servermediasession.cpp

流媒体传输协议的实现代码,非常有用.可以支持rtsp mms等流媒体传输协议

/**********
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This library 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 this library; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2004 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.)
// Implementation

#include "ServerMediaSession.hh"
#include <GroupsockHelper.hh>
#include <math.h>

////////// ServerMediaSession //////////

ServerMediaSession* ServerMediaSession
::createNew(UsageEnvironment& env,
	    char const* streamName, char const* info,
	    char const* description, Boolean isSSM, char const* miscSDPLines) {
  return new ServerMediaSession(env, streamName, info, description,
				isSSM, miscSDPLines);
}

Boolean ServerMediaSession
::lookupByName(UsageEnvironment& env, char const* mediumName,
	       ServerMediaSession*& resultSession) {
  resultSession = NULL; // unless we succeed

  Medium* medium;
  if (!Medium::lookupByName(env, mediumName, medium)) return False;

  if (!medium->isServerMediaSession()) {
    env.setResultMsg(mediumName, " is not a 'ServerMediaSession' object");
    return False;
  }

  resultSession = (ServerMediaSession*)medium;
  return True;
}

static char const* const libNameStr = "LIVE.COM Streaming Media v";
char const* const libVersionStr = LIVEMEDIA_LIBRARY_VERSION_STRING;

ServerMediaSession::ServerMediaSession(UsageEnvironment& env,
				       char const* streamName,
				       char const* info,
				       char const* description,
				       Boolean isSSM, char const* miscSDPLines)
  : Medium(env), fIsSSM(isSSM), fSubsessionsHead(NULL),
    fSubsessionsTail(NULL), fSubsessionCounter(0),
    fReferenceCount(0), fDeleteWhenUnreferenced(False) {
  fStreamName = strDup(streamName == NULL ? "" : streamName);
  fInfoSDPString = strDup(info == NULL ? libNameStr : info);
  fDescriptionSDPString
    = strDup(description == NULL ? libNameStr : description);
  fMiscSDPLines = strDup(miscSDPLines == NULL ? "" : miscSDPLines);

  gettimeofday(&fCreationTime, NULL);
}

ServerMediaSession::~ServerMediaSession() {
  delete fSubsessionsHead;
  delete[] fStreamName;
  delete[] fInfoSDPString;
  delete[] fDescriptionSDPString;
  delete[] fMiscSDPLines;
}

Boolean
ServerMediaSession::addSubsession(ServerMediaSubsession* subsession) {
  if (subsession->fParentSession != NULL) return False; // it's already used

  if (fSubsessionsTail == NULL) {
    fSubsessionsHead = subsession;
  } else {
    fSubsessionsTail->fNext = subsession;
  }
  fSubsessionsTail = subsession;

  subsession->fParentSession = this;
  subsession->fTrackNumber = ++fSubsessionCounter;
  return True;
}

void ServerMediaSession::testScaleFactor(float& scale) {
  // First, try setting all subsessions to the desired scale.
  // If the subsessions' actual scales differ from each other, choose the
  // value that's closest to 1, and then try re-setting all subsessions to that
  // value.  If the subsessions' actual scales still differ, re-set them all to 1.
  float minSSScale = 1.0;
  float maxSSScale = 1.0;
  float bestSSScale = 1.0;
  float bestDistanceTo1 = 0.0;
  ServerMediaSubsession* subsession;
  for (subsession = fSubsessionsHead; subsession != NULL;
       subsession = subsession->fNext) {
    float ssscale = scale;
    subsession->testScaleFactor(ssscale);
    if (subsession == fSubsessionsHead) { // this is the first subsession
      minSSScale = maxSSScale = bestSSScale = ssscale;
      bestDistanceTo1 = (float)fabs(ssscale - 1.0f);
    } else {
      if (ssscale < minSSScale) {
	minSSScale = ssscale;
      } else if (ssscale > maxSSScale) {
	maxSSScale = ssscale;
      }

      float distanceTo1 = (float)fabs(ssscale - 1.0f);
      if (distanceTo1 < bestDistanceTo1) {
	bestSSScale = ssscale;
	bestDistanceTo1 = distanceTo1;
      }
    }
  }
  if (minSSScale == maxSSScale) {
    // All subsessions are at the same scale: minSSScale == bestSSScale == maxSSScale
    scale = minSSScale;
    return;
  }

