* More work on framing, interpolation and scaling for longer window than FFT size.

This adds the --smoothing option to the command line tool and SmoothingOn/Off
  options to the API, introducing a double-length window with presum FFT and
  time-domain smoothing.  Behaviour elsewhere _should_ be unchanged.

main/main.cpp

@@ -83,6 +83,7 @@ int main(int argc, char **argv)
     bool lamination = true;
     bool longwin = false;
     bool shortwin = false;
+    bool smoothing = false;
     bool hqpitch = false;
     bool formant = false;
     bool crispchanged = false;
@@ -132,6 +133,7 @@ int main(int argc, char **argv)
             { "bl-transients", 0, 0, '8' },
             { "detector-perc", 0, 0, '5' },
             { "detector-soft", 0, 0, '6' },
+            { "smoothing",     0, 0, '9' },
             { "pitch-hq",      0, 0, '%' },
             { "threads",       0, 0, '@' },
             { "quiet",         0, 0, 'q' },
@@ -165,6 +167,7 @@ int main(int argc, char **argv)
         case '5': detector = PercussiveDetector; crispchanged = true; break;
         case '6': detector = SoftDetector; crispchanged = true; break;
         case '8': transients = BandLimitedTransients; crispchanged = true; break;
+        case '9': smoothing = true; crispchanged = true; break;
         case '%': hqpitch = true; break;
         case 'c': crispness = atoi(optarg); break;
         case 'q': quiet = true; break;
@@ -223,6 +226,7 @@ int main(int argc, char **argv)
         cerr << "         --no-lamination  Disable phase lamination" << endl;
         cerr << "         --window-long    Use longer processing window (actual size may vary)" << endl;
         cerr << "         --window-short   Use shorter processing window" << endl;
+        cerr << "         --smoothing      Apply window presum and time-domain smoothing" << endl;
         cerr << "         --detector-perc  Use percussive transient detector (as in pre-1.5)" << endl;
         cerr << "         --detector-soft  Use soft transient detector" << endl;
         cerr << "         --pitch-hq       In RT mode, use a slower, higher quality pitch shift" << endl;
@@ -362,6 +366,7 @@ int main(int argc, char **argv)
     if (!lamination) options |= RubberBandStretcher::OptionPhaseIndependent;
     if (longwin)     options |= RubberBandStretcher::OptionWindowLong;
     if (shortwin)    options |= RubberBandStretcher::OptionWindowShort;
+    if (smoothing)   options |= RubberBandStretcher::OptionSmoothingOn;
     if (formant)     options |= RubberBandStretcher::OptionFormantPreserved;
     if (hqpitch)     options |= RubberBandStretcher::OptionPitchHighQuality;
 

rubberband/RubberBandStretcher.h

@@ -191,7 +191,18 @@ public:
      *   likely to result in a smoother sound at the expense of
      *   clarity and timing.
      *
-     * 8. Flags prefixed \c OptionFormant control the handling of
+     * 8. Flags prefixed \c OptionSmoothing control the use of
+     * window-presum FFT and time-domain smoothing.  These options may
+     * not be changed after construction.
+     *
+     *   \li \c OptionSmoothingOff - Do not use time-domain smoothing.
+     *
+     *   \li \c OptionSmoothingOn - Use time-domain smoothing.
+     *   This will result in a softer sound, but it may be
+     *   appropriate for longer stretches of some instruments and
+     *   can mix well with OptionWindowShort.
+     *
+     * 9. Flags prefixed \c OptionFormant control the handling of
      * formant shape (spectral envelope) when pitch-shifting.  These
      * options may be changed at any time.
      *
@@ -204,7 +215,7 @@ public:
      *   note frequency without so substantially affecting the
      *   perceived pitch profile of the voice or instrument.
      *
-     * 9. Flags prefixed \c OptionPitch control the method used for
+     * 10. Flags prefixed \c OptionPitch control the method used for
      * pitch shifting.  These options may be changed at any time.
      * They are only effective in realtime mode; in offline mode, the
      * pitch-shift method is fixed.
@@ -253,6 +264,9 @@ public:
         OptionWindowShort          = 0x00100000,
         OptionWindowLong           = 0x00200000,
 
