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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  * Muxers take encoded data in the form of @ref AVPacket "AVPackets" and write
177  * it into files or other output bytestreams in the specified container format.
178  *
179  * The main API functions for muxing are avformat_write_header() for writing the
180  * file header, av_write_frame() / av_interleaved_write_frame() for writing the
181  * packets and av_write_trailer() for finalizing the file.
182  *
183  * At the beginning of the muxing process, the caller must first call
184  * avformat_alloc_context() to create a muxing context. The caller then sets up
185  * the muxer by filling the various fields in this context:
186  *
187  * - The @ref AVFormatContext.oformat "oformat" field must be set to select the
188  * muxer that will be used.
189  * - Unless the format is of the AVFMT_NOFILE type, the @ref AVFormatContext.pb
190  * "pb" field must be set to an opened IO context, either returned from
191  * avio_open2() or a custom one.
192  * - Unless the format is of the AVFMT_NOSTREAMS type, at least one stream must
193  * be created with the avformat_new_stream() function. The caller should fill
194  * the @ref AVStream.codec "stream codec context" information, such as the
195  * codec @ref AVCodecContext.codec_type "type", @ref AVCodecContext.codec_id
196  * "id" and other parameters (e.g. width / height, the pixel or sample format,
197  * etc.) as known. The @ref AVStream.time_base "stream timebase" should
198  * be set to the timebase that the caller desires to use for this stream (note
199  * that the timebase actually used by the muxer can be different, as will be
200  * described later).
201  * - The caller may fill in additional information, such as @ref
202  * AVFormatContext.metadata "global" or @ref AVStream.metadata "per-stream"
203  * metadata, @ref AVFormatContext.chapters "chapters", @ref
204  * AVFormatContext.programs "programs", etc. as described in the
205  * AVFormatContext documentation. Whether such information will actually be
206  * stored in the output depends on what the container format and the muxer
207  * support.
208  *
209  * When the muxing context is fully set up, the caller must call
210  * avformat_write_header() to initialize the muxer internals and write the file
211  * header. Whether anything actually is written to the IO context at this step
212  * depends on the muxer, but this function must always be called. Any muxer
213  * private options must be passed in the options parameter to this function.
214  *
215  * The data is then sent to the muxer by repeatedly calling av_write_frame() or
216  * av_interleaved_write_frame() (consult those functions' documentation for
217  * discussion on the difference between them; only one of them may be used with
218  * a single muxing context, they should not be mixed). Do note that the timing
219  * information on the packets sent to the muxer must be in the corresponding
220  * AVStream's timebase. That timebase is set by the muxer (in the
221  * avformat_write_header() step) and may be different from the timebase
222  * requested by the caller.
223  *
224  * Once all the data has been written, the caller must call av_write_trailer()
225  * to flush any buffered packets and finalize the output file, then close the IO
226  * context (if any) and finally free the muxing context with
227  * avformat_free_context().
228  * @}
229  *
230  * @defgroup lavf_io I/O Read/Write
231  * @{
232  * @}
233  *
234  * @defgroup lavf_codec Demuxers
235  * @{
236  * @defgroup lavf_codec_native Native Demuxers
237  * @{
238  * @}
239  * @defgroup lavf_codec_wrappers External library wrappers
240  * @{
241  * @}
242  * @}
243  * @defgroup lavf_protos I/O Protocols
244  * @{
245  * @}
246  * @defgroup lavf_internal Internal
247  * @{
248  * @}
249  * @}
250  *
251  */
252 
253 #include <time.h>
254 #include <stdio.h> /* FILE */
255 #include "libavcodec/avcodec.h"
256 #include "libavutil/dict.h"
257 #include "libavutil/log.h"
258 
259 #include "avio.h"
260 #include "libavformat/version.h"
261 
262 struct AVFormatContext;
263 
264 struct AVDeviceInfoList;
266 
267 /**
268  * @defgroup metadata_api Public Metadata API
269  * @{
270  * @ingroup libavf
271  * The metadata API allows libavformat to export metadata tags to a client
272  * application when demuxing. Conversely it allows a client application to
273  * set metadata when muxing.
274  *
275  * Metadata is exported or set as pairs of key/value strings in the 'metadata'
276  * fields of the AVFormatContext, AVStream, AVChapter and AVProgram structs
277  * using the @ref lavu_dict "AVDictionary" API. Like all strings in FFmpeg,
278  * metadata is assumed to be UTF-8 encoded Unicode. Note that metadata
279  * exported by demuxers isn't checked to be valid UTF-8 in most cases.
280  *
281  * Important concepts to keep in mind:
282  * - Keys are unique; there can never be 2 tags with the same key. This is
283  * also meant semantically, i.e., a demuxer should not knowingly produce
284  * several keys that are literally different but semantically identical.
285  * E.g., key=Author5, key=Author6. In this example, all authors must be
286  * placed in the same tag.
287  * - Metadata is flat, not hierarchical; there are no subtags. If you
288  * want to store, e.g., the email address of the child of producer Alice
289  * and actor Bob, that could have key=alice_and_bobs_childs_email_address.
290  * - Several modifiers can be applied to the tag name. This is done by
291  * appending a dash character ('-') and the modifier name in the order
292  * they appear in the list below -- e.g. foo-eng-sort, not foo-sort-eng.
293  * - language -- a tag whose value is localized for a particular language
294  * is appended with the ISO 639-2/B 3-letter language code.
295  * For example: Author-ger=Michael, Author-eng=Mike
296  * The original/default language is in the unqualified "Author" tag.
297  * A demuxer should set a default if it sets any translated tag.
298  * - sorting -- a modified version of a tag that should be used for
299  * sorting will have '-sort' appended. E.g. artist="The Beatles",
300  * artist-sort="Beatles, The".
301  * - Some protocols and demuxers support metadata updates. After a successful
302  * call to av_read_packet(), AVFormatContext.event_flags or AVStream.event_flags
303  * will be updated to indicate if metadata changed. In order to detect metadata
304  * changes on a stream, you need to loop through all streams in the AVFormatContext
305  * and check their individual event_flags.
306  *
307  * - Demuxers attempt to export metadata in a generic format, however tags
308  * with no generic equivalents are left as they are stored in the container.
309  * Follows a list of generic tag names:
310  *
311  @verbatim
312  album -- name of the set this work belongs to
313  album_artist -- main creator of the set/album, if different from artist.
314  e.g. "Various Artists" for compilation albums.
315  artist -- main creator of the work
316  comment -- any additional description of the file.
317  composer -- who composed the work, if different from artist.
318  copyright -- name of copyright holder.
319  creation_time-- date when the file was created, preferably in ISO 8601.
320  date -- date when the work was created, preferably in ISO 8601.
321  disc -- number of a subset, e.g. disc in a multi-disc collection.
322  encoder -- name/settings of the software/hardware that produced the file.
323  encoded_by -- person/group who created the file.
324  filename -- original name of the file.
325  genre -- <self-evident>.
326  language -- main language in which the work is performed, preferably
327  in ISO 639-2 format. Multiple languages can be specified by
328  separating them with commas.
329  performer -- artist who performed the work, if different from artist.
330  E.g for "Also sprach Zarathustra", artist would be "Richard
331  Strauss" and performer "London Philharmonic Orchestra".
332  publisher -- name of the label/publisher.
333  service_name -- name of the service in broadcasting (channel name).
334  service_provider -- name of the service provider in broadcasting.
335  title -- name of the work.
336  track -- number of this work in the set, can be in form current/total.
337  variant_bitrate -- the total bitrate of the bitrate variant that the current stream is part of
338  @endverbatim
339  *
340  * Look in the examples section for an application example how to use the Metadata API.
341  *
342  * @}
343  */
344 
345 /* packet functions */
346 
347 
348 /**
349  * Allocate and read the payload of a packet and initialize its
350  * fields with default values.
351  *
352  * @param s associated IO context
353  * @param pkt packet
354  * @param size desired payload size
355  * @return >0 (read size) if OK, AVERROR_xxx otherwise
356  */
358 
359 
360 /**
361  * Read data and append it to the current content of the AVPacket.
362  * If pkt->size is 0 this is identical to av_get_packet.
363  * Note that this uses av_grow_packet and thus involves a realloc
364  * which is inefficient. Thus this function should only be used
365  * when there is no reasonable way to know (an upper bound of)
366  * the final size.
367  *
368  * @param s associated IO context
369  * @param pkt packet
370  * @param size amount of data to read
371  * @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data
372  * will not be lost even if an error occurs.
373  */
375 
376 #if FF_API_LAVF_FRAC
377 /*************************************************/
378 /* fractional numbers for exact pts handling */
379 
380 /**
381  * The exact value of the fractional number is: 'val + num / den'.
382  * num is assumed to be 0 <= num < den.
383  */
384 typedef struct AVFrac {
385  int64_t val, num, den;
386 } AVFrac;
387 #endif
388 
389 /*************************************************/
390 /* input/output formats */
391 
392 struct AVCodecTag;
393 
394 /**
395  * This structure contains the data a format has to probe a file.
396  */
397 typedef struct AVProbeData {
398  const char *filename;
399  unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
400  int buf_size; /**< Size of buf except extra allocated bytes */
401  const char *mime_type; /**< mime_type, when known. */
402 } AVProbeData;
403 
404 #define AVPROBE_SCORE_RETRY (AVPROBE_SCORE_MAX/4)
405 #define AVPROBE_SCORE_STREAM_RETRY (AVPROBE_SCORE_MAX/4-1)
406 
407 #define AVPROBE_SCORE_EXTENSION 50 ///< score for file extension
408 #define AVPROBE_SCORE_MIME 75 ///< score for file mime type
409 #define AVPROBE_SCORE_MAX 100 ///< maximum score
410 
411 #define AVPROBE_PADDING_SIZE 32 ///< extra allocated bytes at the end of the probe buffer
412 
413 /// Demuxer will use avio_open, no opened file should be provided by the caller.
