diff tests/TestPhaseVocoder.cpp @ 115:f3c69325cca2 pvoc

Do actual phase unwrapping in the phase vocoder!

--- a/tests/TestPhaseVocoder.cpp	Wed Oct 02 15:04:38 2013 +0100
+++ b/tests/TestPhaseVocoder.cpp	Wed Oct 02 15:05:34 2013 +0100
@@ -27,21 +27,27 @@
 
 BOOST_AUTO_TEST_CASE(fullcycle)
 {
-    // Cosine with one cycle exactly equal to pvoc hopsize. We aren't
-    // windowing the input frame because (for once) it actually *is*
-    // just a short part of a continuous infinite sinusoid.
+    // Cosine with one cycle exactly equal to pvoc hopsize. This is
+    // pretty much the most trivial case -- in fact it's
+    // indistinguishable from totally silent input (in the phase
+    // values) because the measured phases are zero throughout.
+
+    // We aren't windowing the input frame because (for once) it
+    // actually *is* just a short part of a continuous infinite
+    // sinusoid.
 
     double frame[] = { 1, 0, -1, 0, 1, 0, -1, 0 };
 
-    PhaseVocoder pvoc(8);
+    PhaseVocoder pvoc(8, 4);
 
     // Make these arrays one element too long at each end, so as to
     // test for overruns. For frame size 8, we expect 8/2+1 = 5
     // mag/phase pairs.
     double mag[]   = { 999, 999, 999, 999, 999, 999, 999 };
     double phase[] = { 999, 999, 999, 999, 999, 999, 999 };
+    double unw[]   = { 999, 999, 999, 999, 999, 999, 999 };
 
-    pvoc.process(frame, mag + 1, phase + 1);
+    pvoc.process(frame, mag + 1, phase + 1, unw + 1);
 
     double magExpected0[] = { 999, 0, 0, 4, 0, 0, 999 };
     COMPARE_ARRAY_EXACT(mag, magExpected0);
@@ -49,22 +55,53 @@
     double phaseExpected0[] = { 999, 0, 0, 0, 0, 0, 999 };
     COMPARE_ARRAY_EXACT(phase, phaseExpected0);
 
-    pvoc.process(frame, mag + 1, phase + 1);
+    double unwExpected0[] = { 999, 0, 0, 0, 0, 0, 999 };
+    COMPARE_ARRAY(unw, unwExpected0);
+
+    pvoc.process(frame, mag + 1, phase + 1, unw + 1);
 
     double magExpected1[] = { 999, 0, 0, 4, 0, 0, 999 };
     COMPARE_ARRAY_EXACT(mag, magExpected1);
 
-    double phaseExpected1[] = { 999, 0, 0, 2 * M_PI, 0, 0, 999 };
+    double phaseExpected1[] = { 999, 0, 0, 0, 0, 0, 999 };
     COMPARE_ARRAY(phase, phaseExpected1);
 
-    pvoc.process(frame, mag + 1, phase + 1);
+    // Derivation of values:
+    // 
+    // * Bin 0 (DC) always has phase 0 and expected phase 0
+    //
+    // * Bin 1 has expected phase pi (the hop size is half a cycle at
+    //   its frequency), but measured phase 0 (because there is no
+    //   signal in that bin). So it has phase error -pi, which is
+    //   mapped into (-pi,pi] range as pi, giving an unwrapped phase
+    //   of 2*pi.
+    //  
+    // * Bin 2 has expected unwrapped phase 2*pi, measured phase 0,
+    //   hence error 0 and unwrapped phase 2*pi.
+    //
+    // * Bin 3 is like bin 1: it has expected phase 3*pi, measured
+    //   phase 0, so phase error -pi and unwrapped phase 4*pi.
+    //
+    // * Bin 4 (Nyquist) is like bin 2: expected phase 4*pi, measured
+    //   phase 0, hence error 0 and unwrapped phase 4*pi.
+
+    double unwExpected1[] = { 999, 0, 2*M_PI, 2*M_PI, 4*M_PI, 4*M_PI, 999 };
+    COMPARE_ARRAY(unw, unwExpected1);
+
+    pvoc.process(frame, mag + 1, phase + 1, unw + 1);
 
     double magExpected2[] = { 999, 0, 0, 4, 0, 0, 999 };
     COMPARE_ARRAY_EXACT(mag, magExpected2);
 
-    double phaseExpected2[] = { 999, 0, 0, 4 * M_PI, 0, 0, 999 };
+    double phaseExpected2[] = { 999, 0, 0, 0, 0, 0, 999 };
     COMPARE_ARRAY(phase, phaseExpected2);
+
+    double unwExpected2[] = { 999, 0, 4*M_PI, 4*M_PI, 8*M_PI, 8*M_PI, 999 };
+    COMPARE_ARRAY(unw, unwExpected2);
 }
 
+//!!! signal that starts mid-phase
+
+
 BOOST_AUTO_TEST_SUITE_END()