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intra-prediction(2)

intra-prediction(2)

作者: 阿King_ | 来源:发表于2018-11-18 18:30 被阅读0次

    I_4x4的9种模式

    pixel布局
    7种模式的方向 
    enum {
  VERT_PRED            = 0,
  HOR_PRED             = 1,
  DC_PRED              = 2,
  DIAG_DOWN_LEFT_PRED  = 3,
  DIAG_DOWN_RIGHT_PRED = 4,
  VERT_RIGHT_PRED      = 5,
  HOR_DOWN_PRED        = 6,
  VERT_LEFT_PRED       = 7,
  HOR_UP_PRED          = 8
} I4x4PredModes;

    0.vertical

    vertical方向

    只需要用到ABCD，且有
    a=e=i=m = A
    b=f=j=n = B
    c=g=k=o = C
    d=h=i=p = D

    1.horizontal

    horizontal方向

    只需要用到IJKL，且有
    a=b=c=d = I
    e=f=g=h = J
    i=j=k=l = K
    m=n=o=p = L

    static inline void get_i4x4_horizontal(imgpel **cur_pred, imgpel *PredPel)
{
  int i;

  for (i=0; i < BLOCK_SIZE; i++)
  {
    cur_pred[i][0]  =
    cur_pred[i][1]  =
    cur_pred[i][2]  =
    cur_pred[i][3]  = (imgpel) (&P_I)[i];
  }
}

    2.DC

    DC布局
    • 左边和上边都可用
      mean = sum（A+B+C+D+I+J+K+L+4）>> 3
    • 只有左边可用
      mean = sum(I+J+K+L+2) >>2
    • 只有上边可用
      mean = sum(A+B+C+D+2) >>2
    • 都不可用
      mean = 128
    #define BLOCK_SHIFT            2
static inline void get_i4x4_dc(imgpel **cur_pred, imgpel *PredPel, int left_available, int up_available)
{
  int i, j, s0 = 0;
  if (up_available && left_available)
  {
    // no edge
    s0 = (P_A + P_B + P_C + P_D + P_I + P_J + P_K + P_L + 4) >> (BLOCK_SHIFT + 1);
  }
  else if (!up_available && left_available)
  {
    // upper edge
    s0 = (P_I + P_J + P_K + P_L + 2) >> BLOCK_SHIFT;
  }
  else if (up_available && !left_available)
  {
    // left edge
    s0 = (P_A + P_B + P_C + P_D + 2) >> BLOCK_SHIFT;
  }
  else //if (!up_available && !left_available)
  {
    // top left corner, nothing to predict from
    s0 = P_A; // P_A already set to p_Vid->dc_pred_value;
  }

  for (j=0; j < BLOCK_SIZE; j++)
  {
    for (i=0; i < BLOCK_SIZE; i++)
      cur_pred[j][i] = (imgpel) s0;
  }
}

    3.Diagonal down left

    down left方向

    要用到ABCDEFGH，当EFDH不可用时，令E=F=G=H = D

    if (block_available_up_right)
  {
    memcpy(&PredPel[5], &img_enc[pix_c.pos_y][pix_c.pos_x], BLOCK_SIZE * sizeof(imgpel));
  }
  else  //EFGH arenot available
  {
    P_E = P_F = P_G = P_H = P_D;
  }

    a=
    b=e=
    c=f=i=
    d=g=j=m=
    h=n=k=
    i=o=
    p=

    static inline void get_i4x4_downleft(imgpel **cur_pred, imgpel *PredPel)
{
  cur_pred[0][0] = (imgpel) ((P_A + P_C + ((P_B) << 1) + 2) >> 2);
  cur_pred[0][1] =
  cur_pred[1][0] = (imgpel) ((P_B + P_D + ((P_C) << 1) + 2) >> 2);
  cur_pred[0][2] =
  cur_pred[1][1] =
  cur_pred[2][0] = (imgpel) ((P_C + P_E + ((P_D) << 1) + 2) >> 2);
  cur_pred[0][3] =
  cur_pred[1][2] =
  cur_pred[2][1] =
  cur_pred[3][0] = (imgpel) ((P_D + P_F + ((P_E) << 1) + 2) >> 2);
  cur_pred[1][3] =
  cur_pred[2][2] =
  cur_pred[3][1] = (imgpel) ((P_E + P_G + ((P_F)<<1) + 2) >> 2);
  cur_pred[2][3] =
  cur_pred[3][2] = (imgpel) ((P_F + P_H + ((P_G)<<1) + 2) >> 2);
  cur_pred[3][3] = (imgpel) ((P_G + 3*(P_H) + 2) >> 2);
}

    4.Diagonal down right

    down right方向

    要用到ABCDIJLKL
    m=
    i=n=
    e=j=o=
    a=f=k=p=
    b=g=l=
    c=h=
    d=

    static inline void get_i4x4_downright(imgpel **cur_pred, imgpel *PredPel)
{
  cur_pred[3][0] = (imgpel) ((P_L + 2*P_K + P_J + 2) >> 2);
  cur_pred[2][0] =
  cur_pred[3][1] = (imgpel) ((P_K + 2*P_J + P_I + 2) >> 2);
  cur_pred[1][0] =
  cur_pred[2][1] =
  cur_pred[3][2] = (imgpel) ((P_J + 2*P_I + P_X + 2) >> 2);
  cur_pred[0][0] =
  cur_pred[1][1] =
  cur_pred[2][2] =
  cur_pred[3][3] = (imgpel) ((P_I + 2*P_X + P_A + 2) >> 2);
  cur_pred[0][1] =
  cur_pred[1][2] =
  cur_pred[2][3] = (imgpel) ((P_X + 2*P_A + P_B + 2) >> 2);
  cur_pred[0][2] =
  cur_pred[1][3] = (imgpel) ((P_A + 2*P_B + P_C + 2) >> 2);
  cur_pred[0][3] = (imgpel) ((P_B + 2*P_C + P_D + 2) >> 2);
}

