FFmpeg/libavformat/avformat.h

/*
 * copyright (c) 2001 Fabrice Bellard
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifndef AVFORMAT_AVFORMAT_H
#define AVFORMAT_AVFORMAT_H

#define LIBAVFORMAT_VERSION_MAJOR 52
#define LIBAVFORMAT_VERSION_MINOR 73
#define LIBAVFORMAT_VERSION_MICRO  0

#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                               LIBAVFORMAT_VERSION_MINOR, \
                                               LIBAVFORMAT_VERSION_MICRO)
#define LIBAVFORMAT_VERSION     AV_VERSION(LIBAVFORMAT_VERSION_MAJOR,   \
                                           LIBAVFORMAT_VERSION_MINOR,   \
                                           LIBAVFORMAT_VERSION_MICRO)
#define LIBAVFORMAT_BUILD       LIBAVFORMAT_VERSION_INT

#define LIBAVFORMAT_IDENT       "Lavf" AV_STRINGIFY(LIBAVFORMAT_VERSION)

/**
 * I return the LIBAVFORMAT_VERSION_INT constant.  You got
 * a fucking problem with that, douchebag?
 */
unsigned avformat_version(void);

/**
 * Return the libavformat build-time configuration.
 */
const char *avformat_configuration(void);

/**
 * Return the libavformat license.
 */
const char *avformat_license(void);

#include <time.h>
#include <stdio.h>  /* FILE */
#include "libavcodec/avcodec.h"

#include "avio.h"

struct AVFormatContext;


/*
 * Public Metadata API.
 * The metadata API allows libavformat to export metadata tags to a client
 * application using a sequence of key/value pairs. Like all strings in FFmpeg,
 * metadata must be stored as UTF-8 encoded Unicode. Note that metadata
 * exported by demuxers isn't checked to be valid UTF-8 in most cases.
 * Important concepts to keep in mind:
 * 1. Keys are unique; there can never be 2 tags with the same key. This is
 *    also meant semantically, i.e., a demuxer should not knowingly produce
 *    several keys that are literally different but semantically identical.
 *    E.g., key=Author5, key=Author6. In this example, all authors must be
 *    placed in the same tag.
 * 2. Metadata is flat, not hierarchical; there are no subtags. If you
 *    want to store, e.g., the email address of the child of producer Alice
 *    and actor Bob, that could have key=alice_and_bobs_childs_email_address.
 * 3. Several modifiers can be applied to the tag name. This is done by
 *    appending a dash character ('-') and the modifier name in the order
 *    they appear in the list below -- e.g. foo-eng-sort, not foo-sort-eng.
 *    a) language -- a tag whose value is localized for a particular language
 *       is appended with the ISO 639-2/B 3-letter language code.
 *       For example: Author-ger=Michael, Author-eng=Mike
 *       The original/default language is in the unqualified "Author" tag.
 *       A demuxer should set a default if it sets any translated tag.
 *    b) sorting  -- a modified version of a tag that should be used for
 *       sorting will have '-sort' appended. E.g. artist="The Beatles",
 *       artist-sort="Beatles, The".
 *
 * 4. Tag names are normally exported exactly as stored in the container to
 *    allow lossless remuxing to the same format. For container-independent
 *    handling of metadata, av_metadata_conv() can convert it to ffmpeg generic
 *    format. Follows a list of generic tag names:
 *
 * album        -- name of the set this work belongs to
 * album_artist -- main creator of the set/album, if different from artist.
 *                 e.g. "Various Artists" for compilation albums.
 * artist       -- main creator of the work
 * comment      -- any additional description of the file.
 * composer     -- who composed the work, if different from artist.
 * copyright    -- name of copyright holder.
 * date         -- date when the work was created, preferably in ISO 8601.
 * disc         -- number of a subset, e.g. disc in a multi-disc collection.
 * encoder      -- name/settings of the software/hardware that produced the file.
 * encoded_by   -- person/group who created the file.
 * filename     -- original name of the file.
 * genre        -- <self-evident>.
 * language     -- main language in which the work is performed, preferably
 *                 in ISO 639-2 format.
 * performer    -- artist who performed the work, if different from artist.
 *                 E.g for "Also sprach Zarathustra", artist would be "Richard
 *                 Strauss" and performer "London Philharmonic Orchestra".
 * publisher    -- name of the label/publisher.
 * title        -- name of the work.
 * track        -- number of this work in the set, can be in form current/total.
 */

#define AV_METADATA_MATCH_CASE      1
#define AV_METADATA_IGNORE_SUFFIX   2
#define AV_METADATA_DONT_STRDUP_KEY 4
#define AV_METADATA_DONT_STRDUP_VAL 8
#define AV_METADATA_DONT_OVERWRITE 16   ///< Don't overwrite existing tags.

typedef struct {
    char *key;
    char *value;
}AVMetadataTag;

typedef struct AVMetadata AVMetadata;
typedef struct AVMetadataConv AVMetadataConv;

/**
 * Get a metadata element with matching key.
 * @param prev Set to the previous matching element to find the next.
 *             If set to NULL the first matching element is returned.
 * @param flags Allows case as well as suffix-insensitive comparisons.
 * @return Found tag or NULL, changing key or value leads to undefined behavior.
 */
AVMetadataTag *
av_metadata_get(AVMetadata *m, const char *key, const AVMetadataTag *prev, int flags);

#if LIBAVFORMAT_VERSION_MAJOR == 52
/**
 * Set the given tag in m, overwriting an existing tag.
 * @param key tag key to add to m (will be av_strduped)
 * @param value tag value to add to m (will be av_strduped)
 * @return >= 0 on success otherwise an error code <0
 * @deprecated Use av_metadata_set2() instead.
 */
attribute_deprecated int av_metadata_set(AVMetadata **pm, const char *key, const char *value);
#endif

/**
 * Set the given tag in m, overwriting an existing tag.
 * @param key tag key to add to m (will be av_strduped depending on flags)
 * @param value tag value to add to m (will be av_strduped depending on flags).
 *        Passing a NULL value will cause an existing tag to be deleted.
 * @return >= 0 on success otherwise an error code <0
 */
int av_metadata_set2(AVMetadata **pm, const char *key, const char *value, int flags);

