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;
265	struct AVDeviceCapabilitiesQuery;
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	*
302	* - Demuxers attempt to export metadata in a generic format, however tags
303	* with no generic equivalents are left as they are stored in the container.
304	* Follows a list of generic tag names:
305	*
306	@verbatim
307	album -- name of the set this work belongs to
308	album_artist -- main creator of the set/album, if different from artist.
309	e.g. "Various Artists" for compilation albums.
310	artist -- main creator of the work
311	comment -- any additional description of the file.
312	composer -- who composed the work, if different from artist.
313	copyright -- name of copyright holder.
314	creation_time-- date when the file was created, preferably in ISO 8601.
315	date -- date when the work was created, preferably in ISO 8601.
316	disc -- number of a subset, e.g. disc in a multi-disc collection.
317	encoder -- name/settings of the software/hardware that produced the file.
318	encoded_by -- person/group who created the file.
319	filename -- original name of the file.
320	genre -- <self-evident>.
321	language -- main language in which the work is performed, preferably
322	in ISO 639-2 format. Multiple languages can be specified by
323	separating them with commas.
324	performer -- artist who performed the work, if different from artist.
325	E.g for "Also sprach Zarathustra", artist would be "Richard
326	Strauss" and performer "London Philharmonic Orchestra".
327	publisher -- name of the label/publisher.
328	service_name -- name of the service in broadcasting (channel name).
329	service_provider -- name of the service provider in broadcasting.
330	title -- name of the work.
331	track -- number of this work in the set, can be in form current/total.
332	variant_bitrate -- the total bitrate of the bitrate variant that the current stream is part of
333	@endverbatim
334	*
335	* Look in the examples section for an application example how to use the Metadata API.
336	*
337	* @}
338	*/
339
340	/* packet functions */
341
342
343	/**
344	* Allocate and read the payload of a packet and initialize its
345	* fields with default values.
346	*
347	* @param s associated IO context
348	* @param pkt packet
349	* @param size desired payload size
350	* @return >0 (read size) if OK, AVERROR_xxx otherwise
351	*/
352	int av_get_packet(AVIOContext *s, AVPacket *pkt, int size);
353
354
355	/**
356	* Read data and append it to the current content of the AVPacket.
357	* If pkt->size is 0 this is identical to av_get_packet.
358	* Note that this uses av_grow_packet and thus involves a realloc
359	* which is inefficient. Thus this function should only be used
360	* when there is no reasonable way to know (an upper bound of)
361	* the final size.
362	*
363	* @param s associated IO context
364	* @param pkt packet
365	* @param size amount of data to read
366	* @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data
367	* will not be lost even if an error occurs.
368	*/
369	int av_append_packet(AVIOContext *s, AVPacket *pkt, int size);
370
371	#if FF_API_LAVF_FRAC
372	/*************************************************/
373	/* fractional numbers for exact pts handling */
374
375	/**
376	* The exact value of the fractional number is: 'val + num / den'.
377	* num is assumed to be 0 <= num < den.
378	*/
379	typedef struct AVFrac {
380	int64_t val, num, den;
381	} AVFrac;
382	#endif
383
384	/*************************************************/
385	/* input/output formats */
386
387	struct AVCodecTag;
388
389	/**
390	* This structure contains the data a format has to probe a file.
391	*/
392	typedef struct AVProbeData {
393	const char *filename;
394	unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
395	int buf_size; /**< Size of buf except extra allocated bytes */
396	} AVProbeData;
397
398	#define AVPROBE_SCORE_RETRY (AVPROBE_SCORE_MAX/4)
399	#define AVPROBE_SCORE_STREAM_RETRY (AVPROBE_SCORE_MAX/4-1)
400
401	#define AVPROBE_SCORE_EXTENSION 50 ///< score for file extension
402	#define AVPROBE_SCORE_MAX 100 ///< maximum score
403
404	#define AVPROBE_PADDING_SIZE 32 ///< extra allocated bytes at the end of the probe buffer
405
406	/// Demuxer will use avio_open, no opened file should be provided by the caller.
407	#define AVFMT_NOFILE 0x0001
408	#define AVFMT_NEEDNUMBER 0x0002 /**< Needs '%d' in filename. */
409	#define AVFMT_SHOW_IDS 0x0008 /**< Show format stream IDs numbers. */
410	#define AVFMT_RAWPICTURE 0x0020 /**< Format wants AVPicture structure for
411	raw picture data. */
412	#define AVFMT_GLOBALHEADER 0x0040 /**< Format wants global header. */
413	#define AVFMT_NOTIMESTAMPS 0x0080 /**< Format does not need / have any timestamps. */
414	#define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */
415	#define AVFMT_TS_DISCONT 0x0200 /**< Format allows timestamp discontinuities. Note, muxers always require valid (monotone) timestamps */
416	#define AVFMT_VARIABLE_FPS 0x0400 /**< Format allows variable fps. */
417	#define AVFMT_NODIMENSIONS 0x0800 /**< Format does not need width/height */
418	#define AVFMT_NOSTREAMS 0x1000 /**< Format does not require any streams */
419	#define AVFMT_NOBINSEARCH 0x2000 /**< Format does not allow to fall back on binary search via read_timestamp */
420	#define AVFMT_NOGENSEARCH 0x4000 /**< Format does not allow to fall back on generic search */
421	#define AVFMT_NO_BYTE_SEEK 0x8000 /**< Format does not allow seeking by bytes */
422	#define AVFMT_ALLOW_FLUSH 0x10000 /**< Format allows flushing. If not set, the muxer will not receive a NULL packet in the write_packet function. */
423	#if LIBAVFORMAT_VERSION_MAJOR <= 54
424	#define AVFMT_TS_NONSTRICT 0x8020000 //we try to be compatible to the ABIs of ffmpeg and major forks
425	#else
426	#define AVFMT_TS_NONSTRICT 0x20000
427	#endif
428	/**< Format does not require strictly
429	increasing timestamps, but they must
430	still be monotonic */
431	#define AVFMT_TS_NEGATIVE 0x40000 /**< Format allows muxing negative
432	timestamps. If not set the timestamp
433	will be shifted in av_write_frame and
434	av_interleaved_write_frame so they
435	start from 0.
436	The user or muxer can override this through
437	AVFormatContext.avoid_negative_ts
438	*/
439
440	#define AVFMT_SEEK_TO_PTS 0x4000000 /**< Seeking is based on PTS */
441
442	/**
443	* @addtogroup lavf_encoding
444	* @{
445	*/
446	typedef struct AVOutputFormat {
447	const char *name;
448	/**
449	* Descriptive name for the format, meant to be more human-readable
450	* than name. You should use the NULL_IF_CONFIG_SMALL() macro
451	* to define it.
452	*/
453	const char *long_name;
454	const char *mime_type;
455	const char *extensions; /**< comma-separated filename extensions */
456	/* output support */
457	enum AVCodecID audio_codec; /**< default audio codec */
458	enum AVCodecID video_codec; /**< default video codec */
459	enum AVCodecID subtitle_codec; /**< default subtitle codec */
460	/**
461	* can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_RAWPICTURE,
462	* AVFMT_GLOBALHEADER, AVFMT_NOTIMESTAMPS, AVFMT_VARIABLE_FPS,
463	* AVFMT_NODIMENSIONS, AVFMT_NOSTREAMS, AVFMT_ALLOW_FLUSH,
464	* AVFMT_TS_NONSTRICT
465	*/
466	int flags;
467
468	/**
469	* List of supported codec_id-codec_tag pairs, ordered by "better
470	* choice first". The arrays are all terminated by AV_CODEC_ID_NONE.
471	*/
472	const struct AVCodecTag * const *codec_tag;
473
474
475	const AVClass *priv_class; ///< AVClass for the private context
476
477	/*****************************************************************
478	* No fields below this line are part of the public API. They
479	* may not be used outside of libavformat and can be changed and
480	* removed at will.
481	* New public fields should be added right above.
482	*****************************************************************
483	*/
484	struct AVOutputFormat *next;
485	/**
486	* size of private data so that it can be allocated in the wrapper
487	*/
488	int priv_data_size;
489
490	int (*write_header)(struct AVFormatContext *);
491	/**
492	* Write a packet. If AVFMT_ALLOW_FLUSH is set in flags,
493	* pkt can be NULL in order to flush data buffered in the muxer.
494	* When flushing, return 0 if there still is more data to flush,
495	* or 1 if everything was flushed and there is no more buffered
496	* data.
497	*/
498	int (*write_packet)(struct AVFormatContext *, AVPacket *pkt);
499	int (*write_trailer)(struct AVFormatContext *);
500	/**
501	* Currently only used to set pixel format if not YUV420P.
502	*/
503	int (*interleave_packet)(struct AVFormatContext *, AVPacket *out,
504	AVPacket *in, int flush);
505	/**
506	* Test if the given codec can be stored in this container.
507	*
508	* @return 1 if the codec is supported, 0 if it is not.
509	* A negative number if unknown.
510	* MKTAG('A', 'P', 'I', 'C') if the codec is only supported as AV_DISPOSITION_ATTACHED_PIC
511	*/
512	int (*query_codec)(enum AVCodecID id, int std_compliance);
513
514	void (*get_output_timestamp)(struct AVFormatContext *s, int stream,
515	int64_t *dts, int64_t *wall);
516	/**
517	* Allows sending messages from application to device.
518	*/
519	int (*control_message)(struct AVFormatContext *s, int type,
520	void *data, size_t data_size);
521
522	/**
523	* Write an uncoded AVFrame.
524	*
525	* See av_write_uncoded_frame() for details.
526	*
527	* The library will free *frame afterwards, but the muxer can prevent it
528	* by setting the pointer to NULL.
529	*/
530	int (*write_uncoded_frame)(struct AVFormatContext *, int stream_index,
531	AVFrame **frame, unsigned flags);
532	/**
533	* Returns device list with it properties.
534	* @see avdevice_list_devices() for more details.
535	*/
536	int (*get_device_list)(struct AVFormatContext *s, struct AVDeviceInfoList *device_list);
537	/**
538	* Initialize device capabilities submodule.
539	* @see avdevice_capabilities_create() for more details.
540	*/
541	int (*create_device_capabilities)(struct AVFormatContext *s, struct AVDeviceCapabilitiesQuery *caps);
542	/**
543	* Free device capabilities submodule.
544	* @see avdevice_capabilities_free() for more details.
545	*/
546	int (*free_device_capabilities)(struct AVFormatContext *s, struct AVDeviceCapabilitiesQuery *caps);
547	} AVOutputFormat;
548	/**
549	* @}
550	*/
551
552	/**
553	* @addtogroup lavf_decoding
554	* @{
555	*/
556	typedef struct AVInputFormat {
557	/**
558	* A comma separated list of short names for the format. New names
559	* may be appended with a minor bump.
560	*/
561	const char *name;
562
563	/**
564	* Descriptive name for the format, meant to be more human-readable
565	* than name. You should use the NULL_IF_CONFIG_SMALL() macro
566	* to define it.
567	*/
568	const char *long_name;
569
570	/**
571	* Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS,
572	* AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH,
573	* AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK, AVFMT_SEEK_TO_PTS.
