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  * The packet data belongs to the demuxer and is invalid after the next call to

   162  * av_read_frame(). The user must free the packet with av_free_packet() before

   163  * calling av_read_frame() again or closing the file.

   164  *

   165  * @section lavf_decoding_seek Seeking

   166  * @}

   167  *

   168  * @defgroup lavf_encoding Muxing

   169  * @{

   170  * @}

   171  *

   172  * @defgroup lavf_io I/O Read/Write

   173  * @{

   174  * @}

   175  *

   176  * @defgroup lavf_codec Demuxers

   177  * @{

   178  * @defgroup lavf_codec_native Native Demuxers

   179  * @{

   180  * @}

   181  * @defgroup lavf_codec_wrappers External library wrappers

   182  * @{

   183  * @}

   184  * @}

   185  * @defgroup lavf_protos I/O Protocols

   186  * @{

   187  * @}

   188  * @defgroup lavf_internal Internal

   189  * @{

   190  * @}

   191  * @}

   192  *

   193  */

   194 

   195 #include <time.h>

   196 #include <stdio.h>  /* FILE */

   197 #include "libavcodec/avcodec.h"

   198 #include "libavutil/dict.h"

   199 #include "libavutil/log.h"

   200 

   201 #include "avio.h"

   202 #include "libavformat/version.h"

   203 

   204 #if FF_API_AV_GETTIME

   205 #include "libavutil/time.h"

   206 #endif

   207 

   208 struct AVFormatContext;

   209 

   210 

   211 /**

   212  * @defgroup metadata_api Public Metadata API

   213  * @{

   214  * @ingroup libavf

   215  * The metadata API allows libavformat to export metadata tags to a client

   216  * application when demuxing. Conversely it allows a client application to

   217  * set metadata when muxing.

   218  *

   219  * Metadata is exported or set as pairs of key/value strings in the 'metadata'

   220  * fields of the AVFormatContext, AVStream, AVChapter and AVProgram structs

   221  * using the @ref lavu_dict "AVDictionary" API. Like all strings in Libav,

   222  * metadata is assumed to be UTF-8 encoded Unicode. Note that metadata

   223  * exported by demuxers isn't checked to be valid UTF-8 in most cases.

   224  *

   225  * Important concepts to keep in mind:

   226  * -  Keys are unique; there can never be 2 tags with the same key. This is

   227  *    also meant semantically, i.e., a demuxer should not knowingly produce

   228  *    several keys that are literally different but semantically identical.

   229  *    E.g., key=Author5, key=Author6. In this example, all authors must be

   230  *    placed in the same tag.

   231  * -  Metadata is flat, not hierarchical; there are no subtags. If you

   232  *    want to store, e.g., the email address of the child of producer Alice

   233  *    and actor Bob, that could have key=alice_and_bobs_childs_email_address.

   234  * -  Several modifiers can be applied to the tag name. This is done by

   235  *    appending a dash character ('-') and the modifier name in the order

   236  *    they appear in the list below -- e.g. foo-eng-sort, not foo-sort-eng.

   237  *    -  language -- a tag whose value is localized for a particular language

   238  *       is appended with the ISO 639-2/B 3-letter language code.

   239  *       For example: Author-ger=Michael, Author-eng=Mike

   240  *       The original/default language is in the unqualified "Author" tag.

   241  *       A demuxer should set a default if it sets any translated tag.

   242  *    -  sorting  -- a modified version of a tag that should be used for

   243  *       sorting will have '-sort' appended. E.g. artist="The Beatles",

   244  *       artist-sort="Beatles, The".

   245  *

   246  * -  Demuxers attempt to export metadata in a generic format, however tags

   247  *    with no generic equivalents are left as they are stored in the container.

   248  *    Follows a list of generic tag names:

   249  *

   250  @verbatim

   251  album        -- name of the set this work belongs to

   252  album_artist -- main creator of the set/album, if different from artist.

   253                  e.g. "Various Artists" for compilation albums.

   254  artist       -- main creator of the work

   255  comment      -- any additional description of the file.

   256  composer     -- who composed the work, if different from artist.

   257  copyright    -- name of copyright holder.

   258  creation_time-- date when the file was created, preferably in ISO 8601.

   259  date         -- date when the work was created, preferably in ISO 8601.

   260  disc         -- number of a subset, e.g. disc in a multi-disc collection.

   261  encoder      -- name/settings of the software/hardware that produced the file.

   262  encoded_by   -- person/group who created the file.

   263  filename     -- original name of the file.

   264  genre        -- <self-evident>.

   265  language     -- main language in which the work is performed, preferably

   266                  in ISO 639-2 format. Multiple languages can be specified by

   267                  separating them with commas.

   268  performer    -- artist who performed the work, if different from artist.