/**
 * Convert all the metadata sets from ctx according to the source and
 * destination conversion tables. If one of the tables is NULL, then
 * tags are converted to/from ffmpeg generic tag names.
 * @param d_conv destination tags format conversion table
 * @param s_conv source tags format conversion table
 */
void av_metadata_conv(struct AVFormatContext *ctx,const AVMetadataConv *d_conv,
                                                  const AVMetadataConv *s_conv);

/**
 * Free all the memory allocated for an AVMetadata struct.
 */
void av_metadata_free(AVMetadata **m);


/* packet functions */


/**
 * Allocate and read the payload of a packet and initialize its
 * fields with default values.
 *
 * @param pkt packet
 * @param size desired payload size
 * @return >0 (read size) if OK, AVERROR_xxx otherwise
 */
int av_get_packet(ByteIOContext *s, AVPacket *pkt, int size);


/*************************************************/
/* fractional numbers for exact pts handling */

/**
 * The exact value of the fractional number is: 'val + num / den'.
 * num is assumed to be 0 <= num < den.
 */
typedef struct AVFrac {
    int64_t val, num, den;
} AVFrac;

/*************************************************/
/* input/output formats */

struct AVCodecTag;

/** This structure contains the data a format has to probe a file. */
typedef struct AVProbeData {
    const char *filename;
    unsigned char *buf; /**< Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero. */
    int buf_size;       /**< Size of buf except extra allocated bytes */
} AVProbeData;

#define AVPROBE_SCORE_MAX 100               ///< maximum score, half of that is used for file-extension-based detection
#define AVPROBE_PADDING_SIZE 32             ///< extra allocated bytes at the end of the probe buffer

typedef struct AVFormatParameters {
    AVRational time_base;
    int sample_rate;
    int channels;
    int width;
    int height;
    enum PixelFormat pix_fmt;
    int channel; /**< Used to select DV channel. */
    const char *standard; /**< TV standard, NTSC, PAL, SECAM */
    unsigned int mpeg2ts_raw:1;  /**< Force raw MPEG-2 transport stream output, if possible. */
    unsigned int mpeg2ts_compute_pcr:1; /**< Compute exact PCR for each transport
                                            stream packet (only meaningful if
                                            mpeg2ts_raw is TRUE). */
    unsigned int initial_pause:1;       /**< Do not begin to play the stream
                                            immediately (RTSP only). */
    unsigned int prealloced_context:1;
#if LIBAVFORMAT_VERSION_INT < (53<<16)
    enum CodecID video_codec_id;
    enum CodecID audio_codec_id;
#endif
} AVFormatParameters;

//! Demuxer will use url_fopen, no opened file should be provided by the caller.
#define AVFMT_NOFILE        0x0001
#define AVFMT_NEEDNUMBER    0x0002 /**< Needs '%d' in filename. */
#define AVFMT_SHOW_IDS      0x0008 /**< Show format stream IDs numbers. */
#define AVFMT_RAWPICTURE    0x0020 /**< Format wants AVPicture structure for
                                      raw picture data. */
#define AVFMT_GLOBALHEADER  0x0040 /**< Format wants global header. */
#define AVFMT_NOTIMESTAMPS  0x0080 /**< Format does not need / have any timestamps. */
#define AVFMT_GENERIC_INDEX 0x0100 /**< Use generic index building code. */
#define AVFMT_TS_DISCONT    0x0200 /**< Format allows timestamp discontinuities. */
#define AVFMT_VARIABLE_FPS  0x0400 /**< Format allows variable fps. */
#define AVFMT_NODIMENSIONS  0x0800 /**< Format does not need width/height */

typedef struct AVOutputFormat {
    const char *name;
    /**
     * Descriptive name for the format, meant to be more human-readable
     * than name. You should use the NULL_IF_CONFIG_SMALL() macro
     * to define it.
     */
    const char *long_name;
    const char *mime_type;
    const char *extensions; /**< comma-separated filename extensions */
    /** size of private data so that it can be allocated in the wrapper */
    int priv_data_size;
    /* output support */
    enum CodecID audio_codec; /**< default audio codec */
    enum CodecID video_codec; /**< default video codec */
    int (*write_header)(struct AVFormatContext *);
    int (*write_packet)(struct AVFormatContext *, AVPacket *pkt);
    int (*write_trailer)(struct AVFormatContext *);
    /** can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_GLOBALHEADER */
    int flags;
    /** Currently only used to set pixel format if not YUV420P. */
    int (*set_parameters)(struct AVFormatContext *, AVFormatParameters *);
    int (*interleave_packet)(struct AVFormatContext *, AVPacket *out,
                             AVPacket *in, int flush);

    /**
     * List of supported codec_id-codec_tag pairs, ordered by "better
     * choice first". The arrays are all terminated by CODEC_ID_NONE.
     */
    const struct AVCodecTag * const *codec_tag;

    enum CodecID subtitle_codec; /**< default subtitle codec */

    const AVMetadataConv *metadata_conv;

    /* private fields */
    struct AVOutputFormat *next;
} AVOutputFormat;

typedef struct AVInputFormat {
    const char *name;
    /**
     * Descriptive name for the format, meant to be more human-readable
     * than name. You should use the NULL_IF_CONFIG_SMALL() macro
     * to define it.
     */
    const char *long_name;
    /** Size of private data so that it can be allocated in the wrapper. */
    int priv_data_size;
    /**
     * Tell if a given file has a chance of being parsed as this format.
     * The buffer provided is guaranteed to be AVPROBE_PADDING_SIZE bytes
     * big so you do not have to check for that unless you need more.
     */
    int (*read_probe)(AVProbeData *);
    /** Read the format header and initialize the AVFormatContext
       structure. Return 0 if OK. 'ap' if non-NULL contains
       additional parameters. Only used in raw format right
       now. 'av_new_stream' should be called to create new streams.  */
    int (*read_header)(struct AVFormatContext *,
                       AVFormatParameters *ap);
    /** Read one packet and put it in 'pkt'. pts and flags are also
       set. 'av_new_stream' can be called only if the flag
       AVFMTCTX_NOHEADER is used.
       @return 0 on success, < 0 on error.
               When returning an error, pkt must not have been allocated
               or must be freed before returning */
    int (*read_packet)(struct AVFormatContext *, AVPacket *pkt);
    /** Close the stream. The AVFormatContext and AVStreams are not
       freed by this function */
    int (*read_close)(struct AVFormatContext *);

