Add a crossover frequency field for the device

Used when upsampling low-order ambisonic signals to higher order. Rather than a
hardcoded 400hz, it ensures a consistent crossover point when an ambdec
configuration is used. It can also allow for an alsoft config option.

al/source.cpp

@@ -475,7 +475,7 @@ void InitVoice(Voice *voice, ALsource *source, BufferlistItem *BufferList, ALCco
             AmbiIndex::OrderFromChannel.data()};
         const auto scales = BFormatDec::GetHFOrderScales(voice->mAmbiOrder, device->mAmbiOrder);
 
-        const BandSplitter splitter{400.0f / static_cast<float>(device->Frequency)};
+        const BandSplitter splitter{device->mXOverFreq / static_cast<float>(device->Frequency)};
 
         for(auto &chandata : voice->mChans)
         {

alc/alc.cpp

@@ -2219,7 +2219,8 @@ static ALCenum UpdateDeviceParams(ALCdevice *device, const int *attrList)
                     AmbiIndex::OrderFrom2DChannel.data() :
                     AmbiIndex::OrderFromChannel.data()};
 
-                const BandSplitter splitter{400.0f / static_cast<float>(device->Frequency)};
+                const BandSplitter splitter{device->mXOverFreq /
+                    static_cast<float>(device->Frequency)};
 
                 const auto scales = BFormatDec::GetHFOrderScales(voice->mAmbiOrder,
                     device->mAmbiOrder);

alc/alcmain.h

@@ -205,6 +205,7 @@ struct ALCdevice : public al::intrusive_ref<ALCdevice> {
      */
     DevAmbiLayout mAmbiLayout{DevAmbiLayout::Default};
     DevAmbiScaling mAmbiScale{DevAmbiScaling::Default};
+    float mXOverFreq{400.0f};
 
     ALCenum LimiterState{ALC_DONT_CARE_SOFT};
 

alc/effects/convolution.cpp

@@ -247,7 +247,7 @@ void ConvolutionState::setBuffer(const ALCdevice *device, const BufferStorage *b
         (uint64_t{buffer->mSampleLen}*device->Frequency + (buffer->mSampleRate-1)) /
         buffer->mSampleRate);
 
-    const BandSplitter splitter{400.0f / static_cast<float>(device->Frequency)};
+    const BandSplitter splitter{device->mXOverFreq / static_cast<float>(device->Frequency)};
     for(auto &e : *mChans)
         e.mFilter = splitter;
 

alc/effects/reverb.cpp

@@ -672,7 +672,7 @@ void ReverbState::deviceUpdate(const ALCdevice *device)
         mMixOut = &ReverbState::MixOutPlain;
         mOrderScales.fill(1.0f);
     }
-    mAmbiSplitter[0][0].init(400.0f / frequency);
+    mAmbiSplitter[0][0].init(device->mXOverFreq / frequency);
     std::fill(mAmbiSplitter[0].begin()+1, mAmbiSplitter[0].end(), mAmbiSplitter[0][0]);
     std::fill(mAmbiSplitter[1].begin(), mAmbiSplitter[1].end(), mAmbiSplitter[0][0]);
 }

alc/hrtf.cpp

@@ -279,7 +279,7 @@ std::unique_ptr<DirectHrtfState> DirectHrtfState::Create(size_t num_chans)
 
 void DirectHrtfState::build(const HrtfStore *Hrtf, const uint irSize,
     const al::span<const AngularPoint> AmbiPoints, const float (*AmbiMatrix)[MaxAmbiChannels],
-    const al::span<const float,MaxAmbiOrder+1> AmbiOrderHFGain)
+    const float XOverFreq, const al::span<const float,MaxAmbiOrder+1> AmbiOrderHFGain)
 {
     using double2 = std::array<double,2>;
     struct ImpulseResponse {
@@ -287,7 +287,7 @@ void DirectHrtfState::build(const HrtfStore *Hrtf, const uint irSize,
         uint ldelay, rdelay;
     };
 
-    const double xover_norm{400.0 / Hrtf->sampleRate};
+    const double xover_norm{double{XOverFreq} / Hrtf->sampleRate};
     for(size_t i{0};i < mChannels.size();++i)
     {
         const size_t order{AmbiIndex::OrderFromChannel[i]};

alc/hrtf.h

@@ -73,7 +73,7 @@ struct DirectHrtfState {
      */
     void build(const HrtfStore *Hrtf, const uint irSize,
         const al::span<const AngularPoint> AmbiPoints, const float (*AmbiMatrix)[MaxAmbiChannels],
-        const al::span<const float,MaxAmbiOrder+1> AmbiOrderHFGain);
+        const float XOverFreq, const al::span<const float,MaxAmbiOrder+1> AmbiOrderHFGain);
 
     static std::unique_ptr<DirectHrtfState> Create(size_t num_chans);
 

alc/panning.cpp

@@ -595,6 +595,7 @@ void InitCustomPanning(ALCdevice *device, const bool hqdec, const bool stablize,
     if(!hqdec && conf->FreqBands != 1)
         ERR("Basic renderer uses the high-frequency matrix as single-band (xover_freq = %.0fhz)\n",
             conf->XOverFreq);
+    device->mXOverFreq = conf->XOverFreq;
 
     const ALuint order{(conf->ChanMask > Ambi2OrderMask) ? 3u :
         (conf->ChanMask > Ambi1OrderMask) ? 2u : 1u};
@@ -813,7 +814,8 @@ void InitHrtfPanning(ALCdevice *device)
 
     HrtfStore *Hrtf{device->mHrtf.get()};
     auto hrtfstate = DirectHrtfState::Create(count);
-    hrtfstate->build(Hrtf, device->mIrSize, AmbiPoints, AmbiMatrix, AmbiOrderHFGain);
+    hrtfstate->build(Hrtf, device->mIrSize, AmbiPoints, AmbiMatrix, device->mXOverFreq,
+        AmbiOrderHFGain);
     device->mHrtfState = std::move(hrtfstate);
 
     InitNearFieldCtrl(device, Hrtf->field[0].distance, ambi_order, true);
@@ -848,6 +850,7 @@ void aluInitRenderer(ALCdevice *device, int hrtf_id, HrtfRequestMode hrtf_appreq
     device->mHrtf = nullptr;
     device->mIrSize = 0;
     device->HrtfName.clear();
+    device->mXOverFreq = 400.0f;
     device->mRenderMode = RenderMode::Normal;
 
     if(device->FmtChans != DevFmtStereo)