www.pudn.com > h263_.rar > Gethdr.cpp

// Gethdr.cpp: implementation of the CGethdr class. 
// 
////////////////////////////////////////////////////////////////////// 
 
#include "stdafx.h" 
#include "视频编解码器.h" 
#include "Gethdr.h" 
 
#ifdef _DEBUG 
#undef THIS_FILE 
static char THIS_FILE[]=__FILE__; 
#define new DEBUG_NEW 
#endif 
 
////////////////////////////////////////////////////////////////////// 
// Construction/Destruction 
////////////////////////////////////////////////////////////////////// 
extern int mv_outside_frame,long_vectors; 
int adv_pred_mode,pb_frame; 
extern int syntax_arith_coding; 
int trb,trd,temp_ref; 
extern int  quiet,source_format,pict_type,quant,bquant,verbose; 
extern ldecode *ld; 
 
CGethdr::CGethdr() 
{ 
 
} 
 
CGethdr::~CGethdr() 
{ 
 
} 
 
int CGethdr::getheader() 
{ 
  unsigned int code, gob; 
  startcode();  // 寻找startcode  
  code = m_getbits.getbits(PSC_LENGTH);//17 
  gob = m_getbits.getbits(5);//GN 
  if (gob == SEC)  
      return 0; 
  if (gob == 0) //第一个块组和图像头再一块 
  { 
    getpicturehdr(); 
    if (syntax_arith_coding)		 
      m_sacode.decoder_reset();	         
  } 
  return gob + 1; 
 
} 
 
void CGethdr::startcode() 
{ 
  while (m_getbits.showbits(PSC_LENGTH)!=1l) //移位搜索 
  	 m_getbits.flushbits(1); 
 
} 
 
void CGethdr::getpicturehdr() 
{ 
  int pos, pei, tmp; 
  int prev_temp_ref; 
 
  pos = ld->bitcnt; 
  prev_temp_ref = temp_ref; 
  //时间参考 
  temp_ref = m_getbits.getbits(8); 
  trd = temp_ref - prev_temp_ref; 
  if (trd < 0) 
    trd += 256; 
  tmp = m_getbits.getbits(1); // 总是 "1" 
  if (!tmp) 
    if (!quiet) 
      AfxMessageBox("warning: spare in picture header should be \"1\"!"); 
  tmp = m_getbits.getbits(1); // 总是 "0" 
  if (tmp) 
    if (!quiet) 
      AfxMessageBox("warning: H.261 distinction bit should be \"0\"!"); 
  tmp = m_getbits.getbits(1); // split_screen_indicator 
  if (tmp)  
  { 
    if (!quiet) 
      AfxMessageBox("error: split-screen not supported in this version!"); 
      exit (-1); 
  } 
  tmp = m_getbits.getbits(1); //document_camera_indicator  
  if (tmp) 
    if (!quiet) 
      AfxMessageBox("warning: document camera indicator not supported in this version!"); 
 
  tmp = m_getbits.getbits(1); // freeze_picture_release 
  if (tmp) 
    if (!quiet) 
      AfxMessageBox("warning: frozen picture not supported in this version!"); 
 
  source_format = m_getbits.getbits(3); 
  pict_type     = m_getbits.getbits(1); 
  //可选模式 
  mv_outside_frame = m_getbits.getbits(1);  //0 
  long_vectors     = (mv_outside_frame ? 1 : 0); 
  syntax_arith_coding = m_getbits.getbits(1); //SAC 
  adv_pred_mode     = m_getbits.getbits(1);       //advance 
  mv_outside_frame  = (adv_pred_mode ? 1 : mv_outside_frame);//Umv 
  pb_frame = m_getbits.getbits(1); //pb-mode 
  //量化因子 
  quant    = m_getbits.getbits(5);    //quant 
  tmp      = m_getbits.getbits(1);   //CPM 
  if (tmp)  
  { 
    if (!quiet) 
      AfxMessageBox("error: CPM not supported in this version!"); 
    exit(-1); 
  } 
  if (pb_frame)  
  { 
    trb    = m_getbits.getbits(3); 
    bquant = m_getbits.getbits(2); 
  } 
  //PEI 
  pei = m_getbits.getbits(1); 
  while(pei) 
  { 
	  m_getbits.getbits(8); 
	  pei=m_getbits.getbits(1); 
  } 
     
  if (verbose>0)  
  { 
	CString picinfor,hdrinfor; 
	picinfor.Format("picture header (byte %d)\n",(pos>>3)-4); 
    if (verbose>1)  
	{ 
      hdrinfor.Format("  temp_ref=%d\n",temp_ref); 
      picinfor+=hdrinfor; 
	  hdrinfor.Format("  pict_type=%d\n",pict_type); 
      picinfor+=hdrinfor; 
	  hdrinfor.Format("  source_format=%d\n", source_format); 
      picinfor+=hdrinfor; 
	  hdrinfor.Format("  quant=%d\n",quant); 
      picinfor+=hdrinfor; 
	  if (syntax_arith_coding)  
      { 
		  hdrinfor.Format("  SAC coding mode used \n"); 
		  picinfor+=hdrinfor; 
	  } 
      if (mv_outside_frame) 
	  { 
		  hdrinfor.Format("  unrestricted motion vector mode used\n"); 
		  picinfor+=hdrinfor; 
	  } 
      if (adv_pred_mode) 
	  { 
		  hdrinfor.Format("  advanced prediction mode used\n"); 
		  picinfor+=hdrinfor; 
	  } 
      if (pb_frame)  
	  { 
	     hdrinfor.Format("  pb-frames mode used\n"); 
		 picinfor+=hdrinfor; 
	     hdrinfor.Format("  trb=%d\n",trb); 
	     picinfor+=hdrinfor; 
		 hdrinfor.Format("  bquant=%d\n", bquant); 
		 picinfor+=hdrinfor; 
      } 
    } 
  } 
 
}