 0x0020
620 
621 /**
622  * Track should be used during playback by default.
623  * Useful for subtitle track that should be displayed
624  * even when user did not explicitly ask for subtitles.
625  */
626 #define AV_DISPOSITION_FORCED 0x0040
627 #define AV_DISPOSITION_HEARING_IMPAIRED 0x0080 /**< stream for hearing impaired audiences */
628 #define AV_DISPOSITION_VISUAL_IMPAIRED 0x0100 /**< stream for visual impaired audiences */
629 #define AV_DISPOSITION_CLEAN_EFFECTS 0x0200 /**< stream without voice */
630 /**
631  * The stream is stored in the file as an attached picture/"cover art" (e.g.
632  * APIC frame in ID3v2). The single packet associated with it will be returned
633  * among the first few packets read from the file unless seeking takes place.
634  * It can also be accessed at any time in AVStream.attached_pic.
635  */
636 #define AV_DISPOSITION_ATTACHED_PIC 0x0400
637 
638 /**
639  * To specify text track kind (different from subtitles default).
640  */
641 #define AV_DISPOSITION_CAPTIONS 0x10000
642 #define AV_DISPOSITION_DESCRIPTIONS 0x20000
643 #define AV_DISPOSITION_METADATA 0x40000
644 
645 /**
646  * Options for behavior on timestamp wrap detection.
647  */
648 #define AV_PTS_WRAP_IGNORE 0 ///< ignore the wrap
649 #define AV_PTS_WRAP_ADD_OFFSET 1 ///< add the format specific offset on wrap detection
650 #define AV_PTS_WRAP_SUB_OFFSET -1 ///< subtract the format specific offset on wrap detection
651 
652 /**
653  * Stream structure.
654  * New fields can be added to the end with minor version bumps.
655  * Removal, reordering and changes to existing fields require a major
656  * version bump.
657  * sizeof(AVStream) must not be used outside libav*.
658  */
659 typedef struct AVStream {
660  int index; /**< stream index in AVFormatContext */
661  /**
662  * Format-specific stream ID.
663  * decoding: set by libavformat
664  * encoding: set by the user, replaced by libavformat if left unset
665  */
666  int id;
667  /**
668  * Codec context associated with this stream. Allocated and freed by
669  * libavformat.
670  *
671  * - decoding: The demuxer exports codec information stored in the headers
672  * here.
673  * - encoding: The user sets codec information, the muxer writes it to the
674  * output. Mandatory fields as specified in AVCodecContext
675  * documentation must be set even if this AVCodecContext is
676  * not actually used for encoding.
677  */
679  void *priv_data;
680 
681  /**
682  * encoding: pts generation when outputting stream
683  */
684  struct AVFrac pts;
685 
686  /**
687  * This is the fundamental unit of time (in seconds) in terms
688  * of which frame timestamps are represented.
689  *
690  * decoding: set by libavformat
691  * encoding: set by libavformat in avformat_write_header. The muxer may use the
692  * user-provided value of @ref AVCodecContext.time_base "codec->time_base"
693  * as a hint.
694  */
696 
697  /**
698  * Decoding: pts of the first frame of the stream in presentation order, in stream time base.
699  * Only set this if you are absolutely 100% sure that the value you set
700  * it to really is the pts of the first frame.
701  * This may be undefined (AV_NOPTS_VALUE).
702  * @note The ASF header does NOT contain a correct start_time the ASF
703  * demuxer must NOT set this.
704  */
705  int64_t start_time;
706 
707  /**
708  * Decoding: duration of the stream, in stream time base.
709  * If a source file does not specify a duration, but does specify
710  * a bitrate, this value will be estimated from bitrate and file size.
711  */
712  int64_t duration;
713 
714  int64_t nb_frames; ///< number of frames in this stream if known or 0
715 
716  int disposition; /**< AV_DISPOSITION_* bit field */
717 
718  enum AVDiscard discard; ///< Selects which packets can be discarded at will and do not need to be demuxed.
719 
720  /**
721  * sample aspect ratio (0 if unknown)
722  * - encoding: Set by user.
723  * - decoding: Set by libavformat.
724  */
726 
728 
729  /**
730  * Average framerate
731  */
733 
734  /**
735  * For streams with AV_DISPOSITION_ATTACHED_PIC disposition, this packet
736  * will contain the attached picture.
737  *
738  * decoding: set by libavformat, must not be modified by the caller.
739  * encoding: unused
740  */
742 
743  /*****************************************************************
744  * All fields below this line are not part of the public API. They
745  * may not be used outside of libavformat and can be changed and
746  * removed at will.
747  * New public fields should be added right above.
748  *****************************************************************
749  */
750 
751  /**
752  * Stream information used internally by av_find_stream_info()
753  */
754 #define MAX_STD_TIMEBASES (60*12+6)
755  struct {
756  int64_t last_dts;
757  int64_t duration_gcd;
763 
764  int64_t last_duration;
765 
766  /**
767  * Those are used for average framerate estimation.
768  */
769  int64_t fps_first_dts;
771  int64_t fps_last_dts;
773 
774  } *info;
775 
776  int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */
777 
778  // Timestamp generation support:
779  /**
780  * Timestamp corresponding to the last dts sync point.
781  *
782  * Initialized when AVCodecParserContext.dts_sync_point >= 0 and
783  * a DTS is received from the underlying container. Otherwise set to
784  * AV_NOPTS_VALUE by default.
785  */
786  int64_t reference_dts;
787  int64_t first_dts;
788  int64_t cur_dts;
789  int64_t last_IP_pts;
791 
792  /**
793  * Number of packets to buffer for codec probing
794  */
795 #define MAX_PROBE_PACKETS 2500
797 
798  /**
799  * Number of frames that have been demuxed during av_find_stream_info()
800  */
802 
803  /* av_read_frame() support */
806 
807  /**
808  * last packet in packet_buffer for this stream when muxing.
809  */
812 #define MAX_REORDER_DELAY 16
814 
815  AVIndexEntry *index_entries; /**< Only used if the format does not
816  support seeking natively. */
819 
820  /**
821  * Real base framerate of the stream.
822  * This is the lowest framerate with which all timestamps can be
823  * represented accurately (it is the least common multiple of all
824  * framerates in the stream). Note, this value is just a guess!
825  * For example, if the time base is 1/90000 and all frames have either
826  * approximately 3600 or 1800 timer ticks, then r_frame_rate will be 50/1.
827  *
828  * Code outside avformat should access this field using:
829  * av_stream_get/set_r_frame_rate(stream)
830  */
832 
833  /**
834  * Stream Identifier
835  * This is the MPEG-TS stream identifier +1
836  * 0 means unknown
837  */
839 
842 
843  /**
844  * stream probing state
845  * -1 -> probing finished
846  * 0 -> no probing requested
847  * rest -> perform probing with request_probe being the minimum score to accept.
