improve performance by using a pre-calculated window

YuAo · Dec 20, 2021 · 5b326d2 · 5b326d2
1 parent a45fa56
commit 5b326d2
Showing 1 changed file with 6 additions and 3 deletions.
diff --git a/Sources/AudioPrism/AudioPrism.swift b/Sources/AudioPrism/AudioPrism.swift
@@ -152,6 +152,8 @@ public final class AudioPrism: @unchecked Sendable {
     private var sampleBuffer: [Float] = []
     private var previousFFTValues: [Float]
 
+    private let window: [Float]
+
     private var _timeDomainData: TimeDomainData?
     private var _frequencyData: FrequencyData?
 
@@ -177,6 +179,10 @@ public final class AudioPrism: @unchecked Sendable {
         self.options = options
         self.frequencyBinCount = options.fftSize/2
         self.previousFFTValues = [Float](repeating: 0, count: frequencyBinCount)
+
+        var window = [Float](repeating: 0, count: options.fftSize)
+        vDSP_blkman_window(&window, vDSP_Length(options.fftSize), 0)
+        self.window = window
     }
 
     deinit {
@@ -229,9 +235,6 @@ public final class AudioPrism: @unchecked Sendable {
 
         var samples = Array(sampleBuffer.suffix(options.fftSize))
 
-        var window = [Float](repeating: 0, count: options.fftSize)
-        vDSP_blkman_window(&window, vDSP_Length(options.fftSize), 0)
-
         var frequencyData = [Float](repeating: 0, count: frequencyBinCount)
         var uint8Values = [UInt8](repeating: 0, count: frequencyBinCount)