   269                  E.g for "Also sprach Zarathustra", artist would be "Richard

   270                  Strauss" and performer "London Philharmonic Orchestra".

   271  publisher    -- name of the label/publisher.

   272  service_name     -- name of the service in broadcasting (channel name).

   273  service_provider -- name of the service provider in broadcasting.

   274  title        -- name of the work.

   275  track        -- number of this work in the set, can be in form current/total.

   276  variant_bitrate -- the total bitrate of the bitrate variant that the current stream is part of

   277  @endverbatim

   278  *

   279  * Look in the examples section for an application example how to use the Metadata API.

   280  *

   281  * @}

   282  */

   283 

   284 /* packet functions */

   285 

   286 

   287 /**

   288  * Allocate and read the payload of a packet and initialize its

   289  * fields with default values.

   290  *

   291  * @param pkt packet

   292  * @param size desired payload size

   293  * @return >0 (read size) if OK, AVERROR_xxx otherwise

   294  */

   295 int av_get_packet(AVIOContext *s, AVPacket *pkt, int size);

   296 

   297 

   298 /**

   299  * Read data and append it to the current content of the AVPacket.

   300  * If pkt->size is 0 this is identical to av_get_packet.

   301  * Note that this uses av_grow_packet and thus involves a realloc

   302  * which is inefficient. Thus this function should only be used

   303  * when there is no reasonable way to know (an upper bound of)

   304  * the final size.

   305  *

   306  * @param pkt packet

   307  * @param size amount of data to read

   308  * @return >0 (read size) if OK, AVERROR_xxx otherwise, previous data

   309  *         will not be lost even if an error occurs.

   310  */

   311 int av_append_packet(AVIOContext *s, AVPacket *pkt, int size);

   312 

   313 /*************************************************/

   314 /* fractional numbers for exact pts handling */

   315 

   316 /**

   317  * The exact value of the fractional number is: 'val + num / den'.

   318  * num is assumed to be 0 <= num < den.

   319  */

   320 typedef struct AVFrac {

   321     int64_t val, num, den;

   322 } AVFrac;

   323 

   324 /*************************************************/

   325 /* input/output formats */

   326 

   327 struct AVCodecTag;

   328 

   329 /**

   330  * This structure contains the data a format has to probe a file.

   331  */

   332 typedef struct AVProbeData {

   333     const char *filename;

   334     unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */

   335     int buf_size;       /**< Size of buf except extra allocated bytes */

   336 } AVProbeData;

   337 

   338 #define AVPROBE_SCORE_MAX 100               ///< maximum score, half of that is used for file-extension-based detection

   339 #define AVPROBE_PADDING_SIZE 32             ///< extra allocated bytes at the end of the probe buffer

   340 

   341 /// Demuxer will use avio_open, no opened file should be provided by the caller.

   342 #define AVFMT_NOFILE        0x0001

   343 #define AVFMT_NEEDNUMBER    0x0002 /**< Needs '%d' in filename. */

   344 #define AVFMT_SHOW_IDS      0x0008 /**< Show format stream IDs numbers. */

   345 #define AVFMT_RAWPICTURE    0x0020 /**< Format wants AVPicture structure for

   346                                       raw picture data. */

   347 #define AVFMT_GLOBALHEADER  0x0040 /**< Format wants global header. */

   348 #define AVFMT_NOTIMESTAMPS  0x0080 /**< Format does not need / have any timestamps. */

   349 #define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */

   350 #define AVFMT_TS_DISCONT    0x0200 /**< Format allows timestamp discontinuities. Note, muxers always require valid (monotone) timestamps */

   351 #define AVFMT_VARIABLE_FPS  0x0400 /**< Format allows variable fps. */

   352 #define AVFMT_NODIMENSIONS  0x0800 /**< Format does not need width/height */

   353 #define AVFMT_NOSTREAMS     0x1000 /**< Format does not require any streams */

   354 #define AVFMT_NOBINSEARCH   0x2000 /**< Format does not allow to fallback to binary search via read_timestamp */

   355 #define AVFMT_NOGENSEARCH   0x4000 /**< Format does not allow to fallback to generic search */

   356 #define AVFMT_NO_BYTE_SEEK  0x8000 /**< Format does not allow seeking by bytes */

   357 #define AVFMT_ALLOW_FLUSH  0x10000 /**< Format allows flushing. If not set, the muxer will not receive a NULL packet in the write_packet function. */

   358 #define AVFMT_TS_NONSTRICT 0x20000 /**< Format does not require strictly

   359                                         increasing timestamps, but they must

   360                                         still be monotonic */

   361 

   362 /**

   363  * @addtogroup lavf_encoding

   364  * @{

   365  */

   366 typedef struct AVOutputFormat {

   367     const char *name;

   368     /**

   369      * Descriptive name for the format, meant to be more human-readable

   370      * than name. You should use the NULL_IF_CONFIG_SMALL() macro

   371      * to define it.