848  * NOT PART OF PUBLIC API
849  */
851  /**
852  * Indicates that everything up to the next keyframe
853  * should be discarded.
854  */
856 
857  /**
858  * Number of samples to skip at the start of the frame decoded from the next packet.
859  */
861 
862  /**
863  * Number of internally decoded frames, used internally in libavformat, do not access
864  * its lifetime differs from info which is why it is not in that structure.
865  */
867 
868  /**
869  * Timestamp offset added to timestamps before muxing
870  * NOT PART OF PUBLIC API
871  */
872  int64_t mux_ts_offset;
873 
874  /**
875  * Internal data to check for wrapping of the time stamp
876  */
878 
879  /**
880  * Options for behavior, when a wrap is detected.
881  *
882  * Defined by AV_PTS_WRAP_ values.
883  *
884  * If correction is enabled, there are two possibilities:
885  * If the first time stamp is near the wrap point, the wrap offset
886  * will be subtracted, which will create negative time stamps.
887  * Otherwise the offset will be added.
888  */
890 
891 } AVStream;
892 
895 
896 #define AV_PROGRAM_RUNNING 1
897 
898 /**
899  * New fields can be added to the end with minor version bumps.
900  * Removal, reordering and changes to existing fields require a major
901  * version bump.
902  * sizeof(AVProgram) must not be used outside libav*.
903  */
904 typedef struct AVProgram {
905  int id;
906  int flags;
907  enum AVDiscard discard; ///< selects which program to discard and which to feed to the caller
908  unsigned int *stream_index;
909  unsigned int nb_stream_indexes;
911 
913  int pmt_pid;
914  int pcr_pid;
915 
916  /*****************************************************************
917  * All fields below this line are not part of the public API. They
918  * may not be used outside of libavformat and can be changed and
919  * removed at will.
920  * New public fields should be added right above.
921  *****************************************************************
922  */
923  int64_t start_time;
924  int64_t end_time;
925 
926  int64_t pts_wrap_reference; ///< reference dts for wrap detection
927  int pts_wrap_behavior; ///< behavior on wrap detection
928 } AVProgram;
929 
930 #define AVFMTCTX_NOHEADER 0x0001 /**< signal that no header is present
931  (streams are added dynamically) */
932 
933 typedef struct AVChapter {
934  int id; ///< unique ID to identify the chapter
935  AVRational time_base; ///< time base in which the start/end timestamps are specified
936  int64_t start, end; ///< chapter start/end time in time_base units
938 } AVChapter;
939 
940 
941 /**
942  * The duration of a video can be estimated through various ways, and this enum can be used
943  * to know how the duration was estimated.
944  */
946  AVFMT_DURATION_FROM_PTS, ///< Duration accurately estimated from PTSes
947  AVFMT_DURATION_FROM_STREAM, ///< Duration estimated from a stream with a known duration
948  AVFMT_DURATION_FROM_BITRATE ///< Duration estimated from bitrate (less accurate)
949 };
950 
951 /**
952  * Format I/O context.
953  * New fields can be added to the end with minor version bumps.
954  * Removal, reordering and changes to existing fields require a major
955  * version bump.
956  * sizeof(AVFormatContext) must not be used outside libav*, use
957  * avformat_alloc_context() to create an AVFormatContext.
958  */
959 typedef struct AVFormatContext {
960  /**
961  * A class for logging and AVOptions. Set by avformat_alloc_context().
962  * Exports (de)muxer private options if they exist.
963  */
965 
966  /**
967  * Can only be iformat or oformat, not both at the same time.
968  *
969  * decoding: set by avformat_open_input().
970  * encoding: set by the user.
971  */
974 
975  /**
976  * Format private data. This is an AVOptions-enabled struct
977  * if and only if iformat/oformat.priv_class is not NULL.
978  */
979  void *priv_data;
980 
981  /**
982  * I/O context.
983  *
984  * decoding: either set by the user before avformat_open_input() (then
985  * the user must close it manually) or set by avformat_open_input().
986  * encoding: set by the user.
987  *
988  * Do NOT set this field if AVFMT_NOFILE flag is set in
989  * iformat/oformat.flags. In such a case, the (de)muxer will handle
990  * I/O in some other way and this field will be NULL.
991  */
993 
994  /* stream info */
995  int ctx_flags; /**< Format-specific flags, see AVFMTCTX_xx */
996 
997  /**
998  * A list of all streams in the file. New streams are created with
999  * avformat_new_stream().
1000  *
1001  * decoding: streams are created by libavformat in avformat_open_input().
1002  * If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also
1003  * appear in av_read_frame().
1004  * encoding: streams are created by the user before avformat_write_header().
1005  */
1006  unsigned int nb_streams;
1008 
1009  char filename[1024]; /**< input or output filename */
1010 
1011  /**
1012  * Decoding: position of the first frame of the component, in
1013  * AV_TIME_BASE fractional seconds. NEVER set this value directly:
1014  * It is deduced from the AVStream values.
1015  */
1016  int64_t start_time;
1017 
1018  /**
1019  * Decoding: duration of the stream, in AV_TIME_BASE fractional
1020  * seconds. Only set this value if you know none of the individual stream
1021  * durations and also do not set any of them. This is deduced from the
1022  * AVStream values if not set.
1023  */
1024  int64_t duration;
1025 
1026  /**
1027  * Decoding: total stream bitrate in bit/s, 0 if not
1028  * available. Never set it directly if the file_size and the
1029  * duration are known as FFmpeg can compute it automatically.
1030  */
1032 
1033  unsigned int packet_size;
1035 
1036  int flags;
1037 #define AVFMT_FLAG_GENPTS 0x0001 ///< Generate missing pts even if it requires parsing future frames.
1038 #define AVFMT_FLAG_IGNIDX 0x0002 ///< Ignore index.
1039 #define AVFMT_FLAG_NONBLOCK 0x0004 ///< Do not block when reading packets from input.
1040 #define AVFMT_FLAG_IGNDTS 0x0008 ///< Ignore DTS on frames that contain both DTS & PTS
1041 #define AVFMT_FLAG_NOFILLIN 0x0010 ///< Do not infer any values from other values, just return what is stored in the container
1042 #define AVFMT_FLAG_NOPARSE 0x0020 ///< Do not use AVParsers, you also must set AVFMT_FLAG_NOFILLIN as the fillin code works on frames and no parsing -> no frames. Also seeking to frames can not work if parsing to find frame boundaries has been disabled
1043 #define AVFMT_FLAG_NOBUFFER 0x0040 ///< Do not buffer frames when possible
1044 #define AVFMT_FLAG_CUSTOM_IO 0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.