574	*/
575	int flags;
576
577	/**
578	* If extensions are defined, then no probe is done. You should
579	* usually not use extension format guessing because it is not
580	* reliable enough
581	*/
582	const char *extensions;
583
584	const struct AVCodecTag * const *codec_tag;
585
586	const AVClass *priv_class; ///< AVClass for the private context
587
588	/*****************************************************************
589	* No fields below this line are part of the public API. They
590	* may not be used outside of libavformat and can be changed and
591	* removed at will.
592	* New public fields should be added right above.
593	*****************************************************************
594	*/
595	struct AVInputFormat *next;
596
597	/**
598	* Raw demuxers store their codec ID here.
599	*/
600	int raw_codec_id;
601
602	/**
603	* Size of private data so that it can be allocated in the wrapper.
604	*/
605	int priv_data_size;
606
607	/**
608	* Tell if a given file has a chance of being parsed as this format.
609	* The buffer provided is guaranteed to be AVPROBE_PADDING_SIZE bytes
610	* big so you do not have to check for that unless you need more.
611	*/
612	int (*read_probe)(AVProbeData *);
613
614	/**
615	* Read the format header and initialize the AVFormatContext
616	* structure. Return 0 if OK. Only used in raw format right
617	* now. 'avformat_new_stream' should be called to create new streams.
618	*/
619	int (*read_header)(struct AVFormatContext *);
620
621	/**
622	* Read one packet and put it in 'pkt'. pts and flags are also
623	* set. 'avformat_new_stream' can be called only if the flag
624	* AVFMTCTX_NOHEADER is used and only in the calling thread (not in a
625	* background thread).
626	* @return 0 on success, < 0 on error.
627	* When returning an error, pkt must not have been allocated
628	* or must be freed before returning
629	*/
630	int (*read_packet)(struct AVFormatContext *, AVPacket *pkt);
631
632	/**
633	* Close the stream. The AVFormatContext and AVStreams are not
634	* freed by this function
635	*/
636	int (*read_close)(struct AVFormatContext *);
637
638	/**
639	* Seek to a given timestamp relative to the frames in
640	* stream component stream_index.
641	* @param stream_index Must not be -1.
642	* @param flags Selects which direction should be preferred if no exact
643	* match is available.
644	* @return >= 0 on success (but not necessarily the new offset)
645	*/
646	int (*read_seek)(struct AVFormatContext *,
647	int stream_index, int64_t timestamp, int flags);
648
649	/**
650	* Get the next timestamp in stream[stream_index].time_base units.
651	* @return the timestamp or AV_NOPTS_VALUE if an error occurred
652	*/
653	int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,
654	int64_t *pos, int64_t pos_limit);
655
656	/**
657	* Start/resume playing - only meaningful if using a network-based format
658	* (RTSP).
659	*/
660	int (*read_play)(struct AVFormatContext *);
661
662	/**
663	* Pause playing - only meaningful if using a network-based format
664	* (RTSP).
665	*/
666	int (*read_pause)(struct AVFormatContext *);
667
668	/**
669	* Seek to timestamp ts.
670	* Seeking will be done so that the point from which all active streams
671	* can be presented successfully will be closest to ts and within min/max_ts.
672	* Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
673	*/
674	int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
675
676	/**
677	* Returns device list with it properties.
678	* @see avdevice_list_devices() for more details.
679	*/
680	int (*get_device_list)(struct AVFormatContext *s, struct AVDeviceInfoList *device_list);
681
682	/**
683	* Initialize device capabilities submodule.
684	* @see avdevice_capabilities_create() for more details.
685	*/
686	int (*create_device_capabilities)(struct AVFormatContext *s, struct AVDeviceCapabilitiesQuery *caps);
687
688	/**
689	* Free device capabilities submodule.
690	* @see avdevice_capabilities_free() for more details.
691	*/
692	int (*free_device_capabilities)(struct AVFormatContext *s, struct AVDeviceCapabilitiesQuery *caps);
693	} AVInputFormat;
694	/**
695	* @}
696	*/
697
698	enum AVStreamParseType {
699	AVSTREAM_PARSE_NONE,
700	AVSTREAM_PARSE_FULL, /**< full parsing and repack */
701	AVSTREAM_PARSE_HEADERS, /**< Only parse headers, do not repack. */
702	AVSTREAM_PARSE_TIMESTAMPS, /**< full parsing and interpolation of timestamps for frames not starting on a packet boundary */
703	AVSTREAM_PARSE_FULL_ONCE, /**< full parsing and repack of the first frame only, only implemented for H.264 currently */
704	AVSTREAM_PARSE_FULL_RAW=MKTAG(0,'R','A','W'), /**< full parsing and repack with timestamp and position generation by parser for raw
705	this assumes that each packet in the file contains no demuxer level headers and
706	just codec level data, otherwise position generation would fail */
707	};
708
709	typedef struct AVIndexEntry {
710	int64_t pos;
711	int64_t timestamp; /**<
712	* Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are available
713	* when seeking to this entry. That means preferable PTS on keyframe based formats.
714	* But demuxers can choose to store a different timestamp, if it is more convenient for the implementation or nothing better
715	* is known
716	*/
717	#define AVINDEX_KEYFRAME 0x0001
718	int flags:2;
719	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).
720	int min_distance; /**< Minimum distance between this and the previous keyframe, used to avoid unneeded searching. */
721	} AVIndexEntry;
722
723	#define AV_DISPOSITION_DEFAULT 0x0001
724	#define AV_DISPOSITION_DUB 0x0002
725	#define AV_DISPOSITION_ORIGINAL 0x0004
726	#define AV_DISPOSITION_COMMENT 0x0008
727	#define AV_DISPOSITION_LYRICS 0x0010
728	#define AV_DISPOSITION_KARAOKE 0x0020
729
730	/**
731	* Track should be used during playback by default.
732	* Useful for subtitle track that should be displayed
733	* even when user did not explicitly ask for subtitles.
734	*/
735	#define AV_DISPOSITION_FORCED 0x0040
736	#define AV_DISPOSITION_HEARING_IMPAIRED 0x0080 /**< stream for hearing impaired audiences */
737	#define AV_DISPOSITION_VISUAL_IMPAIRED 0x0100 /**< stream for visual impaired audiences */
738	#define AV_DISPOSITION_CLEAN_EFFECTS 0x0200 /**< stream without voice */
739	/**
740	* The stream is stored in the file as an attached picture/"cover art" (e.g.
741	* APIC frame in ID3v2). The single packet associated with it will be returned
742	* among the first few packets read from the file unless seeking takes place.
743	* It can also be accessed at any time in AVStream.attached_pic.
744	*/
745	#define AV_DISPOSITION_ATTACHED_PIC 0x0400
746
747	/**
748	* To specify text track kind (different from subtitles default).
749	*/
750	#define AV_DISPOSITION_CAPTIONS 0x10000
751	#define AV_DISPOSITION_DESCRIPTIONS 0x20000
752	#define AV_DISPOSITION_METADATA 0x40000
753
754	/**
755	* Options for behavior on timestamp wrap detection.
756	*/
757	#define AV_PTS_WRAP_IGNORE 0 ///< ignore the wrap
758	#define AV_PTS_WRAP_ADD_OFFSET 1 ///< add the format specific offset on wrap detection
759	#define AV_PTS_WRAP_SUB_OFFSET -1 ///< subtract the format specific offset on wrap detection
760
761	/**
762	* Stream structure.
763	* New fields can be added to the end with minor version bumps.
764	* Removal, reordering and changes to existing fields require a major
765	* version bump.
766	* sizeof(AVStream) must not be used outside libav*.
767	*/
768	typedef struct AVStream {
769	int index; /**< stream index in AVFormatContext */
770	/**
771	* Format-specific stream ID.
772	* decoding: set by libavformat
773	* encoding: set by the user, replaced by libavformat if left unset
774	*/
775	int id;
776	/**
777	* Codec context associated with this stream. Allocated and freed by
778	* libavformat.
779	*
780	* - decoding: The demuxer exports codec information stored in the headers
781	* here.
782	* - encoding: The user sets codec information, the muxer writes it to the
783	* output. Mandatory fields as specified in AVCodecContext
784	* documentation must be set even if this AVCodecContext is
785	* not actually used for encoding.
786	*/
787	AVCodecContext *codec;
788	void *priv_data;
789
790	#if FF_API_LAVF_FRAC
791	/**
792	* @deprecated this field is unused
793	*/
794	attribute_deprecated
795	struct AVFrac pts;
796	#endif
797
798	/**
799	* This is the fundamental unit of time (in seconds) in terms
800	* of which frame timestamps are represented.
801	*
802	* decoding: set by libavformat
803	* encoding: May be set by the caller before avformat_write_header() to
804	* provide a hint to the muxer about the desired timebase. In
805	* avformat_write_header(), the muxer will overwrite this field
806	* with the timebase that will actually be used for the timestamps
807	* written into the file (which may or may not be related to the
808	* user-provided one, depending on the format).
809	*/
810	AVRational time_base;
811
812	/**
813	* Decoding: pts of the first frame of the stream in presentation order, in stream time base.
814	* Only set this if you are absolutely 100% sure that the value you set
815	* it to really is the pts of the first frame.
816	* This may be undefined (AV_NOPTS_VALUE).
817	* @note The ASF header does NOT contain a correct start_time the ASF
818	* demuxer must NOT set this.
819	*/
820	int64_t start_time;
821
822	/**
823	* Decoding: duration of the stream, in stream time base.
824	* If a source file does not specify a duration, but does specify
825	* a bitrate, this value will be estimated from bitrate and file size.
826	*/
827	int64_t duration;
828
829	int64_t nb_frames; ///< number of frames in this stream if known or 0
830
831	int disposition; /**< AV_DISPOSITION_* bit field */
832
833	enum AVDiscard discard; ///< Selects which packets can be discarded at will and do not need to be demuxed.
834
835	/**
836	* sample aspect ratio (0 if unknown)
837	* - encoding: Set by user.
838	* - decoding: Set by libavformat.
839	*/
840	AVRational sample_aspect_ratio;
841
842	AVDictionary *metadata;
843
844	/**
845	* Average framerate
846	*
847	* - demuxing: May be set by libavformat when creating the stream or in
848	* avformat_find_stream_info().
849	* - muxing: May be set by the caller before avformat_write_header().
850	*/
851	AVRational avg_frame_rate;
852
853	/**
854	* For streams with AV_DISPOSITION_ATTACHED_PIC disposition, this packet
855	* will contain the attached picture.
856	*
857	* decoding: set by libavformat, must not be modified by the caller.
858	* encoding: unused
859	*/
860	AVPacket attached_pic;
861
862	/**
863	* An array of side data that applies to the whole stream (i.e. the
864	* container does not allow it to change between packets).
865	*
866	* There may be no overlap between the side data in this array and side data
867	* in the packets. I.e. a given side data is either exported by the muxer
868	* (demuxing) / set by the caller (muxing) in this array, then it never
869	* appears in the packets, or the side data is exported / sent through
870	* the packets (always in the first packet where the value becomes known or
871	* changes), then it does not appear in this array.
872	*
873	* - demuxing: Set by libavformat when the stream is created.
