IOS 组播组播app

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技术极先锋 2023-08-16 17:59:10

文章标签 IOS 组播 Android 组播 Source 文章分类 iOS 移动开发

背景：

live555作为知名的流媒体开源框架，在实际项目中，经常使用到。在Android播放器中，可以使用其作为流媒体部分的拉流端，特别是对于RTSP及组播播放，live555相对还是很稳定的。
这次将其移植到Android SDK上，并完成RTSP及组播拉流小程序，权当玩乐及熟悉live555之用。
RTSP拉流小程序基本就是原来live555测试代码testRTSPClient.cpp，仅对其做了点小修改，让其能完成对电视节目RTSP流的获取，所以后面有机会再讲live555 RTSP内部实现流程吧。
这次就讲Android上移植live555及实现组播简单拉流代码。

Android移植live555

live555 Android平台移植方法CSDN上很多可以参考，并不难，我简单说下我的移植方法

首先官网下载live555源码 http://www.live555.com/liveMedia/public/ 对于Android，可以删除不必要的目录，我仅保留如下目录：

IOS 组播组播app_组播

编写Android.mk文件，如下，

将liveMedia目录中的CPP和C代码全部包含进来，另外其他几个目录需要用到的文件也添加进来。

指定LOCAL_CPPFLAGS 和LOCAL_LDFLAGS ，主要是对STL的支持。

这样编译即可，会在live555源码out目录下生成liblive555.so库。

编译过程中可能有些小错误，不同live555的错误可能略有不同，主要是对NDK的兼容问题，网上查查修改即可，比较简单。

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE := liblive555
LOCAL_MODULE_PATH := $(LOCAL_PATH)/out

LOCAL_C_INCLUDES := \
    $(LOCAL_PATH) \
    $(LOCAL_PATH)/BasicUsageEnvironment/include \
    $(LOCAL_PATH)/BasicUsageEnvironment \
    $(LOCAL_PATH)/UsageEnvironment/include \
    $(LOCAL_PATH)/UsageEnvironment \
    $(LOCAL_PATH)/groupsock/include \
    $(LOCAL_PATH)/groupsock \
    $(LOCAL_PATH)/liveMedia/include \
    $(LOCAL_PATH)/liveMedia \

LOCAL_MODULE_TAGS := optional

prebuilt_stdcxx_PATH := prebuilts/ndk/current/sources/cxx-stl/gnu-libstdc++
SRC_LIST := $(wildcard $(LOCAL_PATH)/liveMedia/*.cpp)
SRC_LIST += $(wildcard $(LOCAL_PATH)/liveMedia/*.c)

LOCAL_SRC_FILES := $(SRC_LIST:$(LOCAL_PATH)/%=%)

LOCAL_SRC_FILES += \
    groupsock/GroupsockHelper.cpp \
    groupsock/GroupEId.cpp \
    groupsock/inet.c \
    groupsock/Groupsock.cpp \
    groupsock/NetInterface.cpp \
    groupsock/NetAddress.cpp \
    groupsock/IOHandlers.cpp \
    UsageEnvironment/UsageEnvironment.cpp \
    UsageEnvironment/HashTable.cpp \
    UsageEnvironment/strDup.cpp \
    BasicUsageEnvironment/BasicUsageEnvironment0.cpp \
    BasicUsageEnvironment/BasicUsageEnvironment.cpp \
    BasicUsageEnvironment/BasicTaskScheduler0.cpp \
    BasicUsageEnvironment/BasicTaskScheduler.cpp \
    BasicUsageEnvironment/DelayQueue.cpp \
    BasicUsageEnvironment/BasicHashTable.cpp \

LOCAL_LDLIBS :=  -lm -llog

LOCAL_CPPFLAGS := -fexceptions -DXLOCALE_NOT_USED=1 -DNULL=0 -DNO_SSTREAM=1 -UIP_ADD_SOURCE_MEMBERSHIP
LOCAL_LDFLAGS := -L$(prebuilt_stdcxx_PATH)/libs/$(TARGET_CPU_ABI) -lgnustl_static -lsupc++

include $(BUILD_SHARED_LIBRARY)