1045 #define AVFMT_FLAG_DISCARD_CORRUPT 0x0100 ///< Discard frames marked corrupted
1046 #define AVFMT_FLAG_MP4A_LATM 0x8000 ///< Enable RTP MP4A-LATM payload
1047 #define AVFMT_FLAG_SORT_DTS 0x10000 ///< try to interleave outputted packets by dts (using this flag can slow demuxing down)
1048 #define AVFMT_FLAG_PRIV_OPT 0x20000 ///< Enable use of private options by delaying codec open (this could be made default once all code is converted)
1049 #define AVFMT_FLAG_KEEP_SIDE_DATA 0x40000 ///< Don't merge side data but keep it separate.
1050 
1051  /**
1052  * decoding: size of data to probe; encoding: unused.
1053  */
1054  unsigned int probesize;
1055 
1056  /**
1057  * decoding: maximum time (in AV_TIME_BASE units) during which the input should
1058  * be analyzed in avformat_find_stream_info().
1059  */
1061 
1062  const uint8_t *key;
1063  int keylen;
1064 
1065  unsigned int nb_programs;
1067 
1068  /**
1069  * Forced video codec_id.
1070  * Demuxing: Set by user.
1071  */
1073 
1074  /**
1075  * Forced audio codec_id.
1076  * Demuxing: Set by user.
1077  */
1079 
1080  /**
1081  * Forced subtitle codec_id.
1082  * Demuxing: Set by user.
1083  */
1085 
1086  /**
1087  * Maximum amount of memory in bytes to use for the index of each stream.
1088  * If the index exceeds this size, entries will be discarded as
1089  * needed to maintain a smaller size. This can lead to slower or less
1090  * accurate seeking (depends on demuxer).
1091  * Demuxers for which a full in-memory index is mandatory will ignore
1092  * this.
1093  * muxing : unused
1094  * demuxing: set by user
1095  */
1096  unsigned int max_index_size;
1097 
1098  /**
1099  * Maximum amount of memory in bytes to use for buffering frames
1100  * obtained from realtime capture devices.
1101  */
1102  unsigned int max_picture_buffer;
1103 
1104  unsigned int nb_chapters;
1106 
1108 
1109  /**
1110  * Start time of the stream in real world time, in microseconds
1111  * since the unix epoch (00:00 1st January 1970). That is, pts=0
1112  * in the stream was captured at this real world time.
1113  * - encoding: Set by user.
1114  * - decoding: Unused.
1115  */
1117 
1118  /**
1119  * decoding: number of frames used to probe fps
1120  */
1122 
1123  /**
1124  * Error recognition; higher values will detect more errors but may
1125  * misdetect some more or less valid parts as errors.
1126  * - encoding: unused
1127  * - decoding: Set by user.
1128  */
1130 
1131  /**
1132  * Custom interrupt callbacks for the I/O layer.
1133  *
1134  * decoding: set by the user before avformat_open_input().
1135  * encoding: set by the user before avformat_write_header()
1136  * (mainly useful for AVFMT_NOFILE formats). The callback
1137  * should also be passed to avio_open2() if it's used to
1138  * open the file.
1139  */
1141 
1142  /**
1143  * Flags to enable debugging.
1144  */
1145  int debug;
1146 #define FF_FDEBUG_TS 0x0001
1147 
1148  /**
1149  * Transport stream id.
1150  * This will be moved into demuxer private options. Thus no API/ABI compatibility
1151  */
1152  int ts_id;
1153 
1154  /**
1155  * Audio preload in microseconds.
1156  * Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1157  * - encoding: Set by user via AVOptions (NO direct access)
1158  * - decoding: unused
1159  */
1161 
1162  /**
1163  * Max chunk time in microseconds.
1164  * Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1165  * - encoding: Set by user via AVOptions (NO direct access)
1166  * - decoding: unused
1167  */
1169 
1170  /**
1171  * Max chunk size in bytes
1172  * Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1173  * - encoding: Set by user via AVOptions (NO direct access)
1174  * - decoding: unused
1175  */
1177 
1178  /**
1179  * forces the use of wallclock timestamps as pts/dts of packets
1180  * This has undefined results in the presence of B frames.
1181  * - encoding: unused
1182  * - decoding: Set by user via AVOptions (NO direct access)
1183  */
1185 
1186  /**
1187  * Avoid negative timestamps during muxing.
1188  * 0 -> allow negative timestamps
1189  * 1 -> avoid negative timestamps
1190  * -1 -> choose automatically (default)
1191  * Note, this only works when interleave_packet_per_dts is in use.
1192  * - encoding: Set by user via AVOptions (NO direct access)
1193  * - decoding: unused
1194  */
1196 
1197  /**
1198  * avio flags, used to force AVIO_FLAG_DIRECT.
1199  * - encoding: unused
1200  * - decoding: Set by user via AVOptions (NO direct access)
1201  */
1203 
1204  /**
1205  * The duration field can be estimated through various ways, and this field can be used
1206  * to know how the duration was estimated.
1207  * - encoding: unused
1208  * - decoding: Read by user via AVOptions (NO direct access)
1209  */
1211 
1212  /**
1213  * Skip initial bytes when opening stream
1214  * - encoding: unused
1215  * - decoding: Set by user via AVOptions (NO direct access)
1216  */
1217  unsigned int skip_initial_bytes;
1218 
1219  /**
1220  * Correct single timestamp overflows
1221  * - encoding: unused
1222  * - decoding: Set by user via AVOPtions (NO direct access)
1223  */
1224  unsigned int correct_ts_overflow;
1225 
1226  /**
1227  * Force seeking to any (also non key) frames.
1228  * - encoding: unused
1229  * - decoding: Set by user via AVOPtions (NO direct access)
1230  */
1232 
1233  /**
1234  * Flush the I/O context after each packet.
1235  * - encoding: Set by user via AVOptions (NO direct access)
1236  * - decoding: unused
1237  */
1239 
1240  /*****************************************************************
1241  * All fields below this line are not part of the public API. They
1242  * may not be used outside of libavformat and can be changed and
1243  * removed at will.
1244  * New public fields should be added right above.
1245  *****************************************************************
1246  */
1247 
1248  /**
1249  * This buffer is only needed when packets were already buffered but
1250  * not decoded, for example to get the codec parameters in MPEG
1251  * streams.
1252  */
1255 
1256  /* av_seek_frame() support */
1257  int64_t data_offset; /**< offset of the first packet */
1258 
1259  /**
1260  * Raw packets from the demuxer, prior to parsing and decoding.