   372      */

   373     const char *long_name;

   374     const char *mime_type;

   375     const char *extensions; /**< comma-separated filename extensions */

   376     /* output support */

   377     enum AVCodecID audio_codec;    /**< default audio codec */

   378     enum AVCodecID video_codec;    /**< default video codec */

   379     enum AVCodecID subtitle_codec; /**< default subtitle codec */

   380     /**

   381      * can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_RAWPICTURE,

   382      * AVFMT_GLOBALHEADER, AVFMT_NOTIMESTAMPS, AVFMT_VARIABLE_FPS,

   383      * AVFMT_NODIMENSIONS, AVFMT_NOSTREAMS, AVFMT_ALLOW_FLUSH,

   384      * AVFMT_TS_NONSTRICT

   385      */

   386     int flags;

   387 

   388     /**

   389      * List of supported codec_id-codec_tag pairs, ordered by "better

   390      * choice first". The arrays are all terminated by AV_CODEC_ID_NONE.

   391      */

   392     const struct AVCodecTag * const *codec_tag;

   393 

   394 

   395     const AVClass *priv_class; ///< AVClass for the private context

   396 

   397     /*****************************************************************

   398      * No fields below this line are part of the public API. They

   399      * may not be used outside of libavformat and can be changed and

   400      * removed at will.

   401      * New public fields should be added right above.

   402      *****************************************************************

   403      */

   404     struct AVOutputFormat *next;

   405     /**

   406      * size of private data so that it can be allocated in the wrapper

   407      */

   408     int priv_data_size;

   409 

   410     int (*write_header)(struct AVFormatContext *);

   411     /**

   412      * Write a packet. If AVFMT_ALLOW_FLUSH is set in flags,

   413      * pkt can be NULL in order to flush data buffered in the muxer.

   414      * When flushing, return 0 if there still is more data to flush,

   415      * or 1 if everything was flushed and there is no more buffered

   416      * data.

   417      */

   418     int (*write_packet)(struct AVFormatContext *, AVPacket *pkt);

   419     int (*write_trailer)(struct AVFormatContext *);

   420     /**

   421      * Currently only used to set pixel format if not YUV420P.

   422      */

   423     int (*interleave_packet)(struct AVFormatContext *, AVPacket *out,

   424                              AVPacket *in, int flush);

   425     /**

   426      * Test if the given codec can be stored in this container.

   427      *

   428      * @return 1 if the codec is supported, 0 if it is not.

   429      *         A negative number if unknown.

   430      */

   431     int (*query_codec)(enum AVCodecID id, int std_compliance);

   432 } AVOutputFormat;

   433 /**

   434  * @}

   435  */

   436 

   437 /**

   438  * @addtogroup lavf_decoding

   439  * @{

   440  */

   441 typedef struct AVInputFormat {

   442     /**

   443      * A comma separated list of short names for the format. New names

   444      * may be appended with a minor bump.

   445      */

   446     const char *name;

   447 

   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 

   455     /**

   456      * Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_SHOW_IDS,

   457      * AVFMT_GENERIC_INDEX, AVFMT_TS_DISCONT, AVFMT_NOBINSEARCH,

   458      * AVFMT_NOGENSEARCH, AVFMT_NO_BYTE_SEEK.

   459      */

   460     int flags;

   461 

   462     /**

   463      * If extensions are defined, then no probe is done. You should

   464      * usually not use extension format guessing because it is not

   465      * reliable enough

   466      */

   467     const char *extensions;

   468 

   469     const struct AVCodecTag * const *codec_tag;

   470 

   471     const AVClass *priv_class; ///< AVClass for the private context

   472 

   473     /*****************************************************************

   474      * No fields below this line are part of the public API. They

   475      * may not be used outside of libavformat and can be changed and

   476      * removed at will.

   477      * New public fields should be added right above.

   478      *****************************************************************

   479      */

   480     struct AVInputFormat *next;

   481 

   482     /**

   483      * Raw demuxers store their codec ID here.

   484      */

   485     int raw_codec_id;

   486 

   487     /**

   488      * Size of private data so that it can be allocated in the wrapper.

   489      */

   490     int priv_data_size;

   491 

   492     /**

   493      * Tell if a given file has a chance of being parsed as this format.

   494      * The buffer provided is guaranteed to be AVPROBE_PADDING_SIZE bytes

   495      * big so you do not have to check for that unless you need more.

   496      */

   497     int (*read_probe)(AVProbeData *);

   498 

   499     /**

   500      * Read the format header and initialize the AVFormatContext

   501      * structure. Return 0 if OK. Only used in raw format right

   502      * now. 'avformat_new_stream' should be called to create new streams.

