lavf: extend / improve the AVFormatContext doxy
[libav.git] / libavformat / avformat.h
1 /*
2 * copyright (c) 2001 Fabrice Bellard
3 *
4 * This file is part of Libav.
5 *
6 * Libav 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 * Libav 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 Libav; 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 Libav 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 AVCodecContext.time_base "codec 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 the
222 * caller set on the codec context.
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
265 /**
266 * @defgroup metadata_api Public Metadata API
267 * @{
268 * @ingroup libavf
269 * The metadata API allows libavformat to export metadata tags to a client
270 * application when demuxing. Conversely it allows a client application to
271 * set metadata when muxing.
272 *
273 * Metadata is exported or set as pairs of key/value strings in the 'metadata'
274 * fields of the AVFormatContext, AVStream, AVChapter and AVProgram structs
275 * using the @ref lavu_dict "AVDictionary" API. Like all strings in Libav,
276 * metadata is assumed to be UTF-8 encoded Unicode. Note that metadata
277 * exported by demuxers isn't checked to be valid UTF-8 in most cases.
278 *
279 * Important concepts to keep in mind:
280 * - Keys are unique; there can never be 2 tags with the same key. This is
281 * also meant semantically, i.e., a demuxer should not knowingly produce
282 * several keys that are literally different but semantically identical.
283 * E.g., key=Author5, key=Author6. In this example, all authors must be
284 * placed in the same tag.
285 * - Metadata is flat, not hierarchical; there are no subtags. If you
286 * want to store, e.g., the email address of the child of producer Alice
287 * and actor Bob, that could have key=alice_and_bobs_childs_email_address.
288 * - Several modifiers can be applied to the tag name. This is done by
289 * appending a dash character ('-') and the modifier name in the order
290 * they appear in the list below -- e.g. foo-eng-sort, not foo-sort-eng.
291 * - language -- a tag whose value is localized for a particular language
292 * is appended with the ISO 639-2/B 3-letter language code.
293 * For example: Author-ger=Michael, Author-eng=Mike
294 * The original/default language is in the unqualified "Author" tag.
295 * A demuxer should set a default if it sets any translated tag.
296 * - sorting -- a modified version of a tag that should be used for
297 * sorting will have '-sort' appended. E.g. artist="The Beatles",
298 * artist-sort="Beatles, The".
299 *
300 * - Demuxers attempt to export metadata in a generic format, however tags
301 * with no generic equivalents are left as they are stored in the container.
302 * Follows a list of generic tag names:
303 *
304 @verbatim
305 album -- name of the set this work belongs to
306 album_artist -- main creator of the set/album, if different from artist.
307 e.g. "Various Artists" for compilation albums.
308 artist -- main creator of the work
309 comment -- any additional description of the file.
310 composer -- who composed the work, if different from artist.
311 copyright -- name of copyright holder.
312 creation_time-- date when the file was created, preferably in ISO 8601.
313 date -- date when the work was created, preferably in ISO 8601.
314 disc -- number of a subset, e.g. disc in a multi-disc collection.
315 encoder -- name/settings of the software/hardware that produced the file.
316 encoded_by -- person/group who created the file.
317 filename -- original name of the file.
318 genre -- <self-evident>.
319 language -- main language in which the work is performed, preferably
320 in ISO 639-2 format. Multiple languages can be specified by
321 separating them with commas.
322 performer -- artist who performed the work, if different from artist.
323 E.g for "Also sprach Zarathustra", artist would be "Richard
324 Strauss" and performer "London Philharmonic Orchestra".
325 publisher -- name of the label/publisher.
326 service_name -- name of the service in broadcasting (channel name).
327 service_provider -- name of the service provider in broadcasting.
328 title -- name of the work.
329 track -- number of this work in the set, can be in form current/total.
330 variant_bitrate -- the total bitrate of the bitrate variant that the current stream is part of
331 @endverbatim
332 *
333 * Look in the examples section for an application example how to use the Metadata API.
334 *
335 * @}
336 */
337
338 /* packet functions */
339
340
341 /**
342 * Allocate and read the payload of a packet and initialize its
343 * fields with default values.
344 *
345 * @param pkt packet
346 * @param size desired payload size
347 * @return >0 (read size) if OK, AVERROR_xxx otherwise
348 */
349 int av_get_packet(AVIOContext *s, AVPacket *pkt, int size);
350
351
352 /**
353 * Read data and append it to the current content of the AVPacket.
354 * If pkt->size is 0 this is identical to av_get_packet.
355 * Note that this uses av_grow_packet and thus involves a realloc
356 * which is inefficient. Thus this function should only be used
357 * when there is no reasonable way to know (an upper bound of)
358 * the final size.
359 *
360 * @param pkt packet
361 * @param size amount of data to read
362 * @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data
363 * will not be lost even if an error occurs.
364 */
365 int av_append_packet(AVIOContext *s, AVPacket *pkt, int size);
366
367 /*************************************************/
368 /* fractional numbers for exact pts handling */
369
370 /**
371 * The exact value of the fractional number is: 'val + num / den'.
372 * num is assumed to be 0 <= num < den.
373 */
374 typedef struct AVFrac {
375 int64_t val, num, den;
376 } AVFrac;
377
378 /*************************************************/
379 /* input/output formats */
380
381 struct AVCodecTag;
382
383 /**
384 * This structure contains the data a format has to probe a file.
385 */
386 typedef struct AVProbeData {
387 const char *filename;
388 unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
389 int buf_size; /**< Size of buf except extra allocated bytes */
390 } AVProbeData;
391
392 #define AVPROBE_SCORE_EXTENSION 50 ///< score for file extension
393 #define AVPROBE_SCORE_MAX 100 ///< maximum score
394
395 #define AVPROBE_PADDING_SIZE 32 ///< extra allocated bytes at the end of the probe buffer
396
397 /// Demuxer will use avio_open, no opened file should be provided by the caller.
398 #define AVFMT_NOFILE 0x0001
399 #define AVFMT_NEEDNUMBER 0x0002 /**< Needs '%d' in filename. */
400 #define AVFMT_SHOW_IDS 0x0008 /**< Show format stream IDs numbers. */
401 #define AVFMT_RAWPICTURE 0x0020 /**< Format wants AVPicture structure for
402 raw picture data. */
403 #define AVFMT_GLOBALHEADER 0x0040 /**< Format wants global header. */
404 #define AVFMT_NOTIMESTAMPS 0x0080 /**< Format does not need / have any timestamps. */
405 #define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */
406 #define AVFMT_TS_DISCONT 0x0200 /**< Format allows timestamp discontinuities. Note, muxers always require valid (monotone) timestamps */
407 #define AVFMT_VARIABLE_FPS 0x0400 /**< Format allows variable fps. */
408 #define AVFMT_NODIMENSIONS 0x0800 /**< Format does not need width/height */
409 #define AVFMT_NOSTREAMS 0x1000 /**< Format does not require any streams */
410 #define AVFMT_NOBINSEARCH 0x2000 /**< Format does not allow to fall back on binary search via read_timestamp */
411 #define AVFMT_NOGENSEARCH 0x4000 /**< Format does not allow to fall back on generic search */
412 #define AVFMT_NO_BYTE_SEEK 0x8000 /**< Format does not allow seeking by bytes */
413 #define AVFMT_ALLOW_FLUSH 0x10000 /**< Format allows flushing. If not set, the muxer will not receive a NULL packet in the write_packet function. */
414 #define AVFMT_TS_NONSTRICT 0x20000 /**< Format does not require strictly
415 increasing timestamps, but they must
416 still be monotonic */
417 #define AVFMT_TS_NEGATIVE 0x40000 /**< Format allows muxing negative
418 timestamps. If not set the timestamp
419 will be shifted in av_write_frame and
420 av_interleaved_write_frame so they
421 start from 0. */
422
423 /**
424 * @addtogroup lavf_encoding
425 * @{
426 */
427 typedef struct AVOutputFormat {
428 const char *name;
429 /**
430 * Descriptive name for the format, meant to be more human-readable
431 * than name. You should use the NULL_IF_CONFIG_SMALL() macro
432 * to define it.
