Automated SPqcd to use the LSBs as well.

aous72 · Nov 7, 2024 · e803914 · e803914
1 parent 9d2a048
commit e803914
Show file tree

Hide file tree

Showing 2 changed files with 19 additions and 8 deletions.
diff --git a/src/core/codestream/ojph_params.cpp b/src/core/codestream/ojph_params.cpp
@@ -952,16 +952,16 @@ namespace ojph {
       int s = 0;
       double bibo_l = bibo_gains::get_bibo_gain_l(num_decomps, true);
       ui32 X = (ui32) ceil(log(bibo_l * bibo_l) / M_LN2);
-      u8_SPqcd[s++] = (ui8)((B + X) << reversible_SPqcd_shift);
+      u8_SPqcd[s++] = encode_SPqcd((ui8)(B + X));
       for (ui32 d = num_decomps; d > 0; --d)
       {
         double bibo_l = bibo_gains::get_bibo_gain_l(d, true);
         double bibo_h = bibo_gains::get_bibo_gain_h(d - 1, true);
         X = (ui32) ceil(log(bibo_h * bibo_l) / M_LN2);
-        u8_SPqcd[s++] = (ui8)((B + X) << reversible_SPqcd_shift);
-        u8_SPqcd[s++] = (ui8)((B + X) << reversible_SPqcd_shift);
+        u8_SPqcd[s++] = encode_SPqcd((ui8)(B + X));
+        u8_SPqcd[s++] = encode_SPqcd((ui8)(B + X));
         X = (ui32) ceil(log(bibo_h * bibo_h) / M_LN2);
-        u8_SPqcd[s++] = (ui8)((B + X) << reversible_SPqcd_shift);
+        u8_SPqcd[s++] = encode_SPqcd((ui8)(B + X));
       }
     }
 
@@ -1018,7 +1018,7 @@ namespace ojph {
       int irrev = Sqcd & 0x1F;
       if (irrev == 0) //reversible
         for (ui32 i = 0; i < num_subbands; ++i) {
-          ui32 t = (u8_SPqcd[i] >> reversible_SPqcd_shift);
+          ui32 t = decode_SPqcd(u8_SPqcd[i]);
           t += get_num_guard_bits() - 1u;
           B = ojph_max(B, t);
         }
@@ -1093,7 +1093,7 @@ namespace ojph {
       int irrev = Sqcd & 0x1F;
       if (irrev == 0) // reversible; this is (10.22) from the J2K book
       {
-        num_bits += u8_SPqcd[idx] >> reversible_SPqcd_shift;
+        num_bits += decode_SPqcd(u8_SPqcd[idx]);
         num_bits = num_bits == 0 ? 0 : num_bits - 1;
       }
       else if (irrev == 1)

diff --git a/src/core/codestream/ojph_params_local.h b/src/core/codestream/ojph_params_local.h
@@ -590,7 +590,7 @@ namespace ojph {
     {
       friend ::ojph::param_qcd;
     public:
-      param_qcd() : reversible_SPqcd_shift(3)
+      param_qcd() : reversible_SPqcd_shift(3), old_SPqcd(false)
       { 
         Lqcd = 0;
         Sqcd = 0;
@@ -643,10 +643,21 @@ namespace ojph {
                          bool is_employing_color_transform);
       void set_irrev_quant(ui32 num_decomps);
 
-    protected:
+      ui8 decode_SPqcd(ui8 v) const
+      {
+        if (old_SPqcd) return (ui8)(v >> reversible_SPqcd_shift); // old
+        else return (ui8)((v << 6) | (v >> 3)); // new
+      }
+      ui8 encode_SPqcd(ui8 v) const
+      {
+        if (old_SPqcd) return (ui8)(v << reversible_SPqcd_shift); // old
+        else return (ui8)((v >> 6) | (v << 3)); // new
+      }
+   protected:
       ui16 Lqcd;
       ui8 Sqcd;
       const ui8 reversible_SPqcd_shift;
+      const bool old_SPqcd;
       union
       {
         ui8 u8_SPqcd[97];