Add a 2D fourth-order upsampler

This will be necessary for 2D fourth-order sources with 3D fourth-order output.

2 files changed, 53 insertions, 1 deletions

diff --git a/core/ambidefs.cpp b/core/ambidefs.cpp
index e33197c1..4112a4bc 100644
--- a/core/ambidefs.cpp
+++ b/core/ambidefs.cpp
@@ -310,6 +310,56 @@ auto CalcThirdOrder2DUp()
     return res;
 }
 
+
+constexpr std::array<std::array<float,25>,10> FourthOrder2DDecoder{{
+    {{ 1.000000000e-01f,  3.568220898e-02f, 0.0f,  1.098185471e-01f,  6.070619982e-02f, 0.0f, 0.0f, 0.0f,  8.355491589e-02f,  7.735682057e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  5.620301997e-02f,  8.573754253e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  2.785781628e-02f, }},
+    {{ 1.000000000e-01f,  9.341723590e-02f, 0.0f,  6.787159473e-02f,  9.822469464e-02f, 0.0f, 0.0f, 0.0f, -3.191513794e-02f,  2.954767620e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -9.093839659e-02f, -5.298871540e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -7.293270986e-02f, }},
+    {{ 1.000000000e-01f,  1.154700538e-01f, 0.0f,  0.000000000e+00f,  0.000000000e+00f, 0.0f, 0.0f, 0.0f, -1.032795559e-01f, -9.561828875e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  0.000000000e+00f,  0.000000000e+00f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  9.014978717e-02f, }},
+    {{ 1.000000000e-01f,  9.341723590e-02f, 0.0f, -6.787159473e-02f, -9.822469464e-02f, 0.0f, 0.0f, 0.0f, -3.191513794e-02f,  2.954767620e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  9.093839659e-02f,  5.298871540e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -7.293270986e-02f, }},
+    {{ 1.000000000e-01f,  3.568220898e-02f, 0.0f, -1.098185471e-01f, -6.070619982e-02f, 0.0f, 0.0f, 0.0f,  8.355491589e-02f,  7.735682057e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -5.620301997e-02f, -8.573754253e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  2.785781628e-02f, }},
+    {{ 1.000000000e-01f, -3.568220898e-02f, 0.0f, -1.098185471e-01f,  6.070619982e-02f, 0.0f, 0.0f, 0.0f,  8.355491589e-02f, -7.735682057e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -5.620301997e-02f,  8.573754253e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  2.785781628e-02f, }},
+    {{ 1.000000000e-01f, -9.341723590e-02f, 0.0f, -6.787159473e-02f,  9.822469464e-02f, 0.0f, 0.0f, 0.0f, -3.191513794e-02f, -2.954767620e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  9.093839659e-02f, -5.298871540e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -7.293270986e-02f, }},
+    {{ 1.000000000e-01f, -1.154700538e-01f, 0.0f,  0.000000000e+00f,  0.000000000e+00f, 0.0f, 0.0f, 0.0f, -1.032795559e-01f,  9.561828875e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  0.000000000e+00f,  0.000000000e+00f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  9.014978717e-02f, }},
+    {{ 1.000000000e-01f, -9.341723590e-02f, 0.0f,  6.787159473e-02f, -9.822469464e-02f, 0.0f, 0.0f, 0.0f, -3.191513794e-02f, -2.954767620e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -9.093839659e-02f,  5.298871540e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, -7.293270986e-02f, }},
+    {{ 1.000000000e-01f, -3.568220898e-02f, 0.0f,  1.098185471e-01f, -6.070619982e-02f, 0.0f, 0.0f, 0.0f,  8.355491589e-02f, -7.735682057e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  5.620301997e-02f, -8.573754253e-02f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f,  2.785781628e-02f, }},
+}};
+constexpr std::array<AmbiChannelFloatArray,10> FourthOrder2DEncoder{{
+    CalcAmbiCoeffs( 3.090169944e-01f,  0.000000000e+00f,  9.510565163e-01f),
+    CalcAmbiCoeffs( 8.090169944e-01f,  0.000000000e+00f,  5.877852523e-01f),
+    CalcAmbiCoeffs( 1.000000000e+00f,  0.000000000e+00f,  0.000000000e+00f),
+    CalcAmbiCoeffs( 8.090169944e-01f,  0.000000000e+00f, -5.877852523e-01f),
+    CalcAmbiCoeffs( 3.090169944e-01f,  0.000000000e+00f, -9.510565163e-01f),
+    CalcAmbiCoeffs(-3.090169944e-01f,  0.000000000e+00f, -9.510565163e-01f),
+    CalcAmbiCoeffs(-8.090169944e-01f,  0.000000000e+00f, -5.877852523e-01f),
+    CalcAmbiCoeffs(-1.000000000e+00f,  0.000000000e+00f,  0.000000000e+00f),
+    CalcAmbiCoeffs(-8.090169944e-01f,  0.000000000e+00f,  5.877852523e-01f),
+    CalcAmbiCoeffs(-3.090169944e-01f,  0.000000000e+00f,  9.510565163e-01f),
+}};
+static_assert(FourthOrder2DDecoder.size() == FourthOrder2DEncoder.size(), "Fourth-order 2D mismatch");
+
+/* This calculates a 2D fourth-order "upsampler" matrix. There is no 3D fourth-
+ * order upsampler since fourth-order is the max order we'll be supporting for
+ * the foreseeable future. This is only necessary for mixing horizontal-only
+ * fourth-order content to 3D.
+ */
+auto CalcFourthOrder2DUp()
+{
+    std::array<AmbiChannelFloatArray,25> res{};
+
+    for(size_t i{0};i < FourthOrder2DDecoder[0].size();++i)
+    {
+        for(size_t j{0};j < FourthOrder2DEncoder[0].size();++j)
+        {
+            double sum{0.0};
+            for(size_t k{0};k < FourthOrder2DDecoder.size();++k)
+                sum += double{FourthOrder2DDecoder[k][i]} * FourthOrder2DEncoder[k][j];
+            res[i][j] = static_cast<float>(sum);
+        }
+    }
+
+    return res;
+}
+
 } // namespace
 
