block_encoder.cpp

该源码是JPEG2000的c++源代码,希望对研究JPEG2000标准以及编解码的朋友们有用.

        cword = *cp;
        if (!(cword & (CLEANUP_MEMBER_MASK<<0)))
          { // Process first row of stripe column (row 0)
            state_ref = states+KAPPA_SIG_BASE+sig_lut[cword & NBRHD_MASK];
            val = sp[0]<<shift;
            sym = val & KDU_INT32_MIN;
            _mq_enc_(coder,sym,*state_ref);
            if (val >= 0) // New magnitude bit was 0, so still insignificant
              goto row_1;
row_0_significant:
            // Compute distortion change
            val =  (val>>(31-DISTORTION_LSBS)) & (SIGNIFICANCE_DISTORTIONS-1);
            distortion_change += distortion_lut[val];
            // Encode sign bit
            sym = cword & ((CHI_BIT>>3) | (SIGMA_CC_BIT>>3) |
                           (CHI_BIT<<3) | (SIGMA_CC_BIT<<3));
            sym >>= 1; // Shift down so that top sigma bit has address 0
            sym |= (cp[-1] & ((CHI_BIT<<0) | (SIGMA_CC_BIT<<0))) >> (1+1);
            sym |= (cp[ 1] & ((CHI_BIT<<0) | (SIGMA_CC_BIT<<0))) >> (1-1);
            sym |= (sym >> (CHI_POS-1-SIGMA_CC_POS)); // Interleave chi & sigma
            val = sign_lut[sym & 0x000000FF];
            state_ref = states + KAPPA_SIGN_BASE + (val>>1);
            sym = val << 31; // Get sign flipping to `sym'
            val = sp[0] & KDU_INT32_MIN; // Get the sign bit
            sym ^= val; // Moves flipped sign bit into `sym'
            _mq_enc_(coder,sym,*state_ref);
            // Broadcast neighbourhood context changes; sign bit is in `val'
            cp[-1] |= (SIGMA_CR_BIT<<0);
            cp[1]  |= (SIGMA_CL_BIT<<0);
            if (val < 0)
              {
                cword |= (SIGMA_CC_BIT<<0) | (CHI_BIT<<0);
                if (!causal)
                  {
                    cp[-context_row_gap-1] |= (SIGMA_BR_BIT<<9);
                    cp[-context_row_gap  ] |= (SIGMA_BC_BIT<<9) | NEXT_CHI_BIT;
                    cp[-context_row_gap+1] |= (SIGMA_BL_BIT<<9);
                  }
              }
            else
              {
                cword |= (SIGMA_CC_BIT<<0);
                if (!causal)
                  {
                    cp[-context_row_gap-1] |= (SIGMA_BR_BIT<<9);
                    cp[-context_row_gap  ] |= (SIGMA_BC_BIT<<9);
                    cp[-context_row_gap+1] |= (SIGMA_BL_BIT<<9);
                  }
              }
          }
row_1:
        if (!(cword & (CLEANUP_MEMBER_MASK<<3)))
          { // Process second row of stripe column (row 1)
            state_ref = states+KAPPA_SIG_BASE+sig_lut[(cword>>3) & NBRHD_MASK];
            val = sp[width]<<shift;
            sym = val & KDU_INT32_MIN;
            _mq_enc_(coder,sym,*state_ref);
            if (val >= 0) // New magnitude bit was 0, so still insignificant
              goto row_2;
row_1_significant:
            // Compute distortion change
            val =  (val>>(31-DISTORTION_LSBS)) & (SIGNIFICANCE_DISTORTIONS-1);
            distortion_change += distortion_lut[val];
            // Encode sign bit
            sym = cword & ((CHI_BIT<<0) | (SIGMA_CC_BIT<<0) |
                           (CHI_BIT<<6) | (SIGMA_CC_BIT<<6));
            sym >>= 4; // Shift down so that top sigma bit has address 0
            sym |= (cp[-1] & ((CHI_BIT<<3) | (SIGMA_CC_BIT<<3))) >> (4+1);
            sym |= (cp[ 1] & ((CHI_BIT<<3) | (SIGMA_CC_BIT<<3))) >> (4-1);
            sym |= (sym >> (CHI_POS-1-SIGMA_CC_POS)); // Interleave chi & sigma
            val = sign_lut[sym & 0x000000FF];
            state_ref = states + KAPPA_SIGN_BASE + (val>>1);
            sym = val << 31; // Get sign flipping to `sym'
            val = sp[width] & KDU_INT32_MIN; // Get the sign bit
            sym ^= val; // Moves flipped sign bit into `sym'
            _mq_enc_(coder,sym,*state_ref);
            // Broadcast neighbourhood context changes; sign bit is in `val'
            cp[-1] |= (SIGMA_CR_BIT<<3);
            cp[1]  |= (SIGMA_CL_BIT<<3);
            cword |= (SIGMA_CC_BIT<<3);
            val = (kdu_int32)(((kdu_uint32) val)>>(31-(CHI_POS+3))); // SRL
            cword |= val;
          }
row_2:
