Don't hardcode the max channels for HRTF B-Format decoding

Alc/hrtf.c

@@ -202,13 +202,15 @@ void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei N
 #define NUM_BANDS 2
     BandSplitter splitter;
     ALdouble (*tmpres)[HRIR_LENGTH][2];
-    ALsizei idx[HRTF_AMBI_MAX_CHANNELS];
+    ALsizei *restrict idx;
     ALsizei min_delay = HRTF_HISTORY_LENGTH;
     ALsizei max_delay = 0;
     ALfloat temps[3][HRIR_LENGTH];
     ALsizei max_length;
     ALsizei i, c, b;
 
+    idx = al_calloc(DEF_ALIGN, AmbiCount*sizeof(*idx));
+
     for(c = 0;c < AmbiCount;c++)
     {
         ALuint evidx, azidx;
@@ -312,6 +314,8 @@ void BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei N
     }
     al_free(tmpres);
     tmpres = NULL;
+    al_free(idx);
+    idx = NULL;
 
     if(NUM_BANDS == 1)
         max_length = mini(max_delay-min_delay + Hrtf->irSize, HRIR_LENGTH);

Alc/hrtf.h

@@ -9,12 +9,6 @@
 #include "atomic.h"
 
 
-/* The maximum number of virtual speakers used to generate HRTF coefficients
- * for decoding B-Format.
- */
-#define HRTF_AMBI_MAX_CHANNELS 18
-
-
 #define HRTF_HISTORY_BITS   (6)
 #define HRTF_HISTORY_LENGTH (1<<HRTF_HISTORY_BITS)
 #define HRTF_HISTORY_MASK   (HRTF_HISTORY_LENGTH-1)

Alc/panning.c

@@ -884,7 +884,6 @@ static void InitHrtfPanning(ALCdevice *device)
 
     static_assert(COUNTOF(AmbiPoints) == COUNTOF(AmbiMatrixFOA), "FOA Ambisonic HRTF mismatch");
     static_assert(COUNTOF(AmbiPoints) == COUNTOF(AmbiMatrixHOA), "HOA Ambisonic HRTF mismatch");
-    static_assert(COUNTOF(AmbiPoints) <= HRTF_AMBI_MAX_CHANNELS, "HRTF_AMBI_MAX_CHANNELS is too small");
 
     if(device->AmbiUp)
     {