changeset 357:650bbacf8288

Add forwardMagnitude

--- a/dsp/phasevocoder/PhaseVocoder.h	Tue Oct 15 11:52:00 2013 +0100
+++ b/dsp/phasevocoder/PhaseVocoder.h	Tue Oct 15 18:26:38 2013 +0100
@@ -21,7 +21,6 @@
 class PhaseVocoder  
 {
 public:
-    //!!! review: size must be a power of two, or not?
     PhaseVocoder(int size, int hop);
     virtual ~PhaseVocoder();
 

--- a/dsp/transforms/FFT.cpp	Tue Oct 15 11:52:00 2013 +0100
+++ b/dsp/transforms/FFT.cpp	Tue Oct 15 18:26:38 2013 +0100
@@ -132,6 +132,19 @@
         }
     }
 
+    void forwardMagnitude(const double *ri, double *mo) {
+
+        double *io = new double[m_n];
+
+        forward(ri, mo, io);
+
+        for (int i = 0; i < m_n; ++i) {
+            mo[i] = sqrt(mo[i] * mo[i] + io[i] * io[i]);
+        }
+
+        delete[] io;
+    }
+
     void inverse(const double *ri, const double *ii, double *ro) {
 
         for (int i = 0; i < m_n; ++i) {
@@ -172,6 +185,12 @@
 }
 
 void
+FFTReal::forwardMagnitude(const double *ri, double *mo)
+{
+    m_d->forwardMagnitude(ri, mo);
+}
+
+void
 FFTReal::inverse(const double *ri, const double *ii, double *ro)
 {
     m_d->inverse(ri, ii, ro);

--- a/dsp/transforms/FFT.h	Tue Oct 15 11:52:00 2013 +0100
+++ b/dsp/transforms/FFT.h	Tue Oct 15 18:26:38 2013 +0100
@@ -49,8 +49,9 @@
     /**
      * Construct an FFT object to carry out real-to-complex transforms
      * of size nsamples. nsamples does not have to be a power of two,
-     * but it does have to be even. (A std::invalid_argument exception
-     * will be thrown if nsamples is odd.)
+     * but it does have to be even. (Use the complex-complex FFT above
+     * if you need an odd FFT size. This constructor will throw
+     * std::invalid_argument if nsamples is odd.)
      */
     FFTReal(int nsamples);
     ~FFTReal();
@@ -68,6 +69,18 @@
                  double *realOut, double *imagOut);
 
     /**
+     * Carry out a forward real-to-complex transform of size nsamples,
+     * where nsamples is the value provided to the constructor
+     * above. Return only the magnitudes of the complex output values.
+     *
+     * realIn and magOut must point to (enough space for) nsamples
+     * values. For consistency with the FFT class above, and
+     * compatibility with existing code, the conjugate half of the
+     * output is returned even though it is redundant.
+     */
+    void forwardMagnitude(const double *realIn, double *magOut);
+
+    /**
      * Carry out an inverse real transform (i.e. complex-to-real) of
      * size nsamples, where nsamples is the value provided to the
      * constructor above.