1261  * This buffer is used for buffering packets until the codec can
1262  * be identified, as parsing cannot be done without knowing the
1263  * codec.
1264  */
1267  /**
1268  * Packets split by the parser get queued here.
1269  */
1272  /**
1273  * Remaining size available for raw_packet_buffer, in bytes.
1274  */
1275 #define RAW_PACKET_BUFFER_SIZE 2500000
1277 
1278  /**
1279  * Offset to remap timestamps to be non-negative.
1280  * Expressed in timebase units.
1281  * @see AVStream.mux_ts_offset
1282  */
1283  int64_t offset;
1284 
1285  /**
1286  * Timebase for the timestamp offset.
1287  */
1289 
1290  /**
1291  * IO repositioned flag.
1292  * This is set by avformat when the underlaying IO context read pointer
1293  * is repositioned, for example when doing byte based seeking.
1294  * Demuxers can use the flag to detect such changes.
1295  */
1297 } AVFormatContext;
1298 
1299 /**
1300  * Returns the method used to set ctx->duration.
1301  *
1302  * @return AVFMT_DURATION_FROM_PTS, AVFMT_DURATION_FROM_STREAM, or AVFMT_DURATION_FROM_BITRATE.
1303  */
1305 
1306 typedef struct AVPacketList {
1309 } AVPacketList;
1310 
1311 
1312 /**
1313  * @defgroup lavf_core Core functions
1314  * @ingroup libavf
1315  *
1316  * Functions for querying libavformat capabilities, allocating core structures,
1317  * etc.
1318  * @{
1319  */
1320 
1321 /**
1322  * Return the LIBAVFORMAT_VERSION_INT constant.
1323  */
1324 unsigned avformat_version(void);
1325 
1326 /**
1327  * Return the libavformat build-time configuration.
1328  */
1329 const char *avformat_configuration(void);
1330 
1331 /**
1332  * Return the libavformat license.
1333  */
1334 const char *avformat_license(void);
1335 
1336 /**
1337  * Initialize libavformat and register all the muxers, demuxers and
1338  * protocols. If you do not call this function, then you can select
1339  * exactly which formats you want to support.
1340  *
1341  * @see av_register_input_format()
1342  * @see av_register_output_format()
1343  */
1344 void av_register_all(void);
1345 
1348 
1349 /**
1350  * Do global initialization of network components. This is optional,
1351  * but recommended, since it avoids the overhead of implicitly
1352  * doing the setup for each session.
1353  *
1354  * Calling this function will become mandatory if using network
1355  * protocols at some major version bump.
1356  */
1357 int avformat_network_init(void);
1358 
1359 /**
1360  * Undo the initialization done by avformat_network_init.
1361  */
1362 int avformat_network_deinit(void);
1363 
1364 /**
1365  * If f is NULL, returns the first registered input format,
1366  * if f is non-NULL, returns the next registered input format after f
1367  * or NULL if f is the last one.
1368  */
1370 
1371 /**
1372  * If f is NULL, returns the first registered output format,
1373  * if f is non-NULL, returns the next registered output format after f
1374  * or NULL if f is the last one.
1375  */
1377 
1378 /**
1379  * Allocate an AVFormatContext.
1380  * avformat_free_context() can be used to free the context and everything
1381  * allocated by the framework within it.
1382  */
1384 
1385 /**
1386  * Free an AVFormatContext and all its streams.
1387  * @param s context to free
1388  */
1390 
1391 /**
1392  * Get the AVClass for AVFormatContext. It can be used in combination with
1393  * AV_OPT_SEARCH_FAKE_OBJ for examining options.
1394  *
1395  * @see av_opt_find().
1396  */
1397 const AVClass *avformat_get_class(void);
1398 
1399 /**
1400  * Add a new stream to a media file.
1401  *
1402  * When demuxing, it is called by the demuxer in read_header(). If the
1403  * flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also
1404  * be called in read_packet().
1405  *
1406  * When muxing, should be called by the user before avformat_write_header().
1407  *
1408  * @param c If non-NULL, the AVCodecContext corresponding to the new stream
1409  * will be initialized to use this codec. This is needed for e.g. codec-specific
1410  * defaults to be set, so codec should be provided if it is known.
1411  *
1412  * @return newly created stream or NULL on error.
1413  */
1415 
1417 
1418 /**
1419  * @}
1420  */
1421 
1422 
1423 #if FF_API_PKT_DUMP
1424 attribute_deprecated void av_pkt_dump(FILE *f, AVPacket *pkt, int dump_payload);
1425 attribute_deprecated void av_pkt_dump_log(void *avcl, int level, AVPacket *pkt,
1426  int dump_payload);
1427 #endif
1428 
1429 #if FF_API_ALLOC_OUTPUT_CONTEXT
1430 /**
1431  * @deprecated deprecated in favor of avformat_alloc_output_context2()
1432  */
1434 AVFormatContext *avformat_alloc_output_context(const char *format,
1435  AVOutputFormat *oformat,
1436  const char *filename);
1437 #endif
1438 
1439 /**
1440  * Allocate an AVFormatContext for an output format.
1441  * avformat_free_context() can be used to free the context and
1442  * everything allocated by the framework within it.
1443  *
1444  * @param *ctx is set to the created format context, or to NULL in
1445  * case of failure
1446  * @param oformat format to use for allocating the context, if NULL
1447  * format_name and filename are used instead
1448  * @param format_name the name of output format to use for allocating the
1449  * context, if NULL filename is used instead
1450  * @param filename the name of the filename to use for allocating the
1451  * context, may be NULL
1452  * @return >= 0 in case of success, a negative AVERROR code in case of
1453  * failure
1454  */
1456  const char *format_name, const char *filename);
1457 
1458 /**
1459  * @addtogroup lavf_decoding
1460  * @{
1461  */
1462 
1463 /**
1464  * Find AVInputFormat based on the short name of the input format.
1465  */
1466 AVInputFormat *av_find_input_format(const char *short_name);
1467 
1468 /**
1469  * Guess the file format.
1470  *
1471  * @param is_opened Whether the file is already opened; determines whether
1472  * demuxers with or without AVFMT_NOFILE are probed.
1473  */
1474 AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened);
1475 
1476 /**
1477  * Guess the file format.
1478  *
1479  * @param is_opened Whether the file is already opened; determines whether
1480  * demuxers with or without AVFMT_NOFILE are probed.
1481  * @param score_max A probe score larger that this is required to accept a
1482  * detection, the variable is set to the actual detection
1483  * score afterwards.
1484  * If the score is <= AVPROBE_SCORE_MAX / 4 it is recommended
1485  * to retry with a larger probe buffer.