414 #define AVFMT_NOFILE 0x0001
415 #define AVFMT_NEEDNUMBER 0x0002 /**< Needs '%d' in filename. */
416 #define AVFMT_SHOW_IDS 0x0008 /**< Show format stream IDs numbers. */
417 #define AVFMT_RAWPICTURE 0x0020 /**< Format wants AVPicture structure for
418  raw picture data. */
419 #define AVFMT_GLOBALHEADER 0x0040 /**< Format wants global header. */
420 #define AVFMT_NOTIMESTAMPS 0x0080 /**< Format does not need / have any timestamps. */
421 #define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */
422 #define AVFMT_TS_DISCONT 0x0200 /**< Format allows timestamp discontinuities. Note, muxers always require valid (monotone) timestamps */
423 #define AVFMT_VARIABLE_FPS 0x0400 /**< Format allows variable fps. */
424 #define AVFMT_NODIMENSIONS 0x0800 /**< Format does not need width/height */
425 #define AVFMT_NOSTREAMS 0x1000 /**< Format does not require any streams */
426 #define AVFMT_NOBINSEARCH 0x2000 /**< Format does not allow to fall back on binary search via read_timestamp */
427 #define AVFMT_NOGENSEARCH 0x4000 /**< Format does not allow to fall back on generic search */
428 #define AVFMT_NO_BYTE_SEEK 0x8000 /**< Format does not allow seeking by bytes */
429 #define AVFMT_ALLOW_FLUSH 0x10000 /**< Format allows flushing. If not set, the muxer will not receive a NULL packet in the write_packet function. */
430 #if LIBAVFORMAT_VERSION_MAJOR <= 54
431 #define AVFMT_TS_NONSTRICT 0x8020000 //we try to be compatible to the ABIs of ffmpeg and major forks
432 #else
433 #define AVFMT_TS_NONSTRICT 0x20000
434 #endif
435  /**< Format does not require strictly
436  increasing timestamps, but they must
437  still be monotonic */
438 #define AVFMT_TS_NEGATIVE 0x40000 /**< Format allows muxing negative
439  timestamps. If not set the timestamp
440  will be shifted in av_write_frame and
441  av_interleaved_write_frame so they
442  start from 0.
443  The user or muxer can override this through
444  AVFormatContext.avoid_negative_ts
445  */
446 
447 #define AVFMT_SEEK_TO_PTS 0x4000000 /**< Seeking is based on PTS */
448 
449 /**
450  * @addtogroup lavf_encoding
451  * @{
452  */
453 typedef struct AVOutputFormat {
454  const char *name;
455  /**
456  * Descriptive name for the format, meant to be more human-readable
457  * than name. You should use the NULL_IF_CONFIG_SMALL() macro
458  * to define it.
459  */
460  const char *long_name;
461  const char *mime_type;
462  const char *extensions; /**< comma-separated filename extensions */
463  /* output support */
464  enum AVCodecID audio_codec; /**< default audio codec */
465  enum AVCodecID video_codec; /**< default video codec */
466  enum AVCodecID subtitle_codec; /**< default subtitle codec */
467  /**
468  * can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_RAWPICTURE,
469  * AVFMT_GLOBALHEADER, AVFMT_NOTIMESTAMPS, AVFMT_VARIABLE_FPS,
470  * AVFMT_NODIMENSIONS, AVFMT_NOSTREAMS, AVFMT_ALLOW_FLUSH,
471  * AVFMT_TS_NONSTRICT
472  */
473  int flags;
474 
475  /**
476  * List of supported codec_id-codec_tag pairs, ordered by "better
477  * choice first". The arrays are all terminated by AV_CODEC_ID_NONE.
478  */
479  const struct AVCodecTag * const *codec_tag;
480 
481 
482  const AVClass *priv_class; ///< AVClass for the private context
483 
484  /*****************************************************************
485  * No fields below this line are part of the public API. They
486  * may not be used outside of libavformat and can be changed and
487  * removed at will.
488  * New public fields should be added right above.
489  *****************************************************************
490  */
492  /**
493  * size of private data so that it can be allocated in the wrapper
494  */
496 
497  int (*write_header)(struct AVFormatContext *);
498  /**
499  * Write a packet. If AVFMT_ALLOW_FLUSH is set in flags,
500  * pkt can be NULL in order to flush data buffered in the muxer.
501  * When flushing, return 0 if there still is more data to flush,
502  * or 1 if everything was flushed and there is no more buffered
503  * data.
504  */
506  int (*write_trailer)(struct AVFormatContext *);
507  /**
508  * Currently only used to set pixel format if not YUV420P.
509  */
511  AVPacket *in, int flush);
512  /**
513  * Test if the given codec can be stored in this container.
514  *
515  * @return 1 if the codec is supported, 0 if it is not.
516  * A negative number if unknown.
517  * MKTAG('A', 'P', 'I', 'C') if the codec is only supported as AV_DISPOSITION_ATTACHED_PIC
518  */
519  int (*query_codec)(enum AVCodecID id, int std_compliance);
520 
521  void (*get_output_timestamp)(struct AVFormatContext *s, int stream,
522  int64_t *dts, int64_t *wall);
523  /**
524  * Allows sending messages from application to device.
525  */
526  int (*control_message)(struct AVFormatContext *s, int type,
527  void *data, size_t data_size);
528 
529  /**
530  * Write an uncoded AVFrame.
531  *
532  * See av_write_uncoded_frame() for details.
533  *
534  * The library will free *frame afterwards, but the muxer can prevent it
535  * by setting the pointer to NULL.
536  */
537  int (*write_uncoded_frame)(struct AVFormatContext *, int stream_index,
538  AVFrame **frame, unsigned flags);
539  /**
540  * Returns device list with it properties.
541  * @see avdevice_list_devices() for more details.
542  */
543  int (*get_device_list)(struct AVFormatContext *s, struct AVDeviceInfoList *device_list);
544  /**
545  * Initialize device capabilities submodule.
546  * @see avdevice_capabilities_create() for more details.
547  */
549  /**
550  * Free device capabilities submodule.
551  * @see avdevice_capabilities_free() for more details.
552  */
555 /**
556  * @}
557  */
558 
559 /**
560  * @addtogroup lavf_decoding
561  * @{
562  */
563 typedef struct AVInputFormat {
564  /**
565  * A comma separated list of short names for the format. New names
566  * may be appended with a minor bump.
567  */
568  const char *name;
569 
570  /**
571  * Descriptive name for the format, meant to be more human-readable
572  * than name. You should use the NULL_IF_CONFIG_SMALL() macro
573  * to define it.
574  */
575  const char *long_name;
576 
577  /**
578  * Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS,
579  * AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH,
580  * AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK, AVFMT_SEEK_TO_PTS.
581  */
582  int flags;
583 
584  /**
585  * If extensions are defined, then no probe is done. You should
586  * usually not use extension format guessing because it is not
587  * reliable enough
588  */
589  const char *extensions;
590 
591  const struct AVCodecTag * const *codec_tag;
592 
593  const AVClass *priv_class; ///< AVClass for the private context
594 
595  /**
596  * Comma-separated list of mime types.
597  * It is used check for matching mime types while probing.
598  * @see av_probe_input_format2
599  */
600  const char *mime_type;
601 
602  /*****************************************************************
603  * No fields below this line are part of the public API. They
604  * may not be used outside of libavformat and can be changed and
605  * removed at will.
606  * New public fields should be added right above.
607  *****************************************************************
608  */
610 
611  /**
612  * Raw demuxers store their codec ID here.
613  */
615 
616  /**
617  * Size of private data so that it can be allocated in the wrapper.
618  */
620 
621  /**
622  * Tell if a given file has a chance of being parsed as this format.
623  * The buffer provided is guaranteed to be AVPROBE_PADDING_SIZE bytes
624  * big so you do not have to check for that unless you need more.
625  */
627 
628  /**
629  * Read the format header and initialize the AVFormatContext
630  * structure. Return 0 if OK. Only used in raw format right
631  * now. 'avformat_new_stream' should be called to create new streams.
632  */
633  int (*read_header)(struct AVFormatContext *);
634 
635  /**
636  * Read one packet and put it in 'pkt'. pts and flags are also
637  * set. 'avformat_new_stream' can be called only if the flag
638  * AVFMTCTX_NOHEADER is used and only in the calling thread (not in a
639  * background thread).
640  * @return 0 on success, < 0 on error.
641  * When returning an error, pkt must not have been allocated
642  * or must be freed before returning
643  */
645 
646  /**
647  * Close the stream. The AVFormatContext and AVStreams are not
648  * freed by this function
649  */
650  int (*read_close)(struct AVFormatContext *);
651 
652  /**
653  * Seek to a given timestamp relative to the frames in
654  * stream component stream_index.
655  * @param stream_index Must not be -1.
656  * @param flags Selects which direction should be preferred if no exact
657  * match is available.
658  * @return >= 0 on success (but not necessarily the new offset)
659  */
660  int (*read_seek)(struct AVFormatContext *,
661  int stream_index, int64_t timestamp, int flags);
662 
663  /**
664  * Get the next timestamp in stream[stream_index].time_base units.
665  * @return the timestamp or AV_NOPTS_VALUE if an error occurred
666  */
667  int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,
668  int64_t *pos, int64_t pos_limit);
669 
670  /**
671  * Start/resume playing - only meaningful if using a network-based format
672  * (RTSP).
673  */
674  int (*read_play)(struct AVFormatContext *);
675 
676  /**
677  * Pause playing - only meaningful if using a network-based format
678  * (RTSP).
679  */
680  int (*read_pause)(struct AVFormatContext *);
681 
682  /**
683  * Seek to timestamp ts.
684  * Seeking will be done so that the point from which all active streams
685  * can be presented successfully will be closest to ts and within min/max_ts.
686  * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
687  */
688  int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
689 
690  /**
691  * Returns device list with it properties.
692  * @see avdevice_list_devices() for more details.
693  */
694  int (*get_device_list)(struct AVFormatContext *s, struct AVDeviceInfoList *device_list);
695 
696  /**
697  * Initialize device capabilities submodule.
698  * @see avdevice_capabilities_create() for more details.
699  */
701 
702  /**
703  * Free device capabilities submodule.
704  * @see avdevice_capabilities_free() for more details.
705  */
707 } AVInputFormat;
708 /**
709  * @}
710  */
711 
714  AVSTREAM_PARSE_FULL, /**< full parsing and repack */
715  AVSTREAM_PARSE_HEADERS, /**< Only parse headers, do not repack. */
716  AVSTREAM_PARSE_TIMESTAMPS, /**< full parsing and interpolation of timestamps for frames not starting on a packet boundary */
717  AVSTREAM_PARSE_FULL_ONCE, /**< full parsing and repack of the first frame only, only implemented for H.264 currently */
718  AVSTREAM_PARSE_FULL_RAW=MKTAG(0,'R','A','W'), /**< full parsing and repack with timestamp and position generation by parser for raw
719  this assumes that each packet in the file contains no demuxer level headers and
720  just codec level data, otherwise position generation would fail */
721 };
722 
723 typedef struct AVIndexEntry {
724  int64_t pos;
725  int64_t timestamp; /**<
726  * Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are available
727  * when seeking to this entry. That means preferable PTS on keyframe based formats.
728  * But demuxers can choose to store a different timestamp, if it is more convenient for the implementation or nothing better
729  * is known
730  */
731 #define AVINDEX_KEYFRAME 0x0001
732  int flags:2;
733  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).
734  int min_distance; /**< Minimum distance between this and the previous keyframe, used to avoid unneeded searching. */
735 } AVIndexEntry;
736 
737 #define AV_DISPOSITION_DEFAULT 0x0001
738 #define AV_DISPOSITION_DUB 0x0002
739 #define AV_DISPOSITION_ORIGINAL 0x0004
740 #define AV_DISPOSITION_COMMENT 0x0008
741 #define AV_DISPOSITION_LYRICS 0x0010
742 #define AV_DISPOSITION_KARAOKE 0x0020
743 
744 /**
745  * Track should be used during playback by default.