组播拉流程序

代码参考测试代码testMPEG2TransportReceiver.cpp实现。

1、

Source 和 Sink 在live555中是两个非常重要的概念。

Source 发送端，流的起点，可直观理解为生产者，负责读取文件或网络流的信息。

Sink 接收端，流的终点，可理解为是消费者。

可以又多级source，对上级source在进行处理，也可以成为filter（实际上也是source），数据流向简单来说如下：

IOS 组播组播app_IOS 组播_02

2、

Source 对于RTP封装的组播和UDP组播裸流传递的有所不同。

有RTP封装的情况下，创建SimpleRTPSource；

UDP裸流传递的情况下，则是创建BasicUDPSource；

同时创建MPEG2TransportStreamFramer这个filter来处理从source接受到TS流。当然也可以不用这个filter，testMPEG2TransportReceiver.cpp中就没有使用，经过MPEG2TransportStreamFramer可以对TS进行一些解析和处理等。

代码如下：

int main(int argc, char** argv) {
  if (argc < 2) {
    return 1;
  }
  char ipStr[64] = "";
  unsigned short portNum = 0;
 
  Boolean isRTP = (strstr(argv[1],"rtp://") != 0)? True:False;
  if(isRTP){
    sscanf(argv[1],"rtp://%[^:]:%hu",ipStr,&portNum);
  }else{
    sscanf(argv[1],"udp://%[^:]:%hu",ipStr,&portNum);
  }
  if(portNum == 0 || ipStr[0] == 0){
     return 1;   
  }
  
  TaskScheduler* scheduler = BasicTaskScheduler::createNew();
  env = BasicUsageEnvironment::createNew(*scheduler);
 
  struct in_addr sessionAddress;
  sessionAddress.s_addr = our_inet_addr(ipStr);
  const unsigned char ttl = 1; // low, in case routers don't admin scope
  
  //RTP & UDP Socket
  const Port port(portNum);
  Groupsock inputsock(*env, sessionAddress, port, ttl);
  
  //RTCP Socket
  const Port rtcpPort(portNum+1);
  Groupsock rtcpGroupsock(*env, sessionAddress, rtcpPort, ttl);
  
#if 1
if(isRTP){
      //RTP
      // Create the data source: a "MPEG-2 TransportStream RTP source" (which uses a 'simple' RTP payload format):
      sessionState.udpSource = NULL;
      sessionState.rtpSource = SimpleRTPSource::createNew(*env, &inputsock, 33, 90000, "video/MP2T", 0, False /*no 'M' bit*/);
      sessionState.readSource= MPEG2TransportStreamFramer::createNew(*env, sessionState.rtpSource);
      if(sessionState.readSource == NULL){
          *env << "create source error...\n";
          return 1;
      }
      
      // Create (and start) a 'RTCP instance' for the RTP source:
      const unsigned estimatedSessionBandwidth = 5000; // in kbps; for RTCP b/w share
      const unsigned maxCNAMElen = 100;
      unsigned char CNAME[maxCNAMElen+1];
      gethostname((char*)CNAME, maxCNAMElen);
      CNAME[maxCNAMElen] = '\0'; // just in case
      sessionState.rtcpInstance
        = RTCPInstance::createNew(*env, &rtcpGroupsock,
                      estimatedSessionBandwidth, CNAME,
                      NULL /* we're a client */, sessionState.rtpSource);
      // Note: This starts RTCP running automatically
  }
  else{
      //UDP 
      // Create the data source: a "MPEG-2 TransportStream udp source"
      sessionState.rtpSource = NULL;
      sessionState.udpSource = BasicUDPSource::createNew(*env, &inputsock);
      sessionState.readSource = MPEG2TransportStreamFramer::createNew(*env, sessionState.udpSource);
      if(sessionState.readSource == NULL){
          *env << "create source error...\n";
          return 1;
      }

  }
......省略
}

3、
Sink 实现如下：
igmpSink继承MediaSink ，每次收取一帧数据，会调用到afterGettingFrame，通过continuePlaying又会处理获取下一帧数据，从而成为一个循环。所以在afterGettingFrame将流数据dump到文件mDumpFile之中。

// igmpSink //
class igmpSink: public MediaSink {
public:
    