874	* - muxing: May be set by the caller before avformat_write_header().
875	*
876	* Freed by libavformat in avformat_free_context().
877	*
878	* @see av_format_inject_global_side_data()
879	*/
880	AVPacketSideData *side_data;
881	/**
882	* The number of elements in the AVStream.side_data array.
883	*/
884	int nb_side_data;
885
886	/*****************************************************************
887	* All fields below this line are not part of the public API. They
888	* may not be used outside of libavformat and can be changed and
889	* removed at will.
890	* New public fields should be added right above.
891	*****************************************************************
892	*/
893
894	/**
895	* Stream information used internally by av_find_stream_info()
896	*/
897	#define MAX_STD_TIMEBASES (60*12+6)
898	struct {
899	int64_t last_dts;
900	int64_t duration_gcd;
901	int duration_count;
902	int64_t rfps_duration_sum;
903	double (*duration_error)[2][MAX_STD_TIMEBASES];
904	int64_t codec_info_duration;
905	int64_t codec_info_duration_fields;
906
907	/**
908	* 0 -> decoder has not been searched for yet.
909	* >0 -> decoder found
910	* <0 -> decoder with codec_id == -found_decoder has not been found
911	*/
912	int found_decoder;
913
914	int64_t last_duration;
915
916	/**
917	* Those are used for average framerate estimation.
918	*/
919	int64_t fps_first_dts;
920	int fps_first_dts_idx;
921	int64_t fps_last_dts;
922	int fps_last_dts_idx;
923
924	} *info;
925
926	int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */
927
928	#if FF_API_REFERENCE_DTS
929	/* a hack to keep ABI compatibility for ffmpeg and other applications, which accesses parser even
930	* though it should not */
931	int64_t do_not_use;
932	#endif
933	// Timestamp generation support:
934	/**
935	* Timestamp corresponding to the last dts sync point.
936	*
937	* Initialized when AVCodecParserContext.dts_sync_point >= 0 and
938	* a DTS is received from the underlying container. Otherwise set to
939	* AV_NOPTS_VALUE by default.
940	*/
941	int64_t first_dts;
942	int64_t cur_dts;
943	int64_t last_IP_pts;
944	int last_IP_duration;
945
946	/**
947	* Number of packets to buffer for codec probing
948	*/
949	#define MAX_PROBE_PACKETS 2500
950	int probe_packets;
951
952	/**
953	* Number of frames that have been demuxed during av_find_stream_info()
954	*/
955	int codec_info_nb_frames;
956
957	/* av_read_frame() support */
958	enum AVStreamParseType need_parsing;
959	struct AVCodecParserContext *parser;
960
961	/**
962	* last packet in packet_buffer for this stream when muxing.
963	*/
964	struct AVPacketList *last_in_packet_buffer;
965	AVProbeData probe_data;
966	#define MAX_REORDER_DELAY 16
967	int64_t pts_buffer[MAX_REORDER_DELAY+1];
968
969	AVIndexEntry *index_entries; /**< Only used if the format does not
970	support seeking natively. */
971	int nb_index_entries;
972	unsigned int index_entries_allocated_size;
973
974	/**
975	* Real base framerate of the stream.
976	* This is the lowest framerate with which all timestamps can be
977	* represented accurately (it is the least common multiple of all
978	* framerates in the stream). Note, this value is just a guess!
979	* For example, if the time base is 1/90000 and all frames have either
980	* approximately 3600 or 1800 timer ticks, then r_frame_rate will be 50/1.
981	*
982	* Code outside avformat should access this field using:
983	* av_stream_get/set_r_frame_rate(stream)
984	*/
985	AVRational r_frame_rate;
986
987	/**
988	* Stream Identifier
989	* This is the MPEG-TS stream identifier +1
990	* 0 means unknown
991	*/
992	int stream_identifier;
993
994	int64_t interleaver_chunk_size;
995	int64_t interleaver_chunk_duration;
996
997	/**
998	* stream probing state
999	* -1 -> probing finished
1000	* 0 -> no probing requested
1001	* rest -> perform probing with request_probe being the minimum score to accept.
1002	* NOT PART OF PUBLIC API
1003	*/
1004	int request_probe;
1005	/**
1006	* Indicates that everything up to the next keyframe
1007	* should be discarded.
1008	*/
1009	int skip_to_keyframe;
1010
1011	/**
1012	* Number of samples to skip at the start of the frame decoded from the next packet.
1013	*/
1014	int skip_samples;
1015
1016	/**
1017	* Number of internally decoded frames, used internally in libavformat, do not access
1018	* its lifetime differs from info which is why it is not in that structure.
1019	*/
1020	int nb_decoded_frames;
1021
1022	/**
1023	* Timestamp offset added to timestamps before muxing
1024	* NOT PART OF PUBLIC API
1025	*/
1026	int64_t mux_ts_offset;
1027
1028	/**
1029	* Internal data to check for wrapping of the time stamp
1030	*/
1031	int64_t pts_wrap_reference;
1032
1033	/**
1034	* Options for behavior, when a wrap is detected.
1035	*
1036	* Defined by AV_PTS_WRAP_ values.
1037	*
1038	* If correction is enabled, there are two possibilities:
1039	* If the first time stamp is near the wrap point, the wrap offset
1040	* will be subtracted, which will create negative time stamps.
1041	* Otherwise the offset will be added.
1042	*/
1043	int pts_wrap_behavior;
1044
1045	/**
1046	* Internal data to prevent doing update_initial_durations() twice
1047	*/
1048	int update_initial_durations_done;
1049
1050	/**
1051	* Internal data to generate dts from pts
1052	*/
1053	int64_t pts_reorder_error[MAX_REORDER_DELAY+1];
1054	uint8_t pts_reorder_error_count[MAX_REORDER_DELAY+1];
1055
1056	/**
1057	* Internal data to analyze DTS and detect faulty mpeg streams
1058	*/
1059	int64_t last_dts_for_order_check;
1060	uint8_t dts_ordered;
1061	uint8_t dts_misordered;
1062
1063	/**
1064	* Internal data to inject global side data
1065	*/
1066	int inject_global_side_data;
1067
1068	} AVStream;
1069
1070	AVRational av_stream_get_r_frame_rate(const AVStream *s);
1071	void av_stream_set_r_frame_rate(AVStream *s, AVRational r);
1072	struct AVCodecParserContext *av_stream_get_parser(const AVStream *s);
1073
1074	/**
1075	* Returns the pts of the last muxed packet + its duration
1076	*
1077	* the retuned value is undefined when used with a demuxer.
1078	*/
1079	int64_t av_stream_get_end_pts(const AVStream *st);
1080
1081	#define AV_PROGRAM_RUNNING 1
1082
1083	/**
1084	* New fields can be added to the end with minor version bumps.
1085	* Removal, reordering and changes to existing fields require a major
1086	* version bump.
1087	* sizeof(AVProgram) must not be used outside libav*.
1088	*/
1089	typedef struct AVProgram {
1090	int id;
1091	int flags;
1092	enum AVDiscard discard; ///< selects which program to discard and which to feed to the caller
1093	unsigned int *stream_index;
1094	unsigned int nb_stream_indexes;
1095	AVDictionary *metadata;
1096
1097	int program_num;
1098	int pmt_pid;
1099	int pcr_pid;
1100
1101	/*****************************************************************
1102	* All fields below this line are not part of the public API. They
1103	* may not be used outside of libavformat and can be changed and
1104	* removed at will.
1105	* New public fields should be added right above.
1106	*****************************************************************
1107	*/
1108	int64_t start_time;
1109	int64_t end_time;
1110
1111	int64_t pts_wrap_reference; ///< reference dts for wrap detection
1112	int pts_wrap_behavior; ///< behavior on wrap detection
1113	} AVProgram;
1114
1115	#define AVFMTCTX_NOHEADER 0x0001 /**< signal that no header is present
1116	(streams are added dynamically) */
1117
1118	typedef struct AVChapter {
1119	int id; ///< unique ID to identify the chapter
1120	AVRational time_base; ///< time base in which the start/end timestamps are specified
1121	int64_t start, end; ///< chapter start/end time in time_base units
1122	AVDictionary *metadata;
1123	} AVChapter;
1124
1125
1126	/**
1127	* Callback used by devices to communicate with application.
1128	*/
1129	typedef int (*av_format_control_message)(struct AVFormatContext *s, int type,
1130	void *data, size_t data_size);
1131
1132
1133	/**
1134	* The duration of a video can be estimated through various ways, and this enum can be used
1135	* to know how the duration was estimated.
1136	*/
1137	enum AVDurationEstimationMethod {
1138	AVFMT_DURATION_FROM_PTS, ///< Duration accurately estimated from PTSes
1139	AVFMT_DURATION_FROM_STREAM, ///< Duration estimated from a stream with a known duration
1140	AVFMT_DURATION_FROM_BITRATE ///< Duration estimated from bitrate (less accurate)
1141	};
1142
1143	typedef struct AVFormatInternal AVFormatInternal;
1144
1145	/**
1146	* Format I/O context.
1147	* New fields can be added to the end with minor version bumps.
1148	* Removal, reordering and changes to existing fields require a major
1149	* version bump.
1150	* sizeof(AVFormatContext) must not be used outside libav*, use
1151	* avformat_alloc_context() to create an AVFormatContext.
1152	*/
1153	typedef struct AVFormatContext {
1154	/**
1155	* A class for logging and @ref avoptions. Set by avformat_alloc_context().
1156	* Exports (de)muxer private options if they exist.
1157	*/
1158	const AVClass *av_class;
1159
1160	/**
1161	* The input container format.
1162	*
1163	* Demuxing only, set by avformat_open_input().
1164	*/
1165	struct AVInputFormat *iformat;
1166
1167	/**
1168	* The output container format.
1169	*
1170	* Muxing only, must be set by the caller before avformat_write_header().
1171	*/
1172	struct AVOutputFormat *oformat;
1173
1174	/**
1175	* Format private data. This is an AVOptions-enabled struct
1176	* if and only if iformat/oformat.priv_class is not NULL.
1177	*
1178	* - muxing: set by avformat_write_header()
1179	* - demuxing: set by avformat_open_input()
1180	*/
1181	void *priv_data;
1182
1183	/**
1184	* I/O context.
1185	*
1186	* - demuxing: either set by the user before avformat_open_input() (then
1187	* the user must close it manually) or set by avformat_open_input().
1188	* - muxing: set by the user before avformat_write_header(). The caller must
1189	* take care of closing / freeing the IO context.
1190	*
1191	* Do NOT set this field if AVFMT_NOFILE flag is set in
1192	* iformat/oformat.flags. In such a case, the (de)muxer will handle
1193	* I/O in some other way and this field will be NULL.
1194	*/
1195	AVIOContext *pb;
1196
1197	/* stream info */
1198	/**
1199	* Flags signalling stream properties. A combination of AVFMTCTX_*.
1200	* Set by libavformat.
1201	*/
1202	int ctx_flags;
1203
1204	/**
1205	* Number of elements in AVFormatContext.streams.
1206	*
1207	* Set by avformat_new_stream(), must not be modified by any other code.
1208	*/
1209	unsigned int nb_streams;
1210	/**
1211	* A list of all streams in the file. New streams are created with
1212	* avformat_new_stream().