433 */
434 const char *long_name;
435 const char *mime_type;
436 const char *extensions; /**< comma-separated filename extensions */
437 /* output support */
438 enum AVCodecID audio_codec; /**< default audio codec */
439 enum AVCodecID video_codec; /**< default video codec */
440 enum AVCodecID subtitle_codec; /**< default subtitle codec */
441 /**
442 * can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_RAWPICTURE,
443 * AVFMT_GLOBALHEADER, AVFMT_NOTIMESTAMPS, AVFMT_VARIABLE_FPS,
444 * AVFMT_NODIMENSIONS, AVFMT_NOSTREAMS, AVFMT_ALLOW_FLUSH,
445 * AVFMT_TS_NONSTRICT
446 */
447 int flags;
448
449 /**
450 * List of supported codec_id-codec_tag pairs, ordered by "better
451 * choice first". The arrays are all terminated by AV_CODEC_ID_NONE.
452 */
453 const struct AVCodecTag * const *codec_tag;
454
455
456 const AVClass *priv_class; ///< AVClass for the private context
457
458 /*****************************************************************
459 * No fields below this line are part of the public API. They
460 * may not be used outside of libavformat and can be changed and
461 * removed at will.
462 * New public fields should be added right above.
463 *****************************************************************
464 */
465 struct AVOutputFormat *next;
466 /**
467 * size of private data so that it can be allocated in the wrapper
468 */
469 int priv_data_size;
470
471 int (*write_header)(struct AVFormatContext *);
472 /**
473 * Write a packet. If AVFMT_ALLOW_FLUSH is set in flags,
474 * pkt can be NULL in order to flush data buffered in the muxer.
475 * When flushing, return 0 if there still is more data to flush,
476 * or 1 if everything was flushed and there is no more buffered
477 * data.
478 */
479 int (*write_packet)(struct AVFormatContext *, AVPacket *pkt);
480 int (*write_trailer)(struct AVFormatContext *);
481 /**
482 * Currently only used to set pixel format if not YUV420P.
483 */
484 int (*interleave_packet)(struct AVFormatContext *, AVPacket *out,
485 AVPacket *in, int flush);
486 /**
487 * Test if the given codec can be stored in this container.
488 *
489 * @return 1 if the codec is supported, 0 if it is not.
490 * A negative number if unknown.
491 */
492 int (*query_codec)(enum AVCodecID id, int std_compliance);
493 } AVOutputFormat;
494 /**
495 * @}
496 */
497
498 /**
499 * @addtogroup lavf_decoding
500 * @{
501 */
502 typedef struct AVInputFormat {
503 /**
504 * A comma separated list of short names for the format. New names
505 * may be appended with a minor bump.
506 */
507 const char *name;
508
509 /**
510 * Descriptive name for the format, meant to be more human-readable
511 * than name. You should use the NULL_IF_CONFIG_SMALL() macro
512 * to define it.
513 */
514 const char *long_name;
515
516 /**
517 * Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS,
518 * AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH,
519 * AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK.
520 */
521 int flags;
522
523 /**
524 * If extensions are defined, then no probe is done. You should
525 * usually not use extension format guessing because it is not
526 * reliable enough
527 */
528 const char *extensions;
529
530 const struct AVCodecTag * const *codec_tag;
531
532 const AVClass *priv_class; ///< AVClass for the private context
533
534 /*****************************************************************
535 * No fields below this line are part of the public API. They
536 * may not be used outside of libavformat and can be changed and
537 * removed at will.
538 * New public fields should be added right above.
539 *****************************************************************
540 */
541 struct AVInputFormat *next;
542
543 /**
544 * Raw demuxers store their codec ID here.
545 */
546 int raw_codec_id;
547
548 /**
549 * Size of private data so that it can be allocated in the wrapper.
550 */
551 int priv_data_size;
552
553 /**
554 * Tell if a given file has a chance of being parsed as this format.
555 * The buffer provided is guaranteed to be AVPROBE_PADDING_SIZE bytes
556 * big so you do not have to check for that unless you need more.
557 */
558 int (*read_probe)(AVProbeData *);
559
560 /**
561 * Read the format header and initialize the AVFormatContext
562 * structure. Return 0 if OK. Only used in raw format right
563 * now. 'avformat_new_stream' should be called to create new streams.
564 */
565 int (*read_header)(struct AVFormatContext *);
566
567 /**
568 * Read one packet and put it in 'pkt'. pts and flags are also
569 * set. 'avformat_new_stream' can be called only if the flag
570 * AVFMTCTX_NOHEADER is used and only in the calling thread (not in a
571 * background thread).
572 * @return 0 on success, < 0 on error.
573 * When returning an error, pkt must not have been allocated
574 * or must be freed before returning
575 */
576 int (*read_packet)(struct AVFormatContext *, AVPacket *pkt);
577
578 /**
579 * Close the stream. The AVFormatContext and AVStreams are not
580 * freed by this function
581 */
582 int (*read_close)(struct AVFormatContext *);
583
584 /**
585 * Seek to a given timestamp relative to the frames in
586 * stream component stream_index.
587 * @param stream_index Must not be -1.
588 * @param flags Selects which direction should be preferred if no exact
589 * match is available.
590 * @return >= 0 on success (but not necessarily the new offset)
591 */
592 int (*read_seek)(struct AVFormatContext *,
593 int stream_index, int64_t timestamp, int flags);
594
595 /**
596 * Get the next timestamp in stream[stream_index].time_base units.
597 * @return the timestamp or AV_NOPTS_VALUE if an error occurred
598 */
599 int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,
600 int64_t *pos, int64_t pos_limit);
601
602 /**
603 * Start/resume playing - only meaningful if using a network-based format
604 * (RTSP).
605 */
606 int (*read_play)(struct AVFormatContext *);
607
608 /**
609 * Pause playing - only meaningful if using a network-based format
610 * (RTSP).
611 */
612 int (*read_pause)(struct AVFormatContext *);
613
614 /**
615 * Seek to timestamp ts.
616 * Seeking will be done so that the point from which all active streams
617 * can be presented successfully will be closest to ts and within min/max_ts.
618 * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
619 */
620 int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
621 } AVInputFormat;
622 /**
623 * @}
624 */
625
626 enum AVStreamParseType {
627 AVSTREAM_PARSE_NONE,
628 AVSTREAM_PARSE_FULL, /**< full parsing and repack */
629 AVSTREAM_PARSE_HEADERS, /**< Only parse headers, do not repack. */
630 AVSTREAM_PARSE_TIMESTAMPS, /**< full parsing and interpolation of timestamps for frames not starting on a packet boundary */
631 AVSTREAM_PARSE_FULL_ONCE, /**< full parsing and repack of the first frame only, only implemented for H.264 currently */
632 };
633
634 typedef struct AVIndexEntry {
635 int64_t pos;
636 int64_t timestamp;
637 #define AVINDEX_KEYFRAME 0x0001
638 int flags:2;
639 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).
