FFmpeg/libavformat/rtpdec.h

/*
 * RTP demuxer definitions
 * Copyright (c) 2002 Fabrice Bellard
 * Copyright (c) 2006 Ryan Martell <rdm4@martellventures.com>
 *
 * 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_RTPDEC_H
#define AVFORMAT_RTPDEC_H

#include "libavcodec/avcodec.h"
#include "avformat.h"
#include "rtp.h"
#include "url.h"
#include "srtp.h"

typedef struct PayloadContext PayloadContext;
typedef struct RTPDynamicProtocolHandler RTPDynamicProtocolHandler;

#define RTP_MIN_PACKET_LENGTH 12
#define RTP_MAX_PACKET_LENGTH 8192

#define RTP_REORDER_QUEUE_DEFAULT_SIZE 500

#define RTP_NOTS_VALUE ((uint32_t)-1)

typedef struct RTPDemuxContext RTPDemuxContext;
RTPDemuxContext *ff_rtp_parse_open(AVFormatContext *s1, AVStream *st,
                                   int payload_type, int queue_size);
void ff_rtp_parse_set_dynamic_protocol(RTPDemuxContext *s, PayloadContext *ctx,
                                       const RTPDynamicProtocolHandler *handler);
void ff_rtp_parse_set_crypto(RTPDemuxContext *s, const char *suite,
                             const char *params);
int ff_rtp_parse_packet(RTPDemuxContext *s, AVPacket *pkt,
                        uint8_t **buf, int len);
void ff_rtp_parse_close(RTPDemuxContext *s);
int64_t ff_rtp_queued_packet_time(RTPDemuxContext *s);
void ff_rtp_reset_packet_queue(RTPDemuxContext *s);

/**
 * Send a dummy packet on both port pairs to set up the connection
 * state in potential NAT routers, so that we're able to receive
 * packets.
 *
 * Note, this only works if the NAT router doesn't remap ports. This
 * isn't a standardized procedure, but it works in many cases in practice.
 *
 * The same routine is used with RDT too, even if RDT doesn't use normal
 * RTP packets otherwise.
 */
void ff_rtp_send_punch_packets(URLContext* rtp_handle);

/**
 * some rtp servers assume client is dead if they don't hear from them...
 * so we send a Receiver Report to the provided URLContext or AVIOContext
 * (we don't have access to the rtcp handle from here)
 */
int ff_rtp_check_and_send_back_rr(RTPDemuxContext *s, URLContext *fd,
                                  AVIOContext *avio, int count);
int ff_rtp_send_rtcp_feedback(RTPDemuxContext *s, URLContext *fd,
                              AVIOContext *avio);

// these statistics are used for rtcp receiver reports...
typedef struct RTPStatistics {
    uint16_t max_seq;           ///< highest sequence number seen
    uint32_t cycles;            ///< shifted count of sequence number cycles
    uint32_t base_seq;          ///< base sequence number
    uint32_t bad_seq;           ///< last bad sequence number + 1
    int probation;              ///< sequence packets till source is valid
    uint32_t received;          ///< packets received
    uint32_t expected_prior;    ///< packets expected in last interval
    uint32_t received_prior;    ///< packets received in last interval
    uint32_t transit;           ///< relative transit time for previous packet
    uint32_t jitter;            ///< estimated jitter.
} RTPStatistics;

#define RTP_FLAG_KEY    0x1 ///< RTP packet contains a keyframe
#define RTP_FLAG_MARKER 0x2 ///< RTP marker bit was set for this packet
/**
 * Packet parsing for "private" payloads in the RTP specs.
 *
 * @param ctx RTSP demuxer context
 * @param s stream context
 * @param st stream that this packet belongs to
 * @param pkt packet in which to write the parsed data
 * @param timestamp pointer to the RTP timestamp of the input data, can be
 *                  updated by the function if returning older, buffered data
 * @param buf pointer to raw RTP packet data
 * @param len length of buf
 * @param seq RTP sequence number of the packet
 * @param flags flags from the RTP packet header (RTP_FLAG_*)
 */
typedef int (*DynamicPayloadPacketHandlerProc)(AVFormatContext *ctx,
                                               PayloadContext *s,
                                               AVStream *st, AVPacket *pkt,
                                               uint32_t *timestamp,
                                               const uint8_t * buf,
                                               int len, uint16_t seq, int flags);

struct RTPDynamicProtocolHandler {
    const char *enc_name;
    enum AVMediaType codec_type;
    enum AVCodecID codec_id;
    enum AVStreamParseType need_parsing;
    int static_payload_id; /* 0 means no payload id is set. 0 is a valid
                            * payload ID (PCMU), too, but that format doesn't
                            * require any custom depacketization code. */
    int priv_data_size;

