Use the difference in HF scale for upsampling ambisonics

5 files changed, 32 insertions, 34 deletions

diff --git a/alc/effects/convolution.cpp b/alc/effects/convolution.cpp
index 90220a50..196238fc 100644
--- a/alc/effects/convolution.cpp
+++ b/alc/effects/convolution.cpp
@@ -420,7 +420,7 @@ void ConvolutionState::update(const ContextBase *context, const EffectSlot *slot
         if(device->mAmbiOrder > mAmbiOrder)
         {
             mMix = &ConvolutionState::UpsampleMix;
-            const auto scales = AmbiScale::GetHFOrderScales(mAmbiOrder, true);
+            const auto scales = AmbiScale::GetHFOrderScales(mAmbiOrder, device->mAmbiOrder);
             (*mChans)[0].mHfScale = scales[0];
             for(size_t i{1};i < mChans->size();++i)
                 (*mChans)[i].mHfScale = scales[1];
diff --git a/alc/effects/reverb.cpp b/alc/effects/reverb.cpp
index ea3367d0..71640a87 100644
--- a/alc/effects/reverb.cpp
+++ b/alc/effects/reverb.cpp
@@ -686,7 +686,7 @@ void ReverbState::deviceUpdate(const DeviceBase *device, const Buffer&)
     if(device->mAmbiOrder > 1)
     {
         mUpmixOutput = true;
-        mOrderScales = AmbiScale::GetHFOrderScales(1, true);
+        mOrderScales = AmbiScale::GetHFOrderScales(1, device->mAmbiOrder);
     }
     else
     {
diff --git a/core/ambidefs.cpp b/core/ambidefs.cpp
index 31ac699e..49b2d144 100644
--- a/core/ambidefs.cpp
+++ b/core/ambidefs.cpp
@@ -14,6 +14,22 @@ constexpr auto inv_sqrt2f = static_cast<float>(1.0/al::numbers::sqrt2);
 constexpr auto inv_sqrt3f = static_cast<float>(1.0/al::numbers::sqrt3);
 
 
+/* These HF gains are derived from the same 32-point speaker array. The scale
+ * factor between orders represents the same scale factors for any (regular)
+ * speaker array decoder. e.g. Given a first-order source and second-order
+ * output, applying an HF scale of HFScales[1][0] / HFScales[2][0] to channel 0
+ * will result in that channel being subsequently decoded for second-order as
+ * if it was a first-order decoder for that same speaker array.
+ */
+constexpr std::array<std::array<float,MaxAmbiOrder+1>,MaxAmbiOrder+1> HFScales{{
+    {{ 4.000000000e+00f, 2.309401077e+00f, 1.192569588e+00f, 7.189495850e-01f }},
+    {{ 4.000000000e+00f, 2.309401077e+00f, 1.192569588e+00f, 7.189495850e-01f }},
+    {{ 2.981423970e+00f, 2.309401077e+00f, 1.192569588e+00f, 7.189495850e-01f }},
+    {{ 2.359168820e+00f, 2.031565936e+00f, 1.444598386e+00f, 7.189495850e-01f }},
+    /* 1.947005434e+00f, 1.764337084e+00f, 1.424707344e+00f, 9.755104127e-01f, 4.784482742e-01f */
+}};
+
+
 constexpr std::array<std::array<float,4>,8> FirstOrderDecoder{{
     {{ 1.250000000e-01f,  1.250000000e-01f,  1.250000000e-01f,  1.250000000e-01f, }},
     {{ 1.250000000e-01f,  1.250000000e-01f,  1.250000000e-01f, -1.250000000e-01f, }},
@@ -367,21 +383,14 @@ const std::array<AmbiChannelFloatArray,16> AmbiScale::ThirdOrderUp{CalcThirdOrde
 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
-}};
-const std::array<float,MaxAmbiOrder+1> AmbiScale::DecoderHFScale1O2D{{
-    1.414213562e+00f, 1.000000000e+00f
-}};
-const std::array<float,MaxAmbiOrder+1> AmbiScale::DecoderHFScale2O{{
-    1.825741858e+00f, 1.414213562e+00f, 7.302967433e-01f
-}};
-const std::array<float,MaxAmbiOrder+1> AmbiScale::DecoderHFScale2O2D{{
-    1.414213562e+00f, 1.224744871e+00f, 7.071067812e-01f
-}};
-const std::array<float,MaxAmbiOrder+1> AmbiScale::DecoderHFScale3O{{
-    1.865086714e+00f, 1.606093894e+00f, 1.142055301e+00f, 5.683795528e-01f
-}};
-const std::array<float,MaxAmbiOrder+1> AmbiScale::DecoderHFScale3O2D{{
-    1.414213562e+00f, 1.306562965e+00f, 1.000000000e+00f, 5.411961001e-01f
-}};
+
+std::array<float,MaxAmbiOrder+1> AmbiScale::GetHFOrderScales(const uint src_order,
+    const uint dev_order) noexcept
+{
+    std::array<float,MaxAmbiOrder+1> res{};
+
+    for(size_t i{0};i < MaxAmbiOrder+1;++i)
+        res[i] = HFScales[src_order][i] / HFScales[dev_order][i];
+
+    return res;
+}
diff --git a/core/ambidefs.h b/core/ambidefs.h
index 7f0f14ad..aa69b2e6 100644
--- a/core/ambidefs.h
+++ b/core/ambidefs.h
@@ -114,19 +114,8 @@ struct AmbiScale {
     }
 