   503      */

   504     int (*read_header)(struct AVFormatContext *);

   505 

   506     /**

   507      * Read one packet and put it in 'pkt'. pts and flags are also

   508      * set. 'avformat_new_stream' can be called only if the flag

   509      * AVFMTCTX_NOHEADER is used and only in the calling thread (not in a

   510      * background thread).

   511      * @return 0 on success, < 0 on error.

   512      *         When returning an error, pkt must not have been allocated

   513      *         or must be freed before returning

   514      */

   515     int (*read_packet)(struct AVFormatContext *, AVPacket *pkt);

   516 

   517     /**

   518      * Close the stream. The AVFormatContext and AVStreams are not

   519      * freed by this function

   520      */

   521     int (*read_close)(struct AVFormatContext *);

   522 

   523     /**

   524      * Seek to a given timestamp relative to the frames in

   525      * stream component stream_index.

   526      * @param stream_index Must not be -1.

   527      * @param flags Selects which direction should be preferred if no exact

   528      *              match is available.

   529      * @return >= 0 on success (but not necessarily the new offset)

   530      */

   531     int (*read_seek)(struct AVFormatContext *,

   532                      int stream_index, int64_t timestamp, int flags);

   533 

   534     /**

   535      * Get the next timestamp in stream[stream_index].time_base units.

   536      * @return the timestamp or AV_NOPTS_VALUE if an error occurred

   537      */

   538     int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,

   539                               int64_t *pos, int64_t pos_limit);

   540 

   541     /**

   542      * Start/resume playing - only meaningful if using a network-based format

   543      * (RTSP).

   544      */

   545     int (*read_play)(struct AVFormatContext *);

   546 

   547     /**

   548      * Pause playing - only meaningful if using a network-based format

   549      * (RTSP).

   550      */

   551     int (*read_pause)(struct AVFormatContext *);

   552 

   553     /**

   554      * Seek to timestamp ts.

   555      * Seeking will be done so that the point from which all active streams

   556      * can be presented successfully will be closest to ts and within min/max_ts.

   557      * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.

   558      */

   559     int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);

   560 } AVInputFormat;

   561 /**

   562  * @}

   563  */

   564 

   565 enum AVStreamParseType {

   566     AVSTREAM_PARSE_NONE,

   567     AVSTREAM_PARSE_FULL,       /**< full parsing and repack */

   568     AVSTREAM_PARSE_HEADERS,    /**< Only parse headers, do not repack. */

   569     AVSTREAM_PARSE_TIMESTAMPS, /**< full parsing and interpolation of timestamps for frames not starting on a packet boundary */

   570     AVSTREAM_PARSE_FULL_ONCE,  /**< full parsing and repack of the first frame only, only implemented for H.264 currently */

   571 };

   572 

   573 typedef struct AVIndexEntry {

   574     int64_t pos;

   575     int64_t timestamp;

   576 #define AVINDEX_KEYFRAME 0x0001

   577     int flags:2;

   578     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).

   579     int min_distance;         /**< Minimum distance between this and the previous keyframe, used to avoid unneeded searching. */

   580 } AVIndexEntry;

   581 

   582 #define AV_DISPOSITION_DEFAULT   0x0001

   583 #define AV_DISPOSITION_DUB       0x0002

   584 #define AV_DISPOSITION_ORIGINAL  0x0004

   585 #define AV_DISPOSITION_COMMENT   0x0008

   586 #define AV_DISPOSITION_LYRICS    0x0010

   587 #define AV_DISPOSITION_KARAOKE   0x0020

   588 

   589 /**

   590  * Track should be used during playback by default.

   591  * Useful for subtitle track that should be displayed

   592  * even when user did not explicitly ask for subtitles.

   593  */

   594 #define AV_DISPOSITION_FORCED    0x0040

   595 #define AV_DISPOSITION_HEARING_IMPAIRED  0x0080  /**< stream for hearing impaired audiences */

   596 #define AV_DISPOSITION_VISUAL_IMPAIRED   0x0100  /**< stream for visual impaired audiences */

   597 #define AV_DISPOSITION_CLEAN_EFFECTS     0x0200  /**< stream without voice */

   598 /**

   599  * The stream is stored in the file as an attached picture/"cover art" (e.g.

   600  * APIC frame in ID3v2). The single packet associated with it will be returned

   601  * among the first few packets read from the file unless seeking takes place.

   602  * It can also be accessed at any time in AVStream.attached_pic.

   603  */

   604 #define AV_DISPOSITION_ATTACHED_PIC      0x0400

   605 

   606 /**

   607  * Stream structure.

   608  * New fields can be added to the end with minor version bumps.