746  * Useful for subtitle track that should be displayed
747  * even when user did not explicitly ask for subtitles.
748  */
749 #define AV_DISPOSITION_FORCED 0x0040
750 #define AV_DISPOSITION_HEARING_IMPAIRED 0x0080 /**< stream for hearing impaired audiences */
751 #define AV_DISPOSITION_VISUAL_IMPAIRED 0x0100 /**< stream for visual impaired audiences */
752 #define AV_DISPOSITION_CLEAN_EFFECTS 0x0200 /**< stream without voice */
753 /**
754  * The stream is stored in the file as an attached picture/"cover art" (e.g.
755  * APIC frame in ID3v2). The single packet associated with it will be returned
756  * among the first few packets read from the file unless seeking takes place.
757  * It can also be accessed at any time in AVStream.attached_pic.
758  */
759 #define AV_DISPOSITION_ATTACHED_PIC 0x0400
760 
761 /**
762  * To specify text track kind (different from subtitles default).
763  */
764 #define AV_DISPOSITION_CAPTIONS 0x10000
765 #define AV_DISPOSITION_DESCRIPTIONS 0x20000
766 #define AV_DISPOSITION_METADATA 0x40000
767 
768 /**
769  * Options for behavior on timestamp wrap detection.
770  */
771 #define AV_PTS_WRAP_IGNORE 0 ///< ignore the wrap
772 #define AV_PTS_WRAP_ADD_OFFSET 1 ///< add the format specific offset on wrap detection
773 #define AV_PTS_WRAP_SUB_OFFSET -1 ///< subtract the format specific offset on wrap detection
774 
775 /**
776  * Stream structure.
777  * New fields can be added to the end with minor version bumps.
778  * Removal, reordering and changes to existing fields require a major
779  * version bump.
780  * sizeof(AVStream) must not be used outside libav*.
781  */
782 typedef struct AVStream {
783  int index; /**< stream index in AVFormatContext */
784  /**
785  * Format-specific stream ID.
786  * decoding: set by libavformat
787  * encoding: set by the user, replaced by libavformat if left unset
788  */
789  int id;
790  /**
791  * Codec context associated with this stream. Allocated and freed by
792  * libavformat.
793  *
794  * - decoding: The demuxer exports codec information stored in the headers
795  * here.
796  * - encoding: The user sets codec information, the muxer writes it to the
797  * output. Mandatory fields as specified in AVCodecContext
798  * documentation must be set even if this AVCodecContext is
799  * not actually used for encoding.
800  */
802  void *priv_data;
803 
804 #if FF_API_LAVF_FRAC
805  /**
806  * @deprecated this field is unused
807  */
809  struct AVFrac pts;
810 #endif
811 
812  /**
813  * This is the fundamental unit of time (in seconds) in terms
814  * of which frame timestamps are represented.
815  *
816  * decoding: set by libavformat
817  * encoding: May be set by the caller before avformat_write_header() to
818  * provide a hint to the muxer about the desired timebase. In
819  * avformat_write_header(), the muxer will overwrite this field
820  * with the timebase that will actually be used for the timestamps
821  * written into the file (which may or may not be related to the
822  * user-provided one, depending on the format).
823  */
825 
826  /**
827  * Decoding: pts of the first frame of the stream in presentation order, in stream time base.
828  * Only set this if you are absolutely 100% sure that the value you set
829  * it to really is the pts of the first frame.
830  * This may be undefined (AV_NOPTS_VALUE).
831  * @note The ASF header does NOT contain a correct start_time the ASF
832  * demuxer must NOT set this.
833  */
834  int64_t start_time;
835 
836  /**
837  * Decoding: duration of the stream, in stream time base.
838  * If a source file does not specify a duration, but does specify
839  * a bitrate, this value will be estimated from bitrate and file size.
840  */
841  int64_t duration;
842 
843  int64_t nb_frames; ///< number of frames in this stream if known or 0
844 
845  int disposition; /**< AV_DISPOSITION_* bit field */
846 
847  enum AVDiscard discard; ///< Selects which packets can be discarded at will and do not need to be demuxed.
848 
849  /**
850  * sample aspect ratio (0 if unknown)
851  * - encoding: Set by user.
852  * - decoding: Set by libavformat.
853  */
855 
857 
858  /**
859  * Average framerate
860  *
861  * - demuxing: May be set by libavformat when creating the stream or in
862  * avformat_find_stream_info().
863  * - muxing: May be set by the caller before avformat_write_header().
864  */
866 
867  /**
868  * For streams with AV_DISPOSITION_ATTACHED_PIC disposition, this packet
869  * will contain the attached picture.
870  *
871  * decoding: set by libavformat, must not be modified by the caller.
872  * encoding: unused
873  */
875 
876  /**
877  * An array of side data that applies to the whole stream (i.e. the
878  * container does not allow it to change between packets).
879  *
880  * There may be no overlap between the side data in this array and side data
881  * in the packets. I.e. a given side data is either exported by the muxer
882  * (demuxing) / set by the caller (muxing) in this array, then it never
883  * appears in the packets, or the side data is exported / sent through
884  * the packets (always in the first packet where the value becomes known or
885  * changes), then it does not appear in this array.
886  *
887  * - demuxing: Set by libavformat when the stream is created.
888  * - muxing: May be set by the caller before avformat_write_header().
889  *
890  * Freed by libavformat in avformat_free_context().
891  *
892  * @see av_format_inject_global_side_data()
893  */
895  /**
896  * The number of elements in the AVStream.side_data array.
897  */
899 
900  /**
901  * Flags for the user to detect events happening on the stream. Flags must
902  * be cleared by the user once the event has been handled.
903  * A combination of AVSTREAM_EVENT_FLAG_*.
904  */
906 #define AVSTREAM_EVENT_FLAG_METADATA_UPDATED 0x0001 ///< The call resulted in updated metadata.
907 
908  /*****************************************************************
909  * All fields below this line are not part of the public API. They
910  * may not be used outside of libavformat and can be changed and
911  * removed at will.
912  * New public fields should be added right above.
913  *****************************************************************
914  */
915 
916  /**
917  * Stream information used internally by av_find_stream_info()
918  */
919 #define MAX_STD_TIMEBASES (30*12+7+6)
920  struct {
921  int64_t last_dts;
922  int64_t duration_gcd;
928 
929  /**
930  * 0 -> decoder has not been searched for yet.
931  * >0 -> decoder found
932  * <0 -> decoder with codec_id == -found_decoder has not been found
933  */
935 
936  int64_t last_duration;
937 
938  /**
939  * Those are used for average framerate estimation.
940  */
941  int64_t fps_first_dts;
943  int64_t fps_last_dts;
945 
946  } *info;
947 
948  int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */
949 
950  // Timestamp generation support:
951  /**
952  * Timestamp corresponding to the last dts sync point.
953  *
954  * Initialized when AVCodecParserContext.dts_sync_point >= 0 and
955  * a DTS is received from the underlying container. Otherwise set to
956  * AV_NOPTS_VALUE by default.
957  */
958  int64_t first_dts;
959  int64_t cur_dts;
960  int64_t last_IP_pts;
962 
963  /**
964  * Number of packets to buffer for codec probing
965  */
966 #define MAX_PROBE_PACKETS 2500
968 
969  /**
970  * Number of frames that have been demuxed during av_find_stream_info()
971  */
973 
974  /* av_read_frame() support */
977 
978  /**
979  * last packet in packet_buffer for this stream when muxing.
980  */
983 #define MAX_REORDER_DELAY 16
985 
986  AVIndexEntry *index_entries; /**< Only used if the format does not
987  support seeking natively. */
990 
991  /**
992  * Real base framerate of the stream.
993  * This is the lowest framerate with which all timestamps can be
994  * represented accurately (it is the least common multiple of all
995  * framerates in the stream). Note, this value is just a guess!
996  * For example, if the time base is 1/90000 and all frames have either
997  * approximately 3600 or 1800 timer ticks, then r_frame_rate will be 50/1.
998  *
999  * Code outside avformat should access this field using:
1000  * av_stream_get/set_r_frame_rate(stream)
1001  */
1003 
1004  /**
1005  * Stream Identifier
1006  * This is the MPEG-TS stream identifier +1
1007  * 0 means unknown
1008  */
1010 
1013 
1014  /**
1015  * stream probing state
1016  * -1 -> probing finished
1017  * 0 -> no probing requested
1018  * rest -> perform probing with request_probe being the minimum score to accept.
1019  * NOT PART OF PUBLIC API
1020  */
1022  /**
1023  * Indicates that everything up to the next keyframe
1024  * should be discarded.
1025  */
1027 
1028  /**
1029  * Number of samples to skip at the start of the frame decoded from the next packet.
1030  */
1032 
1033  /**
1034  * If not 0, the first audio sample that should be discarded from the stream.
1035  * This is broken by design (needs global sample count), but can't be
1036  * avoided for broken by design formats such as mp3 with ad-hoc gapless
1037  * audio support.
1038  */
1040 
1041  /**
1042  * The sample after last sample that is intended to be discarded after
1043  * first_discard_sample. Works on frame boundaries only. Used to prevent
1044  * early EOF if the gapless info is broken (considered concatenated mp3s).
1045  */
1047 
1048  /**
1049  * Number of internally decoded frames, used internally in libavformat, do not access
1050  * its lifetime differs from info which is why it is not in that structure.
1051  */
1053 
1054  /**
1055  * Timestamp offset added to timestamps before muxing
1056  * NOT PART OF PUBLIC API
1057  */
1058  int64_t mux_ts_offset;
1059 
1060  /**
1061  * Internal data to check for wrapping of the time stamp
1062  */
1064 
1065  /**
1066  * Options for behavior, when a wrap is detected.
1067  *
1068  * Defined by AV_PTS_WRAP_ values.
1069  *
1070  * If correction is enabled, there are two possibilities:
1071  * If the first time stamp is near the wrap point, the wrap offset
1072  * will be subtracted, which will create negative time stamps.
1073  * Otherwise the offset will be added.
1074  */
1076 
1077  /**
1078  * Internal data to prevent doing update_initial_durations() twice
1079  */
1081 
1082  /**
1083  * Internal data to generate dts from pts
1084  */
1087 
1088  /**
1089  * Internal data to analyze DTS and detect faulty mpeg streams
1090  */
1094 
1095  /**
1096  * Internal data to inject global side data
1097  */
1099 
1100  /**
1101  * String containing paris of key and values describing recommended encoder configuration.
1102  * Paris are separated by ','.
1103  * Keys are separated from values by '='.
