Improve the external HRTF data file format

Although more parameters are read from the file, some must currently conform to
specific values. In the future, these restrictions may be lifted.

1 files changed, 107 insertions, 30 deletions

diff --git a/Alc/hrtf.c b/Alc/hrtf.c
index cc383163..4d833d1d 100644
--- a/Alc/hrtf.c
+++ b/Alc/hrtf.c
@@ -25,11 +25,29 @@
 #include "alMain.h"
 #include "alSource.h"
 
+/* External HRTF file format (LE byte order):
+ *
+ * ALchar   magic[8] = "MinPHR00";
+ * ALuint   sampleRate;
+ *
+ * ALushort hrirCount; // Required value: 828
+ * ALushort hrirSize;  // Required value: 32
+ * ALubyte  evCount;   // Required value: 19
+ *
+ * ALushort evOffset[evCount]; // Required values:
+ *   { 0, 1, 13, 37, 73, 118, 174, 234, 306, 378, 450, 522, 594, 654, 710, 755, 791, 815, 827 }
+ *
+ * ALushort coefficients[hrirCount][hrirSize];
+ * ALubyte  delays[hrirCount]; // Element values must not exceed 127
+ */
+
+static const ALchar magicMarker[8] = "MinPHR00";
+
 #define HRIR_COUNT 828
+#define ELEV_COUNT 19
 
-static const ALubyte evCount = 19;
-static const ALushort evOffset[19] = { 0, 1, 13, 37, 73, 118, 174, 234, 306, 378, 450, 522, 594, 654, 710, 755, 791, 815, 827 };
-static const ALubyte azCount[19] = { 1, 12, 24, 36, 45, 56, 60, 72, 72, 72, 72, 72, 60, 56, 45, 36, 24, 12, 1 };
+static const ALushort evOffset[ELEV_COUNT] = { 0, 1, 13, 37, 73, 118, 174, 234, 306, 378, 450, 522, 594, 654, 710, 755, 791, 815, 827 };
+static const ALubyte azCount[ELEV_COUNT] = { 1, 12, 24, 36, 45, 56, 60, 72, 72, 72, 72, 72, 60, 56, 45, 36, 24, 12, 1 };
 
 static struct Hrtf {
     ALuint sampleRate;
@@ -41,13 +59,13 @@ static struct Hrtf {
 };
 
 // Calculate the elevation indices given the polar elevation in radians.
-// This will return two indices between 0 and (evCount - 1) and an
+// This will return two indices between 0 and (ELEV_COUNT-1) and an
 // interpolation factor between 0.0 and 1.0.
 static void CalcEvIndices(ALfloat ev, ALuint *evidx, ALfloat *evmu)
 {
-    ev = (M_PI/2.0f + ev) * (evCount-1) / M_PI;
+    ev = (M_PI/2.0f + ev) * (ELEV_COUNT-1) / M_PI;
     evidx[0] = (ALuint)ev;
-    evidx[1] = __min(evidx[0] + 1, evCount - 1);
+    evidx[1] = __min(evidx[0] + 1, ELEV_COUNT-1);
     *evmu = ev - evidx[0];
 }
 
@@ -141,49 +159,106 @@ ALCboolean IsHrtfCompatible(ALCdevice *device)
 
 void InitHrtf(void)
 {
-    const char *str;
+    const char *fname;
     FILE *f = NULL;
 
-    str = GetConfigValue(NULL, "hrtf_tables", "");
-    if(str[0] != '\0')
+    fname = GetConfigValue(NULL, "hrtf_tables", "");
+    if(fname[0] != '\0')
     {
-        f = fopen(str, "rb");
+        f = fopen(fname, "rb");
         if(f == NULL)
-            ERR("Could not open %s\n", str);
+            ERR("Could not open %s\n", fname);
     }
     if(f != NULL)
     {
-        const ALubyte maxDelay = SRC_HISTORY_LENGTH;
+        const ALubyte maxDelay = SRC_HISTORY_LENGTH-1;
         ALboolean failed = AL_FALSE;
         struct Hrtf newdata;
-        size_t i, j;
+        ALchar magic[9];
+        ALsizei i, j;
+
+        if(fread(magic, 1, sizeof(magicMarker), f) != sizeof(magicMarker))
+        {
+            ERR("Failed to read magic marker\n");
+            failed = AL_TRUE;
+        }
+        else if(memcmp(magic, magicMarker, sizeof(magicMarker)) != 0)
+        {
+            magic[8] = 0;
+            ERR("Invalid magic marker: \"%s\"\n", magic);
+            failed = AL_TRUE;
+        }
 