  // The scales for each subsession differ.  Try to set each one to the value
  // that's closest to 1:
  for (subsession = fSubsessionsHead; subsession != NULL;
       subsession = subsession->fNext) {
    float ssscale = bestSSScale;
    subsession->testScaleFactor(ssscale);
    if (ssscale != bestSSScale) break; // no luck
  }
  if (subsession == NULL) {
    // All subsessions are at the same scale: bestSSScale
    scale = bestSSScale;
    return;
  }

  // Still no luck.  Set each subsession's scale to 1:
  for (subsession = fSubsessionsHead; subsession != NULL;
       subsession = subsession->fNext) {
    float ssscale = 1;
    subsession->testScaleFactor(ssscale);
  }
  scale = 1;
}

float ServerMediaSession::duration() const {
  float minSubsessionDuration = 0.0;
  float maxSubsessionDuration = 0.0;
  for (ServerMediaSubsession* subsession = fSubsessionsHead; subsession != NULL;
       subsession = subsession->fNext) {
    float ssduration = subsession->duration();
    if (subsession == fSubsessionsHead) { // this is the first subsession
      minSubsessionDuration = maxSubsessionDuration = ssduration;
    } else if (ssduration < minSubsessionDuration) {
	minSubsessionDuration = ssduration;
    } else if (ssduration > maxSubsessionDuration) {
	maxSubsessionDuration = ssduration;
    }
  }

  if (maxSubsessionDuration != minSubsessionDuration) {
    return -maxSubsessionDuration; // because subsession durations differ
  } else {
    return maxSubsessionDuration; // all subsession durations are the same
  }
}

Boolean ServerMediaSession::isServerMediaSession() const {
  return True;
}

char* ServerMediaSession::generateSDPDescription() {
  struct in_addr ourIPAddress;
  ourIPAddress.s_addr = ourSourceAddressForMulticast(envir());
  char* const ourIPAddressStr
    = strDup(our_inet_ntoa(ourIPAddress));
  unsigned ourIPAddressStrSize = strlen(ourIPAddressStr);

  // For a SSM sessions, we need a "a=source-filter: incl ..." line also:
  char* sourceFilterLine;
  if (fIsSSM) {
    char const* const sourceFilterFmt =
      "a=source-filter: incl IN IP4 * %s\r\n"
      "a=rtcp:unicast reflection\r\n";
    unsigned sourceFilterFmtSize = strlen(sourceFilterFmt)
      + ourIPAddressStrSize;

    sourceFilterLine = new char[sourceFilterFmtSize];
    sprintf(sourceFilterLine, sourceFilterFmt,
            ourIPAddressStr);
  } else {
    sourceFilterLine = strDup("");
  }

  char* rangeLine = NULL; // for now
  char* sdp = NULL; // for now

  do {
    // Count the lengths of each subsession's media-level SDP lines.
    // (We do this first, because the call to "subsession->sdpLines()"
    // causes correct subsession 'duration()'s to be calculated later.)
    unsigned sdpLength = 0;
    ServerMediaSubsession* subsession;
    for (subsession = fSubsessionsHead; subsession != NULL;
	 subsession = subsession->fNext) {
      char const* sdpLines = subsession->sdpLines();
      if (sdpLines == NULL) break; // the media's not available
      sdpLength += strlen(sdpLines);
    }
    if (subsession != NULL) break; // an error occurred

    // Unless subsessions have differing durations, we also have a "a=range:" line:
    float dur = duration();
    if (dur == 0.0) {
      rangeLine = strDup("a=range:npt=0-\r\n");
    } else if (dur > 0.0) {
      char buf[100];
      sprintf(buf, "a=range:npt=0-%.3f\r\n", dur);
      rangeLine = strDup(buf);
    } else { // subsessions have differing durations, so "a=range:" lines go there
      rangeLine = strDup("");
    }
    
    char const* const sdpPrefixFmt =
      "v=0\r\n"
      "o=- %ld%06ld %d IN IP4 %s\r\n"
      "s=%s\r\n"
      "i=%s\r\n"
      "t=0 0\r\n"
      "a=tool:%s%s\r\n"
      "a=type:broadcast\r\n"
      "a=control:*\r\n"
      "%s"
      "%s"
      "a=x-qt-text-nam:%s\r\n"
      "a=x-qt-text-inf:%s\r\n"
      "%s";
    sdpLength += strlen(sdpPrefixFmt)
      + 20 + 6 + 20 + ourIPAddressStrSize
      + strlen(fDescriptionSDPString)
      + strlen(fInfoSDPString)
      + strlen(libNameStr) + strlen(libVersionStr)
      + strlen(sourceFilterLine)
      + strlen(rangeLine)
      + strlen(fDescriptionSDPString)
      + strlen(fInfoSDPString)
      + strlen(fMiscSDPLines);
    sdp = new char[sdpLength];
    if (sdp == NULL) break;
    