    5.Vertical right

    vertical right方向

    要用到ABCDIJKL

    static inline void get_i4x4_vertright(imgpel **cur_pred, imgpel *PredPel)
{
  cur_pred[0][0] =
  cur_pred[2][1] = (imgpel) ((P_X + P_A + 1) >> 1);
  cur_pred[0][1] =
  cur_pred[2][2] = (imgpel) ((P_A + P_B + 1) >> 1);
  cur_pred[0][2] =
  cur_pred[2][3] = (imgpel) ((P_B + P_C + 1) >> 1);
  cur_pred[0][3] = (imgpel) ((P_C + P_D + 1) >> 1);  
  cur_pred[1][0] =
  cur_pred[3][1] = (imgpel) ((P_I + 2*P_X + P_A + 2) >> 2);
  cur_pred[1][1] =
  cur_pred[3][2] = (imgpel) ((P_X + 2*P_A + P_B + 2) >> 2);
  cur_pred[1][2] =
  cur_pred[3][3] = (imgpel) ((P_A + 2*P_B + P_C + 2) >> 2);
  cur_pred[1][3] = (imgpel) ((P_B + 2*P_C + P_D + 2) >> 2);
  cur_pred[2][0] = (imgpel) ((P_X + 2*P_I + P_J + 2) >> 2);
  cur_pred[3][0] = (imgpel) ((P_I + 2*P_J + P_K + 2) >> 2);
}

    6.Horizontal down

    horizontal down方向

    要用到ABCDIJKL

    static inline void get_i4x4_hordown(imgpel **cur_pred, imgpel *PredPel)
{
  cur_pred[0][0] =
  cur_pred[1][2] = (imgpel) ((P_X + P_I + 1) >> 1);
  cur_pred[0][1] =
  cur_pred[1][3] = (imgpel) ((P_I + 2*P_X + P_A + 2) >> 2);
  cur_pred[0][2] = (imgpel) ((P_X + 2*P_A + P_B + 2) >> 2);
  cur_pred[0][3] = (imgpel) ((P_A + 2*P_B + P_C + 2) >> 2);
  cur_pred[1][0] =
  cur_pred[2][2] = (imgpel) ((P_I + P_J + 1) >> 1);
  cur_pred[1][1] =
  cur_pred[2][3] = (imgpel) ((P_X + 2*P_I + P_J + 2) >> 2);
  cur_pred[2][0] =
  cur_pred[3][2] = (imgpel) ((P_J + P_K + 1) >> 1);
  cur_pred[2][1] =
  cur_pred[3][3] = (imgpel) ((P_I + 2*P_J + P_K + 2) >> 2);
  cur_pred[3][0] = (imgpel) ((P_K + P_L + 1) >> 1);
  cur_pred[3][1] = (imgpel) ((P_J + 2*P_K + P_L + 2) >> 2);
}

    7.Vertical left

    vertical left方向

    要用到ABCDEFG，当EFG不可用时，令E=F=G = D

    static inline void get_i4x4_vertleft(imgpel **cur_pred, imgpel *PredPel)
{
  cur_pred[0][0] = (imgpel) ((P_A + P_B + 1) >> 1);
  cur_pred[0][1] =
  cur_pred[2][0] = (imgpel) ((P_B + P_C + 1) >> 1);
  cur_pred[0][2] =
  cur_pred[2][1] = (imgpel) ((P_C + P_D + 1) >> 1);
  cur_pred[0][3] =
  cur_pred[2][2] = (imgpel) ((P_D + P_E + 1) >> 1);
  cur_pred[2][3] = (imgpel) ((P_E + P_F + 1) >> 1);
  cur_pred[1][0] = (imgpel) ((P_A + ((P_B)<<1) + P_C + 2) >> 2);
  cur_pred[1][1] =
  cur_pred[3][0] = (imgpel) ((P_B + ((P_C)<<1) + P_D + 2) >> 2);
  cur_pred[1][2] =
  cur_pred[3][1] = (imgpel) ((P_C + ((P_D)<<1) + P_E + 2) >> 2);
  cur_pred[1][3] =
  cur_pred[3][2] = (imgpel) ((P_D + ((P_E)<<1) + P_F + 2) >> 2);
  cur_pred[3][3] = (imgpel) ((P_E + ((P_F)<<1) + P_G + 2) >> 2);
}

    8.Horizontal up

    horizontal up方向

    要用到IJKL

    static inline void get_i4x4_horup(imgpel **cur_pred, imgpel *PredPel)
{
  cur_pred[0][0] = (imgpel) ((P_I + P_J + 1) >> 1);
  cur_pred[0][1] = (imgpel) ((P_I + 2*P_J + P_K + 2) >> 2);
  cur_pred[0][2] =
  cur_pred[1][0] = (imgpel) ((P_J + P_K + 1) >> 1);
  cur_pred[0][3] =
  cur_pred[1][1] = (imgpel) ((P_J + 2*P_K + P_L + 2) >> 2);
  cur_pred[1][2] =
  cur_pred[2][0] = (imgpel) ((P_K + P_L + 1) >> 1);
  cur_pred[1][3] =
  cur_pred[2][1] = (imgpel) ((P_K + 2*P_L + P_L + 2) >> 2);
  cur_pred[3][0] =
  cur_pred[2][2] =
  cur_pred[2][3] =
  cur_pred[3][1] =
  cur_pred[3][2] =
  cur_pred[3][3] = (imgpel) P_L;
}

    文章归doc.liang@qq.com所有，不得以任何理由任何形式转载

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