1486  */
1487 AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max);
1488 
1489 /**
1490  * Guess the file format.
1491  *
1492  * @param is_opened Whether the file is already opened; determines whether
1493  * demuxers with or without AVFMT_NOFILE are probed.
1494  * @param score_ret The score of the best detection.
1495  */
1496 AVInputFormat *av_probe_input_format3(AVProbeData *pd, int is_opened, int *score_ret);
1497 
1498 /**
1499  * Probe a bytestream to determine the input format. Each time a probe returns
1500  * with a score that is too low, the probe buffer size is increased and another
1501  * attempt is made. When the maximum probe size is reached, the input format
1502  * with the highest score is returned.
1503  *
1504  * @param pb the bytestream to probe
1505  * @param fmt the input format is put here
1506  * @param filename the filename of the stream
1507  * @param logctx the log context
1508  * @param offset the offset within the bytestream to probe from
1509  * @param max_probe_size the maximum probe buffer size (zero for default)
1510  * @return 0 in case of success, a negative value corresponding to an
1511  * AVERROR code otherwise
1512  */
1514  const char *filename, void *logctx,
1515  unsigned int offset, unsigned int max_probe_size);
1516 
1517 /**
1518  * Open an input stream and read the header. The codecs are not opened.
1519  * The stream must be closed with av_close_input_file().
1520  *
1521  * @param ps Pointer to user-supplied AVFormatContext (allocated by avformat_alloc_context).
1522  * May be a pointer to NULL, in which case an AVFormatContext is allocated by this
1523  * function and written into ps.
1524  * Note that a user-supplied AVFormatContext will be freed on failure.
1525  * @param filename Name of the stream to open.
1526  * @param fmt If non-NULL, this parameter forces a specific input format.
1527  * Otherwise the format is autodetected.
1528  * @param options A dictionary filled with AVFormatContext and demuxer-private options.
1529  * On return this parameter will be destroyed and replaced with a dict containing
1530  * options that were not found. May be NULL.
1531  *
1532  * @return 0 on success, a negative AVERROR on failure.
1533  *
1534  * @note If you want to use custom IO, preallocate the format context and set its pb field.
1535  */
1536 int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputFormat *fmt, AVDictionary **options);
1537 
1540 
1541 #if FF_API_FORMAT_PARAMETERS
1542 /**
1543  * Read packets of a media file to get stream information. This
1544  * is useful for file formats with no headers such as MPEG. This
1545  * function also computes the real framerate in case of MPEG-2 repeat
1546  * frame mode.
1547  * The logical file position is not changed by this function;
1548  * examined packets may be buffered for later processing.
1549  *
1550  * @param ic media file handle
1551  * @return >=0 if OK, AVERROR_xxx on error
1552  * @todo Let the user decide somehow what information is needed so that
1553  * we do not waste time getting stuff the user does not need.
1554  *
1555  * @deprecated use avformat_find_stream_info.
1556  */
1558 int av_find_stream_info(AVFormatContext *ic);
1559 #endif
1560 
1561 /**
1562  * Read packets of a media file to get stream information. This
1563  * is useful for file formats with no headers such as MPEG. This
1564  * function also computes the real framerate in case of MPEG-2 repeat
1565  * frame mode.
1566  * The logical file position is not changed by this function;
1567  * examined packets may be buffered for later processing.
1568  *
1569  * @param ic media file handle
1570  * @param options If non-NULL, an ic.nb_streams long array of pointers to
1571  * dictionaries, where i-th member contains options for
1572  * codec corresponding to i-th stream.
1573  * On return each dictionary will be filled with options that were not found.
1574  * @return >=0 if OK, AVERROR_xxx on error
1575  *
1576  * @note this function isn't guaranteed to open all the codecs, so
1577  * options being non-empty at return is a perfectly normal behavior.
1578  *
1579  * @todo Let the user decide somehow what information is needed so that
1580  * we do not waste time getting stuff the user does not need.
1581  */
1583 
1584 /**
1585  * Find the programs which belong to a given stream.
1586  *
1587  * @param ic media file handle
1588  * @param last the last found program, the search will start after this
1589  * program, or from the beginning if it is NULL
1590  * @param s stream index
1591  * @return the next program which belongs to s, NULL if no program is found or
1592  * the last program is not among the programs of ic.
1593  */
1595 
1596 /**
1597  * Find the "best" stream in the file.
1598  * The best stream is determined according to various heuristics as the most
1599  * likely to be what the user expects.
1600  * If the decoder parameter is non-NULL, av_find_best_stream will find the
1601  * default decoder for the stream's codec; streams for which no decoder can
1602  * be found are ignored.
1603  *
1604  * @param ic media file handle
1605  * @param type stream type: video, audio, subtitles, etc.
1606  * @param wanted_stream_nb user-requested stream number,
1607  * or -1 for automatic selection
1608  * @param related_stream try to find a stream related (eg. in the same
1609  * program) to this one, or -1 if none
1610  * @param decoder_ret if non-NULL, returns the decoder for the
1611  * selected stream
1612  * @param flags flags; none are currently defined
1613  * @return the non-negative stream number in case of success,
1614  * AVERROR_STREAM_NOT_FOUND if no stream with the requested type
1615  * could be found,
1616  * AVERROR_DECODER_NOT_FOUND if streams were found but no decoder
1617  * @note If av_find_best_stream returns successfully and decoder_ret is not
1618  * NULL, then *decoder_ret is guaranteed to be set to a valid AVCodec.
1619  */
1621  enum AVMediaType type,
1622  int wanted_stream_nb,
1623  int related_stream,
1624  AVCodec **decoder_ret,
1625  int flags);
1626 
1627 #if FF_API_READ_PACKET
1628 /**
1629  * @deprecated use AVFMT_FLAG_NOFILLIN | AVFMT_FLAG_NOPARSE to read raw
1630  * unprocessed packets
1631  *
1632  * Read a transport packet from a media file.
1633  *
1634  * This function is obsolete and should never be used.
1635  * Use av_read_frame() instead.
1636  *
1637  * @param s media file handle
1638  * @param pkt is filled
1639  * @return 0 if OK, AVERROR_xxx on error
1640  */
1642 int av_read_packet(AVFormatContext *s, AVPacket *pkt);
1643 #endif
1644 
1645 /**
1646  * Return the next frame of a stream.
1647  * This function returns what is stored in the file, and does not validate
1648  * that what is there are valid frames for the decoder. It will split what is
1649  * stored in the file into frames and return one for each call. It will not
1650  * omit invalid data between valid frames so as to give the decoder the maximum
1651  * information possible for decoding.