   609  * Removal, reordering and changes to existing fields require a major

   610  * version bump.

   611  * sizeof(AVStream) must not be used outside libav*.

   612  */

   613 typedef struct AVStream {

   614     int index;    /**< stream index in AVFormatContext */

   615     /**

   616      * Format-specific stream ID.

   617      * decoding: set by libavformat

   618      * encoding: set by the user

   619      */

   620     int id;

   621     /**

   622      * Codec context associated with this stream. Allocated and freed by

   623      * libavformat.

   624      *

   625      * - decoding: The demuxer exports codec information stored in the headers

   626      *             here.

   627      * - encoding: The user sets codec information, the muxer writes it to the

   628      *             output. Mandatory fields as specified in AVCodecContext

   629      *             documentation must be set even if this AVCodecContext is

   630      *             not actually used for encoding.

   631      */

   632     AVCodecContext *codec;

   633 #if FF_API_R_FRAME_RATE

   634     /**

   635      * Real base framerate of the stream.

   636      * This is the lowest framerate with which all timestamps can be

   637      * represented accurately (it is the least common multiple of all

   638      * framerates in the stream). Note, this value is just a guess!

   639      * For example, if the time base is 1/90000 and all frames have either

   640      * approximately 3600 or 1800 timer ticks, then r_frame_rate will be 50/1.

   641      */

   642     AVRational r_frame_rate;

   643 #endif

   644     void *priv_data;

   645 

   646     /**

   647      * encoding: pts generation when outputting stream

   648      */

   649     struct AVFrac pts;

   650 

   651     /**

   652      * This is the fundamental unit of time (in seconds) in terms

   653      * of which frame timestamps are represented.

   654      *

   655      * decoding: set by libavformat

   656      * encoding: set by libavformat in avformat_write_header. The muxer may use the

   657      * user-provided value of @ref AVCodecContext.time_base "codec->time_base"

   658      * as a hint.

   659      */

   660     AVRational time_base;

   661 

   662     /**

   663      * Decoding: pts of the first frame of the stream, in stream time base.

   664      * Only set this if you are absolutely 100% sure that the value you set

   665      * it to really is the pts of the first frame.

   666      * This may be undefined (AV_NOPTS_VALUE).

   667      */

   668     int64_t start_time;

   669 

   670     /**

   671      * Decoding: duration of the stream, in stream time base.

   672      * If a source file does not specify a duration, but does specify

   673      * a bitrate, this value will be estimated from bitrate and file size.

   674      */

   675     int64_t duration;

   676 

   677     int64_t nb_frames;                 ///< number of frames in this stream if known or 0

   678 

   679     int disposition; /**< AV_DISPOSITION_* bit field */

   680 

   681     enum AVDiscard discard; ///< Selects which packets can be discarded at will and do not need to be demuxed.

   682 

   683     /**

   684      * sample aspect ratio (0 if unknown)

   685      * - encoding: Set by user.

   686      * - decoding: Set by libavformat.

   687      */

   688     AVRational sample_aspect_ratio;

   689 

   690     AVDictionary *metadata;

   691 

   692     /**

   693      * Average framerate

   694      */

   695     AVRational avg_frame_rate;

   696 

   697     /**

   698      * For streams with AV_DISPOSITION_ATTACHED_PIC disposition, this packet

   699      * will contain the attached picture.

   700      *

   701      * decoding: set by libavformat, must not be modified by the caller.

   702      * encoding: unused

   703      */

   704     AVPacket attached_pic;

   705 

   706     /*****************************************************************

   707      * All fields below this line are not part of the public API. They

   708      * may not be used outside of libavformat and can be changed and

   709      * removed at will.

   710      * New public fields should be added right above.

   711      *****************************************************************

   712      */

   713 

   714     /**

   715      * Stream information used internally by av_find_stream_info()

   716      */

   717 #define MAX_STD_TIMEBASES (60*12+5)

   718     struct {

   719 #if FF_API_R_FRAME_RATE

   720         int64_t last_dts;

   721         int64_t duration_gcd;

   722         int duration_count;

   723         double duration_error[MAX_STD_TIMEBASES];

   724 #endif

   725         int nb_decoded_frames;

   726         int found_decoder;

   727 

   728         /**

   729          * Those are used for average framerate estimation.

   730          */

   731         int64_t fps_first_dts;

   732         int     fps_first_dts_idx;

   733         int64_t fps_last_dts;

   734         int     fps_last_dts_idx;

   735 

   736     } *info;

   737 

   738     int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */

   739 

   740     // Timestamp generation support:

   741     /**

   742      * Timestamp corresponding to the last dts sync point.