    /** Initialize dynamic protocol handler, called after the full rtpmap line is parsed, may be null */
    int (*init)(AVFormatContext *s, int st_index, PayloadContext *priv_data);
    /** Parse the a= line from the sdp field */
    int (*parse_sdp_a_line)(AVFormatContext *s, int st_index,
                            PayloadContext *priv_data, const char *line);
    /** Free any data needed by the rtp parsing for this dynamic data.
      * Don't free the protocol_data pointer itself, that is freed by the
      * caller. This is called even if the init method failed. */
    void (*close)(PayloadContext *protocol_data);
    /** Parse handler for this dynamic packet */
    DynamicPayloadPacketHandlerProc parse_packet;
    int (*need_keyframe)(PayloadContext *context);

    struct RTPDynamicProtocolHandler *next;
};

typedef struct RTPPacket {
    uint16_t seq;
    uint8_t *buf;
    int len;
    int64_t recvtime;
    struct RTPPacket *next;
} RTPPacket;

struct RTPDemuxContext {
    AVFormatContext *ic;
    AVStream *st;
    int payload_type;
    uint32_t ssrc;
    uint16_t seq;
    uint32_t timestamp;
    uint32_t base_timestamp;
    int64_t  unwrapped_timestamp;
    int64_t  range_start_offset;
    int max_payload_size;
    /* used to send back RTCP RR */
    char hostname[256];

    int srtp_enabled;
    struct SRTPContext srtp;

    /** Statistics for this stream (used by RTCP receiver reports) */
    RTPStatistics statistics;

    /** Fields for packet reordering @{ */
    int prev_ret;     ///< The return value of the actual parsing of the previous packet
    RTPPacket* queue; ///< A sorted queue of buffered packets not yet returned
    int queue_len;    ///< The number of packets in queue
    int queue_size;   ///< The size of queue, or 0 if reordering is disabled
    /*@}*/

    /* rtcp sender statistics receive */
    uint64_t last_rtcp_ntp_time;
    int64_t last_rtcp_reception_time;
    uint64_t first_rtcp_ntp_time;
    uint32_t last_rtcp_timestamp;
    int64_t rtcp_ts_offset;

    /* rtcp sender statistics */
    unsigned int packet_count;
    unsigned int octet_count;
    unsigned int last_octet_count;
    int64_t last_feedback_time;

    /* dynamic payload stuff */
    const RTPDynamicProtocolHandler *handler;
    PayloadContext *dynamic_protocol_context;
};

/**
 * Iterate over all registered rtp dynamic protocol handlers.
 *
 * @param opaque a pointer where libavformat will store the iteration state. Must
 *               point to NULL to start the iteration.
 *
 * @return the next registered rtp dynamic protocol handler or NULL when the iteration is
 *         finished
 */
const RTPDynamicProtocolHandler *ff_rtp_handler_iterate(void **opaque);
/**
 * Find a registered rtp dynamic protocol handler with the specified name.
 *
 * @param name name of the requested rtp dynamic protocol handler
 * @return A rtp dynamic protocol handler if one was found, NULL otherwise.
 */
const RTPDynamicProtocolHandler *ff_rtp_handler_find_by_name(const char *name,
                                                  enum AVMediaType codec_type);
/**
 * Find a registered rtp dynamic protocol handler with a matching codec ID.
 *
 * @param id AVCodecID of the requested rtp dynamic protocol handler.
 * @return A rtp dynamic protocol handler if one was found, NULL otherwise.
 */
const RTPDynamicProtocolHandler *ff_rtp_handler_find_by_id(int id,
                                                enum AVMediaType codec_type);

/* from rtsp.c, but used by rtp dynamic protocol handlers. */
int ff_rtsp_next_attr_and_value(const char **p, char *attr, int attr_size,
                                char *value, int value_size);

int ff_parse_fmtp(AVFormatContext *s,
                  AVStream *stream, PayloadContext *data, const char *p,
                  int (*parse_fmtp)(AVFormatContext *s,
                                    AVStream *stream,
                                    PayloadContext *data,
                                    const char *attr, const char *value));

/**
 * Close the dynamic buffer and make a packet from it.
 */
int ff_rtp_finalize_packet(AVPacket *pkt, AVIOContext **dyn_buf, int stream_idx);

#endif /* AVFORMAT_RTPDEC_H */