        if (!(cword & (CLEANUP_MEMBER_MASK<<6)))
          { // Process third row of stripe column (row 2)
            state_ref = states+KAPPA_SIG_BASE+sig_lut[(cword>>6) & NBRHD_MASK];
            val = sp[width_by2]<<shift;
            sym = val & KDU_INT32_MIN;
            _mq_enc_(coder,sym,*state_ref);
            if (val >= 0) // New magnitude bit was 0, so still insignificant
              goto row_3;
row_2_significant:
            // Compute distortion change
            val =  (val>>(31-DISTORTION_LSBS)) & (SIGNIFICANCE_DISTORTIONS-1);
            distortion_change += distortion_lut[val];
            // Encode sign bit
            sym = cword & ((CHI_BIT<<3) | (SIGMA_CC_BIT<<3) |
                           (CHI_BIT<<9) | (SIGMA_CC_BIT<<9));
            sym >>= 7; // Shift down so that top sigma bit has address 0
            sym |= (cp[-1] & ((CHI_BIT<<6) | (SIGMA_CC_BIT<<6))) >> (7+1);
            sym |= (cp[ 1] & ((CHI_BIT<<6) | (SIGMA_CC_BIT<<6))) >> (7-1);
            sym |= (sym >> (CHI_POS-1-SIGMA_CC_POS)); // Interleave chi & sigma
            val = sign_lut[sym & 0x000000FF];
            state_ref = states + KAPPA_SIGN_BASE + (val>>1);
            sym = val << 31; // Get sign flipping to `sym'
            val = sp[width_by2] & KDU_INT32_MIN; // Get the sign bit
            sym ^= val; // Moves flipped sign bit into `sym'
            _mq_enc_(coder,sym,*state_ref);
            // Broadcast neighbourhood context changes; sign bit is in `val'
            cp[-1] |= (SIGMA_CR_BIT<<6);
            cp[1]  |= (SIGMA_CL_BIT<<6);
            cword |= (SIGMA_CC_BIT<<6);
            val = (kdu_int32)(((kdu_uint32) val)>>(31-(CHI_POS+6))); // SRL
            cword |= val;
          }
row_3:
        if (!(cword & (CLEANUP_MEMBER_MASK<<9)))
          { // Process fourth row of stripe column (row 3)
            state_ref = states+KAPPA_SIG_BASE+sig_lut[(cword>>9) & NBRHD_MASK];
            val = sp[width_by3]<<shift;
            sym = val & KDU_INT32_MIN;
            _mq_enc_(coder,sym,*state_ref);
            if (val >= 0) // New magnitude bit was 0, so still insignificant
              goto done;
row_3_significant:
            // Compute distortion change
            val =  (val>>(31-DISTORTION_LSBS)) & (SIGNIFICANCE_DISTORTIONS-1);
            distortion_change += distortion_lut[val];
            // Decode sign bit
            sym = cword & ((CHI_BIT<<6) | (SIGMA_CC_BIT<<6) |
                                0       | (SIGMA_CC_BIT<<12));
            sym >>= 10; // Shift down so that top sigma bit has address 0
            if (cword < 0) // Use the fact that NEXT_CHI_BIT = 31
              sym |= CHI_BIT<<(12-10);
            sym |= (cp[-1] & ((CHI_BIT<<9) | (SIGMA_CC_BIT<<9))) >> (10+1);
            sym |= (cp[ 1] & ((CHI_BIT<<9) | (SIGMA_CC_BIT<<9))) >> (10-1);
            sym |= (sym >> (CHI_POS-1-SIGMA_CC_POS)); // Interleave chi & sigma
            val = sign_lut[sym & 0x000000FF];
            state_ref = states + KAPPA_SIGN_BASE + (val>>1);
            sym = val << 31; // Get sign flipping to `sym'
            val = sp[width_by3] & KDU_INT32_MIN; // Get the sign bit
            sym ^= val; // Moves flipped sign bit into `sym'
            _mq_enc_(coder,sym,*state_ref);
            // Broadcast neighbourhood context changes; sign bit is in `val'
            cp[context_row_gap-1] |= SIGMA_TR_BIT;
            cp[context_row_gap+1] |= SIGMA_TL_BIT;
            cp[-1] |= (SIGMA_CR_BIT<<9);
            cp[1]  |= (SIGMA_CL_BIT<<9);
            if (val < 0)
              {
                cp[context_row_gap  ] |= SIGMA_TC_BIT | PREV_CHI_BIT;
                cword |= (SIGMA_CC_BIT<<9) | (CHI_BIT<<9);
              }
            else
              {
                cp[context_row_gap  ] |= SIGMA_TC_BIT;
                cword |= (SIGMA_CC_BIT<<9);
              }
          }
done:
        cword |= (cword << (MU_POS - SIGMA_CC_POS)) &
                 ((MU_BIT<<0)|(MU_BIT<<3)|(MU_BIT<<6)|(MU_BIT<<9));
        cword &= ~((PI_BIT<<0)|(PI_BIT<<3)|(PI_BIT<<6)|(PI_BIT<<9));
        *cp = cword;
      }
  _mq_check_in_(coder);
  return distortion_change;
}

