avformat.h

rtsp协议的主要实现代码

    //FIXME move stuff to a flags field?
    /** quality, as it has been removed from AVCodecContext and put in AVVideoFrame
     * MN:dunno if thats the right place, for it */
    float quality;
    /** decoding: position of the first frame of the component, in
       AV_TIME_BASE fractional seconds. */
    int64_t start_time;
    /** decoding: duration of the stream, in AV_TIME_BASE fractional
       seconds. */
    int64_t duration;

    char language[4]; /** ISO 639 3-letter language code (empty string if undefined) */

    /* av_read_frame() support */
    int need_parsing;                  ///< 1->full parsing needed, 2->only parse headers dont repack
    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

#define MAX_REORDER_DELAY 4
    int64_t pts_buffer[MAX_REORDER_DELAY+1];
} AVStream;

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

#define MAX_STREAMS 20

/* format I/O context */
typedef struct AVFormatContext {
    const AVClass *av_class; /**< set by av_alloc_format_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;
    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 */

    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. NEVER set this value directly: it is deduced from the
       AVStream values.  */
    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;
    const uint8_t *cur_ptr;
    int cur_len;
    AVPacket cur_pkt;

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

    int mux_rate;
    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 pts if missing even if it requires parsing future frames
#define AVFMT_FLAG_IGNIDX       0x0002 ///< ignore index

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

    /**
     * maximum duration in AV_TIME_BASE units over which the input should be analyzed in av_find_stream_info()
     */
    int max_analyze_duration;

    const uint8_t *key;
    int keylen;
} AVFormatContext;

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

extern AVInputFormat *first_iformat;
extern AVOutputFormat *first_oformat;

enum CodecID av_guess_image2_codec(const char *filename);

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

#include "rtp.h"

#include "rtsp.h"

/* utils.c */
void av_register_input_format(AVInputFormat *format);
void av_register_output_format(AVOutputFormat *format);
AVOutputFormat *guess_stream_format(const char *short_name,
                                    const char *filename, const char *mime_type);
AVOutputFormat *guess_format(const char *short_name,
                             const char *filename, const char *mime_type);

/**
 * Guesses 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 CodecType 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);

void av_register_all(void);

/** codec tag <-> codec id */
enum CodecID av_codec_get_id(const struct AVCodecTag **tags, unsigned int tag);
unsigned int av_codec_get_tag(const struct AVCodecTag **tags, enum CodecID id);

/* media file input */

/**
 * finds AVInputFormat based on input format's short name.
 */
AVInputFormat *av_find_input_format(const char *short_name);

/**
 * Guess 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);

/**
 * Allocates 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 codec 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 additionnal 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);
/** no av_open for output, so applications will need this: */
AVFormatContext *av_alloc_format_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 frame rate in case of mpeg2 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 if error.
 * @todo let user decide somehow what information is needed so we dont waste time geting stuff the user doesnt need
 */
int av_find_stream_info(AVFormatContext *ic);

/**
 * Read a transport packet from a media file.
 *
 * This function is absolete 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 if 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.timebase units (and guessed if the format cannot
 * provided 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 if error or end of file.
 */
int av_read_frame(AVFormatContext *s, AVPacket *pkt);

/**
 * Seek to the key frame 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