640 int min_distance; /**< Minimum distance between this and the previous keyframe, used to avoid unneeded searching. */
641 } AVIndexEntry;
642
643 #define AV_DISPOSITION_DEFAULT 0x0001
644 #define AV_DISPOSITION_DUB 0x0002
645 #define AV_DISPOSITION_ORIGINAL 0x0004
646 #define AV_DISPOSITION_COMMENT 0x0008
647 #define AV_DISPOSITION_LYRICS 0x0010
648 #define AV_DISPOSITION_KARAOKE 0x0020
649
650 /**
651 * Track should be used during playback by default.
652 * Useful for subtitle track that should be displayed
653 * even when user did not explicitly ask for subtitles.
654 */
655 #define AV_DISPOSITION_FORCED 0x0040
656 #define AV_DISPOSITION_HEARING_IMPAIRED 0x0080 /**< stream for hearing impaired audiences */
657 #define AV_DISPOSITION_VISUAL_IMPAIRED 0x0100 /**< stream for visual impaired audiences */
658 #define AV_DISPOSITION_CLEAN_EFFECTS 0x0200 /**< stream without voice */
659 /**
660 * The stream is stored in the file as an attached picture/"cover art" (e.g.
661 * APIC frame in ID3v2). The single packet associated with it will be returned
662 * among the first few packets read from the file unless seeking takes place.
663 * It can also be accessed at any time in AVStream.attached_pic.
664 */
665 #define AV_DISPOSITION_ATTACHED_PIC 0x0400
666
667 /**
668 * Stream structure.
669 * New fields can be added to the end with minor version bumps.
670 * Removal, reordering and changes to existing fields require a major
671 * version bump.
672 * sizeof(AVStream) must not be used outside libav*.
673 */
674 typedef struct AVStream {
675 int index; /**< stream index in AVFormatContext */
676 /**
677 * Format-specific stream ID.
678 * decoding: set by libavformat
679 * encoding: set by the user, replaced by libavformat if left unset
680 */
681 int id;
682 /**
683 * Codec context associated with this stream. Allocated and freed by
684 * libavformat.
685 *
686 * - decoding: The demuxer exports codec information stored in the headers
687 * here.
688 * - encoding: The user sets codec information, the muxer writes it to the
689 * output. Mandatory fields as specified in AVCodecContext
690 * documentation must be set even if this AVCodecContext is
691 * not actually used for encoding.
692 */
693 AVCodecContext *codec;
694 void *priv_data;
695
696 /**
697 * encoding: pts generation when outputting stream
698 */
699 struct AVFrac pts;
700
701 /**
702 * This is the fundamental unit of time (in seconds) in terms
703 * of which frame timestamps are represented.
704 *
705 * decoding: set by libavformat
706 * encoding: set by libavformat in avformat_write_header. The muxer may use the
707 * user-provided value of @ref AVCodecContext.time_base "codec->time_base"
708 * as a hint.
709 */
710 AVRational time_base;
711
712 /**
713 * Decoding: pts of the first frame of the stream, in stream time base.
714 * Only set this if you are absolutely 100% sure that the value you set
715 * it to really is the pts of the first frame.
716 * This may be undefined (AV_NOPTS_VALUE).
717 */
718 int64_t start_time;
719
720 /**
721 * Decoding: duration of the stream, in stream time base.
722 * If a source file does not specify a duration, but does specify
723 * a bitrate, this value will be estimated from bitrate and file size.
724 */
725 int64_t duration;
726
727 int64_t nb_frames; ///< number of frames in this stream if known or 0
728
729 int disposition; /**< AV_DISPOSITION_* bit field */
730
731 enum AVDiscard discard; ///< Selects which packets can be discarded at will and do not need to be demuxed.
732
733 /**
734 * sample aspect ratio (0 if unknown)
735 * - encoding: Set by user.
736 * - decoding: Set by libavformat.
737 */
738 AVRational sample_aspect_ratio;
739
740 AVDictionary *metadata;
741
742 /**
743 * Average framerate
744 */
745 AVRational avg_frame_rate;
746
747 /**
748 * For streams with AV_DISPOSITION_ATTACHED_PIC disposition, this packet
749 * will contain the attached picture.
750 *
751 * decoding: set by libavformat, must not be modified by the caller.
752 * encoding: unused
753 */
754 AVPacket attached_pic;
755
756 /*****************************************************************
757 * All fields below this line are not part of the public API. They
758 * may not be used outside of libavformat and can be changed and
759 * removed at will.
760 * New public fields should be added right above.
761 *****************************************************************
762 */
763
764 /**
765 * Stream information used internally by av_find_stream_info()
766 */
767 #define MAX_STD_TIMEBASES (60*12+5)
768 struct {
769 int nb_decoded_frames;
770 int found_decoder;
771
772 /**
773 * Those are used for average framerate estimation.
774 */
775 int64_t fps_first_dts;
776 int fps_first_dts_idx;
777 int64_t fps_last_dts;
778 int fps_last_dts_idx;
779
780 } *info;
781
782 int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */
783
784 #if FF_API_REFERENCE_DTS
785 /* a hack to keep ABI compatibility for avconv, which accesses parser even
786 * though it should not */
787 int64_t do_not_use;
788 #endif
789 // Timestamp generation support:
790 int64_t first_dts;
791 int64_t cur_dts;
792 int64_t last_IP_pts;
793 int last_IP_duration;
794
795 /**
796 * Number of packets to buffer for codec probing
797 */
798 #define MAX_PROBE_PACKETS 2500
799 int probe_packets;
800
801 /**
802 * Number of frames that have been demuxed during av_find_stream_info()
803 */
804 int codec_info_nb_frames;
805
806 /* av_read_frame() support */
807 enum AVStreamParseType need_parsing;
808 struct AVCodecParserContext *parser;
809
810 /**
811 * last packet in packet_buffer for this stream when muxing.
812 */
813 struct AVPacketList *last_in_packet_buffer;
814 AVProbeData probe_data;
815 #define MAX_REORDER_DELAY 16
816 int64_t pts_buffer[MAX_REORDER_DELAY+1];
817
818 AVIndexEntry *index_entries; /**< Only used if the format does not
819 support seeking natively. */
820 int nb_index_entries;
821 unsigned int index_entries_allocated_size;
822 } AVStream;
823
824 #define AV_PROGRAM_RUNNING 1
825
826 /**
827 * New fields can be added to the end with minor version bumps.
828 * Removal, reordering and changes to existing fields require a major
829 * version bump.
830 * sizeof(AVProgram) must not be used outside libav*.
831 */
832 typedef struct AVProgram {
833 int id;
834 int flags;
835 enum AVDiscard discard; ///< selects which program to discard and which to feed to the caller
836 unsigned int *stream_index;
837 unsigned int nb_stream_indexes;
838 AVDictionary *metadata;
839 } AVProgram;
840
841 #define AVFMTCTX_NOHEADER 0x0001 /**< signal that no header is present
842 (streams are added dynamically) */
843
844 typedef struct AVChapter {
845 int id; ///< unique ID to identify the chapter
846 AVRational time_base; ///< time base in which the start/end timestamps are specified
847 int64_t start, end; ///< chapter start/end time in time_base units
848 AVDictionary *metadata;
849 } AVChapter;
850
851 typedef struct AVFormatInternal AVFormatInternal;
852
853 /**
854 * Format I/O context.
855 * New fields can be added to the end with minor version bumps.