/* ========================================================================= */
/*               Distortion-Length Slope Calculating Functions               */
/* ========================================================================= */

/*****************************************************************************/
/* INLINE                         slope_to_log                               */
/*****************************************************************************/

static inline kdu_uint16
  slope_to_log(double lambda)
{
  double max_slope = pow(2.0,32.0); // Maximum slope we can reprsent
  double log_scale = 256.0 / log(2.0); // Convert log values to 8.8 fixed point
  double log_slope = lambda / max_slope;
  log_slope = (log_slope > 1.0)?1.0:log_slope;
  log_slope = (log(log_slope) * log_scale) + (double)(1<<16);
  if (log_slope > (double) 0xFFFF)
    return 0xFFFF;
  else if (log_slope < 2.0)
    return 2;
  else
    return (kdu_uint16) log_slope;
}

/*****************************************************************************/
/* INLINE                       slope_from_log                               */
/*****************************************************************************/

static inline double
  slope_from_log(kdu_uint16 slope)
{
  double max_slope = pow(2.0,32.0);
  double log_scale = log(2.0) / 256.0;
  double log_slope = ((double) slope) - ((double)(1<<16));
  log_slope *= log_scale;
  return exp(log_slope) * max_slope;
}

/*****************************************************************************/
/* STATIC                      find_convex_hull                              */
/*****************************************************************************/

static void
  find_convex_hull(int pass_lengths[], double pass_wmse_changes[],
                   kdu_uint16 pass_slopes[], int num_passes)
{
  int z;

  for (z=0; z < num_passes; z++)
    { /* Find the value, lambda(z), defined in equation (8.4) of the book by
         Taubman and Marcellin.  Every coding pass which contributes to the
         convex hull set has this value for its distortion-length slope;
         however, not all coding passes which have a positive lambda(z) value
         actually contribute to the convex hull.  The points which do not
         contribute are weeded out next. */
      double lambda_z = -1.0; // Marks initial condition.
      double delta_L = 0.0, delta_D = 0.0;
      int t;
      for (t=z; t >= 0; t--)
        {
          delta_L += (double) pass_lengths[t];
          delta_D += pass_wmse_changes[t];
          if (delta_D <= 0.0)
            break;
          else if ((delta_L > 0.0) &&
                   ((lambda_z < 0.0) || ((delta_L*lambda_z) > delta_D)))
            lambda_z = delta_D / delta_L;
        }
      if (lambda_z <= 0.0)
        pass_slopes[z] = 0;
      else
        pass_slopes[z] = slope_to_log(lambda_z);
    }

  /* Now weed out the non-contributing passes. */
  for (z=0; z < num_passes; z++)
    {
      for (int t=z+1; t < num_passes; t++)
        if (pass_slopes[t] >= pass_slopes[z])
          { pass_slopes[z] = 0; break; }
    }
}


/* ========================================================================= */
/*                           kdu_block_encoder                               */
/* ========================================================================= */

/*****************************************************************************/
/*                  kdu_block_encoder::kdu_block_encoder                     */
/*****************************************************************************/

kdu_block_encoder::kdu_block_encoder()
{
  state = new kd_block_encoder;
}


/* ========================================================================= */
/*                            kd_block_encoder                               */
/* ========================================================================= */

/*****************************************************************************/
/*                         kd_block_encoder::encode                          */
/*****************************************************************************/

void
  kd_block_encoder::encode(kdu_block *block, bool reversible, double msb_wmse,