diff options
Diffstat (limited to 'libs/qm-dsp/base/Window.h')
-rw-r--r-- | libs/qm-dsp/base/Window.h | 110 |
1 files changed, 70 insertions, 40 deletions
diff --git a/libs/qm-dsp/base/Window.h b/libs/qm-dsp/base/Window.h index 02ca426d66..93909115c0 100644 --- a/libs/qm-dsp/base/Window.h +++ b/libs/qm-dsp/base/Window.h @@ -18,6 +18,7 @@ #include <cmath> #include <iostream> #include <map> +#include <vector> enum WindowType { RectangularWindow, @@ -25,18 +26,28 @@ enum WindowType { HammingWindow, HanningWindow, BlackmanWindow, - GaussianWindow, - ParzenWindow + BlackmanHarrisWindow, + + FirstWindow = RectangularWindow, + LastWindow = BlackmanHarrisWindow }; +/** + * Various shaped windows for sample frame conditioning, including + * cosine windows (Hann etc) and triangular and rectangular windows. + */ template <typename T> class Window { public: /** - * Construct a windower of the given type. + * Construct a windower of the given type and size. + * + * Note that the cosine windows are periodic by design, rather + * than symmetrical. (A window of size N is equivalent to a + * symmetrical window of size N+1 with the final element missing.) */ - Window(WindowType type, size_t size) : m_type(type), m_size(size) { encache(); } + Window(WindowType type, int size) : m_type(type), m_size(size) { encache(); } Window(const Window &w) : m_type(w.m_type), m_size(w.m_size) { encache(); } Window &operator=(const Window &w) { if (&w == this) return *this; @@ -46,79 +57,98 @@ public: return *this; } virtual ~Window() { delete[] m_cache; } - + void cut(T *src) const { cut(src, src); } void cut(const T *src, T *dst) const { - for (size_t i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i]; + for (int i = 0; i < m_size; ++i) dst[i] = src[i] * m_cache[i]; } WindowType getType() const { return m_type; } - size_t getSize() const { return m_size; } + int getSize() const { return m_size; } + + std::vector<T> getWindowData() const { + std::vector<T> d; + for (int i = 0; i < m_size; ++i) { + d.push_back(m_cache[i]); + } + return d; + } protected: WindowType m_type; - size_t m_size; + int m_size; T *m_cache; - + void encache(); }; template <typename T> void Window<T>::encache() { - size_t n = m_size; + int n = m_size; T *mult = new T[n]; - size_t i; + int i; for (i = 0; i < n; ++i) mult[i] = 1.0; switch (m_type) { - + case RectangularWindow: - for (i = 0; i < n; ++i) { - mult[i] = mult[i] * 0.5; + for (i = 0; i < n; ++i) { + mult[i] = mult[i] * 0.5; } break; - + case BartlettWindow: - for (i = 0; i < n/2; ++i) { - mult[i] = mult[i] * (i / T(n/2)); - mult[i + n/2] = mult[i + n/2] * (1.0 - (i / T(n/2))); + if (n == 2) { + mult[0] = mult[1] = 0; // "matlab compatible" + } else if (n == 3) { + mult[0] = 0; + mult[1] = mult[2] = 2./3.; + } else if (n > 3) { + for (i = 0; i < n/2; ++i) { + mult[i] = mult[i] * (i / T(n/2)); + mult[i + n - n/2] = mult[i + n - n/2] * (1.0 - (i / T(n/2))); + } } break; - + case HammingWindow: - for (i = 0; i < n; ++i) { - mult[i] = mult[i] * (0.54 - 0.46 * cos(2 * M_PI * i / n)); + if (n > 1) { + for (i = 0; i < n; ++i) { + mult[i] = mult[i] * (0.54 - 0.46 * cos(2 * M_PI * i / n)); + } } break; - + case HanningWindow: - for (i = 0; i < n; ++i) { - mult[i] = mult[i] * (0.50 - 0.50 * cos(2 * M_PI * i / n)); + if (n > 1) { + for (i = 0; i < n; ++i) { + mult[i] = mult[i] * (0.50 - 0.50 * cos(2 * M_PI * i / n)); + } } break; - + case BlackmanWindow: - for (i = 0; i < n; ++i) { - mult[i] = mult[i] * (0.42 - 0.50 * cos(2 * M_PI * i / n) - + 0.08 * cos(4 * M_PI * i / n)); + if (n > 1) { + for (i = 0; i < n; ++i) { + mult[i] = mult[i] * (0.42 - 0.50 * cos(2 * M_PI * i / n) + + 0.08 * cos(4 * M_PI * i / n)); + } } break; - - case GaussianWindow: - for (i = 0; i < n; ++i) { - mult[i] = mult[i] * exp((-1.0 / (n*n)) * ((T(2*i) - n) * - (T(2*i) - n))); - } - break; - - case ParzenWindow: - for (i = 0; i < n; ++i) { - mult[i] = mult[i] * (1.0 - fabs((T(2*i) - n) / T(n + 1))); + + case BlackmanHarrisWindow: + if (n > 1) { + for (i = 0; i < n; ++i) { + mult[i] = mult[i] * (0.35875 + - 0.48829 * cos(2 * M_PI * i / n) + + 0.14128 * cos(4 * M_PI * i / n) + - 0.01168 * cos(6 * M_PI * i / n)); + } } break; } - + m_cache = mult; } |