856 * Removal, reordering and changes to existing fields require a major
857 * version bump.
858 * sizeof(AVFormatContext) must not be used outside libav*, use
859 * avformat_alloc_context() to create an AVFormatContext.
860 */
861 typedef struct AVFormatContext {
862 /**
863 * A class for logging and @ref avoptions. Set by avformat_alloc_context().
864 * Exports (de)muxer private options if they exist.
865 */
866 const AVClass *av_class;
867
868 /**
869 * The input container format.
870 *
871 * Demuxing only, set by avformat_open_input().
872 */
873 struct AVInputFormat *iformat;
874
875 /**
876 * The output container format.
877 *
878 * Muxing only, must be set by the caller before avformat_write_header().
879 */
880 struct AVOutputFormat *oformat;
881
882 /**
883 * Format private data. This is an AVOptions-enabled struct
884 * if and only if iformat/oformat.priv_class is not NULL.
885 *
886 * - muxing: set by avformat_write_header()
887 * - demuxing: set by avformat_open_input()
888 */
889 void *priv_data;
890
891 /**
892 * I/O context.
893 *
894 * - demuxing: either set by the user before avformat_open_input() (then
895 * the user must close it manually) or set by avformat_open_input().
896 * - muxing: set by the user before avformat_write_header(). The caller must
897 * take care of closing / freeing the IO context.
898 *
899 * Do NOT set this field if AVFMT_NOFILE flag is set in
900 * iformat/oformat.flags. In such a case, the (de)muxer will handle
901 * I/O in some other way and this field will be NULL.
902 */
903 AVIOContext *pb;
904
905 /* stream info */
906 int ctx_flags; /**< Format-specific flags, see AVFMTCTX_xx */
907
908 /**
909 * Number of elements in AVFormatContext.streams.
910 *
911 * Set by avformat_new_stream(), must not be modified by any other code.
912 */
913 unsigned int nb_streams;
914 /**
915 * A list of all streams in the file. New streams are created with
916 * avformat_new_stream().
917 *
918 * - demuxing: streams are created by libavformat in avformat_open_input().
919 * If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also
920 * appear in av_read_frame().
921 * - muxing: streams are created by the user before avformat_write_header().
922 *
923 * Freed by libavformat in avformat_free_context().
924 */
925 AVStream **streams;
926
927 /**
928 * input or output filename
929 *
930 * - demuxing: set by avformat_open_input()
931 * - muxing: may be set by the caller before avformat_write_header()
932 */
933 char filename[1024];
934
935 /**
936 * Position of the first frame of the component, in
937 * AV_TIME_BASE fractional seconds. NEVER set this value directly:
938 * It is deduced from the AVStream values.
939 *
940 * Demuxing only, set by libavformat.
941 */
942 int64_t start_time;
943
944 /**
945 * Duration of the stream, in AV_TIME_BASE fractional
946 * seconds. Only set this value if you know none of the individual stream
947 * durations and also do not set any of them. This is deduced from the
948 * AVStream values if not set.
949 *
950 * Demuxing only, set by libavformat.
951 */
952 int64_t duration;
953
954 /**
955 * Total stream bitrate in bit/s, 0 if not
956 * available. Never set it directly if the file_size and the
957 * duration are known as Libav can compute it automatically.
958 */
959 int bit_rate;
960
961 unsigned int packet_size;
962 int max_delay;
963
964 int flags;
965 #define AVFMT_FLAG_GENPTS 0x0001 ///< Generate missing pts even if it requires parsing future frames.
966 #define AVFMT_FLAG_IGNIDX 0x0002 ///< Ignore index.
967 #define AVFMT_FLAG_NONBLOCK 0x0004 ///< Do not block when reading packets from input.
968 #define AVFMT_FLAG_IGNDTS 0x0008 ///< Ignore DTS on frames that contain both DTS & PTS
969 #define AVFMT_FLAG_NOFILLIN 0x0010 ///< Do not infer any values from other values, just return what is stored in the container
970 #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
971 #define AVFMT_FLAG_NOBUFFER 0x0040 ///< Do not buffer frames when possible
972 #define AVFMT_FLAG_CUSTOM_IO 0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.
973 #define AVFMT_FLAG_DISCARD_CORRUPT 0x0100 ///< Discard frames marked corrupted
974 #define AVFMT_FLAG_FLUSH_PACKETS 0x0200 ///< Flush the AVIOContext every packet.
975
976 /**
977 * Maximum size of the data read from input for determining
978 * the input container format.
979 * Demuxing only, set by the caller before avformat_open_input().
980 */
981 unsigned int probesize;
982
983 /**
984 * Maximum duration (in AV_TIME_BASE units) of the data read
985 * from input in avformat_find_stream_info().
986 * Demuxing only, set by the caller before avformat_find_stream_info().
987 */
988 int max_analyze_duration;
989
990 const uint8_t *key;
991 int keylen;
992
993 unsigned int nb_programs;
994 AVProgram **programs;
995
996 /**
997 * Forced video codec_id.
998 * Demuxing: Set by user.
999 */
1000 enum AVCodecID video_codec_id;
1001
1002 /**
1003 * Forced audio codec_id.
1004 * Demuxing: Set by user.
1005 */
1006 enum AVCodecID audio_codec_id;
1007
1008 /**
1009 * Forced subtitle codec_id.
1010 * Demuxing: Set by user.
1011 */
1012 enum AVCodecID subtitle_codec_id;
1013
1014 /**
1015 * Maximum amount of memory in bytes to use for the index of each stream.
1016 * If the index exceeds this size, entries will be discarded as
1017 * needed to maintain a smaller size. This can lead to slower or less
1018 * accurate seeking (depends on demuxer).
1019 * Demuxers for which a full in-memory index is mandatory will ignore
1020 * this.
1021 * - muxing: unused
1022 * - demuxing: set by user
1023 */
1024 unsigned int max_index_size;
1025
1026 /**
1027 * Maximum amount of memory in bytes to use for buffering frames
1028 * obtained from realtime capture devices.
1029 */
1030 unsigned int max_picture_buffer;
1031
1032 /**
1033 * Number of chapters in AVChapter array.
1034 * When muxing, chapters are normally written in the file header,
1035 * so nb_chapters should normally be initialized before write_header
1036 * is called. Some muxers (e.g. mov and mkv) can also write chapters
1037 * in the trailer. To write chapters in the trailer, nb_chapters
1038 * must be zero when write_header is called and non-zero when
1039 * write_trailer is called.
1040 * - muxing: set by user
1041 * - demuxing: set by libavformat
1042 */
1043 unsigned int nb_chapters;
1044 AVChapter **chapters;
1045
1046 /**
1047 * Metadata that applies to the whole file.
1048 *
1049 * - demuxing: set by libavformat in avformat_open_input()
1050 * - muxing: may be set by the caller before avformat_write_header()
1051 *
1052 * Freed by libavformat in avformat_free_context().
1053 */
1054 AVDictionary *metadata;
1055
1056 /**
1057 * Start time of the stream in real world time, in microseconds
1058 * since the Unix epoch (00:00 1st January 1970). That is, pts=0 in the
1059 * stream was captured at this real world time.
1060 * Muxing only, set by the caller before avformat_write_header().
1061 */
1062 int64_t start_time_realtime;
1063
1064 /**
1065 * The number of frames used for determining the framerate in
1066 * avformat_find_stream_info().
1067 * Demuxing only, set by the caller before avformat_find_stream_info().
