Support B-Format amb file IRs in alconvolve

Be aware this requires proper header data (a WAVE_FORMAT_EXTENSIBLE format with
the proper integer or float B-Format sub-format GUID). A normal 4-channel wave
file will not be recognized, since it's indistinguishable from quadrophonic.

1 files changed, 12 insertions, 1 deletions

diff --git a/examples/alconvolve.c b/examples/alconvolve.c
index bc6ac311..b3d6c4dd 100644
--- a/examples/alconvolve.c
+++ b/examples/alconvolve.c
@@ -325,11 +325,22 @@ static ALuint LoadSound(const char *filename)
     /* Get the sound format, and figure out the OpenAL format. Use floats since
      * impulse responses will usually have more than 16-bit precision.
      */
+    format = AL_NONE;
     if(sfinfo.channels == 1)
         format = AL_FORMAT_MONO_FLOAT32;
     else if(sfinfo.channels == 2)
         format = AL_FORMAT_STEREO_FLOAT32;
-    else
+    else if(sfinfo.channels == 3)
+    {
+        if(sf_command(sndfile, SFC_WAVEX_GET_AMBISONIC, NULL, 0) == SF_AMBISONIC_B_FORMAT)
+            format = AL_FORMAT_BFORMAT2D_FLOAT32;
+    }
+    else if(sfinfo.channels == 4)
+    {
+        if(sf_command(sndfile, SFC_WAVEX_GET_AMBISONIC, NULL, 0) == SF_AMBISONIC_B_FORMAT)
+            format = AL_FORMAT_BFORMAT3D_FLOAT32;
+    }
+    if(!format)
     {
         fprintf(stderr, "Unsupported channel count: %d\n", sfinfo.channels);
         sf_close(sndfile);