+        OptionSmoothingOff         = 0x00000000,
+        OptionSmoothingOn          = 0x00800000,
+
         OptionFormantShifted       = 0x00000000,
         OptionFormantPreserved     = 0x01000000,
 

rubberband/rubberband-c.h

@@ -63,6 +63,9 @@ enum RubberBandOption {
     RubberBandOptionWindowShort          = 0x00100000,
     RubberBandOptionWindowLong           = 0x00200000,
 
+    RubberBandOptionSmoothingOff         = 0x00000000,
+    RubberBandOptionSmoothingOn          = 0x00800000,
+
     RubberBandOptionFormantShifted       = 0x00000000,
     RubberBandOptionFormantPreserved     = 0x01000000,
 

src/StretcherChannelData.cpp

@@ -76,6 +76,8 @@ RubberBandStretcher::Impl::ChannelData::construct(const std::set<size_t> &sizes,
 
     accumulator = allocate<float>(maxSize);
     windowAccumulator = allocate<float>(maxSize);
+    interpolator = allocate<float>(maxSize);
+    interpolatorScale = 0;
 
     for (std::set<size_t>::const_iterator i = sizes.begin();
          i != sizes.end(); ++i) {
@@ -195,6 +197,8 @@ RubberBandStretcher::Impl::ChannelData::setSizes(size_t windowSize,
     deallocate(windowAccumulator);
     windowAccumulator = newAcc;
 
+    interpolatorScale = 0;
+    
     //!!! and resampler?
 
     for (size_t i = 0; i < realSize; ++i) {
@@ -294,6 +298,7 @@ RubberBandStretcher::Impl::ChannelData::reset()
     inCount = 0;
     inputSize = -1;
     outCount = 0;
+    interpolatorScale = 0;
     unchanged = true;
     draining = false;
     outputComplete = false;

src/StretcherChannelData.h

@@ -104,6 +104,8 @@ public:
     float *accumulator;
     size_t accumulatorFill;
     float *windowAccumulator;
+    float *interpolator; // only used when time-domain smoothing is on
+    int interpolatorScale;
 
     float *fltbuf;
     double *dblbuf; // owned by FFT object, only used for time domain FFT i/o

src/StretcherImpl.cpp

@@ -81,7 +81,7 @@ RubberBandStretcher::Impl::Impl(size_t sampleRate,
     m_debugLevel(m_defaultDebugLevel),
     m_mode(JustCreated),
     m_awindow(0),
-    m_asinc(0),
+    m_afilter(0),
     m_swindow(0),
     m_studyFFT(0),
     m_spaceAvailable("space"),
@@ -496,8 +496,15 @@ RubberBandStretcher::Impl::calculateSizes()
     // 4 * m_baseFftSize unless ratio is less than 1/1024.
 
     m_fftSize = windowSize;
+    
+    if (m_options & OptionSmoothingOn) {
+        m_aWindowSize = windowSize * 2;
+        m_sWindowSize = windowSize * 2;
+    } else {
         m_aWindowSize = windowSize;
         m_sWindowSize = windowSize;
+    }
+
     m_increment = inputIncrement;
 
     // When squashing, the greatest theoretically possible output
@@ -596,7 +603,7 @@ RubberBandStretcher::Impl::configure()
             }
         }
         m_awindow = m_windows[m_aWindowSize];
-        m_asinc = m_sincs[m_aWindowSize];
+        m_afilter = m_sincs[m_aWindowSize];
         m_swindow = m_windows[m_sWindowSize];
 
         if (m_debugLevel > 0) {
@@ -750,7 +757,7 @@ RubberBandStretcher::Impl::reconfigure()
         }
 
         m_awindow = m_windows[m_aWindowSize];
-        m_asinc = m_sincs[m_aWindowSize];
+        m_afilter = m_sincs[m_aWindowSize];
         m_swindow = m_windows[m_sWindowSize];
 
