view tests/TestPhaseVocoder.cpp @ 115:f3c69325cca2 pvoc

Do actual phase unwrapping in the phase vocoder!

#include "dsp/phasevocoder/PhaseVocoder.h"

#include "base/Window.h"

#define BOOST_TEST_DYN_LINK
#define BOOST_TEST_MAIN

#include <boost/test/unit_test.hpp>

BOOST_AUTO_TEST_SUITE(TestFFT)

#define COMPARE_CONST(a, n) \
    for (int cmp_i = 0; cmp_i < (int)(sizeof(a)/sizeof(a[0])); ++cmp_i) { \
        BOOST_CHECK_SMALL(a[cmp_i] - n, 1e-14);				\
    }

#define COMPARE_ARRAY(a, b)						\
    for (int cmp_i = 0; cmp_i < (int)(sizeof(a)/sizeof(a[0])); ++cmp_i) { \
        BOOST_CHECK_SMALL(a[cmp_i] - b[cmp_i], 1e-14);			\
    }

#define COMPARE_ARRAY_EXACT(a, b)						\
    for (int cmp_i = 0; cmp_i < (int)(sizeof(a)/sizeof(a[0])); ++cmp_i) { \
        BOOST_CHECK_EQUAL(a[cmp_i], b[cmp_i]);			\
    }

BOOST_AUTO_TEST_CASE(fullcycle)
{
    // 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, 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, unw + 1);

    double magExpected0[] = { 999, 0, 0, 4, 0, 0, 999 };
    COMPARE_ARRAY_EXACT(mag, magExpected0);

    double phaseExpected0[] = { 999, 0, 0, 0, 0, 0, 999 };
    COMPARE_ARRAY_EXACT(phase, phaseExpected0);

    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, 0, 0, 0, 999 };
    COMPARE_ARRAY(phase, phaseExpected1);

    // 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, 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()