ServerMediaSession.hh

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FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
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// "liveMedia"
// Copyright (c) 1996-2017 Live Networks, Inc.  All rights reserved.
// A data structure that represents a session that consists of
// potentially multiple (audio and/or video) sub-sessions
// (This data structure is used for media *streamers* - i.e., servers.
//  For media receivers, use "MediaSession" instead.)
// C++ header

#ifndef _SERVER_MEDIA_SESSION_HH
#define _SERVER_MEDIA_SESSION_HH

#ifndef _RTCP_HH
#include "RTCP.hh"
#endif

class ServerMediaSubsession; // forward

class ServerMediaSession: public Medium {
public:
  static ServerMediaSession* createNew(UsageEnvironment& env,
                                       char const* streamName = NULL,
                                       char const* info = NULL,
                                       char const* description = NULL,
                                       Boolean isSSM = False,
                                       char const* miscSDPLines = NULL);

  static Boolean lookupByName(UsageEnvironment& env,
                              char const* mediumName,
                              ServerMediaSession*& resultSession);

  char* generateSDPDescription(); // based on the entire session
      // Note: The caller is responsible for freeing the returned string

  char const* streamName() const { return fStreamName; }

  Boolean addSubsession(ServerMediaSubsession* subsession);
  unsigned numSubsessions() const { return fSubsessionCounter; }

  void testScaleFactor(float& scale); // sets "scale" to the actual supported scale
  float duration() const;
    // a result == 0 means an unbounded session (the default)
    // a result < 0 means: subsession durations differ; the result is -(the largest).
    // a result > 0 means: this is the duration of a bounded session

  virtual void noteLiveness();
    // called whenever a client - accessing this media - notes liveness.
    // The default implementation does nothing, but subclasses can redefine this - e.g., if you
    // want to remove long-unused "ServerMediaSession"s from the server.

  unsigned referenceCount() const { return fReferenceCount; }
  void incrementReferenceCount() { ++fReferenceCount; }
  void decrementReferenceCount() { if (fReferenceCount > 0) --fReferenceCount; }
  Boolean& deleteWhenUnreferenced() { return fDeleteWhenUnreferenced; }

  void deleteAllSubsessions();
    // Removes and deletes all subsessions added by "addSubsession()", returning us to an 'empty' state
    // Note: If you have already added this "ServerMediaSession" to a "RTSPServer" then, before calling this function,
    //   you must first close any client connections that use it,
    //   by calling "RTSPServer::closeAllClientSessionsForServerMediaSession()".

protected:
  ServerMediaSession(UsageEnvironment& env, char const* streamName,
                     char const* info, char const* description,
                     Boolean isSSM, char const* miscSDPLines);
  // called only by "createNew()"

  virtual ~ServerMediaSession();

private: // redefined virtual functions
  virtual Boolean isServerMediaSession() const;

private:
  Boolean fIsSSM;

  // Linkage fields:
  friend class ServerMediaSubsessionIterator;
  ServerMediaSubsession* fSubsessionsHead;
  ServerMediaSubsession* fSubsessionsTail;
  unsigned fSubsessionCounter;

  char* fStreamName;
  char* fInfoSDPString;
  char* fDescriptionSDPString;
  char* fMiscSDPLines;
  struct timeval fCreationTime;
  unsigned fReferenceCount;
  Boolean fDeleteWhenUnreferenced;
};


class ServerMediaSubsessionIterator {
public:
  ServerMediaSubsessionIterator(ServerMediaSession& session);
  virtual ~ServerMediaSubsessionIterator();

