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

// Getvlc.cpp: implementation of the CGetvlc class. 
// 
////////////////////////////////////////////////////////////////////// 
 
#include "stdafx.h" 
#include "视频编解码器.h" 
#include "Getvlc.h" 
 
#ifdef _DEBUG 
#undef THIS_FILE 
static char THIS_FILE[]=__FILE__; 
#define new DEBUG_NEW 
#endif 
 
////////////////////////////////////////////////////////////////////// 
// Construction/Destruction 
////////////////////////////////////////////////////////////////////// 
extern int quiet,fault,trace;  
CGetvlc::CGetvlc() 
{ 
 
} 
 
CGetvlc::~CGetvlc() 
{ 
 
} 
 
int CGetvlc::getCBPY() 
{ 
  int code; 
  code = m_getbits.showbits(6); 
  if (code < 2)  
  { //无效的CBPY 
    fault = 1; 
    return -1; 
  } 
  if (code>=48) 
  { 
    m_getbits.flushbits(2); 
    return 0; 
  } 
  m_getbits.flushbits(CBPYtab[code].len); 
  return CBPYtab[code].code; 
} 
 
int CGetvlc::getTMNMV() 
{ 
  int code; 
  if (m_getbits.getbits1())//为"1"时  运动矢量为0 
     return 0; 
  
  if ((code = m_getbits.showbits(12))>=512) 
  { 
    code = (code>>8) - 2;//MV表的索引 
    m_getbits.flushbits(TMNMVtab0[code].len);//结构体，MV的长度 
                           //装入N个比特 
    return TMNMVtab0[code].code; 
  } 
 
  if (code>=128) 
  { 
    code = (code>>2) -32; 
    m_getbits.flushbits(TMNMVtab1[code].len); 
    return TMNMVtab1[code].code; 
  } 
 
  if ((code-=5)<0) 
  { 
    if (!quiet) 
      AfxMessageBox("Invalid motion_vector code!"); 
    fault=1; 
    return 0; 
   } 
 
  m_getbits.flushbits(TMNMVtab2[code].len); 
  return TMNMVtab2[code].code; 
 
} 
 
int CGetvlc::getMCBPC() 
{ 
 int code; 
  code = m_getbits.showbits(9);//得到比特数 
  if (code == 1) 
  { 
    // macroblock stuffing  
    m_getbits.flushbits(9);//操作完后将其冲刷掉 
    return -1; 
  } 
 
  if (code == 0)  
  { 
    fault = 1; 
    return 0; 
  } 
     
  if (code>=256) 
  { 
    m_getbits.flushbits(1); 
    return 0; 
  } 
     
  m_getbits.flushbits(MCBPCtab[code].len); 
  return MCBPCtab[code].code; 
 
} 
 
int CGetvlc::getMODB() 
{ 
 int code; 
  int MODB; 
  code = m_getbits.showbits(2); 
 
  if (code < 2) 
  { 
    MODB = 0; 
    m_getbits.flushbits(1); 
  } 
  else if (code == 2) 
  { 
    MODB = 1; 
    m_getbits.flushbits(2); 
  } 
  else  
  { /* code == 3 */ 
     AfxMessageBox("11: MODB = 2!"); 
    MODB = 2; 
    m_getbits.flushbits(2); 
  } 
  return MODB; 
 
} 
 
int CGetvlc::getMCBPCintra() 
{ 
  int code; 
  code = m_getbits.showbits(9); 
 
  if (code == 1)  
  { 
    // macroblock stuffing  
    m_getbits.flushbits(9); 
    return -1; 
  } 
 
  if (code < 8) 
  { 
    fault = 1; 
    return 0; 
  } 
  code >>= 3;//除stuffing外最多有6比特 
  if (code>=32) 
  { 
    m_getbits.flushbits(1); 
    return 3; 
  } 
  m_getbits.flushbits(MCBPCtabintra[code].len); 
  return MCBPCtabintra[code].code; 
 
}