   743      *

   744      * Initialized when AVCodecParserContext.dts_sync_point >= 0 and

   745      * a DTS is received from the underlying container. Otherwise set to

   746      * AV_NOPTS_VALUE by default.

   747      */

   748     int64_t reference_dts;

   749     int64_t first_dts;

   750     int64_t cur_dts;

   751     int64_t last_IP_pts;

   752     int last_IP_duration;

   753 

   754     /**

   755      * Number of packets to buffer for codec probing

   756      */

   757 #define MAX_PROBE_PACKETS 2500

   758     int probe_packets;

   759 

   760     /**

   761      * Number of frames that have been demuxed during av_find_stream_info()

   762      */

   763     int codec_info_nb_frames;

   764 

   765     /* av_read_frame() support */

   766     enum AVStreamParseType need_parsing;

   767     struct AVCodecParserContext *parser;

   768 

   769     /**

   770      * last packet in packet_buffer for this stream when muxing.

   771      */

   772     struct AVPacketList *last_in_packet_buffer;

   773     AVProbeData probe_data;

   774 #define MAX_REORDER_DELAY 16

   775     int64_t pts_buffer[MAX_REORDER_DELAY+1];

   776 

   777     AVIndexEntry *index_entries; /**< Only used if the format does not

   778                                     support seeking natively. */

   779     int nb_index_entries;

   780     unsigned int index_entries_allocated_size;

   781 } AVStream;

   782 

   783 #define AV_PROGRAM_RUNNING 1

   784 

   785 /**

   786  * New fields can be added to the end with minor version bumps.

   787  * Removal, reordering and changes to existing fields require a major

   788  * version bump.

   789  * sizeof(AVProgram) must not be used outside libav*.

   790  */

   791 typedef struct AVProgram {

   792     int            id;

   793     int            flags;

   794     enum AVDiscard discard;        ///< selects which program to discard and which to feed to the caller

   795     unsigned int   *stream_index;

   796     unsigned int   nb_stream_indexes;

   797     AVDictionary *metadata;

   798 } AVProgram;

   799 

   800 #define AVFMTCTX_NOHEADER      0x0001 /**< signal that no header is present

   801                                          (streams are added dynamically) */

   802 

   803 typedef struct AVChapter {

   804     int id;                 ///< unique ID to identify the chapter

   805     AVRational time_base;   ///< time base in which the start/end timestamps are specified

   806     int64_t start, end;     ///< chapter start/end time in time_base units

   807     AVDictionary *metadata;

   808 } AVChapter;

   809 

   810 /**

   811  * Format I/O context.

   812  * New fields can be added to the end with minor version bumps.

   813  * Removal, reordering and changes to existing fields require a major

   814  * version bump.

   815  * sizeof(AVFormatContext) must not be used outside libav*, use

   816  * avformat_alloc_context() to create an AVFormatContext.

   817  */

   818 typedef struct AVFormatContext {

   819     /**

   820      * A class for logging and AVOptions. Set by avformat_alloc_context().

   821      * Exports (de)muxer private options if they exist.

   822      */

   823     const AVClass *av_class;

   824 

   825     /**

   826      * Can only be iformat or oformat, not both at the same time.

   827      *

   828      * decoding: set by avformat_open_input().

   829      * encoding: set by the user.

   830      */

   831     struct AVInputFormat *iformat;

   832     struct AVOutputFormat *oformat;

   833 

   834     /**

   835      * Format private data. This is an AVOptions-enabled struct

   836      * if and only if iformat/oformat.priv_class is not NULL.

   837      */

   838     void *priv_data;

   839 

   840     /**

   841      * I/O context.

   842      *

   843      * decoding: either set by the user before avformat_open_input() (then

   844      * the user must close it manually) or set by avformat_open_input().

   845      * encoding: set by the user.

   846      *

   847      * Do NOT set this field if AVFMT_NOFILE flag is set in

   848      * iformat/oformat.flags. In such a case, the (de)muxer will handle

   849      * I/O in some other way and this field will be NULL.

   850      */

   851     AVIOContext *pb;

   852 

   853     /* stream info */

   854     int ctx_flags; /**< Format-specific flags, see AVFMTCTX_xx */

   855 

   856     /**

   857      * A list of all streams in the file. New streams are created with

   858      * avformat_new_stream().

   859      *

   860      * decoding: streams are created by libavformat in avformat_open_input().

   861      * If AVFMTCTX_NOHEADER is set in ctx_flags, then new streams may also

   862      * appear in av_read_frame().

   863      * encoding: streams are created by the user before avformat_write_header().

   864      */

   865     unsigned int nb_streams;

   866     AVStream **streams;

   867 

   868     char filename[1024]; /**< input or output filename */

   869 

   870     /**

   871      * Decoding: position of the first frame of the component, in

   872      * AV_TIME_BASE fractional seconds. NEVER set this value directly:

   873      * It is deduced from the AVStream values.