#if LIBAVFORMAT_VERSION_MAJOR < 53
    /**
     * Seek to a given timestamp relative to the frames in
     * stream component stream_index.
     * @param stream_index Must not be -1.
     * @param flags Selects which direction should be preferred if no exact
     *              match is available.
     * @return >= 0 on success (but not necessarily the new offset)
     */
    int (*read_seek)(struct AVFormatContext *,
                     int stream_index, int64_t timestamp, int flags);
#endif
    /**
     * Gets the next timestamp in stream[stream_index].time_base units.
     * @return the timestamp or AV_NOPTS_VALUE if an error occurred
     */
    int64_t (*read_timestamp)(struct AVFormatContext *s, int stream_index,
                              int64_t *pos, int64_t pos_limit);
    /** Can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER. */
    int flags;
    /** If extensions are defined, then no probe is done. You should
       usually not use extension format guessing because it is not
       reliable enough */
    const char *extensions;
    /** General purpose read-only value that the format can use. */
    int value;

    /** Start/resume playing - only meaningful if using a network-based format
       (RTSP). */
    int (*read_play)(struct AVFormatContext *);

    /** Pause playing - only meaningful if using a network-based format
       (RTSP). */
    int (*read_pause)(struct AVFormatContext *);

    const struct AVCodecTag * const *codec_tag;

    /**
     * Seek to timestamp ts.
     * Seeking will be done so that the point from which all active streams
     * can be presented successfully will be closest to ts and within min/max_ts.
     * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
     */
    int (*read_seek2)(struct AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);

    const AVMetadataConv *metadata_conv;

    /* private fields */
    struct AVInputFormat *next;
} AVInputFormat;

enum AVStreamParseType {
    AVSTREAM_PARSE_NONE,
    AVSTREAM_PARSE_FULL,       /**< full parsing and repack */
    AVSTREAM_PARSE_HEADERS,    /**< Only parse headers, do not repack. */
    AVSTREAM_PARSE_TIMESTAMPS, /**< full parsing and interpolation of timestamps for frames not starting on a packet boundary */
    AVSTREAM_PARSE_FULL_ONCE,  /**< full parsing and repack of the first frame only, only implemented for H.264 currently */
};

typedef struct AVIndexEntry {
    int64_t pos;
    int64_t timestamp;
#define AVINDEX_KEYFRAME 0x0001
    int flags:2;
    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).
    int min_distance;         /**< Minimum distance between this and the previous keyframe, used to avoid unneeded searching. */
} AVIndexEntry;

#define AV_DISPOSITION_DEFAULT   0x0001
#define AV_DISPOSITION_DUB       0x0002
#define AV_DISPOSITION_ORIGINAL  0x0004
#define AV_DISPOSITION_COMMENT   0x0008
#define AV_DISPOSITION_LYRICS    0x0010
#define AV_DISPOSITION_KARAOKE   0x0020
/** Track should be used during playback by default.
    Useful for subtitle track that should be displayed
    even when user did not explicitly ask for subtitles. */
#define AV_DISPOSITION_FORCED    0x0040

/**
 * Stream structure.
 * New fields can be added to the end with minor version bumps.
 * Removal, reordering and changes to existing fields require a major
 * version bump.
 * sizeof(AVStream) must not be used outside libav*.
 */
typedef struct AVStream {
    int index;    /**< stream index in AVFormatContext */
    int id;       /**< format-specific stream ID */
    AVCodecContext *codec; /**< codec context */
    /**
     * Real base framerate of the stream.
     * This is the lowest framerate with which all timestamps can be
     * represented accurately (it is the least common multiple of all
     * framerates in the stream). Note, this value is just a guess!
     * For example, if the time base is 1/90000 and all frames have either
     * approximately 3600 or 1800 timer ticks, then r_frame_rate will be 50/1.
     */
    AVRational r_frame_rate;
    void *priv_data;

    /* internal data used in av_find_stream_info() */
    int64_t first_dts;
    /** encoding: pts generation when outputting stream */
    struct AVFrac pts;

    /**
     * This is the fundamental unit of time (in seconds) in terms
     * of which frame timestamps are represented. For fixed-fps content,
     * time base should be 1/framerate and timestamp increments should be 1.
     */
    AVRational time_base;
    int pts_wrap_bits; /**< number of bits in pts (used for wrapping control) */
    /* ffmpeg.c private use */
    int stream_copy; /**< If set, just copy stream. */
    enum AVDiscard discard; ///< Selects which packets can be discarded at will and do not need to be demuxed.
    //FIXME move stuff to a flags field?
    /** Quality, as it has been removed from AVCodecContext and put in AVVideoFrame.
     * MN: dunno if that is the right place for it */
    float quality;
    /**
     * Decoding: pts of the first frame of the stream, in stream time base.
     * Only set this if you are absolutely 100% sure that the value you set
     * it to really is the pts of the first frame.
     * This may be undefined (AV_NOPTS_VALUE).
     * @note The ASF header does NOT contain a correct start_time the ASF
     * demuxer must NOT set this.
     */
    int64_t start_time;
    /**
     * Decoding: duration of the stream, in stream time base.
     * If a source file does not specify a duration, but does specify
     * a bitrate, this value will be estimated from bitrate and file size.
     */
    int64_t duration;

#if LIBAVFORMAT_VERSION_INT < (53<<16)
    char language[4]; /** ISO 639-2/B 3-letter language code (empty string if undefined) */
#endif

    /* av_read_frame() support */
    enum AVStreamParseType need_parsing;
    struct AVCodecParserContext *parser;

    int64_t cur_dts;
    int last_IP_duration;
    int64_t last_IP_pts;
    /* av_seek_frame() support */
    AVIndexEntry *index_entries; /**< Only used if the format does not
                                    support seeking natively. */
    int nb_index_entries;
    unsigned int index_entries_allocated_size;

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

#if LIBAVFORMAT_VERSION_INT < (53<<16)
    int64_t unused[4+1];

    char *filename; /**< source filename of the stream */
#endif

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

    AVProbeData probe_data;
#define MAX_REORDER_DELAY 16
    int64_t pts_buffer[MAX_REORDER_DELAY+1];