1068 */
1069 int fps_probe_size;
1070
1071 /**
1072 * Error recognition; higher values will detect more errors but may
1073 * misdetect some more or less valid parts as errors.
1074 * Demuxing only, set by the caller before avformat_open_input().
1075 */
1076 int error_recognition;
1077
1078 /**
1079 * Custom interrupt callbacks for the I/O layer.
1080 *
1081 * demuxing: set by the user before avformat_open_input().
1082 * muxing: set by the user before avformat_write_header()
1083 * (mainly useful for AVFMT_NOFILE formats). The callback
1084 * should also be passed to avio_open2() if it's used to
1085 * open the file.
1086 */
1087 AVIOInterruptCB interrupt_callback;
1088
1089 /**
1090 * Flags to enable debugging.
1091 */
1092 int debug;
1093 #define FF_FDEBUG_TS 0x0001
1094
1095 /**
1096 * Maximum buffering duration for interleaving.
1097 *
1098 * To ensure all the streams are interleaved correctly,
1099 * av_interleaved_write_frame() will wait until it has at least one packet
1100 * for each stream before actually writing any packets to the output file.
1101 * When some streams are "sparse" (i.e. there are large gaps between
1102 * successive packets), this can result in excessive buffering.
1103 *
1104 * This field specifies the maximum difference between the timestamps of the
1105 * first and the last packet in the muxing queue, above which libavformat
1106 * will output a packet regardless of whether it has queued a packet for all
1107 * the streams.
1108 *
1109 * Muxing only, set by the caller before avformat_write_header().
1110 */
1111 int64_t max_interleave_delta;
1112
1113 /*****************************************************************
1114 * All fields below this line are not part of the public API. They
1115 * may not be used outside of libavformat and can be changed and
1116 * removed at will.
1117 * New public fields should be added right above.
1118 *****************************************************************
1119 */
1120
1121 /**
1122 * This buffer is only needed when packets were already buffered but
1123 * not decoded, for example to get the codec parameters in MPEG
1124 * streams.
1125 */
1126 struct AVPacketList *packet_buffer;
1127 struct AVPacketList *packet_buffer_end;
1128
1129 /* av_seek_frame() support */
1130 int64_t data_offset; /**< offset of the first packet */
1131
1132 /**
1133 * Raw packets from the demuxer, prior to parsing and decoding.
1134 * This buffer is used for buffering packets until the codec can
1135 * be identified, as parsing cannot be done without knowing the
1136 * codec.
1137 */
1138 struct AVPacketList *raw_packet_buffer;
1139 struct AVPacketList *raw_packet_buffer_end;
1140 /**
1141 * Packets split by the parser get queued here.
1142 */
1143 struct AVPacketList *parse_queue;
1144 struct AVPacketList *parse_queue_end;
1145 /**
1146 * Remaining size available for raw_packet_buffer, in bytes.
1147 */
1148 #define RAW_PACKET_BUFFER_SIZE 2500000
1149 int raw_packet_buffer_remaining_size;
1150
1151 /**
1152 * Offset to remap timestamps to be non-negative.
1153 * Expressed in timebase units.
1154 */
1155 int64_t offset;
1156
1157 /**
1158 * Timebase for the timestamp offset.
1159 */
1160 AVRational offset_timebase;
1161
1162 /**
1163 * An opaque field for libavformat internal usage.
1164 * Must not be accessed in any way by callers.
1165 */
1166 AVFormatInternal *internal;
1167 } AVFormatContext;
1168
1169 typedef struct AVPacketList {
1170 AVPacket pkt;
1171 struct AVPacketList *next;
1172 } AVPacketList;
1173
1174
1175 /**
1176 * @defgroup lavf_core Core functions
1177 * @ingroup libavf
1178 *
1179 * Functions for querying libavformat capabilities, allocating core structures,
1180 * etc.
1181 * @{
1182 */
1183
1184 /**
1185 * Return the LIBAVFORMAT_VERSION_INT constant.
1186 */
1187 unsigned avformat_version(void);
1188
1189 /**
1190 * Return the libavformat build-time configuration.
1191 */
1192 const char *avformat_configuration(void);
1193
1194 /**
1195 * Return the libavformat license.
1196 */
1197 const char *avformat_license(void);
1198
1199 /**
1200 * Initialize libavformat and register all the muxers, demuxers and
1201 * protocols. If you do not call this function, then you can select
1202 * exactly which formats you want to support.
1203 *
1204 * @see av_register_input_format()
1205 * @see av_register_output_format()
1206 * @see av_register_protocol()
1207 */
1208 void av_register_all(void);
1209
1210 void av_register_input_format(AVInputFormat *format);
1211 void av_register_output_format(AVOutputFormat *format);
1212
1213 /**
1214 * Do global initialization of network components. This is optional,
1215 * but recommended, since it avoids the overhead of implicitly
1216 * doing the setup for each session.
1217 *
1218 * Calling this function will become mandatory if using network
1219 * protocols at some major version bump.
1220 */
1221 int avformat_network_init(void);
1222
1223 /**
1224 * Undo the initialization done by avformat_network_init.
1225 */
1226 int avformat_network_deinit(void);
1227
1228 /**
1229 * If f is NULL, returns the first registered input format,
1230 * if f is non-NULL, returns the next registered input format after f
1231 * or NULL if f is the last one.
1232 */
1233 AVInputFormat *av_iformat_next(AVInputFormat *f);
1234
1235 /**
1236 * If f is NULL, returns the first registered output format,
1237 * if f is non-NULL, returns the next registered output format after f
1238 * or NULL if f is the last one.
1239 */
1240 AVOutputFormat *av_oformat_next(AVOutputFormat *f);
1241
1242 /**
1243 * Allocate an AVFormatContext.
1244 * avformat_free_context() can be used to free the context and everything
1245 * allocated by the framework within it.
1246 */
1247 AVFormatContext *avformat_alloc_context(void);
1248
1249 /**
1250 * Free an AVFormatContext and all its streams.
1251 * @param s context to free
1252 */
1253 void avformat_free_context(AVFormatContext *s);
1254
1255 /**
1256 * Get the AVClass for AVFormatContext. It can be used in combination with
1257 * AV_OPT_SEARCH_FAKE_OBJ for examining options.
1258 *
1259 * @see av_opt_find().
1260 */
1261 const AVClass *avformat_get_class(void);
1262
1263 /**
1264 * Add a new stream to a media file.
1265 *
1266 * When demuxing, it is called by the demuxer in read_header(). If the
1267 * flag AVFMTCTX_NOHEADER is set in s.ctx_flags, then it may also
1268 * be called in read_packet().
1269 *
1270 * When muxing, should be called by the user before avformat_write_header().
1271 *
1272 * @param c If non-NULL, the AVCodecContext corresponding to the new stream
1273 * will be initialized to use this codec. This is needed for e.g. codec-specific
1274 * defaults to be set, so codec should be provided if it is known.
1275 *
1276 * @return newly created stream or NULL on error.
1277 */
1278 AVStream *avformat_new_stream(AVFormatContext *s, AVCodec *c);
1279
1280 AVProgram *av_new_program(AVFormatContext *s, int id);
1281
1282 /**
1283 * @}
1284 */
1285
1286
1287 /**
1288 * @addtogroup lavf_decoding
1289 * @{
1290 */
1291
1292 /**
1293 * Find AVInputFormat based on the short name of the input format.
1294 */
1295 AVInputFormat *av_find_input_format(const char *short_name);
1296
1297 /**
1298 * Guess the file format.
