ggwave v0.2.0 (#20)

* ggwave : add support for fixed length transmissions

* spectrogram : add sample rate offset for debugging purposes

* gwave : fix decoding bug

* waver : wip

* wip

* remove post-marker frames

* add resampler

* ggwave : input/output resampling

* ggwave : fix python build

* ggwave : update spm

* ggwave : refactor duplicate encode/decode code

* ggwave : fix sound marker detection

* waver : fix typo

* ggwave : fix uninitialized members

* ggwave : more sensitive receive

src/resampler.h

@@ -0,0 +1,32 @@
+#pragma once
+
+class Resampler {
+public:
+    int resample(
+            float factor,
+            int nSamples,
+            const float * samplesInp,
+            float * samplesOut);
+private:
+    float gimme_data(long j) const;
+    void new_data(float data);
+    void make_sinc();
+    double sinc(double x) const;
+
+    /* this controls the number of neighboring samples
+       which are used to interpolate the new samples.  The
+       processing time is linearly related to this width */
+    static const int kWidth = 64;
+
+    static const int kDelaySize = 140;
+
+    /* this defines how finely the sinc function
+       is sampled for storage in the table  */
+    static const int kSamplesPerZeroCrossing = 32;
+
+    float m_sincTable[kWidth*kSamplesPerZeroCrossing] = { 0.0 };
+
+    float m_delayBuffer[3*kWidth] = { 0 };
+
+    float m_lastFactor = -1.0f;
+};