   874      */

   875     int64_t start_time;

   876 

   877     /**

   878      * Decoding: duration of the stream, in AV_TIME_BASE fractional

   879      * seconds. Only set this value if you know none of the individual stream

   880      * durations and also do not set any of them. This is deduced from the

   881      * AVStream values if not set.

   882      */

   883     int64_t duration;

   884 

   885     /**

   886      * Decoding: total stream bitrate in bit/s, 0 if not

   887      * available. Never set it directly if the file_size and the

   888      * duration are known as Libav can compute it automatically.

   889      */

   890     int bit_rate;

   891 

   892     unsigned int packet_size;

   893     int max_delay;

   894 

   895     int flags;

   896 #define AVFMT_FLAG_GENPTS       0x0001 ///< Generate missing pts even if it requires parsing future frames.

   897 #define AVFMT_FLAG_IGNIDX       0x0002 ///< Ignore index.

   898 #define AVFMT_FLAG_NONBLOCK     0x0004 ///< Do not block when reading packets from input.

   899 #define AVFMT_FLAG_IGNDTS       0x0008 ///< Ignore DTS on frames that contain both DTS & PTS

   900 #define AVFMT_FLAG_NOFILLIN     0x0010 ///< Do not infer any values from other values, just return what is stored in the container

   901 #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

   902 #define AVFMT_FLAG_NOBUFFER     0x0040 ///< Do not buffer frames when possible

   903 #define AVFMT_FLAG_CUSTOM_IO    0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.

   904 #define AVFMT_FLAG_DISCARD_CORRUPT  0x0100 ///< Discard frames marked corrupted

   905 

   906     /**

   907      * decoding: size of data to probe; encoding: unused.

   908      */

   909     unsigned int probesize;

   910 

   911     /**

   912      * decoding: maximum time (in AV_TIME_BASE units) during which the input should

   913      * be analyzed in avformat_find_stream_info().

   914      */

   915     int max_analyze_duration;

   916 

   917     const uint8_t *key;

   918     int keylen;

   919 

   920     unsigned int nb_programs;

   921     AVProgram **programs;

   922 

   923     /**

   924      * Forced video codec_id.

   925      * Demuxing: Set by user.

   926      */

   927     enum AVCodecID video_codec_id;

   928 

   929     /**

   930      * Forced audio codec_id.

   931      * Demuxing: Set by user.

   932      */

   933     enum AVCodecID audio_codec_id;

   934 

   935     /**

   936      * Forced subtitle codec_id.

   937      * Demuxing: Set by user.

   938      */

   939     enum AVCodecID subtitle_codec_id;

   940 

   941     /**

   942      * Maximum amount of memory in bytes to use for the index of each stream.

   943      * If the index exceeds this size, entries will be discarded as

   944      * needed to maintain a smaller size. This can lead to slower or less

   945      * accurate seeking (depends on demuxer).

   946      * Demuxers for which a full in-memory index is mandatory will ignore

   947      * this.

   948      * muxing  : unused

   949      * demuxing: set by user

   950      */

   951     unsigned int max_index_size;

   952 

   953     /**

   954      * Maximum amount of memory in bytes to use for buffering frames

   955      * obtained from realtime capture devices.

   956      */

   957     unsigned int max_picture_buffer;

   958 

   959     unsigned int nb_chapters;

   960     AVChapter **chapters;

   961 

   962     AVDictionary *metadata;

   963 

   964     /**

   965      * Start time of the stream in real world time, in microseconds

   966      * since the unix epoch (00:00 1st January 1970). That is, pts=0

   967      * in the stream was captured at this real world time.

   968      * - encoding: Set by user.

   969      * - decoding: Unused.

   970      */

   971     int64_t start_time_realtime;

   972 

   973     /**

   974      * decoding: number of frames used to probe fps

   975      */

   976     int fps_probe_size;

   977 

   978     /**

   979      * Error recognition; higher values will detect more errors but may

   980      * misdetect some more or less valid parts as errors.

   981      * - encoding: unused

   982      * - decoding: Set by user.

   983      */

   984     int error_recognition;

   985 

   986     /**

   987      * Custom interrupt callbacks for the I/O layer.

   988      *

   989      * decoding: set by the user before avformat_open_input().

   990      * encoding: set by the user before avformat_write_header()

   991      * (mainly useful for AVFMT_NOFILE formats). The callback

   992      * should also be passed to avio_open2() if it's used to

   993      * open the file.

   994      */

   995     AVIOInterruptCB interrupt_callback;

   996 

   997     /**

   998      * Flags to enable debugging.

