HEVC参考软件平台HM中，在进入正式编码之前需要做一些初始化的工作。这些工作主要在encmain.cpp、TAppEncTop.cpp和TEncTop.cpp中。

1、encmain.cpp

int main(int argc, char* argv[])
{
  TAppEncTop  cTAppEncTop;

  // print information
  fprintf( stdout, "\n" );
  fprintf( stdout, "HM software: Encoder Version [%s]", NV_VERSION );
  fprintf( stdout, NVM_ONOS );
  fprintf( stdout, NVM_COMPILEDBY );
  fprintf( stdout, NVM_BITS );
  fprintf( stdout, "\n" );

  // create application encoder class
  cTAppEncTop.create();

  // parse configuration
  try
  {
    if(!cTAppEncTop.parseCfg( argc, argv ))
    {
      cTAppEncTop.destroy();
      return 1;
    }
  }
  catch (po::ParseFailure& e)
  {
    cerr << "Error parsing option \""<< e.arg <<"\" with argument \""<< e.val <<"\"." << endl;
    return 1;
  }

  // starting time
  double dResult;
  long lBefore = clock();

  // call encoding function
  cTAppEncTop.encode();

  // ending time
  dResult = (double)(clock()-lBefore) / CLOCKS_PER_SEC;
  printf("\n Total Time: %12.3f sec.\n", dResult);

  // destroy application encoder class
  cTAppEncTop.destroy();

  return 0;
}

该部分的大致工作流程如下图所示：

2、TAppEncTop.cpp

Void TAppEncTop::encode()
{
  fstream bitstreamFile(m_pchBitstreamFile, fstream::binary | fstream::out);//m_pchBitstreamFile:output bitstream file（以二进制的形式打开/读取一个可写入文件）
  if (!bitstreamFile)
  {
    fprintf(stderr, "\nfailed to open bitstream file `%s' for writing\n", m_pchBitstreamFile);
    exit(EXIT_FAILURE);
  }

  TComPicYuv*       pcPicYuvOrg = new TComPicYuv;//使用new在运行阶段分配未命名的内存来存储值
  TComPicYuv*       pcPicYuvRec = NULL;
  
  // initialize internal class & member variables
  xInitLibCfg();
  xCreateLib();
  xInitLib(m_isField);
  
  // main encoder loop
  Int   iNumEncoded = 0;
  Bool  bEos = false;
  
  list<AccessUnit> outputAccessUnits; ///< list of access units to write out.  is populated by the encoding process

  // allocate original YUV buffer
  if( m_isField )
  {
    pcPicYuvOrg->create( m_iSourceWidth, m_iSourceHeightOrg, m_uiMaxCUWidth, m_uiMaxCUHeight, m_uiMaxCUDepth );
  }
  else
  {
    pcPicYuvOrg->create( m_iSourceWidth, m_iSourceHeight, m_uiMaxCUWidth, m_uiMaxCUHeight, m_uiMaxCUDepth );
  }
  
  while ( !bEos )
  {
    // get buffers
    xGetBuffer(pcPicYuvRec);

    // read input YUV file
    m_cTVideoIOYuvInputFile.read( pcPicYuvOrg, m_aiPad );

    // increase number of received frames
    m_iFrameRcvd++;
    
    bEos = (m_isField && (m_iFrameRcvd == (m_framesToBeEncoded >> 1) )) || ( !m_isField && (m_iFrameRcvd == m_framesToBeEncoded) );
    Bool flush = 0;
    // if end of file (which is only detected on a read failure) flush the encoder of any queued pictures
    if (m_cTVideoIOYuvInputFile.isEof())
    {
      flush = true;
      bEos = true;
      m_iFrameRcvd--;
      m_cTEncTop.setFramesToBeEncoded(m_iFrameRcvd);
    }

    // call encoding function for one frame
    if ( m_isField )
    {
      m_cTEncTop.encode( bEos, flush ? 0 : pcPicYuvOrg, m_cListPicYuvRec, outputAccessUnits, iNumEncoded, m_isTopFieldFirst);
    }
    else
    {
      m_cTEncTop.encode( bEos, flush ? 0 : pcPicYuvOrg, m_cListPicYuvRec, outputAccessUnits, iNumEncoded );
    }
    
    // write bistream to file if necessary
    if ( iNumEncoded > 0 )
    {
      xWriteOutput(bitstreamFile, iNumEncoded, outputAccessUnits);
      outputAccessUnits.clear();
    }
  }

  m_cTEncTop.printSummary(m_isField);

  // delete original YUV buffer
  pcPicYuvOrg->destroy();
  delete pcPicYuvOrg;//使用delete释放内存（只能用delete来释放使用new分配的内存）
  pcPicYuvOrg = NULL;
  
  // delete used buffers in encoder class
  m_cTEncTop.deletePicBuffer();
  
  // delete buffers & classes
  xDeleteBuffer();
  xDestroyLib();
  
  printRateSummary();

  return;
}

该部分的大致工作流程如下图所示：

3、TEncTop.cpp

Void TEncTop::encode(Bool flush, TComPicYuv* pcPicYuvOrg, TComList<TComPicYuv*>& rcListPicYuvRecOut, std::list<AccessUnit>& accessUnitsOut, Int& iNumEncoded )
{
  if (pcPicYuvOrg) {
    // get original YUV
    TComPic* pcPicCurr = NULL;
    xGetNewPicBuffer( pcPicCurr );
    pcPicYuvOrg->copyToPic( pcPicCurr->getPicYuvOrg() );

    // compute image characteristics
    if ( getUseAdaptiveQP() )
    {
      m_cPreanalyzer.xPreanalyze( dynamic_cast<TEncPic*>( pcPicCurr ) );
    }
  }
  
  if (!m_iNumPicRcvd || (!flush && m_iPOCLast != 0 && m_iNumPicRcvd != m_iGOPSize && m_iGOPSize))
  {
    iNumEncoded = 0;
    return;
  }
  
  if ( m_RCEnableRateControl )
  {
    m_cRateCtrl.initRCGOP( m_iNumPicRcvd );
  }

  // compress GOP

  m_cGOPEncoder.compressGOP(m_iPOCLast, m_iNumPicRcvd, m_cListPic, rcListPicYuvRecOut, accessUnitsOut, false, false);

  if ( m_RCEnableRateControl )
  {
    m_cRateCtrl.destroyRCGOP();
  }
  
  iNumEncoded         = m_iNumPicRcvd;
  m_iNumPicRcvd       = 0;
  m_uiNumAllPicCoded += iNumEncoded;
}

该部分的大致工作流程如下图所示：

以上只是粗略的流程图，特此说明。