    /**
     * sample aspect ratio (0 if unknown)
     * - encoding: Set by user.
     * - decoding: Set by libavformat.
     */
    AVRational sample_aspect_ratio;

    AVMetadata *metadata;

    /* Intended mostly for av_read_frame() support. Not supposed to be used by */
    /* external applications; try to use something else if at all possible.    */
    const uint8_t *cur_ptr;
    int cur_len;
    AVPacket cur_pkt;

    // Timestamp generation support:
    /**
     * Timestamp corresponding to the last dts sync point.
     *
     * Initialized when AVCodecParserContext.dts_sync_point >= 0 and
     * a DTS is received from the underlying container. Otherwise set to
     * AV_NOPTS_VALUE by default.
     */
    int64_t reference_dts;

    /**
     * Number of packets to buffer for codec probing
     * NOT PART OF PUBLIC API
     */
#define MAX_PROBE_PACKETS 2500
    int probe_packets;

    /**
     * last packet in packet_buffer for this stream when muxing.
     * used internally, NOT PART OF PUBLIC API, dont read or write from outside of libav*
     */
    struct AVPacketList *last_in_packet_buffer;

    /**
     * Average framerate
     */
    AVRational avg_frame_rate;

    /**
     * Number of frames that have been demuxed during av_find_stream_info()
     */
    int codec_info_nb_frames;
} AVStream;

#define AV_PROGRAM_RUNNING 1

/**
 * New fields can be added to the end with minor version bumps.
 * Removal, reordering and changes to existing fields require a major
 * version bump.
 * sizeof(AVProgram) must not be used outside libav*.
 */
typedef struct AVProgram {
    int            id;
#if LIBAVFORMAT_VERSION_INT < (53<<16)
    char           *provider_name; ///< network name for DVB streams
    char           *name;          ///< service name for DVB streams
#endif
    int            flags;
    enum AVDiscard discard;        ///< selects which program to discard and which to feed to the caller
    unsigned int   *stream_index;
    unsigned int   nb_stream_indexes;
    AVMetadata *metadata;
} AVProgram;

#define AVFMTCTX_NOHEADER      0x0001 /**< signal that no header is present
                                         (streams are added dynamically) */

typedef struct AVChapter {
    int id;                 ///< unique ID to identify the chapter
    AVRational time_base;   ///< time base in which the start/end timestamps are specified
    int64_t start, end;     ///< chapter start/end time in time_base units
#if LIBAVFORMAT_VERSION_INT < (53<<16)
    char *title;            ///< chapter title
#endif
    AVMetadata *metadata;
} AVChapter;

#if LIBAVFORMAT_VERSION_MAJOR < 53
#define MAX_STREAMS 20
#endif

/**
 * Format I/O context.
 * New fields can be added to the end with minor version bumps.
 * Removal, reordering and changes to existing fields require a major
 * version bump.
 * sizeof(AVFormatContext) must not be used outside libav*.
 */
typedef struct AVFormatContext {
    const AVClass *av_class; /**< Set by avformat_alloc_context. */
    /* Can only be iformat or oformat, not both at the same time. */
    struct AVInputFormat *iformat;
    struct AVOutputFormat *oformat;
    void *priv_data;
    ByteIOContext *pb;
    unsigned int nb_streams;
    AVStream *streams[MAX_STREAMS];
    char filename[1024]; /**< input or output filename */
    /* stream info */
    int64_t timestamp;
#if LIBAVFORMAT_VERSION_INT < (53<<16)
    char title[512];
    char author[512];
    char copyright[512];
    char comment[512];
    char album[512];
    int year;  /**< ID3 year, 0 if none */
    int track; /**< track number, 0 if none */
    char genre[32]; /**< ID3 genre */
#endif

    int ctx_flags; /**< Format-specific flags, see AVFMTCTX_xx */
    /* private data for pts handling (do not modify directly). */
    /** This buffer is only needed when packets were already buffered but
       not decoded, for example to get the codec parameters in MPEG
       streams. */
    struct AVPacketList *packet_buffer;

    /** Decoding: position of the first frame of the component, in
       AV_TIME_BASE fractional seconds. NEVER set this value directly:
       It is deduced from the AVStream values.  */
    int64_t start_time;
    /** Decoding: duration of the stream, in AV_TIME_BASE fractional
       seconds. Only set this value if you know none of the individual stream
       durations and also dont set any of them. This is deduced from the
       AVStream values if not set.  */
    int64_t duration;
    /** decoding: total file size, 0 if unknown */
    int64_t file_size;
    /** Decoding: total stream bitrate in bit/s, 0 if not
       available. Never set it directly if the file_size and the
       duration are known as FFmpeg can compute it automatically. */
    int bit_rate;

    /* av_read_frame() support */
    AVStream *cur_st;
#if LIBAVFORMAT_VERSION_INT < (53<<16)
    const uint8_t *cur_ptr_deprecated;
    int cur_len_deprecated;
    AVPacket cur_pkt_deprecated;
#endif

    /* av_seek_frame() support */
    int64_t data_offset; /** offset of the first packet */
    int index_built;

    int mux_rate;
    unsigned int packet_size;
    int preload;
    int max_delay;

#define AVFMT_NOOUTPUTLOOP -1
#define AVFMT_INFINITEOUTPUTLOOP 0
    /** number of times to loop output in formats that support it */
    int loop_output;

    int flags;
#define AVFMT_FLAG_GENPTS       0x0001 ///< Generate missing pts even if it requires parsing future frames.
#define AVFMT_FLAG_IGNIDX       0x0002 ///< Ignore index.
#define AVFMT_FLAG_NONBLOCK     0x0004 ///< Do not block when reading packets from input.
#define AVFMT_FLAG_IGNDTS       0x0008 ///< Ignore DTS on frames that contain both DTS & PTS
#define AVFMT_FLAG_NOFILLIN     0x0010 ///< Do not infer any values from other values, just return what is stored in the container
#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
#define AVFMT_FLAG_RTP_HINT     0x0040 ///< Add RTP hinting to the output file

    int loop_input;
    /** decoding: size of data to probe; encoding: unused. */
    unsigned int probesize;

