* Add OptionPitchHighConsistency

rubberband/RubberBandStretcher.h

@@ -182,6 +182,13 @@ public:
      *   \li \c OptionPitchHighQuality - Use the highest quality
      *   method for pitch shifting.  This method has a CPU cost
      *   approximately proportional to the required frequency shift.
+
+     *   \li \c OptionPitchHighConsistency - Use the method that gives
+     *   greatest consistency when used to create small variations in
+     *   pitch around the 1.0-ratio level.  Unlike the previous two
+     *   options, this avoids discontinuities when moving across the
+     *   1.0 pitch scale in real-time; it also consumes more CPU than
+     *   the others in the case where the pitch scale is exactly 1.0.
      */
     
     enum Option {
@@ -212,7 +219,8 @@ public:
         OptionFormantPreserved     = 0x01000000,
 
         OptionPitchHighSpeed       = 0x00000000,
-        OptionPitchHighQuality = 0x02000000
+        OptionPitchHighQuality     = 0x02000000,
+        OptionPitchHighConsistency = 0x04000000
     };
 
     typedef int Options;

rubberband/rubberband-c.h

@@ -60,7 +60,8 @@ enum RubberBandOption {
     RubberBandOptionFormantPreserved     = 0x01000000,
 
     RubberBandOptionPitchHighQuality     = 0x00000000,
-    RubberBandOptionPitchHighSpeed   = 0x02000000
+    RubberBandOptionPitchHighSpeed       = 0x02000000,
+    RubberBandOptionPitchHighConsistency = 0x04000000
 };
 
 typedef int RubberBandOptions;

src/StretcherImpl.cpp

@@ -524,7 +524,9 @@ RubberBandStretcher::Impl::configure()
         m_studyFFT->initFloat();
     }
 
-    if (m_pitchScale != 1.0 || m_realtime) {
+    if (m_pitchScale != 1.0 ||
+        (m_options & OptionPitchHighConsistency) ||
+        m_realtime) {
 
         for (size_t c = 0; c < m_channels; ++c) {
 
@@ -708,7 +710,9 @@ RubberBandStretcher::Impl::setPitchOption(Options options)
 
     Options prior = m_options;
 
-    int mask = (OptionPitchHighQuality | OptionPitchHighSpeed);
+    int mask = (OptionPitchHighQuality |
+                OptionPitchHighSpeed |
+                OptionPitchHighConsistency);
     m_options &= ~mask;
     options &= mask;
     m_options |= options;
@@ -989,8 +993,6 @@ RubberBandStretcher::Impl::process(const float *const *input, size_t samples, bo
 
     while (!allConsumed) {
 
-//        cerr << "process looping" << endl;
-
 //#ifndef NO_THREADING
 //        if (m_threaded) {
 //            pthread_mutex_lock(&m_inputProcessedMutex);
@@ -1052,6 +1054,9 @@ RubberBandStretcher::Impl::process(const float *const *input, size_t samples, bo
             }
 */
         }
+
+        if (!allConsumed) cerr << "process looping" << endl;
+
     }
     
 //    cerr << "process returning" << endl;

src/StretcherProcess.cpp

@@ -110,6 +110,8 @@ RubberBandStretcher::Impl::resampleBeforeStretching() const
 
     if (m_options & OptionPitchHighQuality) {
         return (m_pitchScale < 1.0); // better sound
+    } else if (m_options & OptionPitchHighConsistency) {
+        return false;
     } else {
         return (m_pitchScale > 1.0); // better performance
     }
@@ -145,6 +147,8 @@ RubberBandStretcher::Impl::consumeChannel(size_t c, const float *input,
         }
 
 
+//        std::cerr << "resampling on INPUT" << std::endl;
+
         toWrite = cd.resampler->resample(&input,
                                          &cd.resamplebuf,
                                          samples,
@@ -1009,7 +1013,9 @@ RubberBandStretcher::Impl::writeChunk(size_t channel, size_t shiftIncrement, boo
 
     bool resampledAlready = resampleBeforeStretching();
 
-    if (!resampledAlready && m_pitchScale != 1.0 && cd.resampler) {
+    if (!resampledAlready &&
+        (m_pitchScale != 1.0 || m_options & OptionPitchHighConsistency) &&
+        cd.resampler) {
 
         size_t reqSize = int(ceil(si / m_pitchScale));
         if (reqSize > cd.resamplebufSize) {
@@ -1024,6 +1030,8 @@ RubberBandStretcher::Impl::writeChunk(size_t channel, size_t shiftIncrement, boo
         }
 
 
+//        std::cerr << "resampling on OUTPUT" << std::endl;
+        
         size_t outframes = cd.resampler->resample(&cd.accumulator,
                                                   &cd.resamplebuf,
                                                   si,