1299 *
1300 * @param is_opened Whether the file is already opened; determines whether
1301 * demuxers with or without AVFMT_NOFILE are probed.
1302 */
1303 AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened);
1304
1305 /**
1306 * Guess the file format.
1307 *
1308 * @param is_opened Whether the file is already opened; determines whether
1309 * demuxers with or without AVFMT_NOFILE are probed.
1310 * @param score_max A probe score larger that this is required to accept a
1311 * detection, the variable is set to the actual detection
1312 * score afterwards.
1313 * If the score is <= AVPROBE_SCORE_MAX / 4 it is recommended
1314 * to retry with a larger probe buffer.
1315 */
1316 AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max);
1317
1318 /**
1319 * Probe a bytestream to determine the input format. Each time a probe returns
1320 * with a score that is too low, the probe buffer size is increased and another
1321 * attempt is made. When the maximum probe size is reached, the input format
1322 * with the highest score is returned.
1323 *
1324 * @param pb the bytestream to probe
1325 * @param fmt the input format is put here
1326 * @param filename the filename of the stream
1327 * @param logctx the log context
1328 * @param offset the offset within the bytestream to probe from
1329 * @param max_probe_size the maximum probe buffer size (zero for default)
1330 * @return 0 in case of success, a negative value corresponding to an
1331 * AVERROR code otherwise
1332 */
1333 int av_probe_input_buffer(AVIOContext *pb, AVInputFormat **fmt,
1334 const char *filename, void *logctx,
1335 unsigned int offset, unsigned int max_probe_size);
1336
1337 /**
1338 * Open an input stream and read the header. The codecs are not opened.
1339 * The stream must be closed with avformat_close_input().
1340 *
1341 * @param ps Pointer to user-supplied AVFormatContext (allocated by avformat_alloc_context).
1342 * May be a pointer to NULL, in which case an AVFormatContext is allocated by this
1343 * function and written into ps.
1344 * Note that a user-supplied AVFormatContext will be freed on failure.
1345 * @param filename Name of the stream to open.
1346 * @param fmt If non-NULL, this parameter forces a specific input format.
1347 * Otherwise the format is autodetected.
1348 * @param options A dictionary filled with AVFormatContext and demuxer-private options.
1349 * On return this parameter will be destroyed and replaced with a dict containing
1350 * options that were not found. May be NULL.
1351 *
1352 * @return 0 on success, a negative AVERROR on failure.
1353 *
1354 * @note If you want to use custom IO, preallocate the format context and set its pb field.
1355 */
1356 int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputFormat *fmt, AVDictionary **options);
1357
1358 /**
1359 * Read packets of a media file to get stream information. This
1360 * is useful for file formats with no headers such as MPEG. This
1361 * function also computes the real framerate in case of MPEG-2 repeat
1362 * frame mode.
1363 * The logical file position is not changed by this function;
1364 * examined packets may be buffered for later processing.
1365 *
1366 * @param ic media file handle
1367 * @param options If non-NULL, an ic.nb_streams long array of pointers to
1368 * dictionaries, where i-th member contains options for
1369 * codec corresponding to i-th stream.
1370 * On return each dictionary will be filled with options that were not found.
1371 * @return >=0 if OK, AVERROR_xxx on error
1372 *
1373 * @note this function isn't guaranteed to open all the codecs, so
1374 * options being non-empty at return is a perfectly normal behavior.
1375 *
1376 * @todo Let the user decide somehow what information is needed so that
1377 * we do not waste time getting stuff the user does not need.
1378 */
1379 int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options);
1380
1381 /**
1382 * Find the "best" stream in the file.
1383 * The best stream is determined according to various heuristics as the most
1384 * likely to be what the user expects.
1385 * If the decoder parameter is non-NULL, av_find_best_stream will find the
1386 * default decoder for the stream's codec; streams for which no decoder can
1387 * be found are ignored.
1388 *
1389 * @param ic media file handle
1390 * @param type stream type: video, audio, subtitles, etc.
1391 * @param wanted_stream_nb user-requested stream number,
1392 * or -1 for automatic selection
1393 * @param related_stream try to find a stream related (eg. in the same
1394 * program) to this one, or -1 if none
1395 * @param decoder_ret if non-NULL, returns the decoder for the
1396 * selected stream
1397 * @param flags flags; none are currently defined
1398 * @return the non-negative stream number in case of success,
1399 * AVERROR_STREAM_NOT_FOUND if no stream with the requested type
1400 * could be found,
1401 * AVERROR_DECODER_NOT_FOUND if streams were found but no decoder
1402 * @note If av_find_best_stream returns successfully and decoder_ret is not
1403 * NULL, then *decoder_ret is guaranteed to be set to a valid AVCodec.
1404 */
1405 int av_find_best_stream(AVFormatContext *ic,
1406 enum AVMediaType type,
1407 int wanted_stream_nb,
1408 int related_stream,
1409 AVCodec **decoder_ret,
1410 int flags);
1411
1412 /**
1413 * Return the next frame of a stream.
1414 * This function returns what is stored in the file, and does not validate
1415 * that what is there are valid frames for the decoder. It will split what is
1416 * stored in the file into frames and return one for each call. It will not
1417 * omit invalid data between valid frames so as to give the decoder the maximum
1418 * information possible for decoding.
1419 *
1420 * If pkt->buf is NULL, then the packet is valid until the next
1421 * av_read_frame() or until avformat_close_input(). Otherwise the packet
1422 * is valid indefinitely. In both cases the packet must be freed with
1423 * av_free_packet when it is no longer needed. For video, the packet contains
1424 * exactly one frame. For audio, it contains an integer number of frames if each
1425 * frame has a known fixed size (e.g. PCM or ADPCM data). If the audio frames
1426 * have a variable size (e.g. MPEG audio), then it contains one frame.
1427 *
1428 * pkt->pts, pkt->dts and pkt->duration are always set to correct
1429 * values in AVStream.time_base units (and guessed if the format cannot
1430 * provide them). pkt->pts can be AV_NOPTS_VALUE if the video format
1431 * has B-frames, so it is better to rely on pkt->dts if you do not
1432 * decompress the payload.
1433 *
1434 * @return 0 if OK, < 0 on error or end of file
1435 */
1436 int av_read_frame(AVFormatContext *s, AVPacket *pkt);
1437
1438 /**
1439 * Seek to the keyframe at timestamp.
1440 * 'timestamp' in 'stream_index'.
1441 * @param stream_index If stream_index is (-1), a default
1442 * stream is selected, and timestamp is automatically converted
1443 * from AV_TIME_BASE units to the stream specific time_base.
1444 * @param timestamp Timestamp in AVStream.time_base units
1445 * or, if no stream is specified, in AV_TIME_BASE units.
1446 * @param flags flags which select direction and seeking mode
1447 * @return >= 0 on success
1448 */
1449 int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp,
1450 int flags);
1451
1452 /**
1453 * Seek to timestamp ts.
1454 * Seeking will be done so that the point from which all active streams
1455 * can be presented successfully will be closest to ts and within min/max_ts.
1456 * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
1457 *
1458 * If flags contain AVSEEK_FLAG_BYTE, then all timestamps are in bytes and
1459 * are the file position (this may not be supported by all demuxers).
1460 * If flags contain AVSEEK_FLAG_FRAME, then all timestamps are in frames
1461 * in the stream with stream_index (this may not be supported by all demuxers).
1462 * Otherwise all timestamps are in units of the stream selected by stream_index
1463 * or if stream_index is -1, in AV_TIME_BASE units.