    /**
     * Maximum time (in AV_TIME_BASE units) during which the input should
     * be analyzed in av_find_stream_info().
     */
    int max_analyze_duration;

    const uint8_t *key;
    int keylen;

    unsigned int nb_programs;
    AVProgram **programs;

    /**
     * Forced video codec_id.
     * Demuxing: Set by user.
     */
    enum CodecID video_codec_id;
    /**
     * Forced audio codec_id.
     * Demuxing: Set by user.
     */
    enum CodecID audio_codec_id;
    /**
     * Forced subtitle codec_id.
     * Demuxing: Set by user.
     */
    enum CodecID subtitle_codec_id;

    /**
     * Maximum amount of memory in bytes to use for the index of each stream.
     * If the index exceeds this size, entries will be discarded as
     * needed to maintain a smaller size. This can lead to slower or less
     * accurate seeking (depends on demuxer).
     * Demuxers for which a full in-memory index is mandatory will ignore
     * this.
     * muxing  : unused
     * demuxing: set by user
     */
    unsigned int max_index_size;

    /**
     * Maximum amount of memory in bytes to use for buffering frames
     * obtained from realtime capture devices.
     */
    unsigned int max_picture_buffer;

    unsigned int nb_chapters;
    AVChapter **chapters;

    /**
     * Flags to enable debugging.
     */
    int debug;
#define FF_FDEBUG_TS        0x0001

    /**
     * Raw packets from the demuxer, prior to parsing and decoding.
     * This buffer is used for buffering packets until the codec can
     * be identified, as parsing cannot be done without knowing the
     * codec.
     */
    struct AVPacketList *raw_packet_buffer;
    struct AVPacketList *raw_packet_buffer_end;

    struct AVPacketList *packet_buffer_end;

    AVMetadata *metadata;

    /**
     * Remaining size available for raw_packet_buffer, in bytes.
     * NOT PART OF PUBLIC API
     */
#define RAW_PACKET_BUFFER_SIZE 2500000
    int raw_packet_buffer_remaining_size;

    /**
     * Start time of the stream in real world time, in microseconds
     * since the unix epoch (00:00 1st January 1970). That is, pts=0
     * in the stream was captured at this real world time.
     * - encoding: Set by user.
     * - decoding: Unused.
     */
    int64_t start_time_realtime;
} AVFormatContext;

typedef struct AVPacketList {
    AVPacket pkt;
    struct AVPacketList *next;
} AVPacketList;

#if LIBAVFORMAT_VERSION_INT < (53<<16)
extern AVInputFormat *first_iformat;
extern AVOutputFormat *first_oformat;
#endif

/**
 * If f is NULL, returns the first registered input format,
 * if f is non-NULL, returns the next registered input format after f
 * or NULL if f is the last one.
 */
AVInputFormat  *av_iformat_next(AVInputFormat  *f);

/**
 * If f is NULL, returns the first registered output format,
 * if f is non-NULL, returns the next registered output format after f
 * or NULL if f is the last one.
 */
AVOutputFormat *av_oformat_next(AVOutputFormat *f);

enum CodecID av_guess_image2_codec(const char *filename);

/* XXX: Use automatic init with either ELF sections or C file parser */
/* modules. */

/* utils.c */
void av_register_input_format(AVInputFormat *format);
void av_register_output_format(AVOutputFormat *format);
#if LIBAVFORMAT_VERSION_MAJOR < 53
attribute_deprecated AVOutputFormat *guess_stream_format(const char *short_name,
                                    const char *filename,
                                    const char *mime_type);

/**
 * @deprecated Use av_guess_format() instead.
 */
attribute_deprecated AVOutputFormat *guess_format(const char *short_name,
                                                  const char *filename,
                                                  const char *mime_type);
#endif

/**
 * Return the output format in the list of registered output formats
 * which best matches the provided parameters, or return NULL if
 * there is no match.
 *
 * @param short_name if non-NULL checks if short_name matches with the
 * names of the registered formats
 * @param filename if non-NULL checks if filename terminates with the
 * extensions of the registered formats
 * @param mime_type if non-NULL checks if mime_type matches with the
 * MIME type of the registered formats
 */
AVOutputFormat *av_guess_format(const char *short_name,
                                const char *filename,
                                const char *mime_type);

/**
 * Guess the codec ID based upon muxer and filename.
 */
enum CodecID av_guess_codec(AVOutputFormat *fmt, const char *short_name,
                            const char *filename, const char *mime_type,
                            enum AVMediaType type);

/**
 * Send a nice hexadecimal dump of a buffer to the specified file stream.
 *
 * @param f The file stream pointer where the dump should be sent to.
 * @param buf buffer
 * @param size buffer size
 *
 * @see av_hex_dump_log, av_pkt_dump, av_pkt_dump_log
 */
void av_hex_dump(FILE *f, uint8_t *buf, int size);

/**
 * Send a nice hexadecimal dump of a buffer to the log.
 *
 * @param avcl A pointer to an arbitrary struct of which the first field is a
 * pointer to an AVClass struct.
 * @param level The importance level of the message, lower values signifying
 * higher importance.
 * @param buf buffer
 * @param size buffer size
 *
 * @see av_hex_dump, av_pkt_dump, av_pkt_dump_log
 */
void av_hex_dump_log(void *avcl, int level, uint8_t *buf, int size);

/**
 * Send a nice dump of a packet to the specified file stream.
 *
 * @param f The file stream pointer where the dump should be sent to.
 * @param pkt packet to dump
 * @param dump_payload True if the payload must be displayed, too.
 */
void av_pkt_dump(FILE *f, AVPacket *pkt, int dump_payload);

/**
 * Send a nice dump of a packet to the log.
 *
 * @param avcl A pointer to an arbitrary struct of which the first field is a
 * pointer to an AVClass struct.
 * @param level The importance level of the message, lower values signifying
 * higher importance.
 * @param pkt packet to dump
 * @param dump_payload True if the payload must be displayed, too.
 */
void av_pkt_dump_log(void *avcl, int level, AVPacket *pkt, int dump_payload);