1213	*
1214	* - demuxing: streams are created by libavformat in avformat_open_input().
1215	* If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also
1216	* appear in av_read_frame().
1217	* - muxing: streams are created by the user before avformat_write_header().
1218	*
1219	* Freed by libavformat in avformat_free_context().
1220	*/
1221	AVStream **streams;
1222
1223	/**
1224	* input or output filename
1225	*
1226	* - demuxing: set by avformat_open_input()
1227	* - muxing: may be set by the caller before avformat_write_header()
1228	*/
1229	char filename[1024];
1230
1231	/**
1232	* Position of the first frame of the component, in
1233	* AV_TIME_BASE fractional seconds. NEVER set this value directly:
1234	* It is deduced from the AVStream values.
1235	*
1236	* Demuxing only, set by libavformat.
1237	*/
1238	int64_t start_time;
1239
1240	/**
1241	* Duration of the stream, in AV_TIME_BASE fractional
1242	* seconds. Only set this value if you know none of the individual stream
1243	* durations and also do not set any of them. This is deduced from the
1244	* AVStream values if not set.
1245	*
1246	* Demuxing only, set by libavformat.
1247	*/
1248	int64_t duration;
1249
1250	/**
1251	* Total stream bitrate in bit/s, 0 if not
1252	* available. Never set it directly if the file_size and the
1253	* duration are known as FFmpeg can compute it automatically.
1254	*/
1255	int bit_rate;
1256
1257	unsigned int packet_size;
1258	int max_delay;
1259
1260	/**
1261	* Flags modifying the (de)muxer behaviour. A combination of AVFMT_FLAG_*.
1262	* Set by the user before avformat_open_input() / avformat_write_header().
1263	*/
1264	int flags;
1265	#define AVFMT_FLAG_GENPTS 0x0001 ///< Generate missing pts even if it requires parsing future frames.
1266	#define AVFMT_FLAG_IGNIDX 0x0002 ///< Ignore index.
1267	#define AVFMT_FLAG_NONBLOCK 0x0004 ///< Do not block when reading packets from input.
1268	#define AVFMT_FLAG_IGNDTS 0x0008 ///< Ignore DTS on frames that contain both DTS & PTS
1269	#define AVFMT_FLAG_NOFILLIN 0x0010 ///< Do not infer any values from other values, just return what is stored in the container
1270	#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
1271	#define AVFMT_FLAG_NOBUFFER 0x0040 ///< Do not buffer frames when possible
1272	#define AVFMT_FLAG_CUSTOM_IO 0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.
1273	#define AVFMT_FLAG_DISCARD_CORRUPT 0x0100 ///< Discard frames marked corrupted
1274	#define AVFMT_FLAG_FLUSH_PACKETS 0x0200 ///< Flush the AVIOContext every packet.
1275	/**
1276	* When muxing, try to avoid writing any random/volatile data to the output.
1277	* This includes any random IDs, real-time timestamps/dates, muxer version, etc.
1278	*
1279	* This flag is mainly intended for testing.
1280	*/
1281	#define AVFMT_FLAG_BITEXACT 0x0400
1282	#define AVFMT_FLAG_MP4A_LATM 0x8000 ///< Enable RTP MP4A-LATM payload
1283	#define AVFMT_FLAG_SORT_DTS 0x10000 ///< try to interleave outputted packets by dts (using this flag can slow demuxing down)
1284	#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)
1285	#define AVFMT_FLAG_KEEP_SIDE_DATA 0x40000 ///< Don't merge side data but keep it separate.
1286
1287	/**
1288	* Maximum size of the data read from input for determining
1289	* the input container format.
1290	* Demuxing only, set by the caller before avformat_open_input().
1291	*/
1292	unsigned int probesize;
1293
1294	/**
1295	* @deprecated deprecated in favor of max_analyze_duration2
1296	*/
1297	attribute_deprecated
1298	int max_analyze_duration;
1299
1300	const uint8_t *key;
1301	int keylen;
1302
1303	unsigned int nb_programs;
1304	AVProgram **programs;
1305
1306	/**
1307	* Forced video codec_id.
1308	* Demuxing: Set by user.
1309	*/
1310	enum AVCodecID video_codec_id;
1311
1312	/**
1313	* Forced audio codec_id.
1314	* Demuxing: Set by user.
1315	*/
1316	enum AVCodecID audio_codec_id;
1317
1318	/**
1319	* Forced subtitle codec_id.
1320	* Demuxing: Set by user.
1321	*/
1322	enum AVCodecID subtitle_codec_id;
1323
1324	/**
1325	* Maximum amount of memory in bytes to use for the index of each stream.
1326	* If the index exceeds this size, entries will be discarded as
1327	* needed to maintain a smaller size. This can lead to slower or less
1328	* accurate seeking (depends on demuxer).
1329	* Demuxers for which a full in-memory index is mandatory will ignore
1330	* this.
1331	* - muxing: unused
1332	* - demuxing: set by user
1333	*/
1334	unsigned int max_index_size;
1335
1336	/**
1337	* Maximum amount of memory in bytes to use for buffering frames
1338	* obtained from realtime capture devices.
1339	*/
1340	unsigned int max_picture_buffer;
1341
1342	/**
1343	* Number of chapters in AVChapter array.
1344	* When muxing, chapters are normally written in the file header,
1345	* so nb_chapters should normally be initialized before write_header
1346	* is called. Some muxers (e.g. mov and mkv) can also write chapters
1347	* in the trailer. To write chapters in the trailer, nb_chapters
1348	* must be zero when write_header is called and non-zero when
1349	* write_trailer is called.
1350	* - muxing: set by user
1351	* - demuxing: set by libavformat
1352	*/
1353	unsigned int nb_chapters;
1354	AVChapter **chapters;
1355
1356	/**
1357	* Metadata that applies to the whole file.
1358	*
1359	* - demuxing: set by libavformat in avformat_open_input()
1360	* - muxing: may be set by the caller before avformat_write_header()
1361	*
1362	* Freed by libavformat in avformat_free_context().
1363	*/
1364	AVDictionary *metadata;
1365
1366	/**
1367	* Start time of the stream in real world time, in microseconds
1368	* since the Unix epoch (00:00 1st January 1970). That is, pts=0 in the
1369	* stream was captured at this real world time.
1370	* - muxing: Set by the caller before avformat_write_header(). If set to
1371	* either 0 or AV_NOPTS_VALUE, then the current wall-time will
1372	* be used.
1373	* - demuxing: Set by libavformat. AV_NOPTS_VALUE if unknown. Note that
1374	* the value may become known after some number of frames
1375	* have been received.
1376	*/
1377	int64_t start_time_realtime;
1378
1379	/**
1380	* The number of frames used for determining the framerate in
1381	* avformat_find_stream_info().
1382	* Demuxing only, set by the caller before avformat_find_stream_info().
1383	*/
1384	int fps_probe_size;
1385
1386	/**
1387	* Error recognition; higher values will detect more errors but may
1388	* misdetect some more or less valid parts as errors.
1389	* Demuxing only, set by the caller before avformat_open_input().
1390	*/
1391	int error_recognition;
1392
1393	/**
1394	* Custom interrupt callbacks for the I/O layer.
1395	*
1396	* demuxing: set by the user before avformat_open_input().
1397	* muxing: set by the user before avformat_write_header()
1398	* (mainly useful for AVFMT_NOFILE formats). The callback
1399	* should also be passed to avio_open2() if it's used to
1400	* open the file.
1401	*/
1402	AVIOInterruptCB interrupt_callback;
1403
1404	/**
1405	* Flags to enable debugging.
1406	*/
1407	int debug;
1408	#define FF_FDEBUG_TS 0x0001
1409
1410	/**
1411	* Maximum buffering duration for interleaving.
1412	*
1413	* To ensure all the streams are interleaved correctly,
1414	* av_interleaved_write_frame() will wait until it has at least one packet
1415	* for each stream before actually writing any packets to the output file.
1416	* When some streams are "sparse" (i.e. there are large gaps between
1417	* successive packets), this can result in excessive buffering.
1418	*
1419	* This field specifies the maximum difference between the timestamps of the
1420	* first and the last packet in the muxing queue, above which libavformat
1421	* will output a packet regardless of whether it has queued a packet for all
1422	* the streams.
1423	*
1424	* Muxing only, set by the caller before avformat_write_header().
1425	*/
1426	int64_t max_interleave_delta;
1427
1428	/**
1429	* Allow non-standard and experimental extension
1430	* @see AVCodecContext.strict_std_compliance
1431	*/
1432	int strict_std_compliance;
1433
1434	/**
1435	* Transport stream id.
1436	* This will be moved into demuxer private options. Thus no API/ABI compatibility
1437	*/
1438	int ts_id;
1439
1440	/**
1441	* Audio preload in microseconds.
1442	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1443	* - encoding: Set by user via AVOptions (NO direct access)
1444	* - decoding: unused
1445	*/
1446	int audio_preload;
1447
1448	/**
1449	* Max chunk time in microseconds.
1450	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1451	* - encoding: Set by user via AVOptions (NO direct access)
1452	* - decoding: unused
1453	*/
1454	int max_chunk_duration;
1455
1456	/**
1457	* Max chunk size in bytes
1458	* Note, not all formats support this and unpredictable things may happen if it is used when not supported.
1459	* - encoding: Set by user via AVOptions (NO direct access)
1460	* - decoding: unused
1461	*/
1462	int max_chunk_size;
1463
1464	/**
1465	* forces the use of wallclock timestamps as pts/dts of packets
1466	* This has undefined results in the presence of B frames.
1467	* - encoding: unused
1468	* - decoding: Set by user via AVOptions (NO direct access)
1469	*/
1470	int use_wallclock_as_timestamps;
1471
1472	/**
1473	* Avoid negative timestamps during muxing.
1474	* 0 -> allow negative timestamps
1475	* 1 -> avoid negative timestamps
1476	* -1 -> choose automatically (default)
1477	* Note, this only works when interleave_packet_per_dts is in use.
1478	* - encoding: Set by user via AVOptions (NO direct access)
1479	* - decoding: unused
1480	*/
1481	int avoid_negative_ts;
1482
1483	/**
1484	* avio flags, used to force AVIO_FLAG_DIRECT.
1485	* - encoding: unused
1486	* - decoding: Set by user via AVOptions (NO direct access)
1487	*/
1488	int avio_flags;
1489
1490	/**
1491	* The duration field can be estimated through various ways, and this field can be used
1492	* to know how the duration was estimated.
1493	* - encoding: unused
1494	* - decoding: Read by user via AVOptions (NO direct access)
1495	*/
1496	enum AVDurationEstimationMethod duration_estimation_method;
1497
1498	/**
1499	* Skip initial bytes when opening stream
1500	* - encoding: unused
1501	* - decoding: Set by user via AVOptions (NO direct access)
1502	*/
1503	int64_t skip_initial_bytes;
1504
1505	/**
1506	* Correct single timestamp overflows
1507	* - encoding: unused
1508	* - decoding: Set by user via AVOptions (NO direct access)
1509	*/
1510	unsigned int correct_ts_overflow;
1511
1512	/**
1513	* Force seeking to any (also non key) frames.