1104  */
1106 
1107  /**
1108  * display aspect ratio (0 if unknown)
1109  * - encoding: unused
1110  * - decoding: Set by libavformat to calculate sample_aspect_ratio internally
1111  */
1113 } AVStream;
1114 
1119 void av_stream_set_recommended_encoder_configuration(AVStream *s, char *configuration);
1120 
1121 /**
1122  * Returns the pts of the last muxed packet + its duration
1123  *
1124  * the retuned value is undefined when used with a demuxer.
1125  */
1126 int64_t av_stream_get_end_pts(const AVStream *st);
1127 
1128 #define AV_PROGRAM_RUNNING 1
1129 
1130 /**
1131  * New fields can be added to the end with minor version bumps.
1132  * Removal, reordering and changes to existing fields require a major
1133  * version bump.
1134  * sizeof(AVProgram) must not be used outside libav*.
1135  */
1136 typedef struct AVProgram {
1137  int id;
1138  int flags;
1139  enum AVDiscard discard; ///< selects which program to discard and which to feed to the caller
1140  unsigned int *stream_index;
1141  unsigned int nb_stream_indexes;
1143 
1145  int pmt_pid;
1146  int pcr_pid;
1147 
1148  /*****************************************************************
1149  * All fields below this line are not part of the public API. They
1150  * may not be used outside of libavformat and can be changed and
1151  * removed at will.
1152  * New public fields should be added right above.
1153  *****************************************************************
1154  */
1155  int64_t start_time;
1156  int64_t end_time;
1157 
1158  int64_t pts_wrap_reference; ///< reference dts for wrap detection
1159  int pts_wrap_behavior; ///< behavior on wrap detection
1160 } AVProgram;
1161 
1162 #define AVFMTCTX_NOHEADER 0x0001 /**< signal that no header is present
1163  (streams are added dynamically) */
1164 
1165 typedef struct AVChapter {
1166  int id; ///< unique ID to identify the chapter
1167  AVRational time_base; ///< time base in which the start/end timestamps are specified
1168  int64_t start, end; ///< chapter start/end time in time_base units
1170 } AVChapter;
1171 
1172 
1173 /**
1174  * Callback used by devices to communicate with application.
1175  */
1176 typedef int (*av_format_control_message)(struct AVFormatContext *s, int type,
1177  void *data, size_t data_size);
1178 
1179 
1180 /**
1181  * The duration of a video can be estimated through various ways, and this enum can be used
1182  * to know how the duration was estimated.
1183  */
1185  AVFMT_DURATION_FROM_PTS, ///< Duration accurately estimated from PTSes
1186  AVFMT_DURATION_FROM_STREAM, ///< Duration estimated from a stream with a known duration
1187  AVFMT_DURATION_FROM_BITRATE ///< Duration estimated from bitrate (less accurate)
1188 };
1189 
1190 typedef struct AVFormatInternal AVFormatInternal;
1191 
1192 /**
1193  * Format I/O context.
1194  * New fields can be added to the end with minor version bumps.
1195  * Removal, reordering and changes to existing fields require a major
1196  * version bump.
1197  * sizeof(AVFormatContext) must not be used outside libav*, use
1198  * avformat_alloc_context() to create an AVFormatContext.
1199  */
1200 typedef struct AVFormatContext {
1201  /**
1202  * A class for logging and @ref avoptions. Set by avformat_alloc_context().
1203  * Exports (de)muxer private options if they exist.
1204  */
1206 
1207  /**
1208  * The input container format.
1209  *
1210  * Demuxing only, set by avformat_open_input().
1211  */
1213 
1214  /**
1215  * The output container format.
1216  *
1217  * Muxing only, must be set by the caller before avformat_write_header().
1218  */
1220 
1221  /**
1222  * Format private data. This is an AVOptions-enabled struct
1223  * if and only if iformat/oformat.priv_class is not NULL.
1224  *
1225  * - muxing: set by avformat_write_header()
1226  * - demuxing: set by avformat_open_input()
1227  */
1228  void *priv_data;
1229 
1230  /**
1231  * I/O context.
1232  *
1233  * - demuxing: either set by the user before avformat_open_input() (then
1234  * the user must close it manually) or set by avformat_open_input().
1235  * - muxing: set by the user before avformat_write_header(). The caller must
1236  * take care of closing / freeing the IO context.
1237  *
1238  * Do NOT set this field if AVFMT_NOFILE flag is set in
1239  * iformat/oformat.flags. In such a case, the (de)muxer will handle
1240  * I/O in some other way and this field will be NULL.
1241  */
1243 
1244  /* stream info */
1245  /**
1246  * Flags signalling stream properties. A combination of AVFMTCTX_*.
1247  * Set by libavformat.
1248  */
1250 
1251  /**
1252  * Number of elements in AVFormatContext.streams.
1253  *
1254  * Set by avformat_new_stream(), must not be modified by any other code.
1255  */
1256  unsigned int nb_streams;
1257  /**
1258  * A list of all streams in the file. New streams are created with
1259  * avformat_new_stream().
1260  *
1261  * - demuxing: streams are created by libavformat in avformat_open_input().
1262  * If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also
1263  * appear in av_read_frame().
1264  * - muxing: streams are created by the user before avformat_write_header().
1265  *
1266  * Freed by libavformat in avformat_free_context().
1267  */
1269 
1270  /**
1271  * input or output filename
1272  *
1273  * - demuxing: set by avformat_open_input()
1274  * - muxing: may be set by the caller before avformat_write_header()
1275  */
1276  char filename[1024];
1277 
1278  /**
1279  * Position of the first frame of the component, in
1280  * AV_TIME_BASE fractional seconds. NEVER set this value directly:
1281  * It is deduced from the AVStream values.
1282  *
1283  * Demuxing only, set by libavformat.
1284  */
1285  int64_t start_time;
1286 
1287  /**
1288  * Duration of the stream, in AV_TIME_BASE fractional
1289  * seconds. Only set this value if you know none of the individual stream
1290  * durations and also do not set any of them. This is deduced from the
1291  * AVStream values if not set.
1292  *
1293  * Demuxing only, set by libavformat.
1294  */
1295  int64_t duration;
1296 
1297  /**
1298  * Total stream bitrate in bit/s, 0 if not
1299  * available. Never set it directly if the file_size and the
1300  * duration are known as FFmpeg can compute it automatically.
1301  */
1303 
1304  unsigned int packet_size;
1306 
1307  /**
1308  * Flags modifying the (de)muxer behaviour. A combination of AVFMT_FLAG_*.
1309  * Set by the user before avformat_open_input() / avformat_write_header().
1310  */
1311  int flags;
1312 #define AVFMT_FLAG_GENPTS 0x0001 ///< Generate missing pts even if it requires parsing future frames.
1313 #define AVFMT_FLAG_IGNIDX 0x0002 ///< Ignore index.
1314 #define AVFMT_FLAG_NONBLOCK 0x0004 ///< Do not block when reading packets from input.
1315 #define AVFMT_FLAG_IGNDTS 0x0008 ///< Ignore DTS on frames that contain both DTS & PTS
1316 #define AVFMT_FLAG_NOFILLIN 0x0010 ///< Do not infer any values from other values, just return what is stored in the container
1317 #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
1318 #define AVFMT_FLAG_NOBUFFER 0x0040 ///< Do not buffer frames when possible
1319 #define AVFMT_FLAG_CUSTOM_IO 0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.
1320 #define AVFMT_FLAG_DISCARD_CORRUPT 0x0100 ///< Discard frames marked corrupted
1321 #define AVFMT_FLAG_FLUSH_PACKETS 0x0200 ///< Flush the AVIOContext every packet.
1322 /**
1323  * When muxing, try to avoid writing any random/volatile data to the output.
1324  * This includes any random IDs, real-time timestamps/dates, muxer version, etc.
1325  *
1326  * This flag is mainly intended for testing.
1327  */
1328 #define AVFMT_FLAG_BITEXACT 0x0400
1329 #define AVFMT_FLAG_MP4A_LATM 0x8000 ///< Enable RTP MP4A-LATM payload
1330 #define AVFMT_FLAG_SORT_DTS 0x10000 ///< try to interleave outputted packets by dts (using this flag can slow demuxing down)
1331 #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)
1332 #define AVFMT_FLAG_KEEP_SIDE_DATA 0x40000 ///< Don't merge side data but keep it separate.
1333 
1334  /**
1335  * @deprecated deprecated in favor of probesize2
1336  */
1337  unsigned int probesize;
1338 
1339  /**
1340  * @deprecated deprecated in favor of max_analyze_duration2
1341  */
1344 
1345  const uint8_t *key;
1346  int keylen;
1347 
1348  unsigned int nb_programs;
1350 
1351  /**
1352  * Forced video codec_id.
1353  * Demuxing: Set by user.
1354  */
1356 
1357  /**
1358  * Forced audio codec_id.
1359  * Demuxing: Set by user.
1360  */
1362 
1363  /**
1364  * Forced subtitle codec_id.
1365  * Demuxing: Set by user.
1366  */
1368 
1369  /**
1370  * Maximum amount of memory in bytes to use for the index of each stream.
1371  * If the index exceeds this size, entries will be discarded as
1372  * needed to maintain a smaller size. This can lead to slower or less
1373  * accurate seeking (depends on demuxer).
1374  * Demuxers for which a full in-memory index is mandatory will ignore
1375  * this.
1376  * - muxing: unused
1377  * - demuxing: set by user
1378  */
1379  unsigned int max_index_size;
1380 
1381  /**
1382  * Maximum amount of memory in bytes to use for buffering frames
1383  * obtained from realtime capture devices.
1384  */
1385  unsigned int max_picture_buffer;
1386 
1387  /**
1388  * Number of chapters in AVChapter array.
1389  * When muxing, chapters are normally written in the file header,
1390  * so nb_chapters should normally be initialized before write_header
1391  * is called. Some muxers (e.g. mov and mkv) can also write chapters
1392  * in the trailer. To write chapters in the trailer, nb_chapters
1393  * must be zero when write_header is called and non-zero when
1394  * write_trailer is called.
1395  * - muxing: set by user
1396  * - demuxing: set by libavformat
1397  */
1398  unsigned int nb_chapters;
1400 
1401  /**
1402  * Metadata that applies to the whole file.
1403  *
1404  * - demuxing: set by libavformat in avformat_open_input()
1405  * - muxing: may be set by the caller before avformat_write_header()
1406  *
1407  * Freed by libavformat in avformat_free_context().
1408  */
1410 
1411  /**
1412  * Start time of the stream in real world time, in microseconds
1413  * since the Unix epoch (00:00 1st January 1970). That is, pts=0 in the
1414  * stream was captured at this real world time.
1415  * - muxing: Set by the caller before avformat_write_header(). If set to
1416  * either 0 or AV_NOPTS_VALUE, then the current wall-time will
1417  * be used.