  ServerMediaSubsession* next(); // NULL if none
  void reset();

private:
  ServerMediaSession& fOurSession;
  ServerMediaSubsession* fNextPtr;
};


class ServerMediaSubsession: public Medium {
public:
  unsigned trackNumber() const { return fTrackNumber; }
  char const* trackId();
  virtual char const* sdpLines() = 0;
  virtual void getStreamParameters(unsigned clientSessionId, // in
                                   netAddressBits clientAddress, // in
                                   Port const& clientRTPPort, // in
                                   Port const& clientRTCPPort, // in
                                   int tcpSocketNum, // in (-1 means use UDP, not TCP)
                                   unsigned char rtpChannelId, // in (used if TCP)
                                   unsigned char rtcpChannelId, // in (used if TCP)
                                   netAddressBits& destinationAddress, // in out
                                   u_int8_t& destinationTTL, // in out
                                   Boolean& isMulticast, // out
                                   Port& serverRTPPort, // out
                                   Port& serverRTCPPort, // out
                                   void*& streamToken // out
                                   ) = 0;
  virtual void startStream(unsigned clientSessionId, void* streamToken,
                           TaskFunc* rtcpRRHandler,
                           void* rtcpRRHandlerClientData,
                           unsigned short& rtpSeqNum,
                           unsigned& rtpTimestamp,
                           ServerRequestAlternativeByteHandler* serverRequestAlternativeByteHandler,
                           void* serverRequestAlternativeByteHandlerClientData) = 0;
  virtual void pauseStream(unsigned clientSessionId, void* streamToken);
  virtual void seekStream(unsigned clientSessionId, void* streamToken, double& seekNPT,
                          double streamDuration, u_int64_t& numBytes);
     // This routine is used to seek by relative (i.e., NPT) time.
     // "streamDuration", if >0.0, specifies how much data to stream, past "seekNPT".  (If <=0.0, all remaining data is streamed.)
     // "numBytes" returns the size (in bytes) of the data to be streamed, or 0 if unknown or unlimited.
  virtual void seekStream(unsigned clientSessionId, void* streamToken, char*& absStart, char*& absEnd);
     // This routine is used to seek by 'absolute' time.
     // "absStart" should be a string of the form "YYYYMMDDTHHMMSSZ" or "YYYYMMDDTHHMMSS.<frac>Z".
     // "absEnd" should be either NULL (for no end time), or a string of the same form as "absStart".
     // These strings may be modified in-place, or can be reassigned to a newly-allocated value (after delete[]ing the original).
  virtual void nullSeekStream(unsigned clientSessionId, void* streamToken,
                              double streamEndTime, u_int64_t& numBytes);
     // Called whenever we're handling a "PLAY" command without a specified start time.
  virtual void setStreamScale(unsigned clientSessionId, void* streamToken, float scale);
  virtual float getCurrentNPT(void* streamToken);
  virtual FramedSource* getStreamSource(void* streamToken);
  virtual void getRTPSinkandRTCP(void* streamToken,
                                 RTPSink const*& rtpSink, RTCPInstance const*& rtcp) = 0;
     // Returns pointers to the "RTPSink" and "RTCPInstance" objects for "streamToken".
     // (This can be useful if you want to get the associated 'Groupsock' objects, for example.)
     // You must not delete these objects, or start/stop playing them; instead, that is done
     // using the "startStream()" and "deleteStream()" functions.
  virtual void deleteStream(unsigned clientSessionId, void*& streamToken);

  virtual void testScaleFactor(float& scale); // sets "scale" to the actual supported scale
  virtual float duration() const;
    // returns 0 for an unbounded session (the default)
    // returns > 0 for a bounded session
  virtual void getAbsoluteTimeRange(char*& absStartTime, char*& absEndTime) const;
    // Subclasses can reimplement this iff they support seeking by 'absolute' time.

  // The following may be called by (e.g.) SIP servers, for which the
  // address and port number fields in SDP descriptions need to be non-zero:
  void setServerAddressAndPortForSDP(netAddressBits addressBits,
                                     portNumBits portBits);

protected: // we're a virtual base class
  ServerMediaSubsession(UsageEnvironment& env);
  virtual ~ServerMediaSubsession();

  char const* rangeSDPLine() const;
      // returns a string to be delete[]d

  ServerMediaSession* fParentSession;
  netAddressBits fServerAddressForSDP;
  portNumBits fPortNumForSDP;

private:
  friend class ServerMediaSession;
  friend class ServerMediaSubsessionIterator;
  ServerMediaSubsession* fNext;

  unsigned fTrackNumber; // within an enclosing ServerMediaSession
  char const* fTrackId;
};

#endif