Admit FFT window sizes that are not powers of two

adibo · Jul 1, 2016 · fbde8ef · fbde8ef
1 parent bd6aade
commit fbde8ef
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Showing 2 changed files with 5 additions and 30 deletions.
diff --git a/loader/src/specgram.hpp b/loader/src/specgram.hpp
@@ -51,10 +51,6 @@ class Specgram {
       _numCepstra(params->_numCepstra),
       _window(0), _rng(id) {
         assert(_stride != 0);
-        if (powerOfTwo(_windowSize) == false) {
-            throw std::runtime_error("Window size must be a power of 2");
-        }
-
         _maxSignalSize = params->_clipDuration * params->_samplingFreq / 1000;
         _buf = new char[_timeSteps * _windowSize * MAX_SAMPLE_SIZE];
         if (params->_window != 0) {
@@ -139,33 +135,26 @@ class Specgram {
         }
     }
 
-    bool powerOfTwo(int num) {
-        while (((num % 2) == 0) && (num > 1)) {
-            num /= 2;
-        }
-        return (num == 1);
-    }
-
     void none(int) {
     }
 
     void hann(int steps) {
         for (int i = 0; i <= steps; i++) {
-            _window->at<float>(0, i) = 0.5 - 0.5 * cos((2.0 * PI * i) / steps);
+            _window->at<float>(0, i) = 0.5 - 0.5 * cos((2.0 * CV_PI * i) / steps);
         }
     }
 
     void blackman(int steps) {
         for (int i = 0; i <= steps; i++) {
             _window->at<float>(0, i) = 0.42 -
-                                       0.5 * cos((2.0 * PI * i) / steps) +
-                                       0.08 * cos(4.0 * PI * i / steps);
+                                       0.5 * cos((2.0 * CV_PI * i) / steps) +
+                                       0.08 * cos(4.0 * CV_PI * i / steps);
         }
     }
 
     void hamming(int steps) {
         for (int i = 0; i <= steps; i++) {
-            _window->at<float>(0, i) = 0.54 - 0.46 * cos((2.0 * PI * i) / steps);
+            _window->at<float>(0, i) = 0.54 - 0.46 * cos((2.0 * CV_PI * i) / steps);
         }
     }
 
@@ -307,6 +296,5 @@ class Specgram {
     Mat*                        _window;
     Mat                         _fbank;
     cv::RNG                     _rng;
-    constexpr static double     PI = 3.14159265358979323846;
     constexpr static int        MAX_SAMPLE_SIZE = 4;
 };
diff --git a/neon/data/media.py b/neon/data/media.py
@@ -19,7 +19,6 @@
 
 from __future__ import division
 from future.utils import iteritems
-import math
 import logging
 import numpy as np
 import ctypes as ct
@@ -332,19 +331,7 @@ def set_shape(self):
         self.feature = self._features_[self.feature_type]
         self.window = self._windows_[self.window_type]
         self.channel_count = 1
-        samples_per_frame = self.sampling_freq * self.frame_duration // 1000
-        # Get the closest power of 2.
-        log = int(math.log(samples_per_frame) / math.log(2))
-        min_pow = 2 ** log
-        max_pow = 2 ** (log + 1)
-
-        if (max_pow - samples_per_frame) < (samples_per_frame - min_pow):
-            self.window_size = max_pow
-        else:
-            self.window_size = min_pow
-
-        real_frame_duration = 1000 * self.window_size // self.sampling_freq
-        logger.info('Effective frame duration: %dms', real_frame_duration)
+        self.window_size = self.sampling_freq * self.frame_duration // 1000
         assert self.overlap_percent < 100
         self.overlap = self.window_size * self.overlap_percent // 100
         self.stride = self.window_size - self.overlap