         for (size_t c = 0; c < m_channels; ++c) {
@@ -960,7 +967,7 @@ RubberBandStretcher::Impl::study(const float *const *input, size_t samples, bool
                 // greater than the fft size so we are doing a
                 // time-aliased presum fft) or zero-pad, then we might
                 // as well use our standard function for it.  This
-                // means we retain the m_asinc cut if folding as well,
+                // means we retain the m_afilter cut if folding as well,
                 // which is good for consistency with real-time mode.
                 // We get fftshift as well, which we don't want, but
                 // the penalty is nominal.
@@ -971,7 +978,7 @@ RubberBandStretcher::Impl::study(const float *const *input, size_t samples, bool
                     (std::max(m_fftSize, m_aWindowSize) * sizeof(float));
 
                 if (m_aWindowSize > m_fftSize) {
-                    m_asinc->cut(cd.accumulator);
+                    m_afilter->cut(cd.accumulator);
                 }
 
                 cutShiftAndFold(tmp, m_fftSize, cd.accumulator, m_awindow);

src/StretcherImpl.h

@@ -108,7 +108,7 @@ protected:
     void analyseChunk(size_t channel);
     void modifyChunk(size_t channel, size_t outputIncrement, bool phaseReset);
     void formantShiftChunk(size_t channel);
-    void synthesiseChunk(size_t channel);
+    void synthesiseChunk(size_t channel, size_t shiftIncrement);
     void writeChunk(size_t channel, size_t shiftIncrement, bool last);
 
     void calculateSizes();
@@ -173,7 +173,7 @@ protected:
     std::map<size_t, Window<float> *> m_windows;
     std::map<size_t, SincWindow<float> *> m_sincs;
     Window<float> *m_awindow;
-    SincWindow<float> *m_asinc;
+    SincWindow<float> *m_afilter;
     Window<float> *m_swindow;
     FFT *m_studyFFT;
 

src/StretcherProcess.cpp

@@ -377,7 +377,7 @@ RubberBandStretcher::Impl::processChunkForChannel(size_t c,
         // then skip m_increment to advance the read pointer.
 
         modifyChunk(c, phaseIncrement, phaseReset);
-        synthesiseChunk(c); // reads from cd.mag, cd.phase
+        synthesiseChunk(c, shiftIncrement); // reads from cd.mag, cd.phase
 
         if (m_debugLevel > 2) {
             if (phaseReset) {
@@ -647,7 +647,7 @@ RubberBandStretcher::Impl::analyseChunk(size_t channel)
     // cd.fltbuf is known to contain m_aWindowSize samples
 
     if (m_aWindowSize > m_fftSize) {
-        m_asinc->cut(fltbuf);
+        m_afilter->cut(fltbuf);
     }
 
     cutShiftAndFold(dblbuf, m_fftSize, fltbuf, m_awindow);
@@ -859,7 +859,8 @@ RubberBandStretcher::Impl::formantShiftChunk(size_t channel)
 }
 
 void
-RubberBandStretcher::Impl::synthesiseChunk(size_t channel)
+RubberBandStretcher::Impl::synthesiseChunk(size_t channel,
+                                           size_t shiftIncrement)
 {
     Profiler profiler("RubberBandStretcher::Impl::synthesiseChunk");
 
@@ -876,8 +877,11 @@ RubberBandStretcher::Impl::synthesiseChunk(size_t channel)
     float *const R__ accumulator = cd.accumulator;
     float *const R__ windowAccumulator = cd.windowAccumulator;
     
-    int sz = m_fftSize;
+    const int fsz = m_fftSize;
-    int hs = sz / 2;
+    const int hs = fsz / 2;
+
+    const int wsz = m_sWindowSize;
+    
     int i;
 
     if (!cd.unchanged) {
@@ -885,73 +889,40 @@ RubberBandStretcher::Impl::synthesiseChunk(size_t channel)
         cd.fft->inversePolar(cd.mag, cd.phase, cd.dblbuf);
 
         // our ffts produced unscaled results
-        float factor = 1.0 / m_fftSize;
+        float factor = 1.f / fsz;
-        v_scale(dblbuf, factor, sz);
+        v_scale(dblbuf, factor, fsz);
 