1652  *
1653  * If pkt->buf is NULL, then the packet is valid until the next
1654  * av_read_frame() or until av_close_input_file(). Otherwise the packet is valid
1655  * indefinitely. In both cases the packet must be freed with
1656  * av_free_packet when it is no longer needed. For video, the packet contains
1657  * exactly one frame. For audio, it contains an integer number of frames if each
1658  * frame has a known fixed size (e.g. PCM or ADPCM data). If the audio frames
1659  * have a variable size (e.g. MPEG audio), then it contains one frame.
1660  *
1661  * pkt->pts, pkt->dts and pkt->duration are always set to correct
1662  * values in AVStream.time_base units (and guessed if the format cannot
1663  * provide them). pkt->pts can be AV_NOPTS_VALUE if the video format
1664  * has B-frames, so it is better to rely on pkt->dts if you do not
1665  * decompress the payload.
1666  *
1667  * @return 0 if OK, < 0 on error or end of file
1668  */
1670 
1671 /**
1672  * Seek to the keyframe at timestamp.
1673  * 'timestamp' in 'stream_index'.
1674  * @param stream_index If stream_index is (-1), a default
1675  * stream is selected, and timestamp is automatically converted
1676  * from AV_TIME_BASE units to the stream specific time_base.
1677  * @param timestamp Timestamp in AVStream.time_base units
1678  * or, if no stream is specified, in AV_TIME_BASE units.
1679  * @param flags flags which select direction and seeking mode
1680  * @return >= 0 on success
1681  */
1682 int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp,
1683  int flags);
1684 
1685 /**
1686  * Seek to timestamp ts.
1687  * Seeking will be done so that the point from which all active streams
1688  * can be presented successfully will be closest to ts and within min/max_ts.
1689  * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
1690  *
1691  * If flags contain AVSEEK_FLAG_BYTE, then all timestamps are in bytes and
1692  * are the file position (this may not be supported by all demuxers).
1693  * If flags contain AVSEEK_FLAG_FRAME, then all timestamps are in frames
1694  * in the stream with stream_index (this may not be supported by all demuxers).
1695  * Otherwise all timestamps are in units of the stream selected by stream_index
1696  * or if stream_index is -1, in AV_TIME_BASE units.
1697  * If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
1698  * keyframes (this may not be supported by all demuxers).
1699  * If flags contain AVSEEK_FLAG_BACKWARD, it is ignored.
1700  *
1701  * @param stream_index index of the stream which is used as time base reference
1702  * @param min_ts smallest acceptable timestamp
1703  * @param ts target timestamp
1704  * @param max_ts largest acceptable timestamp
1705  * @param flags flags
1706  * @return >=0 on success, error code otherwise
1707  *
1708  * @note This is part of the new seek API which is still under construction.
1709  * Thus do not use this yet. It may change at any time, do not expect
1710  * ABI compatibility yet!
1711  */
1712 int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
1713 
1714 /**
1715  * Start playing a network-based stream (e.g. RTSP stream) at the
1716  * current position.
1717  */
1719 
1720 /**
1721  * Pause a network-based stream (e.g. RTSP stream).
1722  *
1723  * Use av_read_play() to resume it.
1724  */
1726 
1727 #if FF_API_CLOSE_INPUT_FILE
1728 /**
1729  * @deprecated use avformat_close_input()
1730  * Close a media file (but not its codecs).
1731  *
1732  * @param s media file handle
1733  */
1735 void av_close_input_file(AVFormatContext *s);
1736 #endif
1737 
1738 /**
1739  * Close an opened input AVFormatContext. Free it and all its contents
1740  * and set *s to NULL.
1741  */
1743 /**
1744  * @}
1745  */
1746 
1747 #if FF_API_NEW_STREAM
1748 /**
1749  * Add a new stream to a media file.
1750  *
1751  * Can only be called in the read_header() function. If the flag
1752  * AVFMTCTX_NOHEADER is in the format context, then new streams
1753  * can be added in read_packet too.
1754  *
1755  * @param s media file handle
1756  * @param id file-format-dependent stream ID
1757  */
1759 AVStream *av_new_stream(AVFormatContext *s, int id);
1760 #endif
1761 
1762 #if FF_API_SET_PTS_INFO
1763 /**
1764  * @deprecated this function is not supposed to be called outside of lavf
1765  */
1767 void av_set_pts_info(AVStream *s, int pts_wrap_bits,
1768  unsigned int pts_num, unsigned int pts_den);
1769 #endif
1770 
1771 #define AVSEEK_FLAG_BACKWARD 1 ///< seek backward
1772 #define AVSEEK_FLAG_BYTE 2 ///< seeking based on position in bytes
1773 #define AVSEEK_FLAG_ANY 4 ///< seek to any frame, even non-keyframes
1774 #define AVSEEK_FLAG_FRAME 8 ///< seeking based on frame number
1775 
1776 /**
1777  * @addtogroup lavf_encoding
1778  * @{
1779  */
1780 /**
1781  * Allocate the stream private data and write the stream header to
1782  * an output media file.
1783  *
1784  * @param s Media file handle, must be allocated with avformat_alloc_context().
1785  * Its oformat field must be set to the desired output format;
1786  * Its pb field must be set to an already opened AVIOContext.
1787  * @param options An AVDictionary filled with AVFormatContext and muxer-private options.
1788  * On return this parameter will be destroyed and replaced with a dict containing
1789  * options that were not found. May be NULL.
1790  *
1791  * @return 0 on success, negative AVERROR on failure.
1792  *
1793  * @see av_opt_find, av_dict_set, avio_open, av_oformat_next.
1794  */
1796 
1797 /**
1798  * Write a packet to an output media file.
1799  *
1800  * The packet shall contain one audio or video frame.
1801  * The packet must be correctly interleaved according to the container
1802  * specification, if not then av_interleaved_write_frame must be used.
1803  *
1804  * @param s media file handle
1805  * @param pkt The packet, which contains the stream_index, buf/buf_size,
1806  * dts/pts, ...
1807  * This can be NULL (at any time, not just at the end), in
1808  * order to immediately flush data buffered within the muxer,
1809  * for muxers that buffer up data internally before writing it
1810  * to the output.
1811  * @return < 0 on error, = 0 if OK, 1 if flushed and there is no more data to flush
1812  */
1814 
1815 /**
1816  * Write a packet to an output media file ensuring correct interleaving.
1817  *
1818  * The packet must contain one audio or video frame.
1819  * If the packets are already correctly interleaved, the application should
1820  * call av_write_frame() instead as it is slightly faster. It is also important
1821  * to keep in mind that completely non-interleaved input will need huge amounts
1822  * of memory to interleave with this, so it is preferable to interleave at the
1823  * demuxer level.
