Allow initializing splitter filters with constructors

Alc/filters/splitter.h

@@ -14,6 +14,10 @@ class BandSplitterR {
     Real ap_z1{0.0f};
 
 public:
+    BandSplitterR() = default;
+    BandSplitterR(const BandSplitterR&) = default;
+    BandSplitterR(Real f0norm) { init(f0norm); }
+
     void init(Real f0norm);
     void clear() noexcept { lp_z1 = lp_z2 = ap_z1 = 0.0f; }
     void process(Real *hpout, Real *lpout, const Real *input, const int count);
@@ -30,6 +34,10 @@ class SplitterAllpassR {
     Real z1{0.0f};
 
 public:
+    SplitterAllpassR() = default;
+    SplitterAllpassR(const SplitterAllpassR&) = default;
+    SplitterAllpassR(Real f0norm) { init(f0norm); }
+
     void init(Real f0norm);
     void clear() noexcept { z1 = 0.0f; }
     void process(Real *samples, int count);

Alc/hrtf.cpp

@@ -339,10 +339,8 @@ void BuildBFormatHrtf(const HrtfEntry *Hrtf, DirectHrtfState *state, const ALsiz
      */
     static constexpr ALsizei base_delay{DualBand ? 12 : 0};
     const ALdouble xover_norm{400.0 / Hrtf->sampleRate};
-    BandSplitterR<double> splitter;
-    SplitterAllpassR<double> allpass;
-    splitter.init(xover_norm);
-    allpass.init(xover_norm);
+    BandSplitterR<double> splitter{xover_norm};
+    SplitterAllpassR<double> allpass{xover_norm};
 
     auto tmpres = al::vector<HrirArray<ALdouble>>(NumChannels);
     auto tmpfilt = al::vector<std::array<ALdouble,HRIR_LENGTH*4>>(3);

OpenAL32/alSource.cpp

@@ -2936,8 +2936,7 @@ START_API_FUNC
                 OrderFromChan = Order3DFromChan;
             }
 
-            BandSplitter splitter;
-            splitter.init(400.0f / static_cast<ALfloat>(device->Frequency));
+            BandSplitter splitter{400.0f / static_cast<ALfloat>(device->Frequency)};
 
             const auto scales = BFormatDec::GetHFOrderScales(1, device->mAmbiOrder);
             auto init_ambi = [scales,&OrderFromChan,&splitter](ALvoice::ResampleData &resdata) -> void