-        if (m_sWindowSize == m_fftSize) {
+        if (wsz == fsz) {
             v_convert(fltbuf, dblbuf + hs, hs);
             v_convert(fltbuf + hs, dblbuf, hs);
         } else {
-            v_zero(fltbuf, m_sWindowSize);
+            v_zero(fltbuf, wsz);
-#ifdef PARP
+            int j = fsz - wsz/2;
-//!!! centre fft frame (effectively only if swindowsize == fftsize, else discontinuities)
+            while (j < 0) j += fsz;
-            const int count = std::min(m_fftSize, m_sWindowSize);
+            for (int i = 0; i < wsz; ++i) {
-            int i = m_sWindowSize/2 - count/2;
-            int j = m_fftSize - count/2;
-            for (int k = 0; k < count; ++k) {
                 fltbuf[i] += dblbuf[j];
-                if (i++ == m_sWindowSize) i = 0;
+                if (++j == fsz) j = 0;
-                if (j++ == m_fftSize) j = 0;
             }
-#else
-//!!! unwrap
-            int j = sz - m_sWindowSize/2;
-            while (j < 0) j += sz;
-            for (int i = 0; i < m_sWindowSize; ++i) {
-                fltbuf[i] += dblbuf[j];
-                if (++j == sz) j = 0;
         }
-#endif
     }
+
+    if (wsz > fsz) {
+        float *tmp = (float *)alloca(wsz * sizeof(float));
+        int p = shiftIncrement * 2;
+        if (cd.interpolatorScale != p) {
+            SincWindow<float>::write(cd.interpolator, wsz, p);
+        }
+        v_multiply(fltbuf, cd.interpolator, wsz);
+        v_copy(tmp, cd.interpolator, wsz);
+        m_swindow->cut(tmp);
+        v_add(windowAccumulator, tmp, wsz);
+    } else {
+        m_swindow->add(windowAccumulator, m_awindow->getArea() * 1.5f);
     }
 
     m_swindow->cut(fltbuf);
-
+    v_add(accumulator, fltbuf, wsz);
-    v_add(accumulator, fltbuf, m_sWindowSize);
+    cd.accumulatorFill = wsz;
-
-    cd.accumulatorFill = m_sWindowSize;
-
-/*
-    std::cerr << "Note: synthesis window area = " << m_swindow->getArea()
-              << ", analysis window area = " << m_awindow->getArea()
-              << ", analysis sinc area = " << m_asinc->getArea()
-              << std::endl;
-*/
-
-    //!!!
-
-    float *tmp = (float *)alloca(m_sWindowSize * sizeof(float));
-    v_set(tmp, 1.f, m_sWindowSize);
-
-//!!!    m_awindow->cut(tmp); //!!! if (m_aWindowSize == m_sWindowSize)
-    m_swindow->cut(tmp);
-/*
-    if (m_aWindowSize != m_fftSize) {
-        if (m_aWindowSize == m_sWindowSize) {
-            m_asinc->cut(tmp);
-        } else {
-            int sourceIndex = m_aWindowSize/2 - m_sWindowSize/2;
-            for (int i = 0; i < m_sWindowSize; ++i) {
-                if (sourceIndex >= 0 && sourceIndex < m_aWindowSize) {
-                    tmp[i] *= m_asinc->getValue(sourceIndex);
-                }
-                ++sourceIndex;
-            }
-        }
-    }
-*/
-    v_add(windowAccumulator, tmp, m_sWindowSize);
-
 }
 
 void

src/dsp/SincWindow.h

@@ -31,25 +31,44 @@ class SincWindow
 {
 public:
     /**
-     * Construct a sinc windower which produces a window of the given
+     * Construct a sinc windower which produces a window of size n
-     * size containing the values of sinc(x) with x=0 at the centre,
+     * containing the values of sinc(x) with x=0 at index n/2, such
-     * such that the distance from -pi to pi (the point at which the
+     * that the distance from -pi to pi (the point at which the sinc
-     * sinc function first crosses zero, for negative and positive
+     * function first crosses zero, for negative and positive
      * arguments respectively) is p samples.
      */
-    SincWindow(int size, int p) : m_size(size), m_p(p) { encache(); }
+    SincWindow(int n, int p) : m_size(n), m_p(p), m_cache(0) {
-    SincWindow(const SincWindow &w) : m_size(w.m_size), m_p(w.m_p) { encache(); }
+        encache();
+    }
+    SincWindow(const SincWindow &w) : m_size(w.m_size), m_p(w.m_p), m_cache(0) {
+        encache();
+    }
     SincWindow &operator=(const SincWindow &w) {
 	if (&w == this) return *this;
 	m_size = w.m_size;
 	m_p = w.m_p;
+        m_cache = 0;
 	encache();
 	return *this;
     }
-    virtual ~SincWindow() { delete[] m_cache; }
+    virtual ~SincWindow() {
+        deallocate(m_cache);
+    }
 