1514	* - encoding: unused
1515	* - decoding: Set by user via AVOptions (NO direct access)
1516	*/
1517	int seek2any;
1518
1519	/**
1520	* Flush the I/O context after each packet.
1521	* - encoding: Set by user via AVOptions (NO direct access)
1522	* - decoding: unused
1523	*/
1524	int flush_packets;
1525
1526	/**
1527	* format probing score.
1528	* The maximal score is AVPROBE_SCORE_MAX, its set when the demuxer probes
1529	* the format.
1530	* - encoding: unused
1531	* - decoding: set by avformat, read by user via av_format_get_probe_score() (NO direct access)
1532	*/
1533	int probe_score;
1534
1535	/**
1536	* number of bytes to read maximally to identify format.
1537	* - encoding: unused
1538	* - decoding: set by user through AVOPtions (NO direct access)
1539	*/
1540	int format_probesize;
1541
1542	/*****************************************************************
1543	* All fields below this line are not part of the public API. They
1544	* may not be used outside of libavformat and can be changed and
1545	* removed at will.
1546	* New public fields should be added right above.
1547	*****************************************************************
1548	*/
1549
1550	/**
1551	* This buffer is only needed when packets were already buffered but
1552	* not decoded, for example to get the codec parameters in MPEG
1553	* streams.
1554	*/
1555	struct AVPacketList *packet_buffer;
1556	struct AVPacketList *packet_buffer_end;
1557
1558	/* av_seek_frame() support */
1559	int64_t data_offset; /**< offset of the first packet */
1560
1561	/**
1562	* Raw packets from the demuxer, prior to parsing and decoding.
1563	* This buffer is used for buffering packets until the codec can
1564	* be identified, as parsing cannot be done without knowing the
1565	* codec.
1566	*/
1567	struct AVPacketList *raw_packet_buffer;
1568	struct AVPacketList *raw_packet_buffer_end;
1569	/**
1570	* Packets split by the parser get queued here.
1571	*/
1572	struct AVPacketList *parse_queue;
1573	struct AVPacketList *parse_queue_end;
1574	/**
1575	* Remaining size available for raw_packet_buffer, in bytes.
1576	*/
1577	#define RAW_PACKET_BUFFER_SIZE 2500000
1578	int raw_packet_buffer_remaining_size;
1579
1580	/**
1581	* Offset to remap timestamps to be non-negative.
1582	* Expressed in timebase units.
1583	* @see AVStream.mux_ts_offset
1584	*/
1585	int64_t offset;
1586
1587	/**
1588	* Timebase for the timestamp offset.
1589	*/
1590	AVRational offset_timebase;
1591
1592	/**
1593	* An opaque field for libavformat internal usage.
1594	* Must not be accessed in any way by callers.
1595	*/
1596	AVFormatInternal *internal;
1597
1598	/**
1599	* IO repositioned flag.
1600	* This is set by avformat when the underlaying IO context read pointer
1601	* is repositioned, for example when doing byte based seeking.
1602	* Demuxers can use the flag to detect such changes.
1603	*/
1604	int io_repositioned;
1605
1606	/**
1607	* Forced video codec.
1608	* This allows forcing a specific decoder, even when there are multiple with
1609	* the same codec_id.
1610	* Demuxing: Set by user via av_format_set_video_codec (NO direct access).
1611	*/
1612	AVCodec *video_codec;
1613
1614	/**
1615	* Forced audio codec.
1616	* This allows forcing a specific decoder, even when there are multiple with
1617	* the same codec_id.
1618	* Demuxing: Set by user via av_format_set_audio_codec (NO direct access).
1619	*/
1620	AVCodec *audio_codec;
1621
1622	/**
1623	* Forced subtitle codec.
1624	* This allows forcing a specific decoder, even when there are multiple with
1625	* the same codec_id.
1626	* Demuxing: Set by user via av_format_set_subtitle_codec (NO direct access).
1627	*/
1628	AVCodec *subtitle_codec;
1629
1630	/**
1631	* Number of bytes to be written as padding in a metadata header.
1632	* Demuxing: Unused.
1633	* Muxing: Set by user via av_format_set_metadata_header_padding.
1634	*/
1635	int metadata_header_padding;
1636
1637	/**
1638	* User data.
1639	* This is a place for some private data of the user.
1640	* Mostly usable with control_message_cb or any future callbacks in device's context.
1641	*/
1642	void *opaque;
1643
1644	/**
1645	* Callback used by devices to communicate with application.
1646	*/
1647	av_format_control_message control_message_cb;
1648
1649	/**
1650	* Output timestamp offset, in microseconds.
1651	* Muxing: set by user via AVOptions (NO direct access)
1652	*/
1653	int64_t output_ts_offset;
1654
1655	/**
1656	* Maximum duration (in AV_TIME_BASE units) of the data read
1657	* from input in avformat_find_stream_info().
1658	* Demuxing only, set by the caller before avformat_find_stream_info()
1659	* via AVOptions (NO direct access).
1660	* Can be set to 0 to let avformat choose using a heuristic.
1661	*/
1662	int64_t max_analyze_duration2;
1663	} AVFormatContext;
1664
1665	int av_format_get_probe_score(const AVFormatContext *s);
1666	AVCodec * av_format_get_video_codec(const AVFormatContext *s);
1667	void av_format_set_video_codec(AVFormatContext *s, AVCodec *c);
1668	AVCodec * av_format_get_audio_codec(const AVFormatContext *s);
1669	void av_format_set_audio_codec(AVFormatContext *s, AVCodec *c);
1670	AVCodec * av_format_get_subtitle_codec(const AVFormatContext *s);
1671	void av_format_set_subtitle_codec(AVFormatContext *s, AVCodec *c);
1672	int av_format_get_metadata_header_padding(const AVFormatContext *s);
1673	void av_format_set_metadata_header_padding(AVFormatContext *s, int c);
1674	void * av_format_get_opaque(const AVFormatContext *s);
1675	void av_format_set_opaque(AVFormatContext *s, void *opaque);
1676	av_format_control_message av_format_get_control_message_cb(const AVFormatContext *s);
1677	void av_format_set_control_message_cb(AVFormatContext *s, av_format_control_message callback);
1678
1679	/**
1680	* This function will cause global side data to be injected in the next packet
1681	* of each stream as well as after any subsequent seek.
1682	*/
1683	void av_format_inject_global_side_data(AVFormatContext *s);
1684
1685	/**
1686	* Returns the method used to set ctx->duration.
1687	*
1688	* @return AVFMT_DURATION_FROM_PTS, AVFMT_DURATION_FROM_STREAM, or AVFMT_DURATION_FROM_BITRATE.
1689	*/
1690	enum AVDurationEstimationMethod av_fmt_ctx_get_duration_estimation_method(const AVFormatContext* ctx);
1691
1692	typedef struct AVPacketList {
1693	AVPacket pkt;
1694	struct AVPacketList *next;
1695	} AVPacketList;
1696
1697
1698	/**
1699	* @defgroup lavf_core Core functions
1700	* @ingroup libavf
1701	*
1702	* Functions for querying libavformat capabilities, allocating core structures,
1703	* etc.
1704	* @{
1705	*/
1706
1707	/**
1708	* Return the LIBAVFORMAT_VERSION_INT constant.
1709	*/
1710	unsigned avformat_version(void);
1711
1712	/**
1713	* Return the libavformat build-time configuration.
1714	*/
1715	const char *avformat_configuration(void);
1716
1717	/**
1718	* Return the libavformat license.
1719	*/
1720	const char *avformat_license(void);
1721
1722	/**
1723	* Initialize libavformat and register all the muxers, demuxers and
1724	* protocols. If you do not call this function, then you can select
1725	* exactly which formats you want to support.
1726	*
1727	* @see av_register_input_format()
1728	* @see av_register_output_format()
1729	*/
1730	void av_register_all(void);
1731
1732	void av_register_input_format(AVInputFormat *format);
1733	void av_register_output_format(AVOutputFormat *format);
1734
1735	/**
1736	* Do global initialization of network components. This is optional,
1737	* but recommended, since it avoids the overhead of implicitly
1738	* doing the setup for each session.
1739	*
1740	* Calling this function will become mandatory if using network
1741	* protocols at some major version bump.
1742	*/
1743	int avformat_network_init(void);
1744
1745	/**
1746	* Undo the initialization done by avformat_network_init.
1747	*/
1748	int avformat_network_deinit(void);
1749
1750	/**
1751	* If f is NULL, returns the first registered input format,
1752	* if f is non-NULL, returns the next registered input format after f
1753	* or NULL if f is the last one.
1754	*/
1755	AVInputFormat *av_iformat_next(AVInputFormat *f);
1756
1757	/**
1758	* If f is NULL, returns the first registered output format,
1759	* if f is non-NULL, returns the next registered output format after f
1760	* or NULL if f is the last one.
1761	*/
1762	AVOutputFormat *av_oformat_next(AVOutputFormat *f);
1763
1764	/**
1765	* Allocate an AVFormatContext.
1766	* avformat_free_context() can be used to free the context and everything
1767	* allocated by the framework within it.
1768	*/
1769	AVFormatContext *avformat_alloc_context(void);
1770
1771	/**
1772	* Free an AVFormatContext and all its streams.
1773	* @param s context to free
1774	*/
1775	void avformat_free_context(AVFormatContext *s);
1776
1777	/**
1778	* Get the AVClass for AVFormatContext. It can be used in combination with
1779	* AV_OPT_SEARCH_FAKE_OBJ for examining options.
1780	*
1781	* @see av_opt_find().
1782	*/
1783	const AVClass *avformat_get_class(void);
1784
1785	/**
1786	* Add a new stream to a media file.
1787	*
1788	* When demuxing, it is called by the demuxer in read_header(). If the
1789	* flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also
1790	* be called in read_packet().
1791	*
1792	* When muxing, should be called by the user before avformat_write_header().
1793	*
1794	* User is required to call avcodec_close() and avformat_free_context() to
1795	* clean up the allocation by avformat_new_stream().
1796	*
1797	* @param s media file handle
1798	* @param c If non-NULL, the AVCodecContext corresponding to the new stream
1799	* will be initialized to use this codec. This is needed for e.g. codec-specific
1800	* defaults to be set, so codec should be provided if it is known.
1801	*
1802	* @return newly created stream or NULL on error.
1803	*/
1804	AVStream *avformat_new_stream(AVFormatContext *s, const AVCodec *c);
1805
1806	/**
1807	* Get side information from stream.
1808	*
1809	* @param stream stream
1810	* @param type desired side information type
1811	* @param size pointer for side information size to store (optional)
1812	* @return pointer to data if present or NULL otherwise
1813	*/
1814	uint8_t *av_stream_get_side_data(AVStream *stream,
1815	enum AVPacketSideDataType type, int *size);
1816
1817	AVProgram *av_new_program(AVFormatContext *s, int id);
1818
1819	/**
1820	* @}
1821	*/
1822
1823
1824	#if FF_API_ALLOC_OUTPUT_CONTEXT
1825	/**
1826	* @deprecated deprecated in favor of avformat_alloc_output_context2()
1827	*/
1828	attribute_deprecated
1829	AVFormatContext *avformat_alloc_output_context(const char *format,
1830	AVOutputFormat *oformat,
1831	const char *filename);
1832	#endif
1833
1834	/**
1835	* Allocate an AVFormatContext for an output format.