  // "bufferSize" should be at least as large as the largest expected input frame.
  static igmpSink* createNew(UsageEnvironment& env, char const* fileName,
			     unsigned bufferSize = 20000);

protected:
  igmpSink(UsageEnvironment& env, FILE* fid, unsigned bufferSize);
  virtual ~igmpSink();

protected: // redefined virtual functions:
  virtual Boolean continuePlaying();

protected:
  static void afterGettingFrame(void* clientData, unsigned frameSize,
				unsigned numTruncatedBytes,
				struct timeval presentationTime,
				unsigned durationInMicroseconds);
  virtual void afterGettingFrame(unsigned frameSize,
				 unsigned numTruncatedBytes,
				 struct timeval presentationTime);

  FILE* mDumpFile;
  unsigned char* fBuffer;
  unsigned fBufferSize;
};

// igmpSink //
igmpSink::igmpSink(UsageEnvironment& env, FILE* fid, unsigned bufferSize)
  : MediaSink(env), mDumpFile(fid), fBufferSize(bufferSize){
  fBuffer = new unsigned char[bufferSize];
}

igmpSink::~igmpSink() {
  delete[] fBuffer;
  if (mDumpFile != NULL) fclose(mDumpFile);
}

igmpSink* igmpSink::createNew(UsageEnvironment& env, char const* fileName, unsigned bufferSize) {
  FILE* fid;
  fid = fopen(fileName, "wb");
  if (fid == NULL) return NULL;
  
  return new igmpSink(env, fid, bufferSize);
}

Boolean igmpSink::continuePlaying() {
  if (fSource == NULL) return False;
  fSource->getNextFrame(fBuffer, fBufferSize,
			afterGettingFrame, this,
			onSourceClosure, this);
  return True;
}

void igmpSink::afterGettingFrame(void* clientData, unsigned frameSize,
				 unsigned numTruncatedBytes,
				 struct timeval presentationTime,
				 unsigned /*durationInMicroseconds*/) {
  igmpSink* sink = (igmpSink*)clientData;
  sink->afterGettingFrame(frameSize, numTruncatedBytes, presentationTime);
}


void igmpSink::afterGettingFrame(unsigned frameSize,
				 unsigned numTruncatedBytes,
				 struct timeval presentationTime) {
  if (numTruncatedBytes > 0) {
    envir() << "igmpSink::afterGettingFrame(): The input frame data was too large for our buffer size ("
	    << fBufferSize << ").  "
            << numTruncatedBytes << " bytes of trailing data was dropped!  Correct this by increasing the \"bufferSize\" parameter in the \"createNew()\" call to at least "
            << fBufferSize + numTruncatedBytes << "\n";
  }
  
  //envir() << "afterGettingFrame, Write to  file\n";
  if (mDumpFile != NULL && fBuffer != NULL) {
    fwrite(fBuffer, 1, frameSize, mDumpFile);
  }

  if (mDumpFile == NULL || fflush(mDumpFile) == EOF) {
    // The output file has closed.  Handle this the same way as if the input source had closed:
    if (fSource != NULL) fSource->stopGettingFrames();
    onSourceClosure();
    return;
  }

  // Then try getting the next frame:
  continuePlaying();
}

4、
最后只要将source和sink绑定，启动即可。
数据流为：udpSource/ rtpSource–>readSource（MPEG2TransportStreamFramer）–>igmpSink。
env->taskScheduler().doEventLoop(); 在live555内部会通过其SingleStep一直循环。（以后分析RTSP流程时，再分析live555内部流程。）组播流会被dump到指定文件。

sessionState.sink = igmpSink::createNew(*env, "/storage/external_storage/sda1/testIGMP.ts", 5120);
  // Finally, start receiving the multicast stream:
  *env << "Beginning receiving multicast stream...\n";
  sessionState.sink->startPlaying(*sessionState.readSource, afterPlaying, NULL);

  env->taskScheduler().doEventLoop(); // does not return

5、
测试时可以使用VLC推流，RTP和UDP均可，可以看到流会被dump到我们指定的目录，拿出来播放，看是否一样即可。

IOS 组播组播app_IOS 组播_03