-    inline void cut(T *const R__ block) const {
+    /**
-        v_multiply(block, m_cache, m_size);
+     * Regenerate the sinc window with the same size, but a new scale
+     * (the p value is interpreted as for the argument of the same
+     * name to the constructor).  If p is unchanged from the previous
+     * value, do nothing (quickly).
+     */
+    inline void rewrite(int p) {
+        if (m_p == p) return;
+        m_p = p;
+        encache();
+    }
+    
+    inline void cut(T *const R__ dst) const {
+        v_multiply(dst, m_cache, m_size);
     }
 
     inline void cut(const T *const R__ src, T *const R__ dst) const {
@@ -66,41 +85,61 @@ public:
     inline int getSize() const { return m_size; }
     inline int getP() const { return m_p; }
 
+    /**
+     * Write a sinc window of size n with scale p (the p value is
+     * interpreted as for the argument of the same name to the
+     * constructor).
+     */
+    static
+    void write(T *const R__ dst, const int n, const int p) {
+        const int half = n/2;
+        writeHalf(dst, n, p);
+        int target = half - 1;
+        for (int i = half + 1; i < n; ++i) {
+            dst[target--] = dst[i];
+        }
+        const T twopi = 2. * M_PI;
+        T arg = T(half) * twopi / p;
+        dst[0] = sin(arg) / arg;
+    }
+
 protected:
     int m_size;
     int m_p;
     T *R__ m_cache;
     T m_area;
 
-    void encache();
+    /**
-};
+     * Write the positive half (i.e. n/2 to n-1) of a sinc window of
-
+     * size n with scale p (the p value is interpreted as for the
-template <typename T>
+     * argument of the same name to the constructor). The negative
-void SincWindow<T>::encache()
+     * half (indices 0 to n/2-1) of dst is left unchanged.
-{
+     */
-    const int n = m_size;
+    static
-    T *mult = allocate<T>(n);
+    void writeHalf(T *const R__ dst, const int n, const int p) {
-    v_set(mult, T(1.0), n);
+        const int half = n/2;
-    int i;
+        const T twopi = 2. * M_PI;
-
+        dst[half] = T(1.0);
-    for (i = 0; i < n; ++i) {
+        for (int i = 1; i < half; ++i) {
-	T extent = T(n)/2.;
+            T arg = T(i) * twopi / p;
-	T arg = (T(i) - extent) * (2. * M_PI) / m_p;
+            dst[half+i] = sin(arg) / arg;
-	if (arg != 0.) {
-	    mult[i] *= sin(arg) / arg;
         }
     }
     
-    m_cache = mult;
+    void encache() {
+        if (!m_cache) {
+            m_cache = allocate<T>(m_size);
+        }
+
+        write(m_cache, m_size, m_p);
 	
         m_area = 0;
-    for (i = 0; i < n; ++i) {
+        for (int i = 0; i < m_size; ++i) {
-	std::cout << i << ":" << m_cache[i] << " ";
             m_area += m_cache[i];
         }
-    std::cout << std::endl;
+        m_area /= m_size;
-    m_area /= n;
     }
+};
 
 }
 

src/dsp/Window.h

@@ -45,16 +45,23 @@ public:
     /**
      * Construct a windower of the given type.
      */
-    Window(WindowType type, int size) : m_type(type), m_size(size) { encache(); }
+    Window(WindowType type, int size) : m_type(type), m_size(size), m_cache(0) {
-    Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); }
+        encache();
+    }
+    Window(const Window &w) : m_type(w.m_type), m_size(w.m_size), m_cache(0) {
+        encache();
+    }
     Window &operator=(const Window &w) {
 	if (&w == this) return *this;
 	m_type = w.m_type;
 	m_size = w.m_size;
+        m_cache = 0;
 	encache();
 	return *this;
     }
-    virtual ~Window() { delete[] m_cache; }
+    virtual ~Window() {
+        deallocate(m_cache);
+    }
     
     inline void cut(T *const R__ block) const {
         v_multiply(block, m_cache, m_size);
@@ -68,6 +75,16 @@ public:
         v_add_with_gain(dst, m_cache, m_size, scale);
     }
 
