Changeset 5a703bd

Timestamp:

Nov 15, 2018, 2:03:02 AM (6 years ago)

Author:

Paul Brossier <piem@piem.org>

Branches:

feature/autosink, feature/cnn, feature/cnn_org, feature/constantq, feature/crepe, feature/crepe_org, feature/pitchshift, feature/pydocstrings, feature/timestretch, fix/ffmpeg5, master

Children:

5bcd9b9

Parents:

22ec93a

Message:

[fft] fix reconstruction for odd sizes (fftw only)

File:

• src/spectral/fft.c (modified) (2 diffs)

src/spectral/fft.c

@@ -494 +494 @@
   }
 #endif
-  if (compspec->data[compspec->length/2] < 0) {
-    spectrum->phas[spectrum->length - 1] = PI;
+#ifdef HAVE_FFTW3
+  // for even length only, make sure last element is 0 or PI
+  if (2 * (compspec->length / 2) == compspec->length) {
+#endif
+    if (compspec->data[compspec->length/2] < 0) {
+      spectrum->phas[spectrum->length - 1] = PI;
+    } else {
+      spectrum->phas[spectrum->length - 1] = 0.;
+    }
+#ifdef HAVE_FFTW3
   } else {
-    spectrum->phas[spectrum->length - 1] = 0.;
-  }
+    i = spectrum->length - 1;
+    spectrum->phas[i] = ATAN2(compspec->data[compspec->length-i],
+        compspec->data[i]);
+  }
+#endif
 }
 
@@ -508 +519 @@
         + SQR(compspec->data[compspec->length - i]) );
   }
-  spectrum->norm[spectrum->length-1] =
-    ABS(compspec->data[compspec->length/2]);
+#ifdef HAVE_FFTW3
+  // for even length, make sure last element is > 0
+  if (2 * (compspec->length / 2) == compspec->length) {
+#endif
+    spectrum->norm[spectrum->length-1] =
+      ABS(compspec->data[compspec->length/2]);
+#ifdef HAVE_FFTW3
+  } else {
+    i = spectrum->length - 1;
+    spectrum->norm[i] = SQRT(SQR(compspec->data[i])
+        + SQR(compspec->data[compspec->length - i]) );
+  }
+#endif
 }