/**
 * Initialize libavformat and register all the muxers, demuxers and
 * protocols. If you do not call this function, then you can select
 * exactly which formats you want to support.
 *
 * @see av_register_input_format()
 * @see av_register_output_format()
 * @see av_register_protocol()
 */
void av_register_all(void);

/**
 * Get the CodecID for the given codec tag tag.
 * If no codec id is found returns CODEC_ID_NONE.
 *
 * @param tags list of supported codec_id-codec_tag pairs, as stored
 * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
 */
enum CodecID av_codec_get_id(const struct AVCodecTag * const *tags, unsigned int tag);

/**
 * Get the codec tag for the given codec id id.
 * If no codec tag is found returns 0.
 *
 * @param tags list of supported codec_id-codec_tag pairs, as stored
 * in AVInputFormat.codec_tag and AVOutputFormat.codec_tag
 */
unsigned int av_codec_get_tag(const struct AVCodecTag * const *tags, enum CodecID id);

/* media file input */

/**
 * Find AVInputFormat based on the short name of the input format.
 */
AVInputFormat *av_find_input_format(const char *short_name);

/**
 * Guess the file format.
 *
 * @param is_opened Whether the file is already opened; determines whether
 *                  demuxers with or without AVFMT_NOFILE are probed.
 */
AVInputFormat *av_probe_input_format(AVProbeData *pd, int is_opened);

/**
 * Guess the file format.
 *
 * @param is_opened Whether the file is already opened; determines whether
 *                  demuxers with or without AVFMT_NOFILE are probed.
 * @param score_max A probe score larger that this is required to accept a
 *                  detection, the variable is set to the actual detection
 *                  score afterwards.
 *                  If the score is <= AVPROBE_SCORE_MAX / 4 it is recommended
 *                  to retry with a larger probe buffer.
 */
AVInputFormat *av_probe_input_format2(AVProbeData *pd, int is_opened, int *score_max);

/**
 * Allocate all the structures needed to read an input stream.
 *        This does not open the needed codecs for decoding the stream[s].
 */
int av_open_input_stream(AVFormatContext **ic_ptr,
                         ByteIOContext *pb, const char *filename,
                         AVInputFormat *fmt, AVFormatParameters *ap);

/**
 * Open a media file as input. The codecs are not opened. Only the file
 * header (if present) is read.
 *
 * @param ic_ptr The opened media file handle is put here.
 * @param filename filename to open
 * @param fmt If non-NULL, force the file format to use.
 * @param buf_size optional buffer size (zero if default is OK)
 * @param ap Additional parameters needed when opening the file
 *           (NULL if default).
 * @return 0 if OK, AVERROR_xxx otherwise
 */
int av_open_input_file(AVFormatContext **ic_ptr, const char *filename,
                       AVInputFormat *fmt,
                       int buf_size,
                       AVFormatParameters *ap);

#if LIBAVFORMAT_VERSION_MAJOR < 53
/**
 * @deprecated Use avformat_alloc_context() instead.
 */
attribute_deprecated AVFormatContext *av_alloc_format_context(void);
#endif

/**
 * Allocate an AVFormatContext.
 * Can be freed with av_free() but do not forget to free everything you
 * explicitly allocated as well!
 */
AVFormatContext *avformat_alloc_context(void);

/**
 * Read packets of a media file to get stream information. This
 * is useful for file formats with no headers such as MPEG. This
 * function also computes the real framerate in case of MPEG-2 repeat
 * frame mode.
 * The logical file position is not changed by this function;
 * examined packets may be buffered for later processing.
 *
 * @param ic media file handle
 * @return >=0 if OK, AVERROR_xxx on error
 * @todo Let the user decide somehow what information is needed so that
 *       we do not waste time getting stuff the user does not need.
 */
int av_find_stream_info(AVFormatContext *ic);

/**
 * Read a transport packet from a media file.
 *
 * This function is obsolete and should never be used.
 * Use av_read_frame() instead.
 *
 * @param s media file handle
 * @param pkt is filled
 * @return 0 if OK, AVERROR_xxx on error
 */
int av_read_packet(AVFormatContext *s, AVPacket *pkt);

/**
 * Return the next frame of a stream.
 *
 * The returned packet is valid
 * until the next av_read_frame() or until av_close_input_file() and
 * must be freed with av_free_packet. For video, the packet contains
 * exactly one frame. For audio, it contains an integer number of
 * frames if each frame has a known fixed size (e.g. PCM or ADPCM
 * data). If the audio frames have a variable size (e.g. MPEG audio),
 * then it contains one frame.
 *
 * pkt->pts, pkt->dts and pkt->duration are always set to correct
 * values in AVStream.time_base units (and guessed if the format cannot
 * provide them). pkt->pts can be AV_NOPTS_VALUE if the video format
 * has B-frames, so it is better to rely on pkt->dts if you do not
 * decompress the payload.
 *
 * @return 0 if OK, < 0 on error or end of file
 */
int av_read_frame(AVFormatContext *s, AVPacket *pkt);

/**
 * Seek to the keyframe at timestamp.
 * 'timestamp' in 'stream_index'.
 * @param stream_index If stream_index is (-1), a default
 * stream is selected, and timestamp is automatically converted
 * from AV_TIME_BASE units to the stream specific time_base.
 * @param timestamp Timestamp in AVStream.time_base units
 *        or, if no stream is specified, in AV_TIME_BASE units.
 * @param flags flags which select direction and seeking mode
 * @return >= 0 on success
 */
int av_seek_frame(AVFormatContext *s, int stream_index, int64_t timestamp,
                  int flags);

/**
 * Seek to timestamp ts.
 * Seeking will be done so that the point from which all active streams
 * can be presented successfully will be closest to ts and within min/max_ts.
 * Active streams are all streams that have AVStream.discard < AVDISCARD_ALL.
 *
 * If flags contain AVSEEK_FLAG_BYTE, then all timestamps are in bytes and
 * are the file position (this may not be supported by all demuxers).
 * If flags contain AVSEEK_FLAG_FRAME, then all timestamps are in frames
 * in the stream with stream_index (this may not be supported by all demuxers).
 * Otherwise all timestamps are in units of the stream selected by stream_index
 * or if stream_index is -1, in AV_TIME_BASE units.
 * If flags contain AVSEEK_FLAG_ANY, then non-keyframes are treated as
 * keyframes (this may not be supported by all demuxers).
 *
 * @param stream_index index of the stream which is used as time base reference
 * @param min_ts smallest acceptable timestamp
 * @param ts target timestamp
 * @param max_ts largest acceptable timestamp
 * @param flags flags
 * @return >=0 on success, error code otherwise
 *
 * @note This is part of the new seek API which is still under construction.
 *       Thus do not use this yet. It may change at any time, do not expect
 *       ABI compatibility yet!
 */
int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts, int64_t ts, int64_t max_ts, int flags);