1418  * - demuxing: Set by libavformat. AV_NOPTS_VALUE if unknown. Note that
1419  * the value may become known after some number of frames
1420  * have been received.
1421  */
1423 
1424  /**
1425  * The number of frames used for determining the framerate in
1426  * avformat_find_stream_info().
1427  * Demuxing only, set by the caller before avformat_find_stream_info().
1428  */
1430 
1431  /**
1432  * Error recognition; higher values will detect more errors but may
1433  * misdetect some more or less valid parts as errors.
1434  * Demuxing only, set by the caller before avformat_open_input().
1435  */
1437 
1438  /**
1439  * Custom interrupt callbacks for the I/O layer.
1440  *
1441  * demuxing: set by the user before avformat_open_input().
1442  * muxing: set by the user before avformat_write_header()
1443  * (mainly useful for AVFMT_NOFILE formats). The callback
1444  * should also be passed to avio_open2() if it's used to
1445  * open the file.
1446  */
1448 
1449  /**
1450  * Flags to enable debugging.
1451  */
1452  int debug;
1453 #define FF_FDEBUG_TS 0x0001
1454 
1455  /**
1456  * Maximum buffering duration for interleaving.
1457  *
1458  * To ensure all the streams are interleaved correctly,
1459  * av_interleaved_write_frame() will wait until it has at least one packet
1460  * for each stream before actually writing any packets to the output file.
1461  * When some streams are "sparse" (i.e. there are large gaps between
1462  * successive packets), this can result in excessive buffering.
1463  *
1464  * This field specifies the maximum difference between the timestamps of the
1465  * first and the last packet in the muxing queue, above which libavformat
1466  * will output a packet regardless of whether it has queued a packet for all
1467  * the streams.
1468  *
1469  * Muxing only, set by the caller before avformat_write_header().
1470  */
1472 
1473  /**
1474  * Allow non-standard and experimental extension
1475  * @see AVCodecContext.strict_std_compliance
1476  */
1478 
1479  /**
1480  * Flags for the user to detect events happening on the file. Flags must
1481  * be cleared by the user once the event has been handled.
1482  * A combination of AVFMT_EVENT_FLAG_*.
1483  */
1485 #define AVFMT_EVENT_FLAG_METADATA_UPDATED 0x0001 ///< The call resulted in updated metadata.
1486 
1487  /**
1488  * Maximum number of packets to read while waiting for the first timestamp.
1489  * Decoding only.
1490  */
1492 
1493  /**
1494  * Avoid negative timestamps during muxing.
1495  * Any value of the AVFMT_AVOID_NEG_TS_* constants.
1496  * Note, this only works when using av_interleaved_write_frame. (interleave_packet_per_dts is in use)
1497  * - muxing: Set by user
1498  * - demuxing: unused
1499  */
1501 #define AVFMT_AVOID_NEG_TS_AUTO -1 ///< Enabled when required by target format
1502 #define AVFMT_AVOID_NEG_TS_MAKE_NON_NEGATIVE 1 ///< Shift timestamps so they are non negative
1503 #define AVFMT_AVOID_NEG_TS_MAKE_ZERO 2 ///< Shift timestamps so that they start at 0
1504 
1505 
1506  /**
1507  * Transport stream id.
1508  * This will be moved into demuxer private options. Thus no API/ABI compatibility
1509  */
1510  int ts_id;
1511 
1512  /**
1513  * Audio preload in microseconds.
1514  * Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1515  * - encoding: Set by user via AVOptions (NO direct access)
1516  * - decoding: unused
1517  */
1519 
1520  /**
1521  * Max chunk time in microseconds.
1522  * Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1523  * - encoding: Set by user via AVOptions (NO direct access)
1524  * - decoding: unused
1525  */
1527 
1528  /**
1529  * Max chunk size in bytes
1530  * Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1531  * - encoding: Set by user via AVOptions (NO direct access)
1532  * - decoding: unused
1533  */
1535 
1536  /**
1537  * forces the use of wallclock timestamps as pts/dts of packets
1538  * This has undefined results in the presence of B frames.
1539  * - encoding: unused
1540  * - decoding: Set by user via AVOptions (NO direct access)
1541  */
1543 
1544  /**
1545  * avio flags, used to force AVIO_FLAG_DIRECT.
1546  * - encoding: unused
1547  * - decoding: Set by user via AVOptions (NO direct access)
1548  */
1550 
1551  /**
1552  * The duration field can be estimated through various ways, and this field can be used
1553  * to know how the duration was estimated.
1554  * - encoding: unused
1555  * - decoding: Read by user via AVOptions (NO direct access)
1556  */
1558 
1559  /**
1560  * Skip initial bytes when opening stream
1561  * - encoding: unused
1562  * - decoding: Set by user via AVOptions (NO direct access)
1563  */
1565 
1566  /**
1567  * Correct single timestamp overflows
1568  * - encoding: unused
1569  * - decoding: Set by user via AVOptions (NO direct access)
1570  */
1571  unsigned int correct_ts_overflow;
1572 
1573  /**
1574  * Force seeking to any (also non key) frames.
1575  * - encoding: unused
1576  * - decoding: Set by user via AVOptions (NO direct access)
1577  */
1579 
1580  /**
1581  * Flush the I/O context after each packet.
1582  * - encoding: Set by user via AVOptions (NO direct access)
1583  * - decoding: unused
1584  */
1586 
1587  /**
1588  * format probing score.
1589  * The maximal score is AVPROBE_SCORE_MAX, its set when the demuxer probes
1590  * the format.
1591  * - encoding: unused
1592  * - decoding: set by avformat, read by user via av_format_get_probe_score() (NO direct access)
1593  */
1595 
1596  /**
1597  * number of bytes to read maximally to identify format.
1598  * - encoding: unused
1599  * - decoding: set by user through AVOPtions (NO direct access)
1600  */
1602 
1603  /**
1604  * ',' seperated list of allowed decoders.
1605  * If NULL then all are allowed
1606  * - encoding: unused
1607  * - decoding: set by user through AVOptions (NO direct access)
1608  */
1610 
1611  /**
1612  * ',' seperated list of allowed demuxers.
1613  * If NULL then all are allowed
1614  * - encoding: unused
1615  * - decoding: set by user through AVOptions (NO direct access)
1616  */
1618 
1619  /*****************************************************************
1620  * All fields below this line are not part of the public API. They
1621  * may not be used outside of libavformat and can be changed and
1622  * removed at will.
1623  * New public fields should be added right above.
1624  *****************************************************************
1625  */
1626 
1627  /**
1628  * This buffer is only needed when packets were already buffered but
1629  * not decoded, for example to get the codec parameters in MPEG
1630  * streams.
1631  */
1634 
1635  /* av_seek_frame() support */
1636  int64_t data_offset; /**< offset of the first packet */
1637 
1638  /**
1639  * Raw packets from the demuxer, prior to parsing and decoding.
1640  * This buffer is used for buffering packets until the codec can
1641  * be identified, as parsing cannot be done without knowing the
1642  * codec.
1643  */
1646  /**
1647  * Packets split by the parser get queued here.
1648  */
1651  /**
1652  * Remaining size available for raw_packet_buffer, in bytes.
1653  */
1654 #define RAW_PACKET_BUFFER_SIZE 2500000
1656 
1657  /**
1658  * Offset to remap timestamps to be non-negative.
1659  * Expressed in timebase units.
1660  * @see AVStream.mux_ts_offset
1661  */
1662  int64_t offset;
1663 
1664  /**
1665  * Timebase for the timestamp offset.
1666  */
1668 
1669  /**
1670  * An opaque field for libavformat internal usage.
1671  * Must not be accessed in any way by callers.
1672  */
1673  AVFormatInternal *internal;
1674 
1675  /**
1676  * IO repositioned flag.
1677  * This is set by avformat when the underlaying IO context read pointer
1678  * is repositioned, for example when doing byte based seeking.
1679  * Demuxers can use the flag to detect such changes.
1680  */
1682 
1683  /**
1684  * Forced video codec.
1685  * This allows forcing a specific decoder, even when there are multiple with
1686  * the same codec_id.
1687  * Demuxing: Set by user via av_format_set_video_codec (NO direct access).
1688  */
1690 
1691  /**
1692  * Forced audio codec.
1693  * This allows forcing a specific decoder, even when there are multiple with
1694  * the same codec_id.
1695  * Demuxing: Set by user via av_format_set_audio_codec (NO direct access).
1696  */
1698 
1699  /**
1700  * Forced subtitle codec.
1701  * This allows forcing a specific decoder, even when there are multiple with
1702  * the same codec_id.
1703  * Demuxing: Set by user via av_format_set_subtitle_codec (NO direct access).
1704  */
1706 
1707  /**
1708  * Number of bytes to be written as padding in a metadata header.
1709  * Demuxing: Unused.
1710  * Muxing: Set by user via av_format_set_metadata_header_padding.
1711  */
1713 
1714  /**
1715  * User data.
1716  * This is a place for some private data of the user.
1717  * Mostly usable with control_message_cb or any future callbacks in device's context.
1718  */
1719  void *opaque;
1720 
1721  /**
1722  * Callback used by devices to communicate with application.
1723  */
1725 
1726  /**
1727  * Output timestamp offset, in microseconds.
1728  * Muxing: set by user via AVOptions (NO direct access)
1729  */
1731 
1732  /**
1733  * Maximum duration (in AV_TIME_BASE units) of the data read
1734  * from input in avformat_find_stream_info().
1735  * Demuxing only, set by the caller before avformat_find_stream_info()
1736  * via AVOptions (NO direct access).
1737  * Can be set to 0 to let avformat choose using a heuristic.
1738  */
1740 
1741  /**
1742  * Maximum size of the data read from input for determining
1743  * the input container format.
1744  * Demuxing only, set by the caller before avformat_open_input()
1745  * via AVOptions (NO direct access).
1746  */
1747  int64_t probesize2;
1748 
1749  /**
1750  * dump format separator.
1751  * can be ", " or "\n " or anything else
1752  * Code outside libavformat should access this field using AVOptions
1753  * (NO direct access).
1754  * - muxing: Set by user.
1755  * - demuxing: Set by user.
1756  */
1758 } AVFormatContext;
1759 
1769 void * av_format_get_opaque(const AVFormatContext *s);
1770 void av_format_set_opaque(AVFormatContext *s, void *opaque);
1773 
1774 /**
1775  * This function will cause global side data to be injected in the next packet
1776  * of each stream as well as after any subsequent seek.
1777  */
1779 
1780 /**
1781  * Returns the method used to set ctx->duration.
1782  *
1783  * @return AVFMT_DURATION_FROM_PTS, AVFMT_DURATION_FROM_STREAM, or AVFMT_DURATION_FROM_BITRATE.
1784  */
1786 
1787 typedef struct AVPacketList {
1790 } AVPacketList;
1791 
1792 
1793 /**
1794  * @defgroup lavf_core Core functions
1795  * @ingroup libavf
1796  *
1797  * Functions for querying libavformat capabilities, allocating core structures,
1798  * etc.