 const std::array<AmbiChannelFloatArray,4> AmbiScale::FirstOrderUp{CalcFirstOrderUp()};
@@ -318,6 +368,7 @@ const std::array<AmbiChannelFloatArray,9> AmbiScale::SecondOrderUp{CalcSecondOrd
 const std::array<AmbiChannelFloatArray,9> AmbiScale::SecondOrder2DUp{CalcSecondOrder2DUp()};
 const std::array<AmbiChannelFloatArray,16> AmbiScale::ThirdOrderUp{CalcThirdOrderUp()};
 const std::array<AmbiChannelFloatArray,16> AmbiScale::ThirdOrder2DUp{CalcThirdOrder2DUp()};
+const std::array<AmbiChannelFloatArray,25> AmbiScale::FourthOrder2DUp{CalcFourthOrder2DUp()};
 
 const std::array<float,MaxAmbiOrder+1> AmbiScale::DecoderHFScale1O{{
     2.000000000e+00f, 1.154700538e+00f
diff --git a/core/ambidefs.h b/core/ambidefs.h
index e72f0cd4..7f0f14ad 100644
--- a/core/ambidefs.h
+++ b/core/ambidefs.h
@@ -134,6 +134,7 @@ struct AmbiScale {
     static const std::array<std::array<float,MaxAmbiChannels>,9> SecondOrder2DUp;
     static const std::array<std::array<float,MaxAmbiChannels>,16> ThirdOrderUp;
     static const std::array<std::array<float,MaxAmbiChannels>,16> ThirdOrder2DUp;
+    static const std::array<std::array<float,MaxAmbiChannels>,25> FourthOrder2DUp;
 };
 
 struct AmbiIndex {
@@ -248,7 +249,7 @@ constexpr auto CalcAmbiCoeffs(const float y, const float z, const float x)
         /* ACN 16 = sqrt(35)*3/2 * X * Y * (X*X - Y*Y) */
         /* ACN 17 = sqrt(35/2)*3/2 * (3*X*X - Y*Y) * Y * Z */
         /* ACN 18 = sqrt(5)*3/2 * X * Y * (7*Z*Z - 1) */
-        /* ACN 19 = sqrt(5/2)*3/2 * Y * Z * (7*Z*Z - 3)  */
+        /* ACN 19 = sqrt(5/2)*3/2 * Y * Z * (7*Z*Z - 3) */
         /* ACN 20 = 3/8 * (35*Z*Z*Z*Z - 30*Z*Z + 3) */
         /* ACN 21 = sqrt(5/2)*3/2 * X * Z * (7*Z*Z - 3) */
         /* ACN 22 = sqrt(5)*3/4 * (X*X - Y*Y) * (7*Z*Z - 1) */