/**
 * Start playing a network-based stream (e.g. RTSP stream) at the
 * current position.
 */
int av_read_play(AVFormatContext *s);

/**
 * Pause a network-based stream (e.g. RTSP stream).
 *
 * Use av_read_play() to resume it.
 */
int av_read_pause(AVFormatContext *s);

/**
 * Free a AVFormatContext allocated by av_open_input_stream.
 * @param s context to free
 */
void av_close_input_stream(AVFormatContext *s);

/**
 * Close a media file (but not its codecs).
 *
 * @param s media file handle
 */
void av_close_input_file(AVFormatContext *s);

/**
 * Add a new stream to a media file.
 *
 * Can only be called in the read_header() function. If the flag
 * AVFMTCTX_NOHEADER is in the format context, then new streams
 * can be added in read_packet too.
 *
 * @param s media file handle
 * @param id file-format-dependent stream ID
 */
AVStream *av_new_stream(AVFormatContext *s, int id);
AVProgram *av_new_program(AVFormatContext *s, int id);

/**
 * Add a new chapter.
 * This function is NOT part of the public API
 * and should ONLY be used by demuxers.
 *
 * @param s media file handle
 * @param id unique ID for this chapter
 * @param start chapter start time in time_base units
 * @param end chapter end time in time_base units
 * @param title chapter title
 *
 * @return AVChapter or NULL on error
 */
AVChapter *ff_new_chapter(AVFormatContext *s, int id, AVRational time_base,
                          int64_t start, int64_t end, const char *title);

/**
 * Set the pts for a given stream.
 *
 * @param s stream
 * @param pts_wrap_bits number of bits effectively used by the pts
 *        (used for wrap control, 33 is the value for MPEG)
 * @param pts_num numerator to convert to seconds (MPEG: 1)
 * @param pts_den denominator to convert to seconds (MPEG: 90000)
 */
void av_set_pts_info(AVStream *s, int pts_wrap_bits,
                     unsigned int pts_num, unsigned int pts_den);

#define AVSEEK_FLAG_BACKWARD 1 ///< seek backward
#define AVSEEK_FLAG_BYTE     2 ///< seeking based on position in bytes
#define AVSEEK_FLAG_ANY      4 ///< seek to any frame, even non-keyframes
#define AVSEEK_FLAG_FRAME    8 ///< seeking based on frame number

int av_find_default_stream_index(AVFormatContext *s);

/**
 * Get the index for a specific timestamp.
 * @param flags if AVSEEK_FLAG_BACKWARD then the returned index will correspond
 *                 to the timestamp which is <= the requested one, if backward
 *                 is 0, then it will be >=
 *              if AVSEEK_FLAG_ANY seek to any frame, only keyframes otherwise
 * @return < 0 if no such timestamp could be found
 */
int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags);

/**
 * Ensure the index uses less memory than the maximum specified in
 * AVFormatContext.max_index_size by discarding entries if it grows
 * too large.
 * This function is not part of the public API and should only be called
 * by demuxers.
 */
void ff_reduce_index(AVFormatContext *s, int stream_index);

/**
 * Add an index entry into a sorted list. Update the entry if the list
 * already contains it.
 *
 * @param timestamp timestamp in the time base of the given stream
 */
int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
                       int size, int distance, int flags);

/**
 * Perform a binary search using av_index_search_timestamp() and
 * AVCodec.read_timestamp().
 * This is not supposed to be called directly by a user application,
 * but by demuxers.
 * @param target_ts target timestamp in the time base of the given stream
 * @param stream_index stream number
 */
int av_seek_frame_binary(AVFormatContext *s, int stream_index,
                         int64_t target_ts, int flags);

/**
 * Update cur_dts of all streams based on the given timestamp and AVStream.
 *
 * Stream ref_st unchanged, others set cur_dts in their native time base.
 * Only needed for timestamp wrapping or if (dts not set and pts!=dts).
 * @param timestamp new dts expressed in time_base of param ref_st
 * @param ref_st reference stream giving time_base of param timestamp
 */
void av_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp);

/**
 * Perform a binary search using read_timestamp().
 * This is not supposed to be called directly by a user application,
 * but by demuxers.
 * @param target_ts target timestamp in the time base of the given stream
 * @param stream_index stream number
 */
int64_t av_gen_search(AVFormatContext *s, int stream_index,
                      int64_t target_ts, int64_t pos_min,
                      int64_t pos_max, int64_t pos_limit,
                      int64_t ts_min, int64_t ts_max,
                      int flags, int64_t *ts_ret,
                      int64_t (*read_timestamp)(struct AVFormatContext *, int , int64_t *, int64_t ));

/** media file output */
int av_set_parameters(AVFormatContext *s, AVFormatParameters *ap);

/**
 * Split a URL string into components.
 *
 * The pointers to buffers for storing individual components may be null,
 * in order to ignore that component. Buffers for components not found are
 * set to empty strings. If the port is not found, it is set to a negative
 * value.
 *
 * @param proto the buffer for the protocol
 * @param proto_size the size of the proto buffer
 * @param authorization the buffer for the authorization
 * @param authorization_size the size of the authorization buffer
 * @param hostname the buffer for the host name
 * @param hostname_size the size of the hostname buffer
 * @param port_ptr a pointer to store the port number in
 * @param path the buffer for the path
 * @param path_size the size of the path buffer
 * @param url the URL to split
 */
void av_url_split(char *proto,         int proto_size,
                  char *authorization, int authorization_size,
                  char *hostname,      int hostname_size,
                  int *port_ptr,
                  char *path,          int path_size,
                  const char *url);

/**
 * Allocate the stream private data and write the stream header to an
 * output media file.
 *
 * @param s media file handle
 * @return 0 if OK, AVERROR_xxx on error
 */
int av_write_header(AVFormatContext *s);