1799  * @{
1800  */
1801 
1802 /**
1803  * Return the LIBAVFORMAT_VERSION_INT constant.
1804  */
1805 unsigned avformat_version(void);
1806 
1807 /**
1808  * Return the libavformat build-time configuration.
1809  */
1810 const char *avformat_configuration(void);
1811 
1812 /**
1813  * Return the libavformat license.
1814  */
1815 const char *avformat_license(void);
1816 
1817 /**
1818  * Initialize libavformat and register all the muxers, demuxers and
1819  * protocols. If you do not call this function, then you can select
1820  * exactly which formats you want to support.
1821  *
1822  * @see av_register_input_format()
1823  * @see av_register_output_format()
1824  */
1825 void av_register_all(void);
1826 
1829 
1830 /**
1831  * Do global initialization of network components. This is optional,
1832  * but recommended, since it avoids the overhead of implicitly
1833  * doing the setup for each session.
1834  *
1835  * Calling this function will become mandatory if using network
1836  * protocols at some major version bump.
1837  */
1838 int avformat_network_init(void);
1839 
1840 /**
1841  * Undo the initialization done by avformat_network_init.
1842  */
1843 int avformat_network_deinit(void);
1844 
1845 /**
1846  * If f is NULL, returns the first registered input format,
1847  * if f is non-NULL, returns the next registered input format after f
1848  * or NULL if f is the last one.
1849  */
1851 
1852 /**
1853  * If f is NULL, returns the first registered output format,
1854  * if f is non-NULL, returns the next registered output format after f
1855  * or NULL if f is the last one.
1856  */
1858 
1859 /**
1860  * Allocate an AVFormatContext.
1861  * avformat_free_context() can be used to free the context and everything
1862  * allocated by the framework within it.
1863  */
1865 
1866 /**
1867  * Free an AVFormatContext and all its streams.
1868  * @param s context to free
1869  */
1871 
1872 /**
1873  * Get the AVClass for AVFormatContext. It can be used in combination with
1874  * AV_OPT_SEARCH_FAKE_OBJ for examining options.
1875  *
1876  * @see av_opt_find().
1877  */
1878 const AVClass *avformat_get_class(void);
1879 
1880 /**
1881  * Add a new stream to a media file.
1882  *
1883  * When demuxing, it is called by the demuxer in read_header(). If the
1884  * flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also
1885  * be called in read_packet().
1886  *
1887  * When muxing, should be called by the user before avformat_write_header().
1888  *
1889  * User is required to call avcodec_close() and avformat_free_context() to
1890  * clean up the allocation by avformat_new_stream().
1891  *
1892  * @param s media file handle
1893  * @param c If non-NULL, the AVCodecContext corresponding to the new stream
1894  * will be initialized to use this codec. This is needed for e.g. codec-specific
1895  * defaults to be set, so codec should be provided if it is known.
1896  *
1897  * @return newly created stream or NULL on error.
1898  */
1900 
1901 /**
1902  * Get side information from stream.
1903  *
1904  * @param stream stream
1905  * @param type desired side information type
1906  * @param size pointer for side information size to store (optional)
1907  * @return pointer to data if present or NULL otherwise
1908  */
1910  enum AVPacketSideDataType type, int *size);
1911 
1913 
1914 /**
1915  * @}
1916  */
1917 
1918 
1919 /**
1920  * Allocate an AVFormatContext for an output format.
1921  * avformat_free_context() can be used to free the context and
1922  * everything allocated by the framework within it.
1923  *
1924  * @param *ctx is set to the created format context, or to NULL in
1925  * case of failure
1926  * @param oformat format to use for allocating the context, if NULL
1927  * format_name and filename are used instead
1928  * @param format_name the name of output format to use for allocating the
1929  * context, if NULL filename is used instead
1930  * @param filename the name of the filename to use for allocating the
1931  * context, may be NULL
1932  * @return >= 0 in case of success, a negative AVERROR code in case of
1933  * failure
1934  */
1936  const char *format_name, const char *filename);
1937 
1938 /**
1939  * @addtogroup lavf_decoding
1940  * @{
1941  */
1942 
1943 /**
1944  * Find AVInputFormat based on the short name of the input format.
1945  */
1946 AVInputFormat *av_find_input_format(const char *short_name);
1947 
1948 /**
1949  * Guess the file format.
1950  *
1951  * @param pd data to be probed
1952  * @param is_opened Whether the file is already opened; determines whether
1953  * demuxers with or without AVFMT_NOFILE are probed.
1954  */
1955 AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened);
1956 
1957 /**
1958  * Guess the file format.
1959  *
1960  * @param pd data to be probed
1961  * @param is_opened Whether the file is already opened; determines whether
1962  * demuxers with or without AVFMT_NOFILE are probed.
1963  * @param score_max A probe score larger that this is required to accept a
1964  * detection, the variable is set to the actual detection
1965  * score afterwards.
1966  * If the score is <= AVPROBE_SCORE_MAX / 4 it is recommended
1967  * to retry with a larger probe buffer.
1968  */
1969 AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max);
1970 
1971 /**
1972  * Guess the file format.
1973  *
1974  * @param is_opened Whether the file is already opened; determines whether
1975  * demuxers with or without AVFMT_NOFILE are probed.
1976  * @param score_ret The score of the best detection.
1977  */
1978 AVInputFormat *av_probe_input_format3(AVProbeData *pd, int is_opened, int *score_ret);
1979 
1980 /**
1981  * Probe a bytestream to determine the input format. Each time a probe returns
1982  * with a score that is too low, the probe buffer size is increased and another
1983  * attempt is made. When the maximum probe size is reached, the input format
1984  * with the highest score is returned.
1985  *
1986  * @param pb the bytestream to probe
1987  * @param fmt the input format is put here
1988  * @param filename the filename of the stream
1989  * @param logctx the log context
1990  * @param offset the offset within the bytestream to probe from
1991  * @param max_probe_size the maximum probe buffer size (zero for default)
1992  * @return the score in case of success, a negative value corresponding to an
1993  * the maximal score is AVPROBE_SCORE_MAX
1994  * AVERROR code otherwise
1995  */
1997  const char *filename, void *logctx,
1998  unsigned int offset, unsigned int max_probe_size);
1999 
2000 /**
2001  * Like av_probe_input_buffer2() but returns 0 on success
2002  */
2004  const char *filename, void *logctx,
2005  unsigned int offset, unsigned int max_probe_size);
2006 
2007 /**
2008  * Open an input stream and read the header. The codecs are not opened.
2009  * The stream must be closed with avformat_close_input().
2010  *
2011  * @param ps Pointer to user-supplied AVFormatContext (allocated by avformat_alloc_context).
2012  * May be a pointer to NULL, in which case an AVFormatContext is allocated by this
2013  * function and written into ps.
2014  * Note that a user-supplied AVFormatContext will be freed on failure.
2015  * @param filename Name of the stream to open.
2016  * @param fmt If non-NULL, this parameter forces a specific input format.
2017  * Otherwise the format is autodetected.
2018  * @param options A dictionary filled with AVFormatContext and demuxer-private options.
2019  * On return this parameter will be destroyed and replaced with a dict containing
2020  * options that were not found. May be NULL.
2021  *
2022  * @return 0 on success, a negative AVERROR on failure.
2023  *
2024  * @note If you want to use custom IO, preallocate the format context and set its pb field.
2025  */
2026 int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputFormat *fmt, AVDictionary **options);
2027 
2030 
2031 /**
2032  * Read packets of a media file to get stream information. This
2033  * is useful for file formats with no headers such as MPEG. This
2034  * function also computes the real framerate in case of MPEG-2 repeat
2035  * frame mode.
2036  * The logical file position is not changed by this function;
2037  * examined packets may be buffered for later processing.
2038  *
2039  * @param ic media file handle
2040  * @param options If non-NULL, an ic.nb_streams long array of pointers to
2041  * dictionaries, where i-th member contains options for
2042  * codec corresponding to i-th stream.
2043  * On return each dictionary will be filled with options that were not found.
2044  * @return >=0 if OK, AVERROR_xxx on error
2045  *
2046  * @note this function isn't guaranteed to open all the codecs, so
2047  * options being non-empty at return is a perfectly normal behavior.
2048  *
2049  * @todo Let the user decide somehow what information is needed so that
2050  * we do not waste time getting stuff the user does not need.
2051  */
2053 
2054 /**
2055  * Find the programs which belong to a given stream.
2056  *
2057  * @param ic media file handle
2058  * @param last the last found program, the search will start after this
2059  * program, or from the beginning if it is NULL
2060  * @param s stream index
2061  * @return the next program which belongs to s, NULL if no program is found or
2062  * the last program is not among the programs of ic.
2063  */
2065 
2066 /**
2067  * Find the "best" stream in the file.
2068  * The best stream is determined according to various heuristics as the most
2069  * likely to be what the user expects.
2070  * If the decoder parameter is non-NULL, av_find_best_stream will find the
2071  * default decoder for the stream's codec; streams for which no decoder can
2072  * be found are ignored.
2073  *
2074  * @param ic media file handle
2075  * @param type stream type: video, audio, subtitles, etc.
2076  * @param wanted_stream_nb user-requested stream number,
2077  * or -1 for automatic selection
2078  * @param related_stream try to find a stream related (eg. in the same
2079  * program) to this one, or -1 if none
2080  * @param decoder_ret if non-NULL, returns the decoder for the
2081  * selected stream
2082  * @param flags flags; none are currently defined
2083  * @return the non-negative stream number in case of success,
2084  * AVERROR_STREAM_NOT_FOUND if no stream with the requested type
2085  * could be found,
2086  * AVERROR_DECODER_NOT_FOUND if streams were found but no decoder
2087  * @note If av_find_best_stream returns successfully and decoder_ret is not
2088  * NULL, then *decoder_ret is guaranteed to be set to a valid AVCodec.
2089  */
2091  enum AVMediaType type,
2092  int wanted_stream_nb,
2093  int related_stream,
2094  AVCodec **decoder_ret,
2095  int flags);
2096 
2097 /**
2098  * Return the next frame of a stream.
2099  * This function returns what is stored in the file, and does not validate
2100  * that what is there are valid frames for the decoder. It will split what is
2101  * stored in the file into frames and return one for each call. It will not
2102  * omit invalid data between valid frames so as to give the decoder the maximum
2103  * information possible for decoding.
2104  *
2105  * If pkt->buf is NULL, then the packet is valid until the next
2106  * av_read_frame() or until avformat_close_input(). Otherwise the packet
2107  * is valid indefinitely. In both cases the packet must be freed with
2108  * av_free_packet when it is no longer needed. For video, the packet contains
2109  * exactly one frame. For audio, it contains an integer number of frames if each
2110  * frame has a known fixed size (e.g. PCM or ADPCM data). If the audio frames
2111  * have a variable size (e.g. MPEG audio), then it contains one frame.