1464 * If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
1465 * keyframes (this may not be supported by all demuxers).
1466 *
1467 * @param stream_index index of the stream which is used as time base reference
1468 * @param min_ts smallest acceptable timestamp
1469 * @param ts target timestamp
1470 * @param max_ts largest acceptable timestamp
1471 * @param flags flags
1472 * @return >=0 on success, error code otherwise
1473 *
1474 * @note This is part of the new seek API which is still under construction.
1475 * Thus do not use this yet. It may change at any time, do not expect
1476 * ABI compatibility yet!
1477 */
1478 int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);
1479
1480 /**
1481 * Start playing a network-based stream (e.g. RTSP stream) at the
1482 * current position.
1483 */
1484 int av_read_play(AVFormatContext *s);
1485
1486 /**
1487 * Pause a network-based stream (e.g. RTSP stream).
1488 *
1489 * Use av_read_play() to resume it.
1490 */
1491 int av_read_pause(AVFormatContext *s);
1492
1493 /**
1494 * Close an opened input AVFormatContext. Free it and all its contents
1495 * and set *s to NULL.
1496 */
1497 void avformat_close_input(AVFormatContext **s);
1498 /**
1499 * @}
1500 */
1501
1502 #define AVSEEK_FLAG_BACKWARD 1 ///< seek backward
1503 #define AVSEEK_FLAG_BYTE 2 ///< seeking based on position in bytes
1504 #define AVSEEK_FLAG_ANY 4 ///< seek to any frame, even non-keyframes
1505 #define AVSEEK_FLAG_FRAME 8 ///< seeking based on frame number
1506
1507 /**
1508 * @addtogroup lavf_encoding
1509 * @{
1510 */
1511 /**
1512 * Allocate the stream private data and write the stream header to
1513 * an output media file.
1514 *
1515 * @param s Media file handle, must be allocated with avformat_alloc_context().
1516 * Its oformat field must be set to the desired output format;
1517 * Its pb field must be set to an already opened AVIOContext.
1518 * @param options An AVDictionary filled with AVFormatContext and muxer-private options.
1519 * On return this parameter will be destroyed and replaced with a dict containing
1520 * options that were not found. May be NULL.
1521 *
1522 * @return 0 on success, negative AVERROR on failure.
1523 *
1524 * @see av_opt_find, av_dict_set, avio_open, av_oformat_next.
1525 */
1526 int avformat_write_header(AVFormatContext *s, AVDictionary **options);
1527
1528 /**
1529 * Write a packet to an output media file.
1530 *
1531 * This function passes the packet directly to the muxer, without any buffering
1532 * or reordering. The caller is responsible for correctly interleaving the
1533 * packets if the format requires it. Callers that want libavformat to handle
1534 * the interleaving should call av_interleaved_write_frame() instead of this
1535 * function.
1536 *
1537 * @param s media file handle
1538 * @param pkt @parblock
1539 * The packet containing the data to be written. Note that unlike
1540 * av_interleaved_write_frame(), this function does not take
1541 * ownership of the packet passed to it (though some muxers may make
1542 * an internal reference to the input packet).
1543 *
1544 * This parameter can be NULL (at any time, not just at the end), in
1545 * order to immediately flush data buffered within the muxer, for
1546 * muxers that buffer up data internally before writing it to the
1547 * output.
1548 *
1549 * Packet's @ref AVPacket.stream_index "stream_index" field must be
1550 * set to the index of the corresponding stream in @ref
1551 * AVFormatContext.streams "s->streams". It is very strongly
1552 * recommended that timing information (@ref AVPacket.pts "pts", @ref
1553 * AVPacket.dts "dts", @ref AVPacket.duration "duration") is set to
1554 * correct values.
1555 * @endparblock
1556 * @return < 0 on error, = 0 if OK, 1 if flushed and there is no more data to flush
1557 *
1558 * @see av_interleaved_write_frame()
1559 */
1560 int av_write_frame(AVFormatContext *s, AVPacket *pkt);
1561
1562 /**
1563 * Write a packet to an output media file ensuring correct interleaving.
1564 *
1565 * This function will buffer the packets internally as needed to make sure the
1566 * packets in the output file are properly interleaved in the order of
1567 * increasing dts. Callers doing their own interleaving should call
1568 * av_write_frame() instead of this function.
1569 *
1570 * @param s media file handle
1571 * @param pkt @parblock
1572 * The packet containing the data to be written.
1573 *
1574 * If the packet is reference-counted, this function will take
1575 * ownership of this reference and unreference it later when it sees
1576 * fit.
1577 * The caller must not access the data through this reference after
1578 * this function returns. If the packet is not reference-counted,
1579 * libavformat will make a copy.
1580 *
1581 * This parameter can be NULL (at any time, not just at the end), to
1582 * flush the interleaving queues.
1583 *
1584 * Packet's @ref AVPacket.stream_index "stream_index" field must be
1585 * set to the index of the corresponding stream in @ref
1586 * AVFormatContext.streams "s->streams". It is very strongly
1587 * recommended that timing information (@ref AVPacket.pts "pts", @ref
1588 * AVPacket.dts "dts", @ref AVPacket.duration "duration") is set to
1589 * correct values.
1590 * @endparblock
1591 *
1592 * @return 0 on success, a negative AVERROR on error.
1593 *
1594 * @see av_write_frame(), AVFormatContext.max_interleave_delta
1595 */
1596 int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt);
1597
1598 /**
1599 * Write the stream trailer to an output media file and free the
1600 * file private data.
1601 *
1602 * May only be called after a successful call to avformat_write_header.
1603 *
1604 * @param s media file handle
1605 * @return 0 if OK, AVERROR_xxx on error
1606 */
1607 int av_write_trailer(AVFormatContext *s);
1608
1609 /**
1610 * Return the output format in the list of registered output formats
1611 * which best matches the provided parameters, or return NULL if
1612 * there is no match.
1613 *
1614 * @param short_name if non-NULL checks if short_name matches with the
1615 * names of the registered formats
1616 * @param filename if non-NULL checks if filename terminates with the
1617 * extensions of the registered formats
1618 * @param mime_type if non-NULL checks if mime_type matches with the
1619 * MIME type of the registered formats
1620 */
1621 AVOutputFormat *av_guess_format(const char *short_name,
1622 const char *filename,
1623 const char *mime_type);
1624
1625 /**
1626 * Guess the codec ID based upon muxer and filename.
1627 */
1628 enum AVCodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
1629 const char *filename, const char *mime_type,
1630 enum AVMediaType type);
1631
1632 /**
1633 * @}
1634 */
1635
1636
1637 /**
1638 * @defgroup lavf_misc Utility functions
1639 * @ingroup libavf
1640 * @{
1641 *
1642 * Miscellaneous utility functions related to both muxing and demuxing
1643 * (or neither).
1644 */
1645
1646 /**
1647 * Send a nice hexadecimal dump of a buffer to the specified file stream.
1648 *
1649 * @param f The file stream pointer where the dump should be sent to.
1650 * @param buf buffer
1651 * @param size buffer size
1652 *
1653 * @see av_hex_dump_log, av_pkt_dump2, av_pkt_dump_log2
1654 */
1655 void av_hex_dump(FILE *f, const uint8_t *buf, int size);
1656
1657 /**
1658 * Send a nice hexadecimal dump of a buffer to the log.
1659 *
1660 * @param avcl A pointer to an arbitrary struct of which the first field is a
1661 * pointer to an AVClass struct.