1836	* avformat_free_context() can be used to free the context and
1837	* everything allocated by the framework within it.
1838	*
1839	* @param *ctx is set to the created format context, or to NULL in
1840	* case of failure
1841	* @param oformat format to use for allocating the context, if NULL
1842	* format_name and filename are used instead
1843	* @param format_name the name of output format to use for allocating the
1844	* context, if NULL filename is used instead
1845	* @param filename the name of the filename to use for allocating the
1846	* context, may be NULL
1847	* @return >= 0 in case of success, a negative AVERROR code in case of
1848	* failure
1849	*/
1850	int avformat_alloc_output_context2(AVFormatContext **ctx, AVOutputFormat *oformat,
1851	const char *format_name, const char *filename);
1852
1853	/**
1854	* @addtogroup lavf_decoding
1855	* @{
1856	*/
1857
1858	/**
1859	* Find AVInputFormat based on the short name of the input format.
1860	*/
1861	AVInputFormat *av_find_input_format(const char *short_name);
1862
1863	/**
1864	* Guess the file format.
1865	*
1866	* @param pd data to be probed
1867	* @param is_opened Whether the file is already opened; determines whether
1868	* demuxers with or without AVFMT_NOFILE are probed.
1869	*/
1870	AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened);
1871
1872	/**
1873	* Guess the file format.
1874	*
1875	* @param pd data to be probed
1876	* @param is_opened Whether the file is already opened; determines whether
1877	* demuxers with or without AVFMT_NOFILE are probed.
1878	* @param score_max A probe score larger that this is required to accept a
1879	* detection, the variable is set to the actual detection
1880	* score afterwards.
1881	* If the score is <= AVPROBE_SCORE_MAX / 4 it is recommended
1882	* to retry with a larger probe buffer.
1883	*/
1884	AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max);
1885
1886	/**
1887	* Guess the file format.
1888	*
1889	* @param is_opened Whether the file is already opened; determines whether
1890	* demuxers with or without AVFMT_NOFILE are probed.
1891	* @param score_ret The score of the best detection.
1892	*/
1893	AVInputFormat *av_probe_input_format3(AVProbeData *pd, int is_opened, int *score_ret);
1894
1895	/**
1896	* Probe a bytestream to determine the input format. Each time a probe returns
1897	* with a score that is too low, the probe buffer size is increased and another
1898	* attempt is made. When the maximum probe size is reached, the input format
1899	* with the highest score is returned.
1900	*
1901	* @param pb the bytestream to probe
1902	* @param fmt the input format is put here
1903	* @param filename the filename of the stream
1904	* @param logctx the log context
1905	* @param offset the offset within the bytestream to probe from
1906	* @param max_probe_size the maximum probe buffer size (zero for default)
1907	* @return the score in case of success, a negative value corresponding to an
1908	* the maximal score is AVPROBE_SCORE_MAX
1909	* AVERROR code otherwise
1910	*/
1911	int av_probe_input_buffer2(AVIOContext *pb, AVInputFormat **fmt,
1912	const char *filename, void *logctx,
1913	unsigned int offset, unsigned int max_probe_size);
1914
1915	/**
1916	* Like av_probe_input_buffer2() but returns 0 on success
1917	*/
1918	int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt,
1919	const char *filename, void *logctx,
1920	unsigned int offset, unsigned int max_probe_size);
1921
1922	/**
1923	* Open an input stream and read the header. The codecs are not opened.
1924	* The stream must be closed with avformat_close_input().
1925	*
1926	* @param ps Pointer to user-supplied AVFormatContext (allocated by avformat_alloc_context).
1927	* May be a pointer to NULL, in which case an AVFormatContext is allocated by this
1928	* function and written into ps.
1929	* Note that a user-supplied AVFormatContext will be freed on failure.
1930	* @param filename Name of the stream to open.
1931	* @param fmt If non-NULL, this parameter forces a specific input format.
1932	* Otherwise the format is autodetected.
1933	* @param options A dictionary filled with AVFormatContext and demuxer-private options.
1934	* On return this parameter will be destroyed and replaced with a dict containing
1935	* options that were not found. May be NULL.
1936	*
1937	* @return 0 on success, a negative AVERROR on failure.
1938	*
1939	* @note If you want to use custom IO, preallocate the format context and set its pb field.
1940	*/
1941	int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputFormat *fmt, AVDictionary **options);
1942
1943	attribute_deprecated
1944	int av_demuxer_open(AVFormatContext *ic);
1945
1946	#if FF_API_FORMAT_PARAMETERS
1947	/**
1948	* Read packets of a media file to get stream information. This
1949	* is useful for file formats with no headers such as MPEG. This
1950	* function also computes the real framerate in case of MPEG-2 repeat
1951	* frame mode.
1952	* The logical file position is not changed by this function;
1953	* examined packets may be buffered for later processing.
1954	*
1955	* @param ic media file handle
1956	* @return >=0 if OK, AVERROR_xxx on error
1957	* @todo Let the user decide somehow what information is needed so that
1958	* we do not waste time getting stuff the user does not need.
1959	*
1960	* @deprecated use avformat_find_stream_info.
1961	*/
1962	attribute_deprecated
1963	int av_find_stream_info(AVFormatContext *ic);
1964	#endif
1965
1966	/**
1967	* Read packets of a media file to get stream information. This
1968	* is useful for file formats with no headers such as MPEG. This
1969	* function also computes the real framerate in case of MPEG-2 repeat
1970	* frame mode.
1971	* The logical file position is not changed by this function;
1972	* examined packets may be buffered for later processing.
1973	*
1974	* @param ic media file handle
1975	* @param options If non-NULL, an ic.nb_streams long array of pointers to
1976	* dictionaries, where i-th member contains options for
1977	* codec corresponding to i-th stream.
1978	* On return each dictionary will be filled with options that were not found.
1979	* @return >=0 if OK, AVERROR_xxx on error
1980	*
1981	* @note this function isn't guaranteed to open all the codecs, so
1982	* options being non-empty at return is a perfectly normal behavior.
1983	*
1984	* @todo Let the user decide somehow what information is needed so that
1985	* we do not waste time getting stuff the user does not need.
1986	*/
1987	int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options);
1988
1989	/**
1990	* Find the programs which belong to a given stream.
1991	*
1992	* @param ic media file handle
1993	* @param last the last found program, the search will start after this
1994	* program, or from the beginning if it is NULL
1995	* @param s stream index
1996	* @return the next program which belongs to s, NULL if no program is found or
1997	* the last program is not among the programs of ic.
1998	*/
1999	AVProgram *av_find_program_from_stream(AVFormatContext *ic, AVProgram *last, int s);
2000
2001	/**
2002	* Find the "best" stream in the file.
2003	* The best stream is determined according to various heuristics as the most
2004	* likely to be what the user expects.
2005	* If the decoder parameter is non-NULL, av_find_best_stream will find the
2006	* default decoder for the stream's codec; streams for which no decoder can
2007	* be found are ignored.
2008	*
2009	* @param ic media file handle
2010	* @param type stream type: video, audio, subtitles, etc.
2011	* @param wanted_stream_nb user-requested stream number,
2012	* or -1 for automatic selection
2013	* @param related_stream try to find a stream related (eg. in the same
2014	* program) to this one, or -1 if none
2015	* @param decoder_ret if non-NULL, returns the decoder for the
2016	* selected stream
2017	* @param flags flags; none are currently defined
2018	* @return the non-negative stream number in case of success,
2019	* AVERROR_STREAM_NOT_FOUND if no stream with the requested type
2020	* could be found,
2021	* AVERROR_DECODER_NOT_FOUND if streams were found but no decoder
2022	* @note If av_find_best_stream returns successfully and decoder_ret is not
2023	* NULL, then *decoder_ret is guaranteed to be set to a valid AVCodec.
2024	*/
2025	int av_find_best_stream(AVFormatContext *ic,
2026	enum AVMediaType type,
2027	int wanted_stream_nb,
2028	int related_stream,
2029	AVCodec **decoder_ret,
2030	int flags);
2031
2032	#if FF_API_READ_PACKET
2033	/**
2034	* @deprecated use AVFMT_FLAG_NOFILLIN | AVFMT_FLAG_NOPARSE to read raw
2035	* unprocessed packets
2036	*
2037	* Read a transport packet from a media file.
2038	*
2039	* This function is obsolete and should never be used.
2040	* Use av_read_frame() instead.
2041	*
2042	* @param s media file handle
2043	* @param pkt is filled
2044	* @return 0 if OK, AVERROR_xxx on error
2045	*/
2046	attribute_deprecated
2047	int av_read_packet(AVFormatContext *s, AVPacket *pkt);
2048	#endif
2049
2050	/**
2051	* Return the next frame of a stream.
2052	* This function returns what is stored in the file, and does not validate
2053	* that what is there are valid frames for the decoder. It will split what is
2054	* stored in the file into frames and return one for each call. It will not
2055	* omit invalid data between valid frames so as to give the decoder the maximum
2056	* information possible for decoding.
2057	*
2058	* If pkt->buf is NULL, then the packet is valid until the next
2059	* av_read_frame() or until avformat_close_input(). Otherwise the packet
2060	* is valid indefinitely. In both cases the packet must be freed with
2061	* av_free_packet when it is no longer needed. For video, the packet contains
2062	* exactly one frame. For audio, it contains an integer number of frames if each
2063	* frame has a known fixed size (e.g. PCM or ADPCM data). If the audio frames
2064	* have a variable size (e.g. MPEG audio), then it contains one frame.
2065	*
2066	* pkt->pts, pkt->dts and pkt->duration are always set to correct
2067	* values in AVStream.time_base units (and guessed if the format cannot
2068	* provide them). pkt->pts can be AV_NOPTS_VALUE if the video format
2069	* has B-frames, so it is better to rely on pkt->dts if you do not
2070	* decompress the payload.
2071	*
2072	* @return 0 if OK, < 0 on error or end of file
2073	*/
2074	int av_read_frame(AVFormatContext *s, AVPacket *pkt);
2075
2076	/**
2077	* Seek to the keyframe at timestamp.
2078	* 'timestamp' in 'stream_index'.
2079	*
2080	* @param s media file handle
2081	* @param stream_index If stream_index is (-1), a default
2082	* stream is selected, and timestamp is automatically converted
2083	* from AV_TIME_BASE units to the stream specific time_base.
2084	* @param timestamp Timestamp in AVStream.time_base units
2085	* or, if no stream is specified, in AV_TIME_BASE units.
2086	* @param flags flags which select direction and seeking mode
2087	* @return >= 0 on success
2088	*/
2089	int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp,
2090	int flags);
2091
2092	/**
2093	* Seek to timestamp ts.
2094	* Seeking will be done so that the point from which all active streams
2095	* can be presented successfully will be closest to ts and within min/max_ts.
2096	* Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
2097	*
2098	* If flags contain AVSEEK_FLAG_BYTE, then all timestamps are in bytes and
2099	* are the file position (this may not be supported by all demuxers).
