H264标准协议基础3

参考博文

1.解码视频帧的poc计算

2.残差4x4 矩阵中的trailingones & numcoeff

2.1查表

对应jm给出的三维数组表格内置表

  int lentab[3][4][17] = 
  {
    {   // 0702
      { 1, 6, 8, 9,10,11,13,13,13,14,14,15,15,16,16,16,16},
      { 0, 2, 6, 8, 9,10,11,13,13,14,14,15,15,15,16,16,16},
      { 0, 0, 3, 7, 8, 9,10,11,13,13,14,14,15,15,16,16,16},
      { 0, 0, 0, 5, 6, 7, 8, 9,10,11,13,14,14,15,15,16,16},
    },                                                 
    {                                                  
      { 2, 6, 6, 7, 8, 8, 9,11,11,12,12,12,13,13,13,14,14},
      { 0, 2, 5, 6, 6, 7, 8, 9,11,11,12,12,13,13,14,14,14},
      { 0, 0, 3, 6, 6, 7, 8, 9,11,11,12,12,13,13,13,14,14},
      { 0, 0, 0, 4, 4, 5, 6, 6, 7, 9,11,11,12,13,13,13,14},
    },                                                 
    {                                                  
      { 4, 6, 6, 6, 7, 7, 7, 7, 8, 8, 9, 9, 9,10,10,10,10},
      { 0, 4, 5, 5, 5, 5, 6, 6, 7, 8, 8, 9, 9, 9,10,10,10},
      { 0, 0, 4, 5, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,10,10,10},
      { 0, 0, 0, 4, 4, 4, 4, 4, 5, 6, 7, 8, 8, 9,10,10,10},
    },

  };

  int codtab[3][4][17] = 
  {
    {
      { 1, 5, 7, 7, 7, 7,15,11, 8,15,11,15,11,15,11, 7,4}, 
      { 0, 1, 4, 6, 6, 6, 6,14,10,14,10,14,10, 1,14,10,6}, 
      { 0, 0, 1, 5, 5, 5, 5, 5,13, 9,13, 9,13, 9,13, 9,5}, 
      { 0, 0, 0, 3, 3, 4, 4, 4, 4, 4,12,12, 8,12, 8,12,8},
    },
    {
      { 3,11, 7, 7, 7, 4, 7,15,11,15,11, 8,15,11, 7, 9,7}, 
      { 0, 2, 7,10, 6, 6, 6, 6,14,10,14,10,14,10,11, 8,6}, 
      { 0, 0, 3, 9, 5, 5, 5, 5,13, 9,13, 9,13, 9, 6,10,5}, 
      { 0, 0, 0, 5, 4, 6, 8, 4, 4, 4,12, 8,12,12, 8, 1,4},
    },
    {
      {15,15,11, 8,15,11, 9, 8,15,11,15,11, 8,13, 9, 5,1}, 
      { 0,14,15,12,10, 8,14,10,14,14,10,14,10, 7,12, 8,4},
      { 0, 0,13,14,11, 9,13, 9,13,10,13, 9,13, 9,11, 7,3},
      { 0, 0, 0,12,11,10, 9, 8,13,12,12,12, 8,12,10, 6,2},
    },
  };

从上述tab上看，目前只表述nc的范围为0<= nc < 2、2 <=nc<4 、4<=nc <8，分别对应的数组下表为nc、trialingones、numcoeff; 这里两个表分表位编码数值表个编码长度表，适合用来通过长度和数值来获取bit流中的4x4残差数据值

2.读取实例