1824  *
1825  * @param s media file handle
1826  * @param pkt The packet containing the data to be written. pkt->buf must be set
1827  * to a valid AVBufferRef describing the packet data. Libavformat takes
1828  * ownership of this reference and will unref it when it sees fit. The caller
1829  * must not access the data through this reference after this function returns.
1830  * This can be NULL (at any time, not just at the end), to flush the
1831  * interleaving queues.
1832  * Packet's @ref AVPacket.stream_index "stream_index" field must be set to the
1833  * index of the corresponding stream in @ref AVFormatContext.streams
1834  * "s.streams".
1835  * It is very strongly recommended that timing information (@ref AVPacket.pts
1836  * "pts", @ref AVPacket.dts "dts" @ref AVPacket.duration "duration") is set to
1837  * correct values.
1838  *
1839  * @return 0 on success, a negative AVERROR on error.
1840  */
1842 
1843 /**
1844  * Write the stream trailer to an output media file and free the
1845  * file private data.
1846  *
1847  * May only be called after a successful call to avformat_write_header.
1848  *
1849  * @param s media file handle
1850  * @return 0 if OK, AVERROR_xxx on error
1851  */
1853 
1854 /**
1855  * Return the output format in the list of registered output formats
1856  * which best matches the provided parameters, or return NULL if
1857  * there is no match.
1858  *
1859  * @param short_name if non-NULL checks if short_name matches with the
1860  * names of the registered formats
1861  * @param filename if non-NULL checks if filename terminates with the
1862  * extensions of the registered formats
1863  * @param mime_type if non-NULL checks if mime_type matches with the
1864  * MIME type of the registered formats
1865  */
1866 AVOutputFormat *av_guess_format(const char *short_name,
1867  const char *filename,
1868  const char *mime_type);
1869 
1870 /**
1871  * Guess the codec ID based upon muxer and filename.
1872  */
1873 enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
1874  const char *filename, const char *mime_type,
1875  enum AVMediaType type);
1876 
1877 /**
1878  * Get timing information for the data currently output.
1879  * The exact meaning of "currently output" depends on the format.
1880  * It is mostly relevant for devices that have an internal buffer and/or
1881  * work in real time.
1882  * @param s media file handle
1883  * @param stream stream in the media file
1884  * @param[out] dts DTS of the last packet output for the stream, in stream
1885  * time_base units
1886  * @param[out] wall absolute time when that packet whas output,
1887  * in microsecond
1888  * @return 0 if OK, AVERROR(ENOSYS) if the format does not support it
1889  * Note: some formats or devices may not allow to measure dts and wall
1890  * atomically.
1891  */
1892 int av_get_output_timestamp(struct AVFormatContext *s, int stream,
1893  int64_t *dts, int64_t *wall);
1894 
1895 
1896 /**
1897  * @}
1898  */
1899 
1900 
1901 /**
1902  * @defgroup lavf_misc Utility functions
1903  * @ingroup libavf
1904  * @{
1905  *
1906  * Miscellaneous utility functions related to both muxing and demuxing
1907  * (or neither).
1908  */
1909 
1910 /**
1911  * Send a nice hexadecimal dump of a buffer to the specified file stream.
1912  *
1913  * @param f The file stream pointer where the dump should be sent to.
1914  * @param buf buffer
1915  * @param size buffer size
1916  *
1917  * @see av_hex_dump_log, av_pkt_dump2, av_pkt_dump_log2
1918  */
1919 void av_hex_dump(FILE *f, const uint8_t *buf, int size);
1920 
1921 /**
1922  * Send a nice hexadecimal dump of a buffer to the log.
1923  *
1924  * @param avcl A pointer to an arbitrary struct of which the first field is a
1925  * pointer to an AVClass struct.
1926  * @param level The importance level of the message, lower values signifying
1927  * higher importance.
1928  * @param buf buffer
1929  * @param size buffer size
1930  *
1931  * @see av_hex_dump, av_pkt_dump2, av_pkt_dump_log2
1932  */
1933 void av_hex_dump_log(void *avcl, int level, const uint8_t *buf, int size);
1934 
1935 /**
1936  * Send a nice dump of a packet to the specified file stream.
1937  *
1938  * @param f The file stream pointer where the dump should be sent to.
1939  * @param pkt packet to dump
1940  * @param dump_payload True if the payload must be displayed, too.
1941  * @param st AVStream that the packet belongs to
1942  */
1943 void av_pkt_dump2(FILE *f, AVPacket *pkt, int dump_payload, AVStream *st);
1944 
1945 
1946 /**
1947  * Send a nice dump of a packet to the log.
1948  *
1949  * @param avcl A pointer to an arbitrary struct of which the first field is a
1950  * pointer to an AVClass struct.
1951  * @param level The importance level of the message, lower values signifying
1952  * higher importance.
1953  * @param pkt packet to dump
1954  * @param dump_payload True if the payload must be displayed, too.
1955  * @param st AVStream that the packet belongs to
1956  */
1957 void av_pkt_dump_log2(void *avcl, int level, AVPacket *pkt, int dump_payload,
1958  AVStream *st);
1959 
1960 /**
1961  * Get the AVCodecID for the given codec tag tag.
1962  * If no codec id is found returns AV_CODEC_ID_NONE.
1963  *
1964  * @param tags list of supported codec_id-codec_tag pairs, as stored
1965  * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
1966  */
1967 enum AVCodecID av_codec_get_id(const struct AVCodecTag * const *tags, unsigned int tag);
1968 
1969 /**
1970  * Get the codec tag for the given codec id id.
1971  * If no codec tag is found returns 0.
1972  *
1973  * @param tags list of supported codec_id-codec_tag pairs, as stored
1974  * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
1975  */
1976 unsigned int av_codec_get_tag(const struct AVCodecTag * const *tags, enum AVCodecID id);
1977 
1978 /**
1979  * Get the codec tag for the given codec id.
1980  *
1981  * @param tags list of supported codec_id - codec_tag pairs, as stored
1982  * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
1983  * @param id codec id that should be searched for in the list
1984  * @param tag A pointer to the found tag
1985  * @return 0 if id was not found in tags, > 0 if it was found
1986  */
1987 int av_codec_get_tag2(const struct AVCodecTag * const *tags, enum AVCodecID id,
1988  unsigned int *tag);
1989 
1991 
1992 /**
1993  * Get the index for a specific timestamp.
