basicudpsource.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
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FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
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**********/
// "liveMedia"
// Copyright (c) 1996-2004 Live Networks, Inc.  All rights reserved.
// A simple UDP source, where every UDP payload is a complete frame
// Implementation

#include "BasicUDPSource.hh"
#include <GroupsockHelper.hh>

BasicUDPSource* BasicUDPSource::createNew(UsageEnvironment& env,
					Groupsock* inputGS) {
  return new BasicUDPSource(env, inputGS);
}

BasicUDPSource::BasicUDPSource(UsageEnvironment& env, Groupsock* inputGS)
  : FramedSource(env), fInputGS(inputGS) {
  // Try to use a large receive buffer (in the OS):
  increaseReceiveBufferTo(env, inputGS->socketNum(), 50*1024);
}

BasicUDPSource::~BasicUDPSource(){
  envir().taskScheduler().turnOffBackgroundReadHandling(fInputGS->socketNum());
}

void BasicUDPSource::doGetNextFrame() {
  // Await the next incoming packet:
  envir().taskScheduler().turnOnBackgroundReadHandling(fInputGS->socketNum(), 
       (TaskScheduler::BackgroundHandlerProc*)&incomingPacketHandler, this);
}

void BasicUDPSource::incomingPacketHandler(BasicUDPSource* source, int /*mask*/){
  source->incomingPacketHandler1();
}

void BasicUDPSource::incomingPacketHandler1() {
  if (!isCurrentlyAwaitingData()) return; // we're not ready for the data yet

  // Read the packet into our desired destination:
  struct sockaddr_in fromAddress;
  if (!fInputGS->handleRead(fTo, fMaxSize, fFrameSize, fromAddress)) return;
    
  // Tell our client that we have new data:
  afterGetting(this); // we're preceded by a net read; no infinite recursion
}