2100	* If flags contain AVSEEK_FLAG_FRAME, then all timestamps are in frames
2101	* in the stream with stream_index (this may not be supported by all demuxers).
2102	* Otherwise all timestamps are in units of the stream selected by stream_index
2103	* or if stream_index is -1, in AV_TIME_BASE units.
2104	* If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
2105	* keyframes (this may not be supported by all demuxers).
2106	* If flags contain AVSEEK_FLAG_BACKWARD, it is ignored.
2107	*
2108	* @param s media file handle
2109	* @param stream_index index of the stream which is used as time base reference
2110	* @param min_ts smallest acceptable timestamp
2111	* @param ts target timestamp
2112	* @param max_ts largest acceptable timestamp
2113	* @param flags flags
2114	* @return >=0 on success, error code otherwise
2115	*
2116	* @note This is part of the new seek API which is still under construction.
2117	* Thus do not use this yet. It may change at any time, do not expect
2118	* ABI compatibility yet!
2119	*/
2120	int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
2121
2122	/**
2123	* Start playing a network-based stream (e.g. RTSP stream) at the
2124	* current position.
2125	*/
2126	int av_read_play(AVFormatContext *s);
2127
2128	/**
2129	* Pause a network-based stream (e.g. RTSP stream).
2130	*
2131	* Use av_read_play() to resume it.
2132	*/
2133	int av_read_pause(AVFormatContext *s);
2134
2135	#if FF_API_CLOSE_INPUT_FILE
2136	/**
2137	* @deprecated use avformat_close_input()
2138	* Close a media file (but not its codecs).
2139	*
2140	* @param s media file handle
2141	*/
2142	attribute_deprecated
2143	void av_close_input_file(AVFormatContext *s);
2144	#endif
2145
2146	/**
2147	* Close an opened input AVFormatContext. Free it and all its contents
2148	* and set *s to NULL.
2149	*/
2150	void avformat_close_input(AVFormatContext **s);
2151	/**
2152	* @}
2153	*/
2154
2155	#if FF_API_NEW_STREAM
2156	/**
2157	* Add a new stream to a media file.
2158	*
2159	* Can only be called in the read_header() function. If the flag
2160	* AVFMTCTX_NOHEADER is in the format context, then new streams
2161	* can be added in read_packet too.
2162	*
2163	* @param s media file handle
2164	* @param id file-format-dependent stream ID
2165	*/
2166	attribute_deprecated
2167	AVStream *av_new_stream(AVFormatContext *s, int id);
2168	#endif
2169
2170	#if FF_API_SET_PTS_INFO
2171	/**
2172	* @deprecated this function is not supposed to be called outside of lavf
2173	*/
2174	attribute_deprecated
2175	void av_set_pts_info(AVStream *s, int pts_wrap_bits,
2176	unsigned int pts_num, unsigned int pts_den);
2177	#endif
2178
2179	#define AVSEEK_FLAG_BACKWARD 1 ///< seek backward
2180	#define AVSEEK_FLAG_BYTE 2 ///< seeking based on position in bytes
2181	#define AVSEEK_FLAG_ANY 4 ///< seek to any frame, even non-keyframes
2182	#define AVSEEK_FLAG_FRAME 8 ///< seeking based on frame number
2183
2184	/**
2185	* @addtogroup lavf_encoding
2186	* @{
2187	*/
2188	/**
2189	* Allocate the stream private data and write the stream header to
2190	* an output media file.
2191	*
2192	* @param s Media file handle, must be allocated with avformat_alloc_context().
2193	* Its oformat field must be set to the desired output format;
2194	* Its pb field must be set to an already opened AVIOContext.
2195	* @param options An AVDictionary filled with AVFormatContext and muxer-private options.
2196	* On return this parameter will be destroyed and replaced with a dict containing
2197	* options that were not found. May be NULL.
2198	*
2199	* @return 0 on success, negative AVERROR on failure.
2200	*
2201	* @see av_opt_find, av_dict_set, avio_open, av_oformat_next.
2202	*/
2203	int avformat_write_header(AVFormatContext *s, AVDictionary **options);
2204
2205	/**
2206	* Write a packet to an output media file.
2207	*
2208	* This function passes the packet directly to the muxer, without any buffering
2209	* or reordering. The caller is responsible for correctly interleaving the
2210	* packets if the format requires it. Callers that want libavformat to handle
2211	* the interleaving should call av_interleaved_write_frame() instead of this
2212	* function.
2213	*
2214	* @param s media file handle
2215	* @param pkt The packet containing the data to be written. Note that unlike
2216	* av_interleaved_write_frame(), this function does not take
2217	* ownership of the packet passed to it (though some muxers may make
2218	* an internal reference to the input packet).
2219	* <br>
2220	* This parameter can be NULL (at any time, not just at the end), in
2221	* order to immediately flush data buffered within the muxer, for
2222	* muxers that buffer up data internally before writing it to the
2223	* output.
2224	* <br>
2225	* Packet's @ref AVPacket.stream_index "stream_index" field must be
2226	* set to the index of the corresponding stream in @ref
2227	* AVFormatContext.streams "s->streams". It is very strongly
2228	* recommended that timing information (@ref AVPacket.pts "pts", @ref
2229	* AVPacket.dts "dts", @ref AVPacket.duration "duration") is set to
2230	* correct values.
2231	* @return < 0 on error, = 0 if OK, 1 if flushed and there is no more data to flush
2232	*
2233	* @see av_interleaved_write_frame()
2234	*/
2235	int av_write_frame(AVFormatContext *s, AVPacket *pkt);
2236
2237	/**
2238	* Write a packet to an output media file ensuring correct interleaving.
2239	*
2240	* This function will buffer the packets internally as needed to make sure the
2241	* packets in the output file are properly interleaved in the order of
2242	* increasing dts. Callers doing their own interleaving should call
2243	* av_write_frame() instead of this function.
2244	*
2245	* @param s media file handle
2246	* @param pkt The packet containing the data to be written.
2247	* <br>
2248	* If the packet is reference-counted, this function will take
2249	* ownership of this reference and unreference it later when it sees
2250	* fit.
2251	* The caller must not access the data through this reference after
2252	* this function returns. If the packet is not reference-counted,
2253	* libavformat will make a copy.
2254	* <br>
2255	* This parameter can be NULL (at any time, not just at the end), to
2256	* flush the interleaving queues.
2257	* <br>
2258	* Packet's @ref AVPacket.stream_index "stream_index" field must be
2259	* set to the index of the corresponding stream in @ref
2260	* AVFormatContext.streams "s->streams". It is very strongly
2261	* recommended that timing information (@ref AVPacket.pts "pts", @ref
2262	* AVPacket.dts "dts", @ref AVPacket.duration "duration") is set to
2263	* correct values.
2264	*
2265	* @return 0 on success, a negative AVERROR on error. Libavformat will always
2266	* take care of freeing the packet, even if this function fails.
2267	*
2268	* @see av_write_frame(), AVFormatContext.max_interleave_delta
2269	*/
2270	int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt);
2271
2272	/**
2273	* Write a uncoded frame to an output media file.
2274	*
2275	* The frame must be correctly interleaved according to the container
2276	* specification; if not, then av_interleaved_write_frame() must be used.
2277	*
2278	* See av_interleaved_write_frame() for details.
2279	*/
2280	int av_write_uncoded_frame(AVFormatContext *s, int stream_index,
2281	AVFrame *frame);
2282
2283	/**
2284	* Write a uncoded frame to an output media file.
2285	*
2286	* If the muxer supports it, this function allows to write an AVFrame
2287	* structure directly, without encoding it into a packet.
2288	* It is mostly useful for devices and similar special muxers that use raw
2289	* video or PCM data and will not serialize it into a byte stream.
2290	*
2291	* To test whether it is possible to use it with a given muxer and stream,
2292	* use av_write_uncoded_frame_query().
2293	*
2294	* The caller gives up ownership of the frame and must not access it
2295	* afterwards.
2296	*
2297	* @return >=0 for success, a negative code on error
2298	*/
2299	int av_interleaved_write_uncoded_frame(AVFormatContext *s, int stream_index,
2300	AVFrame *frame);
2301
2302	/**
2303	* Test whether a muxer supports uncoded frame.
2304	*
2305	* @return >=0 if an uncoded frame can be written to that muxer and stream,
2306	* <0 if not
2307	*/
2308	int av_write_uncoded_frame_query(AVFormatContext *s, int stream_index);
2309
2310	/**
2311	* Write the stream trailer to an output media file and free the
2312	* file private data.
2313	*
2314	* May only be called after a successful call to avformat_write_header.
2315	*
2316	* @param s media file handle
2317	* @return 0 if OK, AVERROR_xxx on error
2318	*/
2319	int av_write_trailer(AVFormatContext *s);
2320
2321	/**
2322	* Return the output format in the list of registered output formats
2323	* which best matches the provided parameters, or return NULL if
2324	* there is no match.
2325	*
2326	* @param short_name if non-NULL checks if short_name matches with the
2327	* names of the registered formats
2328	* @param filename if non-NULL checks if filename terminates with the
2329	* extensions of the registered formats
2330	* @param mime_type if non-NULL checks if mime_type matches with the
2331	* MIME type of the registered formats
2332	*/
2333	AVOutputFormat *av_guess_format(const char *short_name,
2334	const char *filename,
2335	const char *mime_type);
2336
2337	/**
2338	* Guess the codec ID based upon muxer and filename.
2339	*/
2340	enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
2341	const char *filename, const char *mime_type,
2342	enum AVMediaType type);
2343
2344	/**
2345	* Get timing information for the data currently output.
2346	* The exact meaning of "currently output" depends on the format.
2347	* It is mostly relevant for devices that have an internal buffer and/or
2348	* work in real time.
2349	* @param s media file handle
2350	* @param stream stream in the media file
2351	* @param[out] dts DTS of the last packet output for the stream, in stream
2352	* time_base units
2353	* @param[out] wall absolute time when that packet whas output,
2354	* in microsecond
2355	* @return 0 if OK, AVERROR(ENOSYS) if the format does not support it
2356	* Note: some formats or devices may not allow to measure dts and wall
2357	* atomically.
2358	*/
2359	int av_get_output_timestamp(struct AVFormatContext *s, int stream,
2360	int64_t *dts, int64_t *wall);
2361
2362
2363	/**
2364	* @}
2365	*/
2366
2367
2368	/**
2369	* @defgroup lavf_misc Utility functions
2370	* @ingroup libavf
2371	* @{
2372	*
2373	* Miscellaneous utility functions related to both muxing and demuxing
2374	* (or neither).
2375	*/
2376
2377	/**
2378	* Send a nice hexadecimal dump of a buffer to the specified file stream.
2379	*
2380	* @param f The file stream pointer where the dump should be sent to.
2381	* @param buf buffer
2382	* @param size buffer size
2383	*
2384	* @see av_hex_dump_log, av_pkt_dump2, av_pkt_dump_log2
2385	*/
2386	void av_hex_dump(FILE *f, const uint8_t *buf, int size);
2387
2388	/**
2389	* Send a nice hexadecimal dump of a buffer to the log.