2112  *
2113  * pkt->pts, pkt->dts and pkt->duration are always set to correct
2114  * values in AVStream.time_base units (and guessed if the format cannot
2115  * provide them). pkt->pts can be AV_NOPTS_VALUE if the video format
2116  * has B-frames, so it is better to rely on pkt->dts if you do not
2117  * decompress the payload.
2118  *
2119  * @return 0 if OK, < 0 on error or end of file
2120  */
2122 
2123 /**
2124  * Seek to the keyframe at timestamp.
2125  * 'timestamp' in 'stream_index'.
2126  *
2127  * @param s media file handle
2128  * @param stream_index If stream_index is (-1), a default
2129  * stream is selected, and timestamp is automatically converted
2130  * from AV_TIME_BASE units to the stream specific time_base.
2131  * @param timestamp Timestamp in AVStream.time_base units
2132  * or, if no stream is specified, in AV_TIME_BASE units.
2133  * @param flags flags which select direction and seeking mode
2134  * @return >= 0 on success
2135  */
2136 int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp,
2137  int flags);
2138 
2139 /**
2140  * Seek to timestamp ts.
2141  * Seeking will be done so that the point from which all active streams
2142  * can be presented successfully will be closest to ts and within min/max_ts.
2143  * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
2144  *
2145  * If flags contain AVSEEK_FLAG_BYTE, then all timestamps are in bytes and
2146  * are the file position (this may not be supported by all demuxers).
2147  * If flags contain AVSEEK_FLAG_FRAME, then all timestamps are in frames
2148  * in the stream with stream_index (this may not be supported by all demuxers).
2149  * Otherwise all timestamps are in units of the stream selected by stream_index
2150  * or if stream_index is -1, in AV_TIME_BASE units.
2151  * If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
2152  * keyframes (this may not be supported by all demuxers).
2153  * If flags contain AVSEEK_FLAG_BACKWARD, it is ignored.
2154  *
2155  * @param s media file handle
2156  * @param stream_index index of the stream which is used as time base reference
2157  * @param min_ts smallest acceptable timestamp
2158  * @param ts target timestamp
2159  * @param max_ts largest acceptable timestamp
2160  * @param flags flags
2161  * @return >=0 on success, error code otherwise
2162  *
2163  * @note This is part of the new seek API which is still under construction.
2164  * Thus do not use this yet. It may change at any time, do not expect
2165  * ABI compatibility yet!
2166  */
2167 int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
2168 
2169 /**
2170  * Start playing a network-based stream (e.g. RTSP stream) at the
2171  * current position.
2172  */
2174 
2175 /**
2176  * Pause a network-based stream (e.g. RTSP stream).
2177  *
2178  * Use av_read_play() to resume it.
2179  */
2181 
2182 /**
2183  * Close an opened input AVFormatContext. Free it and all its contents
2184  * and set *s to NULL.
2185  */
2187 /**
2188  * @}
2189  */
2190 
2191 #define AVSEEK_FLAG_BACKWARD 1 ///< seek backward
2192 #define AVSEEK_FLAG_BYTE 2 ///< seeking based on position in bytes
2193 #define AVSEEK_FLAG_ANY 4 ///< seek to any frame, even non-keyframes
2194 #define AVSEEK_FLAG_FRAME 8 ///< seeking based on frame number
2195 
2196 /**
2197  * @addtogroup lavf_encoding
2198  * @{
2199  */
2200 /**
2201  * Allocate the stream private data and write the stream header to
2202  * an output media file.
2203  *
2204  * @param s Media file handle, must be allocated with avformat_alloc_context().
2205  * Its oformat field must be set to the desired output format;
2206  * Its pb field must be set to an already opened AVIOContext.
2207  * @param options An AVDictionary filled with AVFormatContext and muxer-private options.
2208  * On return this parameter will be destroyed and replaced with a dict containing
2209  * options that were not found. May be NULL.
2210  *
2211  * @return 0 on success, negative AVERROR on failure.
2212  *
2213  * @see av_opt_find, av_dict_set, avio_open, av_oformat_next.
2214  */
2216 
2217 /**
2218  * Write a packet to an output media file.
2219  *
2220  * This function passes the packet directly to the muxer, without any buffering
2221  * or reordering. The caller is responsible for correctly interleaving the
2222  * packets if the format requires it. Callers that want libavformat to handle
2223  * the interleaving should call av_interleaved_write_frame() instead of this
2224  * function.
2225  *
2226  * @param s media file handle
2227  * @param pkt The packet containing the data to be written. Note that unlike
2228  * av_interleaved_write_frame(), this function does not take
2229  * ownership of the packet passed to it (though some muxers may make
2230  * an internal reference to the input packet).
2231  * <br>
2232  * This parameter can be NULL (at any time, not just at the end), in
2233  * order to immediately flush data buffered within the muxer, for
2234  * muxers that buffer up data internally before writing it to the
2235  * output.
2236  * <br>
2237  * Packet's @ref AVPacket.stream_index "stream_index" field must be
2238  * set to the index of the corresponding stream in @ref
2239  * AVFormatContext.streams "s->streams". It is very strongly
2240  * recommended that timing information (@ref AVPacket.pts "pts", @ref
2241  * AVPacket.dts "dts", @ref AVPacket.duration "duration") is set to
2242  * correct values.
2243  * @return < 0 on error, = 0 if OK, 1 if flushed and there is no more data to flush
2244  *
2245  * @see av_interleaved_write_frame()
2246  */
2248 
2249 /**
2250  * Write a packet to an output media file ensuring correct interleaving.
2251  *
2252  * This function will buffer the packets internally as needed to make sure the
2253  * packets in the output file are properly interleaved in the order of
2254  * increasing dts. Callers doing their own interleaving should call
2255  * av_write_frame() instead of this function.
2256  *
2257  * @param s media file handle
2258  * @param pkt The packet containing the data to be written.
2259  * <br>
2260  * If the packet is reference-counted, this function will take
2261  * ownership of this reference and unreference it later when it sees
2262  * fit.
2263  * The caller must not access the data through this reference after
2264  * this function returns. If the packet is not reference-counted,
2265  * libavformat will make a copy.
2266  * <br>
2267  * This parameter can be NULL (at any time, not just at the end), to
2268  * flush the interleaving queues.
2269  * <br>
2270  * Packet's @ref AVPacket.stream_index "stream_index" field must be
2271  * set to the index of the corresponding stream in @ref
2272  * AVFormatContext.streams "s->streams". It is very strongly
2273  * recommended that timing information (@ref AVPacket.pts "pts", @ref
2274  * AVPacket.dts "dts", @ref AVPacket.duration "duration") is set to
2275  * correct values.
2276  *
2277  * @return 0 on success, a negative AVERROR on error. Libavformat will always
2278  * take care of freeing the packet, even if this function fails.
2279  *
2280  * @see av_write_frame(), AVFormatContext.max_interleave_delta
2281  */
2283 
2284 /**
2285  * Write a uncoded frame to an output media file.
2286  *
2287  * The frame must be correctly interleaved according to the container
2288  * specification; if not, then av_interleaved_write_frame() must be used.
2289  *
2290  * See av_interleaved_write_frame() for details.
2291  */
2292 int av_write_uncoded_frame(AVFormatContext *s, int stream_index,
2293  AVFrame *frame);
2294 
2295 /**
2296  * Write a uncoded frame to an output media file.
2297  *
2298  * If the muxer supports it, this function allows to write an AVFrame
2299  * structure directly, without encoding it into a packet.
2300  * It is mostly useful for devices and similar special muxers that use raw
2301  * video or PCM data and will not serialize it into a byte stream.
2302  *
2303  * To test whether it is possible to use it with a given muxer and stream,
2304  * use av_write_uncoded_frame_query().
2305  *
2306  * The caller gives up ownership of the frame and must not access it
2307  * afterwards.
2308  *
2309  * @return >=0 for success, a negative code on error
2310  */
2311 int av_interleaved_write_uncoded_frame(AVFormatContext *s, int stream_index,
2312  AVFrame *frame);
2313 
2314 /**
2315  * Test whether a muxer supports uncoded frame.
2316  *
2317  * @return >=0 if an uncoded frame can be written to that muxer and stream,
2318  * <0 if not
2319  */
2320 int av_write_uncoded_frame_query(AVFormatContext *s, int stream_index);
2321 
2322 /**
2323  * Write the stream trailer to an output media file and free the
2324  * file private data.
2325  *
2326  * May only be called after a successful call to avformat_write_header.
2327  *
2328  * @param s media file handle
2329  * @return 0 if OK, AVERROR_xxx on error
2330  */
2332 
2333 /**
2334  * Return the output format in the list of registered output formats
2335  * which best matches the provided parameters, or return NULL if
2336  * there is no match.
2337  *
2338  * @param short_name if non-NULL checks if short_name matches with the
2339  * names of the registered formats
2340  * @param filename if non-NULL checks if filename terminates with the
2341  * extensions of the registered formats
2342  * @param mime_type if non-NULL checks if mime_type matches with the
2343  * MIME type of the registered formats
2344  */
2345 AVOutputFormat *av_guess_format(const char *short_name,
2346  const char *filename,
2347  const char *mime_type);
2348 
2349 /**
2350  * Guess the codec ID based upon muxer and filename.
2351  */
2352 enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
2353  const char *filename, const char *mime_type,
2354  enum AVMediaType type);
2355 
2356 /**
2357  * Get timing information for the data currently output.
2358  * The exact meaning of "currently output" depends on the format.
2359  * It is mostly relevant for devices that have an internal buffer and/or
2360  * work in real time.
2361  * @param s media file handle
2362  * @param stream stream in the media file
2363  * @param[out] dts DTS of the last packet output for the stream, in stream
2364  * time_base units
2365  * @param[out] wall absolute time when that packet whas output,
2366  * in microsecond
2367  * @return 0 if OK, AVERROR(ENOSYS) if the format does not support it
2368  * Note: some formats or devices may not allow to measure dts and wall
2369  * atomically.
2370  */
2371 int av_get_output_timestamp(struct AVFormatContext *s, int stream,
2372  int64_t *dts, int64_t *wall);
2373 
2374 
2375 /**
2376  * @}
2377  */
2378 
2379 
2380 /**
2381  * @defgroup lavf_misc Utility functions
2382  * @ingroup libavf
2383  * @{
2384  *
2385  * Miscellaneous utility functions related to both muxing and demuxing
2386  * (or neither).
2387  */
2388 
2389 /**
2390  * Send a nice hexadecimal dump of a buffer to the specified file stream.
2391  *
2392  * @param f The file stream pointer where the dump should be sent to.