-        newdata.sampleRate = 44100;
-        for(i = 0;i < HRIR_COUNT;i++)
+        if(!failed)
         {
-            for(j = 0;j < HRIR_LENGTH;j++)
+            ALushort hrirCount, hrirSize;
+            ALubyte  evCount;
+
+            newdata.sampleRate  = fgetc(f);
+            newdata.sampleRate |= fgetc(f)<<8;
+            newdata.sampleRate |= fgetc(f)<<16;
+            newdata.sampleRate |= fgetc(f)<<24;
+
+            hrirCount  = fgetc(f);
+            hrirCount |= fgetc(f)<<8;
+
+            hrirSize  = fgetc(f);
+            hrirSize |= fgetc(f)<<8;
+
+            evCount = fgetc(f);
+
+            if(hrirCount != HRIR_COUNT || hrirSize != HRIR_LENGTH || evCount != ELEV_COUNT)
             {
-                ALshort val;
-                val  = fgetc(f);
-                val |= fgetc(f)<<8;
-                newdata.coeffs[i][j] = val;
+                ERR("Unsupported value: hrirCount=%d (%d), hrirSize=%d (%d), evCount=%d (%d)\n",
+                    hrirCount, HRIR_COUNT, hrirSize, HRIR_LENGTH, evCount, ELEV_COUNT);
+                failed = AL_TRUE;
             }
         }
-        for(i = 0;i < HRIR_COUNT;i++)
+
+        if(!failed)
         {
-            ALubyte val;
-            val = fgetc(f);
-            newdata.delays[i] = val;
-            if(val > maxDelay)
+            for(i = 0;i < HRIR_COUNT;i++)
             {
-                ERR("Invalid delay at idx %zu: %u (max: %u), in %s\n", i, val, maxDelay, str);
-                failed = AL_TRUE;
+                ALushort offset;
+                offset  = fgetc(f);
+                offset |= fgetc(f)<<8;
+                if(offset != evOffset[i])
+                {
+                    ERR("Unsupported evOffset[%d] value: %d (%d)\n", i, offset, evOffset[i]);
+                    failed = AL_TRUE;
+                }
             }
         }
-        if(feof(f))
+
+        if(!failed)
         {
-            ERR("Premature end of data while reading %s\n", str);
-            failed = AL_TRUE;
+            for(i = 0;i < HRIR_COUNT;i++)
+            {
+                for(j = 0;j < HRIR_LENGTH;j++)
+                {
+                    ALshort coeff;
+                    coeff  = fgetc(f);
+                    coeff |= fgetc(f)<<8;
+                    newdata.coeffs[i][j] = coeff;
+                }
+            }
+            for(i = 0;i < HRIR_COUNT;i++)
+            {
+                ALubyte delay;
+                delay = fgetc(f);
+                newdata.delays[i] = delay;
+                if(delay > maxDelay)
+                {
+                    ERR("Invalid delay[%d]: %d (%d)\n", i, delay, maxDelay);
+                    failed = AL_TRUE;
+                }
+            }
+
+            if(feof(f))
+            {
+                ERR("Premature end of data\n");
+                failed = AL_TRUE;
+            }
         }
 
         fclose(f);
@@ -191,5 +266,7 @@ void InitHrtf(void)
 
         if(!failed)
             Hrtf = newdata;
+        else
+            ERR("Failed to load %s\n", fname);
     }
 }