+    inline T getRMS() const {
+        T total = 0;
+        for (int i = 0; i < m_size; ++i) {
+            total += m_cache[i] * m_cache[i];
+        }
+        T rms = sqrt(total / m_size);
+        std::cerr << "rms = " << rms << std::endl;
+        return rms;
+    }
+
     inline T getArea() const { return m_area; }
     inline T getValue(int i) const { return m_cache[i]; }
 
@@ -87,41 +104,42 @@ protected:
 template <typename T>
 void Window<T>::encache()
 {
+    if (!m_cache) m_cache = allocate<T>(m_size);
+
     const int n = m_size;
-    T *mult = allocate<T>(n);
+    v_set(m_cache, T(1.0), n);
-    v_set(mult, T(1.0), n);
     int i;
 
     switch (m_type) {
 		
     case RectangularWindow:
 	for (i = 0; i < n; ++i) {
-	    mult[i] *= 0.5;
+	    m_cache[i] *= 0.5;
 	}
 	break;
 	    
     case BartlettWindow:
 	for (i = 0; i < n/2; ++i) {
-	    mult[i] *= (i / T(n/2));
+	    m_cache[i] *= (i / T(n/2));
-	    mult[i + n/2] *= (1.0 - (i / T(n/2)));
+	    m_cache[i + n/2] *= (1.0 - (i / T(n/2)));
 	}
 	break;
 	    
     case HammingWindow:
-        cosinewin(mult, 0.54, 0.46, 0.0, 0.0);
+        cosinewin(m_cache, 0.54, 0.46, 0.0, 0.0);
 	break;
 	    
     case HanningWindow:
-        cosinewin(mult, 0.50, 0.50, 0.0, 0.0);
+        cosinewin(m_cache, 0.50, 0.50, 0.0, 0.0);
 	break;
 	    
     case BlackmanWindow:
-        cosinewin(mult, 0.42, 0.50, 0.08, 0.0);
+        cosinewin(m_cache, 0.42, 0.50, 0.08, 0.0);
 	break;
 	    
     case GaussianWindow:
 	for (i = 0; i < n; ++i) {
-            mult[i] *= pow(2, - pow((i - (n-1)/2.0) / ((n-1)/2.0 / 3), 2));
+            m_cache[i] *= pow(2, - pow((i - (n-1)/2.0) / ((n-1)/2.0 / 3), 2));
 	}
 	break;
 	    
@@ -130,29 +148,27 @@ void Window<T>::encache()
         int N = n-1;
         for (i = 0; i < N/4; ++i) {
             T m = 2 * pow(1.0 - (T(N)/2 - i) / (T(N)/2), 3);
-            mult[i] *= m;
+            m_cache[i] *= m;
-            mult[N-i] *= m;
+            m_cache[N-i] *= m;
         }
         for (i = N/4; i <= N/2; ++i) {
             int wn = i - N/2;
             T m = 1.0 - 6 * pow(wn / (T(N)/2), 2) * (1.0 - abs(wn) / (T(N)/2));
-            mult[i] *= m;
+            m_cache[i] *= m;
-            mult[N-i] *= m;
+            m_cache[N-i] *= m;
         }            
         break;
     }
 
     case NuttallWindow:
-        cosinewin(mult, 0.3635819, 0.4891775, 0.1365995, 0.0106411);
+        cosinewin(m_cache, 0.3635819, 0.4891775, 0.1365995, 0.0106411);
 	break;
 
     case BlackmanHarrisWindow:
-        cosinewin(mult, 0.35875, 0.48829, 0.14128, 0.01168);
+        cosinewin(m_cache, 0.35875, 0.48829, 0.14128, 0.01168);
         break;
     }
 	
-    m_cache = mult;
-
     m_area = 0;
     for (i = 0; i < n; ++i) {
         m_area += m_cache[i];