1994  * @param flags if AVSEEK_FLAG_BACKWARD then the returned index will correspond
1995  * to the timestamp which is <= the requested one, if backward
1996  * is 0, then it will be >=
1997  * if AVSEEK_FLAG_ANY seek to any frame, only keyframes otherwise
1998  * @return < 0 if no such timestamp could be found
1999  */
2000 int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags);
2001 
2002 /**
2003  * Add an index entry into a sorted list. Update the entry if the list
2004  * already contains it.
2005  *
2006  * @param timestamp timestamp in the time base of the given stream
2007  */
2008 int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
2009  int size, int distance, int flags);
2010 
2011 
2012 /**
2013  * Split a URL string into components.
2014  *
2015  * The pointers to buffers for storing individual components may be null,
2016  * in order to ignore that component. Buffers for components not found are
2017  * set to empty strings. If the port is not found, it is set to a negative
2018  * value.
2019  *
2020  * @param proto the buffer for the protocol
2021  * @param proto_size the size of the proto buffer
2022  * @param authorization the buffer for the authorization
2023  * @param authorization_size the size of the authorization buffer
2024  * @param hostname the buffer for the host name
2025  * @param hostname_size the size of the hostname buffer
2026  * @param port_ptr a pointer to store the port number in
2027  * @param path the buffer for the path
2028  * @param path_size the size of the path buffer
2029  * @param url the URL to split
2030  */
2031 void av_url_split(char *proto, int proto_size,
2032  char *authorization, int authorization_size,
2033  char *hostname, int hostname_size,
2034  int *port_ptr,
2035  char *path, int path_size,
2036  const char *url);
2037 
2038 
2040  int index,
2041  const char *url,
2042  int is_output);
2043 
2044 /**
2045  * Return in 'buf' the path with '%d' replaced by a number.
2046  *
2047  * Also handles the '%0nd' format where 'n' is the total number
2048  * of digits and '%%'.
2049  *
2050  * @param buf destination buffer
2051  * @param buf_size destination buffer size
2052  * @param path numbered sequence string
2053  * @param number frame number
2054  * @return 0 if OK, -1 on format error
2055  */
2056 int av_get_frame_filename(char *buf, int buf_size,
2057  const char *path, int number);
2058 
2059 /**
2060  * Check whether filename actually is a numbered sequence generator.
2061  *
2062  * @param filename possible numbered sequence string
2063  * @return 1 if a valid numbered sequence string, 0 otherwise
2064  */
2065 int av_filename_number_test(const char *filename);
2066 
2067 /**
2068  * Generate an SDP for an RTP session.
2069  *
2070  * Note, this overwrites the id values of AVStreams in the muxer contexts
2071  * for getting unique dynamic payload types.
2072  *
2073  * @param ac array of AVFormatContexts describing the RTP streams. If the
2074  * array is composed by only one context, such context can contain
2075  * multiple AVStreams (one AVStream per RTP stream). Otherwise,
2076  * all the contexts in the array (an AVCodecContext per RTP stream)
2077  * must contain only one AVStream.
2078  * @param n_files number of AVCodecContexts contained in ac
2079  * @param buf buffer where the SDP will be stored (must be allocated by
2080  * the caller)
2081  * @param size the size of the buffer
2082  * @return 0 if OK, AVERROR_xxx on error
2083  */
2084 int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size);
2085 
2086 /**
2087  * Return a positive value if the given filename has one of the given
2088  * extensions, 0 otherwise.
2089  *
2090  * @param extensions a comma-separated list of filename extensions
2091  */
2092 int av_match_ext(const char *filename, const char *extensions);
2093 
2094 /**
2095  * Test if the given container can store a codec.
2096  *
2097  * @param std_compliance standards compliance level, one of FF_COMPLIANCE_*
2098  *
2099  * @return 1 if codec with ID codec_id can be stored in ofmt, 0 if it cannot.
2100  * A negative number if this information is not available.
2101  */
2102 int avformat_query_codec(AVOutputFormat *ofmt, enum AVCodecID codec_id, int std_compliance);
2103 
2104 /**
2105  * @defgroup riff_fourcc RIFF FourCCs
2106  * @{
2107  * Get the tables mapping RIFF FourCCs to libavcodec AVCodecIDs. The tables are
2108  * meant to be passed to av_codec_get_id()/av_codec_get_tag() as in the
2109  * following code:
2110  * @code
2111  * uint32_t tag = MKTAG('H', '2', '6', '4');
2112  * const struct AVCodecTag *table[] = { avformat_get_riff_video_tags(), 0 };
2113  * enum AVCodecID id = av_codec_get_id(table, tag);
2114  * @endcode
2115  */
2116 /**
2117  * @return the table mapping RIFF FourCCs for video to libavcodec AVCodecID.
2118  */
2119 const struct AVCodecTag *avformat_get_riff_video_tags(void);
2120 /**
2121  * @return the table mapping RIFF FourCCs for audio to AVCodecID.
2122  */
2123 const struct AVCodecTag *avformat_get_riff_audio_tags(void);
2124 
2125 /**
2126  * @}
2127  */
2128 
2129 /**
2130  * Guess the sample aspect ratio of a frame, based on both the stream and the
2131  * frame aspect ratio.
2132  *
2133  * Since the frame aspect ratio is set by the codec but the stream aspect ratio
2134  * is set by the demuxer, these two may not be equal. This function tries to
2135  * return the value that you should use if you would like to display the frame.
2136  *
2137  * Basic logic is to use the stream aspect ratio if it is set to something sane
2138  * otherwise use the frame aspect ratio. This way a container setting, which is
2139  * usually easy to modify can override the coded value in the frames.
2140  *
2141  * @param format the format context which the stream is part of
2142  * @param stream the stream which the frame is part of
2143  * @param frame the frame with the aspect ratio to be determined
2144  * @return the guessed (valid) sample_aspect_ratio, 0/1 if no idea
2145  */
2147 
2148 /**
2149  * Guess the frame rate, based on both the container and codec information.
2150  *
2151  * @param ctx the format context which the stream is part of
2152  * @param stream the stream which the frame is part of
2153  * @param frame the frame for which the frame rate should be determined, may be NULL
2154  * @return the guessed (valid) frame rate, 0/1 if no idea
2155  */
2157 
2158 /**
2159  * Check if the stream st contained in s is matched by the stream specifier
2160  * spec.
2161  *
2162  * See the "stream specifiers" chapter in the documentation for the syntax
2163  * of spec.
2164  *
2165  * @return >0 if st is matched by spec;
2166  * 0 if st is not matched by spec;
2167  * AVERROR code if spec is invalid
2168  *
2169  * @note A stream specifier can match several streams in the format.
2170  */
2172  const char *spec);
2173 
2175 
2176 
2177 /**
2178  * @}
2179  */
2180 
2181 #endif /* AVFORMAT_AVFORMAT_H */