    // Generate the SDP prefix (session-level lines):
    sprintf(sdp, sdpPrefixFmt,
	    fCreationTime.tv_sec, fCreationTime.tv_usec, // o= <session id>
	    1, // o= <version> // (needs to change if params are modified)
	    ourIPAddressStr, // o= <address>
	    fDescriptionSDPString, // s= <description>
	    fInfoSDPString, // i= <info>
	    libNameStr, libVersionStr, // a=tool:
	    sourceFilterLine, // a=source-filter: incl (if a SSM session)
	    rangeLine, // a=range: line
	    fDescriptionSDPString, // a=x-qt-text-nam: line
	    fInfoSDPString, // a=x-qt-text-inf: line
	    fMiscSDPLines); // miscellaneous session SDP lines (if any)

    // Then, add the (media-level) lines for each subsession:
    char* mediaSDP = sdp;
    for (subsession = fSubsessionsHead; subsession != NULL;
	 subsession = subsession->fNext) {
      mediaSDP += strlen(mediaSDP);
      sprintf(mediaSDP, "%s", subsession->sdpLines());
    }
  } while (0);

  delete[] rangeLine; delete[] sourceFilterLine; delete[] ourIPAddressStr;
  return sdp;
}


////////// ServerMediaSessionIterator //////////

ServerMediaSubsessionIterator
::ServerMediaSubsessionIterator(ServerMediaSession& session)
  : fOurSession(session) {
  reset();
}

ServerMediaSubsessionIterator::~ServerMediaSubsessionIterator() {
}

ServerMediaSubsession* ServerMediaSubsessionIterator::next() {
  ServerMediaSubsession* result = fNextPtr;

  if (fNextPtr != NULL) fNextPtr = fNextPtr->fNext;

  return result;
}

void ServerMediaSubsessionIterator::reset() {
  fNextPtr = fOurSession.fSubsessionsHead;
}


////////// ServerMediaSubsession //////////

ServerMediaSubsession::ServerMediaSubsession(UsageEnvironment& env)
  : Medium(env),
    fParentSession(NULL), fServerAddressForSDP(0), fPortNumForSDP(0),
    fNext(NULL), fTrackNumber(0), fTrackId(NULL) {
}

ServerMediaSubsession::~ServerMediaSubsession() {
  delete[] (char*)fTrackId;
  delete fNext;
}

char const* ServerMediaSubsession::trackId() {
  if (fTrackNumber == 0) return NULL; // not yet in a ServerMediaSession

  if (fTrackId == NULL) {
    char buf[100];
    sprintf(buf, "track%d", fTrackNumber);
    fTrackId = strDup(buf);
  }
  return fTrackId;
}

void ServerMediaSubsession::pauseStream(unsigned /*clientSessionId*/,
					void* /*streamToken*/) {
  // default implementation: do nothing
}
void ServerMediaSubsession::seekStream(unsigned /*clientSessionId*/,
				       void* /*streamToken*/, float /*seekNPT*/) {
  // default implementation: do nothing
}
void ServerMediaSubsession::setStreamScale(unsigned /*clientSessionId*/,
					   void* /*streamToken*/, float /*scale*/) {
  // default implementation: do nothing
}
void ServerMediaSubsession::deleteStream(unsigned /*clientSessionId*/,
					 void*& /*streamToken*/) {
  // default implementation: do nothing
}

void ServerMediaSubsession::testScaleFactor(float& scale) {
  // default implementation: Support scale = 1 only
  scale = 1;
}

float ServerMediaSubsession::duration() const {
  // default implementation: assume an unbounded session:
  return 0.0;
}

void ServerMediaSubsession::setServerAddressAndPortForSDP(netAddressBits addressBits,
							  portNumBits portBits) {
  fServerAddressForSDP = addressBits;
  fPortNumForSDP = portBits;
}

char const*
ServerMediaSubsession::rangeSDPLine() const {
  if (fParentSession == NULL) return NULL;

  // If all of our parent's subsessions have the same duration
  // (as indicated by "fParentSession->duration() >= 0"), there's no "a=range:" line:
  if (fParentSession->duration() >= 0.0) return strDup("");

  // Use our own duration for a "a=range:" line:
  float ourDuration = duration();
  if (ourDuration == 0.0) {
    return strDup("a=range:npt=0-\r\n");
  } else {
    char buf[100];
    sprintf(buf, "a=range:npt=0-%.3f\r\n", ourDuration);
    return strDup(buf);
  }  
}