   999      */

  1000     int debug;

  1001 #define FF_FDEBUG_TS        0x0001

  1002     /*****************************************************************

  1003      * All fields below this line are not part of the public API. They

  1004      * may not be used outside of libavformat and can be changed and

  1005      * removed at will.

  1006      * New public fields should be added right above.

  1007      *****************************************************************

  1008      */

  1009 

  1010     /**

  1011      * This buffer is only needed when packets were already buffered but

  1012      * not decoded, for example to get the codec parameters in MPEG

  1013      * streams.

  1014      */

  1015     struct AVPacketList *packet_buffer;

  1016     struct AVPacketList *packet_buffer_end;

  1017 

  1018     /* av_seek_frame() support */

  1019     int64_t data_offset; /**< offset of the first packet */

  1020 

  1021     /**

  1022      * Raw packets from the demuxer, prior to parsing and decoding.

  1023      * This buffer is used for buffering packets until the codec can

  1024      * be identified, as parsing cannot be done without knowing the

  1025      * codec.

  1026      */

  1027     struct AVPacketList *raw_packet_buffer;

  1028     struct AVPacketList *raw_packet_buffer_end;

  1029     /**

  1030      * Packets split by the parser get queued here.

  1031      */

  1032     struct AVPacketList *parse_queue;

  1033     struct AVPacketList *parse_queue_end;

  1034     /**

  1035      * Remaining size available for raw_packet_buffer, in bytes.

  1036      */

  1037 #define RAW_PACKET_BUFFER_SIZE 2500000

  1038     int raw_packet_buffer_remaining_size;

  1039 } AVFormatContext;

  1040 

  1041 typedef struct AVPacketList {

  1042     AVPacket pkt;

  1043     struct AVPacketList *next;

  1044 } AVPacketList;

  1045 

  1046 

  1047 /**

  1048  * @defgroup lavf_core Core functions

  1049  * @ingroup libavf

  1050  *

  1051  * Functions for querying libavformat capabilities, allocating core structures,

  1052  * etc.

  1053  * @{

  1054  */

  1055 

  1056 /**

  1057  * Return the LIBAVFORMAT_VERSION_INT constant.

  1058  */

  1059 unsigned avformat_version(void);

  1060 

  1061 /**

  1062  * Return the libavformat build-time configuration.

  1063  */

  1064 const char *avformat_configuration(void);

  1065 

  1066 /**

  1067  * Return the libavformat license.

  1068  */

  1069 const char *avformat_license(void);

  1070 

  1071 /**

  1072  * Initialize libavformat and register all the muxers, demuxers and

  1073  * protocols. If you do not call this function, then you can select

  1074  * exactly which formats you want to support.

  1075  *

  1076  * @see av_register_input_format()

  1077  * @see av_register_output_format()

  1078  * @see av_register_protocol()

  1079  */

  1080 void av_register_all(void);

  1081 

  1082 void av_register_input_format(AVInputFormat *format);

  1083 void av_register_output_format(AVOutputFormat *format);

  1084 

  1085 /**

  1086  * Do global initialization of network components. This is optional,

  1087  * but recommended, since it avoids the overhead of implicitly

  1088  * doing the setup for each session.

  1089  *

  1090  * Calling this function will become mandatory if using network

  1091  * protocols at some major version bump.

  1092  */

  1093 int avformat_network_init(void);

  1094 

  1095 /**

  1096  * Undo the initialization done by avformat_network_init.

  1097  */

  1098 int avformat_network_deinit(void);

  1099 

  1100 /**

  1101  * If f is NULL, returns the first registered input format,

  1102  * if f is non-NULL, returns the next registered input format after f

  1103  * or NULL if f is the last one.

  1104  */

  1105 AVInputFormat  *av_iformat_next(AVInputFormat  *f);

  1106 

  1107 /**

  1108  * If f is NULL, returns the first registered output format,

  1109  * if f is non-NULL, returns the next registered output format after f

  1110  * or NULL if f is the last one.

  1111  */

  1112 AVOutputFormat *av_oformat_next(AVOutputFormat *f);

  1113 

  1114 /**

  1115  * Allocate an AVFormatContext.

  1116  * avformat_free_context() can be used to free the context and everything

  1117  * allocated by the framework within it.

  1118  */

  1119 AVFormatContext *avformat_alloc_context(void);

  1120 

  1121 /**

  1122  * Free an AVFormatContext and all its streams.

  1123  * @param s context to free

  1124  */

  1125 void avformat_free_context(AVFormatContext *s);

  1126 

  1127 /**

  1128  * Get the AVClass for AVFormatContext. It can be used in combination with

  1129  * AV_OPT_SEARCH_FAKE_OBJ for examining options.

  1130  *

  1131  * @see av_opt_find().

  1132  */

  1133 const AVClass *avformat_get_class(void);

  1134 

  1135 /**