2393  * @param buf buffer
2394  * @param size buffer size
2395  *
2396  * @see av_hex_dump_log, av_pkt_dump2, av_pkt_dump_log2
2397  */
2398 void av_hex_dump(FILE *f, const uint8_t *buf, int size);
2399 
2400 /**
2401  * Send a nice hexadecimal dump of a buffer to the log.
2402  *
2403  * @param avcl A pointer to an arbitrary struct of which the first field is a
2404  * pointer to an AVClass struct.
2405  * @param level The importance level of the message, lower values signifying
2406  * higher importance.
2407  * @param buf buffer
2408  * @param size buffer size
2409  *
2410  * @see av_hex_dump, av_pkt_dump2, av_pkt_dump_log2
2411  */
2412 void av_hex_dump_log(void *avcl, int level, const uint8_t *buf, int size);
2413 
2414 /**
2415  * Send a nice dump of a packet to the specified file stream.
2416  *
2417  * @param f The file stream pointer where the dump should be sent to.
2418  * @param pkt packet to dump
2419  * @param dump_payload True if the payload must be displayed, too.
2420  * @param st AVStream that the packet belongs to
2421  */
2422 void av_pkt_dump2(FILE *f, const AVPacket *pkt, int dump_payload, const AVStream *st);
2423 
2424 
2425 /**
2426  * Send a nice dump of a packet to the log.
2427  *
2428  * @param avcl A pointer to an arbitrary struct of which the first field is a
2429  * pointer to an AVClass struct.
2430  * @param level The importance level of the message, lower values signifying
2431  * higher importance.
2432  * @param pkt packet to dump
2433  * @param dump_payload True if the payload must be displayed, too.
2434  * @param st AVStream that the packet belongs to
2435  */
2436 void av_pkt_dump_log2(void *avcl, int level, const AVPacket *pkt, int dump_payload,
2437  const AVStream *st);
2438 
2439 /**
2440  * Get the AVCodecID for the given codec tag tag.
2441  * If no codec id is found returns AV_CODEC_ID_NONE.
2442  *
2443  * @param tags list of supported codec_id-codec_tag pairs, as stored
2444  * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2445  * @param tag codec tag to match to a codec ID
2446  */
2447 enum AVCodecID av_codec_get_id(const struct AVCodecTag * const *tags, unsigned int tag);
2448 
2449 /**
2450  * Get the codec tag for the given codec id id.
2451  * If no codec tag is found returns 0.
2452  *
2453  * @param tags list of supported codec_id-codec_tag pairs, as stored
2454  * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2455  * @param id codec ID to match to a codec tag
2456  */
2457 unsigned int av_codec_get_tag(const struct AVCodecTag * const *tags, enum AVCodecID id);
2458 
2459 /**
2460  * Get the codec tag for the given codec id.
2461  *
2462  * @param tags list of supported codec_id - codec_tag pairs, as stored
2463  * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2464  * @param id codec id that should be searched for in the list
2465  * @param tag A pointer to the found tag
2466  * @return 0 if id was not found in tags, > 0 if it was found
2467  */
2468 int av_codec_get_tag2(const struct AVCodecTag * const *tags, enum AVCodecID id,
2469  unsigned int *tag);
2470 
2472 
2473 /**
2474  * Get the index for a specific timestamp.
2475  *
2476  * @param st stream that the timestamp belongs to
2477  * @param timestamp timestamp to retrieve the index for
2478  * @param flags if AVSEEK_FLAG_BACKWARD then the returned index will correspond
2479  * to the timestamp which is <= the requested one, if backward
2480  * is 0, then it will be >=
2481  * if AVSEEK_FLAG_ANY seek to any frame, only keyframes otherwise
2482  * @return < 0 if no such timestamp could be found
2483  */
2484 int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags);
2485 
2486 /**
2487  * Add an index entry into a sorted list. Update the entry if the list
2488  * already contains it.
2489  *
2490  * @param timestamp timestamp in the time base of the given stream
2491  */
2492 int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
2493  int size, int distance, int flags);
2494 
2495 
2496 /**
2497  * Split a URL string into components.
2498  *
2499  * The pointers to buffers for storing individual components may be null,
2500  * in order to ignore that component. Buffers for components not found are
2501  * set to empty strings. If the port is not found, it is set to a negative
2502  * value.
2503  *
2504  * @param proto the buffer for the protocol
2505  * @param proto_size the size of the proto buffer
2506  * @param authorization the buffer for the authorization
2507  * @param authorization_size the size of the authorization buffer
2508  * @param hostname the buffer for the host name
2509  * @param hostname_size the size of the hostname buffer
2510  * @param port_ptr a pointer to store the port number in
2511  * @param path the buffer for the path
2512  * @param path_size the size of the path buffer
2513  * @param url the URL to split
2514  */
2515 void av_url_split(char *proto, int proto_size,
2516  char *authorization, int authorization_size,
2517  char *hostname, int hostname_size,
2518  int *port_ptr,
2519  char *path, int path_size,
2520  const char *url);
2521 
2522 
2523 /**
2524  * Print detailed information about the input or output format, such as
2525  * duration, bitrate, streams, container, programs, metadata, side data,
2526  * codec and time base.
2527  *
2528  * @param ic the context to analyze
2529  * @param index index of the stream to dump information about
2530  * @param url the URL to print, such as source or destination file
2531  * @param is_output Select whether the specified context is an input(0) or output(1)
2532  */
2534  int index,
2535  const char *url,
2536  int is_output);
2537 
2538 /**
2539  * Return in 'buf' the path with '%d' replaced by a number.
2540  *
2541  * Also handles the '%0nd' format where 'n' is the total number
2542  * of digits and '%%'.
2543  *
2544  * @param buf destination buffer
2545  * @param buf_size destination buffer size
2546  * @param path numbered sequence string
2547  * @param number frame number
2548  * @return 0 if OK, -1 on format error
2549  */
2550 int av_get_frame_filename(char *buf, int buf_size,
2551  const char *path, int number);
2552 
2553 /**
2554  * Check whether filename actually is a numbered sequence generator.
2555  *
2556  * @param filename possible numbered sequence string
2557  * @return 1 if a valid numbered sequence string, 0 otherwise
2558  */
2559 int av_filename_number_test(const char *filename);
2560 
2561 /**
2562  * Generate an SDP for an RTP session.
2563  *
2564  * Note, this overwrites the id values of AVStreams in the muxer contexts
2565  * for getting unique dynamic payload types.
2566  *
2567  * @param ac array of AVFormatContexts describing the RTP streams. If the
2568  * array is composed by only one context, such context can contain
2569  * multiple AVStreams (one AVStream per RTP stream). Otherwise,
2570  * all the contexts in the array (an AVCodecContext per RTP stream)
2571  * must contain only one AVStream.
2572  * @param n_files number of AVCodecContexts contained in ac
2573  * @param buf buffer where the SDP will be stored (must be allocated by
2574  * the caller)
2575  * @param size the size of the buffer
2576  * @return 0 if OK, AVERROR_xxx on error
2577  */
2578 int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size);
2579 
2580 /**
2581  * Return a positive value if the given filename has one of the given
2582  * extensions, 0 otherwise.
2583  *
2584  * @param filename file name to check against the given extensions
2585  * @param extensions a comma-separated list of filename extensions
2586  */
2587 int av_match_ext(const char *filename, const char *extensions);
2588 
2589 /**
2590  * Test if the given container can store a codec.
2591  *
2592  * @param ofmt container to check for compatibility
2593  * @param codec_id codec to potentially store in container
2594  * @param std_compliance standards compliance level, one of FF_COMPLIANCE_*
2595  *
2596  * @return 1 if codec with ID codec_id can be stored in ofmt, 0 if it cannot.
2597  * A negative number if this information is not available.
2598  */
2600  int std_compliance);
2601 
2602 /**
2603  * @defgroup riff_fourcc RIFF FourCCs
2604  * @{
2605  * Get the tables mapping RIFF FourCCs to libavcodec AVCodecIDs. The tables are
2606  * meant to be passed to av_codec_get_id()/av_codec_get_tag() as in the
2607  * following code:
2608  * @code
2609  * uint32_t tag = MKTAG('H', '2', '6', '4');
2610  * const struct AVCodecTag *table[] = { avformat_get_riff_video_tags(), 0 };
2611  * enum AVCodecID id = av_codec_get_id(table, tag);
2612  * @endcode
2613  */
2614 /**
2615  * @return the table mapping RIFF FourCCs for video to libavcodec AVCodecID.
2616  */
2617 const struct AVCodecTag *avformat_get_riff_video_tags(void);
2618 /**
2619  * @return the table mapping RIFF FourCCs for audio to AVCodecID.
2620  */
2621 const struct AVCodecTag *avformat_get_riff_audio_tags(void);
2622 /**
2623  * @return the table mapping MOV FourCCs for video to libavcodec AVCodecID.
2624  */
2625 const struct AVCodecTag *avformat_get_mov_video_tags(void);
2626 /**
2627  * @return the table mapping MOV FourCCs for audio to AVCodecID.
2628  */
2629 const struct AVCodecTag *avformat_get_mov_audio_tags(void);
2630 
2631 /**
2632  * @}
2633  */
2634 
2635 /**
2636  * Guess the sample aspect ratio of a frame, based on both the stream and the
2637  * frame aspect ratio.
2638  *
2639  * Since the frame aspect ratio is set by the codec but the stream aspect ratio
2640  * is set by the demuxer, these two may not be equal. This function tries to
2641  * return the value that you should use if you would like to display the frame.
2642  *
2643  * Basic logic is to use the stream aspect ratio if it is set to something sane
2644  * otherwise use the frame aspect ratio. This way a container setting, which is
2645  * usually easy to modify can override the coded value in the frames.
2646  *
2647  * @param format the format context which the stream is part of
2648  * @param stream the stream which the frame is part of
2649  * @param frame the frame with the aspect ratio to be determined
2650  * @return the guessed (valid) sample_aspect_ratio, 0/1 if no idea
2651  */
2653 
2654 /**
2655  * Guess the frame rate, based on both the container and codec information.
2656  *
2657  * @param ctx the format context which the stream is part of
2658  * @param stream the stream which the frame is part of
2659  * @param frame the frame for which the frame rate should be determined, may be NULL
2660  * @return the guessed (valid) frame rate, 0/1 if no idea
2661  */
2663 
2664 /**
2665  * Check if the stream st contained in s is matched by the stream specifier
2666  * spec.
2667  *
2668  * See the "stream specifiers" chapter in the documentation for the syntax
2669  * of spec.
2670  *
2671  * @return >0 if st is matched by spec;
2672  * 0 if st is not matched by spec;
2673  * AVERROR code if spec is invalid
2674  *
2675  * @note A stream specifier can match several streams in the format.
2676  */
2678  const char *spec);
2679 
2681 
2682 
2683 /**
2684  * @}
2685  */
2686 
2687 #endif /* AVFORMAT_AVFORMAT_H */