/**
 * Write a packet to an output media file.
 *
 * The packet shall contain one audio or video frame.
 * The packet must be correctly interleaved according to the container
 * specification, if not then av_interleaved_write_frame must be used.
 *
 * @param s media file handle
 * @param pkt The packet, which contains the stream_index, buf/buf_size,
              dts/pts, ...
 * @return < 0 on error, = 0 if OK, 1 if end of stream wanted
 */
int av_write_frame(AVFormatContext *s, AVPacket *pkt);

/**
 * Write a packet to an output media file ensuring correct interleaving.
 *
 * The packet must contain one audio or video frame.
 * If the packets are already correctly interleaved, the application should
 * call av_write_frame() instead as it is slightly faster. It is also important
 * to keep in mind that completely non-interleaved input will need huge amounts
 * of memory to interleave with this, so it is preferable to interleave at the
 * demuxer level.
 *
 * @param s media file handle
 * @param pkt The packet, which contains the stream_index, buf/buf_size,
              dts/pts, ...
 * @return < 0 on error, = 0 if OK, 1 if end of stream wanted
 */
int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt);

/**
 * Interleave a packet per dts in an output media file.
 *
 * Packets with pkt->destruct == av_destruct_packet will be freed inside this
 * function, so they cannot be used after it. Note that calling av_free_packet()
 * on them is still safe.
 *
 * @param s media file handle
 * @param out the interleaved packet will be output here
 * @param pkt the input packet
 * @param flush 1 if no further packets are available as input and all
 *              remaining packets should be output
 * @return 1 if a packet was output, 0 if no packet could be output,
 *         < 0 if an error occurred
 */
int av_interleave_packet_per_dts(AVFormatContext *s, AVPacket *out,
                                 AVPacket *pkt, int flush);

/**
 * Write the stream trailer to an output media file and free the
 * file private data.
 *
 * May only be called after a successful call to av_write_header.
 *
 * @param s media file handle
 * @return 0 if OK, AVERROR_xxx on error
 */
int av_write_trailer(AVFormatContext *s);

void dump_format(AVFormatContext *ic,
                 int index,
                 const char *url,
                 int is_output);

#if LIBAVFORMAT_VERSION_MAJOR < 53
/**
 * Parse width and height out of string str.
 * @deprecated Use av_parse_video_frame_size instead.
 */
attribute_deprecated int parse_image_size(int *width_ptr, int *height_ptr,
                                          const char *str);

/**
 * Convert framerate from a string to a fraction.
 * @deprecated Use av_parse_video_frame_rate instead.
 */
attribute_deprecated int parse_frame_rate(int *frame_rate, int *frame_rate_base,
                                          const char *arg);
#endif

/**
 * Parse datestr and return a corresponding number of microseconds.
 * @param datestr String representing a date or a duration.
 * - If a date the syntax is:
 * @code
 *  now|{[{YYYY-MM-DD|YYYYMMDD}[T|t| ]]{{HH[:MM[:SS[.m...]]]}|{HH[MM[SS[.m...]]]}}[Z|z]}
 * @endcode
 * If the value is "now" it takes the current time.
 * Time is local time unless Z is appended, in which case it is
 * interpreted as UTC.
 * If the year-month-day part is not specified it takes the current
 * year-month-day.
 * @return the number of microseconds since 1st of January, 1970 up to
 * the time of the parsed date or INT64_MIN if datestr cannot be
 * successfully parsed.
 * - If a duration the syntax is:
 * @code
 *  [-]HH[:MM[:SS[.m...]]]
 *  [-]S+[.m...]
 * @endcode
 * @return the number of microseconds contained in a time interval
 * with the specified duration or INT64_MIN if datestr cannot be
 * successfully parsed.
 * @param duration Flag which tells how to interpret datestr, if
 * not zero datestr is interpreted as a duration, otherwise as a
 * date.
 */
int64_t parse_date(const char *datestr, int duration);

/** Get the current time in microseconds. */
int64_t av_gettime(void);

/* ffm-specific for ffserver */
#define FFM_PACKET_SIZE 4096
int64_t ffm_read_write_index(int fd);
int ffm_write_write_index(int fd, int64_t pos);
void ffm_set_write_index(AVFormatContext *s, int64_t pos, int64_t file_size);

/**
 * Attempt to find a specific tag in a URL.
 *
 * syntax: '?tag1=val1&tag2=val2...'. Little URL decoding is done.
 * Return 1 if found.
 */
int find_info_tag(char *arg, int arg_size, const char *tag1, const char *info);

/**
 * Return in 'buf' the path with '%d' replaced by a number.
 *
 * Also handles the '%0nd' format where 'n' is the total number
 * of digits and '%%'.
 *
 * @param buf destination buffer
 * @param buf_size destination buffer size
 * @param path numbered sequence string
 * @param number frame number
 * @return 0 if OK, -1 on format error
 */
int av_get_frame_filename(char *buf, int buf_size,
                          const char *path, int number);

/**
 * Check whether filename actually is a numbered sequence generator.
 *
 * @param filename possible numbered sequence string
 * @return 1 if a valid numbered sequence string, 0 otherwise
 */
int av_filename_number_test(const char *filename);

/**
 * Generate an SDP for an RTP session.
 *
 * @param ac array of AVFormatContexts describing the RTP streams. If the
 *           array is composed by only one context, such context can contain
 *           multiple AVStreams (one AVStream per RTP stream). Otherwise,
 *           all the contexts in the array (an AVCodecContext per RTP stream)
 *           must contain only one AVStream.
 * @param n_files number of AVCodecContexts contained in ac
 * @param buff buffer where the SDP will be stored (must be allocated by
 *             the caller)
 * @param size the size of the buffer
 * @return 0 if OK, AVERROR_xxx on error
 */
int avf_sdp_create(AVFormatContext *ac[], int n_files, char *buff, int size);

/**
 * Return a positive value if the given filename has one of the given
 * extensions, 0 otherwise.
 *
 * @param extensions a comma-separated list of filename extensions
 */
int av_match_ext(const char *filename, const char *extensions);

#endif /* AVFORMAT_AVFORMAT_H */