1662 * @param level The importance level of the message, lower values signifying
1663 * higher importance.
1664 * @param buf buffer
1665 * @param size buffer size
1666 *
1667 * @see av_hex_dump, av_pkt_dump2, av_pkt_dump_log2
1668 */
1669 void av_hex_dump_log(void *avcl, int level, const uint8_t *buf, int size);
1670
1671 /**
1672 * Send a nice dump of a packet to the specified file stream.
1673 *
1674 * @param f The file stream pointer where the dump should be sent to.
1675 * @param pkt packet to dump
1676 * @param dump_payload True if the payload must be displayed, too.
1677 * @param st AVStream that the packet belongs to
1678 */
1679 void av_pkt_dump2(FILE *f, AVPacket *pkt, int dump_payload, AVStream *st);
1680
1681
1682 /**
1683 * Send a nice dump of a packet to the log.
1684 *
1685 * @param avcl A pointer to an arbitrary struct of which the first field is a
1686 * pointer to an AVClass struct.
1687 * @param level The importance level of the message, lower values signifying
1688 * higher importance.
1689 * @param pkt packet to dump
1690 * @param dump_payload True if the payload must be displayed, too.
1691 * @param st AVStream that the packet belongs to
1692 */
1693 void av_pkt_dump_log2(void *avcl, int level, AVPacket *pkt, int dump_payload,
1694 AVStream *st);
1695
1696 /**
1697 * Get the AVCodecID for the given codec tag tag.
1698 * If no codec id is found returns AV_CODEC_ID_NONE.
1699 *
1700 * @param tags list of supported codec_id-codec_tag pairs, as stored
1701 * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
1702 */
1703 enum AVCodecID av_codec_get_id(const struct AVCodecTag * const *tags, unsigned int tag);
1704
1705 /**
1706 * Get the codec tag for the given codec id id.
1707 * If no codec tag is found returns 0.
1708 *
1709 * @param tags list of supported codec_id-codec_tag pairs, as stored
1710 * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
1711 */
1712 unsigned int av_codec_get_tag(const struct AVCodecTag * const *tags, enum AVCodecID id);
1713
1714 int av_find_default_stream_index(AVFormatContext *s);
1715
1716 /**
1717 * Get the index for a specific timestamp.
1718 * @param flags if AVSEEK_FLAG_BACKWARD then the returned index will correspond
1719 * to the timestamp which is <= the requested one, if backward
1720 * is 0, then it will be >=
1721 * if AVSEEK_FLAG_ANY seek to any frame, only keyframes otherwise
1722 * @return < 0 if no such timestamp could be found
1723 */
1724 int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags);
1725
1726 /**
1727 * Add an index entry into a sorted list. Update the entry if the list
1728 * already contains it.
1729 *
1730 * @param timestamp timestamp in the time base of the given stream
1731 */
1732 int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
1733 int size, int distance, int flags);
1734
1735
1736 /**
1737 * Split a URL string into components.
1738 *
1739 * The pointers to buffers for storing individual components may be null,
1740 * in order to ignore that component. Buffers for components not found are
1741 * set to empty strings. If the port is not found, it is set to a negative
1742 * value.
1743 *
1744 * @param proto the buffer for the protocol
1745 * @param proto_size the size of the proto buffer
1746 * @param authorization the buffer for the authorization
1747 * @param authorization_size the size of the authorization buffer
1748 * @param hostname the buffer for the host name
1749 * @param hostname_size the size of the hostname buffer
1750 * @param port_ptr a pointer to store the port number in
1751 * @param path the buffer for the path
1752 * @param path_size the size of the path buffer
1753 * @param url the URL to split
1754 */
1755 void av_url_split(char *proto, int proto_size,
1756 char *authorization, int authorization_size,
1757 char *hostname, int hostname_size,
1758 int *port_ptr,
1759 char *path, int path_size,
1760 const char *url);
1761
1762
1763 void av_dump_format(AVFormatContext *ic,
1764 int index,
1765 const char *url,
1766 int is_output);
1767
1768 /**
1769 * Return in 'buf' the path with '%d' replaced by a number.
1770 *
1771 * Also handles the '%0nd' format where 'n' is the total number
1772 * of digits and '%%'.
1773 *
1774 * @param buf destination buffer
1775 * @param buf_size destination buffer size
1776 * @param path numbered sequence string
1777 * @param number frame number
1778 * @return 0 if OK, -1 on format error
1779 */
1780 int av_get_frame_filename(char *buf, int buf_size,
1781 const char *path, int number);
1782
1783 /**
1784 * Check whether filename actually is a numbered sequence generator.
1785 *
1786 * @param filename possible numbered sequence string
1787 * @return 1 if a valid numbered sequence string, 0 otherwise
1788 */
1789 int av_filename_number_test(const char *filename);
1790
1791 /**
1792 * Generate an SDP for an RTP session.
1793 *
1794 * Note, this overwrites the id values of AVStreams in the muxer contexts
1795 * for getting unique dynamic payload types.
1796 *
1797 * @param ac array of AVFormatContexts describing the RTP streams. If the
1798 * array is composed by only one context, such context can contain
1799 * multiple AVStreams (one AVStream per RTP stream). Otherwise,
1800 * all the contexts in the array (an AVCodecContext per RTP stream)
1801 * must contain only one AVStream.
1802 * @param n_files number of AVCodecContexts contained in ac
1803 * @param buf buffer where the SDP will be stored (must be allocated by
1804 * the caller)
1805 * @param size the size of the buffer
1806 * @return 0 if OK, AVERROR_xxx on error
1807 */
1808 int av_sdp_create(AVFormatContext *ac[], int n_files, char *buf, int size);
1809
1810 /**
1811 * Return a positive value if the given filename has one of the given
1812 * extensions, 0 otherwise.
1813 *
1814 * @param extensions a comma-separated list of filename extensions
1815 */
1816 int av_match_ext(const char *filename, const char *extensions);
1817
1818 /**
1819 * Test if the given container can store a codec.
1820 *
1821 * @param std_compliance standards compliance level, one of FF_COMPLIANCE_*
1822 *
1823 * @return 1 if codec with ID codec_id can be stored in ofmt, 0 if it cannot.
1824 * A negative number if this information is not available.
1825 */
1826 int avformat_query_codec(AVOutputFormat *ofmt, enum AVCodecID codec_id, int std_compliance);
1827
1828 /**
1829 * @defgroup riff_fourcc RIFF FourCCs
1830 * @{
1831 * Get the tables mapping RIFF FourCCs to libavcodec AVCodecIDs. The tables are
1832 * meant to be passed to av_codec_get_id()/av_codec_get_tag() as in the
1833 * following code:
1834 * @code
1835 * uint32_t tag = MKTAG('H', '2', '6', '4');
1836 * const struct AVCodecTag *table[] = { avformat_get_riff_video_tags(), 0 };
1837 * enum AVCodecID id = av_codec_get_id(table, tag);
1838 * @endcode
1839 */
1840 /**
1841 * @return the table mapping RIFF FourCCs for video to libavcodec AVCodecID.
1842 */
1843 const struct AVCodecTag *avformat_get_riff_video_tags(void);
1844 /**
1845 * @return the table mapping RIFF FourCCs for audio to AVCodecID.
1846 */
1847 const struct AVCodecTag *avformat_get_riff_audio_tags(void);
1848 /**
1849 * @}
1850 */
1851
1852 /**
1853 * @}
1854 */
1855
1856 #endif /* AVFORMAT_AVFORMAT_H */