2390	*
2391	* @param avcl A pointer to an arbitrary struct of which the first field is a
2392	* pointer to an AVClass struct.
2393	* @param level The importance level of the message, lower values signifying
2394	* higher importance.
2395	* @param buf buffer
2396	* @param size buffer size
2397	*
2398	* @see av_hex_dump, av_pkt_dump2, av_pkt_dump_log2
2399	*/
2400	void av_hex_dump_log(void *avcl, int level, const uint8_t *buf, int size);
2401
2402	/**
2403	* Send a nice dump of a packet to the specified file stream.
2404	*
2405	* @param f The file stream pointer where the dump should be sent to.
2406	* @param pkt packet to dump
2407	* @param dump_payload True if the payload must be displayed, too.
2408	* @param st AVStream that the packet belongs to
2409	*/
2410	void av_pkt_dump2(FILE *f, const AVPacket *pkt, int dump_payload, const AVStream *st);
2411
2412
2413	/**
2414	* Send a nice dump of a packet to the log.
2415	*
2416	* @param avcl A pointer to an arbitrary struct of which the first field is a
2417	* pointer to an AVClass struct.
2418	* @param level The importance level of the message, lower values signifying
2419	* higher importance.
2420	* @param pkt packet to dump
2421	* @param dump_payload True if the payload must be displayed, too.
2422	* @param st AVStream that the packet belongs to
2423	*/
2424	void av_pkt_dump_log2(void *avcl, int level, const AVPacket *pkt, int dump_payload,
2425	const AVStream *st);
2426
2427	/**
2428	* Get the AVCodecID for the given codec tag tag.
2429	* If no codec id is found returns AV_CODEC_ID_NONE.
2430	*
2431	* @param tags list of supported codec_id-codec_tag pairs, as stored
2432	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2433	* @param tag codec tag to match to a codec ID
2434	*/
2435	enum AVCodecID av_codec_get_id(const struct AVCodecTag * const *tags, unsigned int tag);
2436
2437	/**
2438	* Get the codec tag for the given codec id id.
2439	* If no codec tag is found returns 0.
2440	*
2441	* @param tags list of supported codec_id-codec_tag pairs, as stored
2442	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2443	* @param id codec ID to match to a codec tag
2444	*/
2445	unsigned int av_codec_get_tag(const struct AVCodecTag * const *tags, enum AVCodecID id);
2446
2447	/**
2448	* Get the codec tag for the given codec id.
2449	*
2450	* @param tags list of supported codec_id - codec_tag pairs, as stored
2451	* in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
2452	* @param id codec id that should be searched for in the list
2453	* @param tag A pointer to the found tag
2454	* @return 0 if id was not found in tags, > 0 if it was found
2455	*/
2456	int av_codec_get_tag2(const struct AVCodecTag * const *tags, enum AVCodecID id,
2457	unsigned int *tag);
2458
2459	int av_find_default_stream_index(AVFormatContext *s);
2460
2461	/**
2462	* Get the index for a specific timestamp.
2463	*
2464	* @param st stream that the timestamp belongs to
2465	* @param timestamp timestamp to retrieve the index for
2466	* @param flags if AVSEEK_FLAG_BACKWARD then the returned index will correspond
2467	* to the timestamp which is <= the requested one, if backward
2468	* is 0, then it will be >=
2469	* if AVSEEK_FLAG_ANY seek to any frame, only keyframes otherwise
2470	* @return < 0 if no such timestamp could be found
2471	*/
2472	int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags);
2473
2474	/**
2475	* Add an index entry into a sorted list. Update the entry if the list
2476	* already contains it.
2477	*
2478	* @param timestamp timestamp in the time base of the given stream
2479	*/
2480	int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
2481	int size, int distance, int flags);
2482
2483
2484	/**
2485	* Split a URL string into components.
2486	*
2487	* The pointers to buffers for storing individual components may be null,
2488	* in order to ignore that component. Buffers for components not found are
2489	* set to empty strings. If the port is not found, it is set to a negative
2490	* value.
2491	*
2492	* @param proto the buffer for the protocol
2493	* @param proto_size the size of the proto buffer
2494	* @param authorization the buffer for the authorization
2495	* @param authorization_size the size of the authorization buffer
2496	* @param hostname the buffer for the host name
2497	* @param hostname_size the size of the hostname buffer
2498	* @param port_ptr a pointer to store the port number in
2499	* @param path the buffer for the path
2500	* @param path_size the size of the path buffer
2501	* @param url the URL to split
2502	*/
2503	void av_url_split(char *proto, int proto_size,
2504	char *authorization, int authorization_size,
2505	char *hostname, int hostname_size,
2506	int *port_ptr,
2507	char *path, int path_size,
2508	const char *url);
2509
2510
2511	/**
2512	* Print detailed information about the input or output format, such as
2513	* duration, bitrate, streams, container, programs, metadata, side data,
2514	* codec and time base.
2515	*
2516	* @param ic the context to analyze
2517	* @param index index of the stream to dump information about
2518	* @param url the URL to print, such as source or destination file
2519	* @param is_output Select whether the specified context is an input(0) or output(1)
2520	*/
2521	void av_dump_format(AVFormatContext *ic,
2522	int index,
2523	const char *url,
2524	int is_output);
2525
2526	/**
2527	* Return in 'buf' the path with '%d' replaced by a number.
2528	*
2529	* Also handles the '%0nd' format where 'n' is the total number
2530	* of digits and '%%'.
2531	*
2532	* @param buf destination buffer
2533	* @param buf_size destination buffer size
2534	* @param path numbered sequence string
2535	* @param number frame number
2536	* @return 0 if OK, -1 on format error
2537	*/
2538	int av_get_frame_filename(char *buf, int buf_size,
2539	const char *path, int number);
2540
2541	/**
2542	* Check whether filename actually is a numbered sequence generator.
2543	*
2544	* @param filename possible numbered sequence string
2545	* @return 1 if a valid numbered sequence string, 0 otherwise
2546	*/
2547	int av_filename_number_test(const char *filename);
2548
2549	/**
2550	* Generate an SDP for an RTP session.
2551	*
2552	* Note, this overwrites the id values of AVStreams in the muxer contexts
2553	* for getting unique dynamic payload types.
2554	*
2555	* @param ac array of AVFormatContexts describing the RTP streams. If the
2556	* array is composed by only one context, such context can contain
2557	* multiple AVStreams (one AVStream per RTP stream). Otherwise,
2558	* all the contexts in the array (an AVCodecContext per RTP stream)
2559	* must contain only one AVStream.
2560	* @param n_files number of AVCodecContexts contained in ac
2561	* @param buf buffer where the SDP will be stored (must be allocated by
2562	* the caller)
2563	* @param size the size of the buffer
2564	* @return 0 if OK, AVERROR_xxx on error
2565	*/
2566	int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size);
2567
2568	/**
2569	* Return a positive value if the given filename has one of the given
2570	* extensions, 0 otherwise.
2571	*
2572	* @param filename file name to check against the given extensions
2573	* @param extensions a comma-separated list of filename extensions
2574	*/
2575	int av_match_ext(const char *filename, const char *extensions);
2576
2577	/**
2578	* Test if the given container can store a codec.
2579	*
2580	* @param ofmt container to check for compatibility
2581	* @param codec_id codec to potentially store in container
2582	* @param std_compliance standards compliance level, one of FF_COMPLIANCE_*
2583	*
2584	* @return 1 if codec with ID codec_id can be stored in ofmt, 0 if it cannot.
2585	* A negative number if this information is not available.
2586	*/
2587	int avformat_query_codec(AVOutputFormat *ofmt, enum AVCodecID codec_id, int std_compliance);
2588
2589	/**
2590	* @defgroup riff_fourcc RIFF FourCCs
2591	* @{
2592	* Get the tables mapping RIFF FourCCs to libavcodec AVCodecIDs. The tables are
2593	* meant to be passed to av_codec_get_id()/av_codec_get_tag() as in the
2594	* following code:
2595	* @code
2596	* uint32_t tag = MKTAG('H', '2', '6', '4');
2597	* const struct AVCodecTag *table[] = { avformat_get_riff_video_tags(), 0 };
2598	* enum AVCodecID id = av_codec_get_id(table, tag);
2599	* @endcode
2600	*/
2601	/**
2602	* @return the table mapping RIFF FourCCs for video to libavcodec AVCodecID.
2603	*/
2604	const struct AVCodecTag *avformat_get_riff_video_tags(void);
2605	/**
2606	* @return the table mapping RIFF FourCCs for audio to AVCodecID.
2607	*/
2608	const struct AVCodecTag *avformat_get_riff_audio_tags(void);
2609	/**
2610	* @return the table mapping MOV FourCCs for video to libavcodec AVCodecID.
2611	*/
2612	const struct AVCodecTag *avformat_get_mov_video_tags(void);
2613	/**
2614	* @return the table mapping MOV FourCCs for audio to AVCodecID.
2615	*/
2616	const struct AVCodecTag *avformat_get_mov_audio_tags(void);
2617
2618	/**
2619	* @}
2620	*/
2621
2622	/**
2623	* Guess the sample aspect ratio of a frame, based on both the stream and the
2624	* frame aspect ratio.
2625	*
2626	* Since the frame aspect ratio is set by the codec but the stream aspect ratio
2627	* is set by the demuxer, these two may not be equal. This function tries to
2628	* return the value that you should use if you would like to display the frame.
2629	*
2630	* Basic logic is to use the stream aspect ratio if it is set to something sane
2631	* otherwise use the frame aspect ratio. This way a container setting, which is
2632	* usually easy to modify can override the coded value in the frames.
2633	*
2634	* @param format the format context which the stream is part of
2635	* @param stream the stream which the frame is part of
2636	* @param frame the frame with the aspect ratio to be determined
2637	* @return the guessed (valid) sample_aspect_ratio, 0/1 if no idea
2638	*/
2639	AVRational av_guess_sample_aspect_ratio(AVFormatContext *format, AVStream *stream, AVFrame *frame);
2640
2641	/**
2642	* Guess the frame rate, based on both the container and codec information.
2643	*
2644	* @param ctx the format context which the stream is part of
2645	* @param stream the stream which the frame is part of
2646	* @param frame the frame for which the frame rate should be determined, may be NULL
2647	* @return the guessed (valid) frame rate, 0/1 if no idea
2648	*/
2649	AVRational av_guess_frame_rate(AVFormatContext *ctx, AVStream *stream, AVFrame *frame);
2650
2651	/**
2652	* Check if the stream st contained in s is matched by the stream specifier
2653	* spec.
2654	*
2655	* See the "stream specifiers" chapter in the documentation for the syntax
2656	* of spec.
2657	*
2658	* @return >0 if st is matched by spec;
2659	* 0 if st is not matched by spec;
2660	* AVERROR code if spec is invalid
2661	*
2662	* @note A stream specifier can match several streams in the format.
2663	*/
2664	int avformat_match_stream_specifier(AVFormatContext *s, AVStream *st,
2665	const char *spec);
2666
2667	int avformat_queue_attached_pictures(AVFormatContext *s);
2668
2669
2670	/**
2671	* @}
2672	*/
2673
2674	#endif /* AVFORMAT_AVFORMAT_H */
2675

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