     /* Retrieves per-order HF scaling factors for "upsampling" ambisonic data. */
-    static std::array<float,MaxAmbiOrder+1> GetHFOrderScales(const uint order, const bool is3D) noexcept
-    {
-        if(order >= 3) return is3D ? DecoderHFScale3O : DecoderHFScale3O2D;
-        if(order == 2) return is3D ? DecoderHFScale2O : DecoderHFScale2O2D;
-        return is3D ? DecoderHFScale1O : DecoderHFScale1O2D;
-    }
-
-    static const std::array<float,MaxAmbiOrder+1> DecoderHFScale1O;
-    static const std::array<float,MaxAmbiOrder+1> DecoderHFScale1O2D;
-    static const std::array<float,MaxAmbiOrder+1> DecoderHFScale2O;
-    static const std::array<float,MaxAmbiOrder+1> DecoderHFScale2O2D;
-    static const std::array<float,MaxAmbiOrder+1> DecoderHFScale3O;
-    static const std::array<float,MaxAmbiOrder+1> DecoderHFScale3O2D;
+    static std::array<float,MaxAmbiOrder+1> GetHFOrderScales(const uint src_order,
+        const uint dev_order) noexcept;
 
     static const std::array<std::array<float,MaxAmbiChannels>,4> FirstOrderUp;
     static const std::array<std::array<float,MaxAmbiChannels>,4> FirstOrder2DUp;
diff --git a/core/voice.cpp b/core/voice.cpp
index 5263202e..8b4cabe2 100644
--- a/core/voice.cpp
+++ b/core/voice.cpp
@@ -899,7 +899,7 @@ void Voice::prepare(DeviceBase *device)
     {
         const uint8_t *OrderFromChan{Is2DAmbisonic(mFmtChannels) ?
             AmbiIndex::OrderFrom2DChannel().data() : AmbiIndex::OrderFromChannel().data()};
-        const auto scales = AmbiScale::GetHFOrderScales(mAmbiOrder, !Is2DAmbisonic(mFmtChannels));
+        const auto scales = AmbiScale::GetHFOrderScales(mAmbiOrder, device->mAmbiOrder);
 
         const BandSplitter splitter{device->mXOverFreq / static_cast<float>(device->Frequency)};
         for(auto &chandata : mChans)