Automatically adjust sampling rates based on device.

gardner-lab · Nov 3, 2015 · 4d7be7c · 4d7be7c
1 parent 729ba55
commit 4d7be7c
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Showing 5 changed files with 49 additions and 15 deletions.
diff --git a/SyllableDetector/SyllableDetector.swift b/SyllableDetector/SyllableDetector.swift
@@ -12,7 +12,8 @@ import AVFoundation
 
 class SyllableDetector: NSObject, AVCaptureAudioDataOutputSampleBufferDelegate
 {
-    let config: SyllableDetectorConfig
+    // should be constant, but sampling rate can be changed when initializing
+    var config: SyllableDetectorConfig
 
     // very specific audio settings required, since down sampling signal
     var audioSettings: [String: AnyObject] {

diff --git a/SyllableDetector/SyllableDetectorConfig.swift b/SyllableDetector/SyllableDetectorConfig.swift
@@ -10,16 +10,43 @@ import Foundation
 
 struct SyllableDetectorConfig
 {
-    let samplingRate: Double // eqv: samplerate
-    let fourierLength: Int // eqv: FFT_SIZE
-    let fourierOverlap: Int // eqv: NOVERLAP = FFT_SIZE - (floor(samplerate * FFT_TIME_SHIFT))
+    var samplingRate: Double // eqv: samplerate
+    var fourierLength: Int // eqv: FFT_SIZE
+    var fourierOverlap: Int // eqv: NOVERLAP = FFT_SIZE - (floor(samplerate * FFT_TIME_SHIFT))
 
     let freqRange: (Double, Double) // eqv: freq_range
     let timeRange: Int // eqv: time_window_steps = double(floor(time_window / timestep))
 
     let threshold: Double // eqv: trigger threshold
 
     let net: NeuralNet
+
+    mutating func modifySamplingRate(newSamplingRate: Double) {
+        // store old things
+        let oldSamplingRate = samplingRate
+        let oldFourierLength = fourierLength
+        let oldFourierOverlap = fourierOverlap
+
+        if oldSamplingRate == newSamplingRate { return }
+
+
+        // get new approximate fourier length
+        let newApproximateFourierLength = newSamplingRate * Double(oldFourierLength) / oldSamplingRate
+
+        // convert to closest power of 2
+        let newFourierLength = 1 << Int(round(log2(newApproximateFourierLength)))
+
+        // get new fourier overlap
+        let newFourierOverlap = newFourierLength - Int(round(newSamplingRate * Double(oldFourierLength - oldFourierOverlap) / oldSamplingRate))
+
+        // change the to new things
+        samplingRate = newSamplingRate
+        fourierLength = newFourierLength
+        fourierOverlap = newFourierOverlap
+
+        DLog("New fourier length: \(newFourierLength)")
+        DLog("New fourier overlap: \(newFourierOverlap)")
+    }
 }
 
 // make parsable

diff --git a/SyllableDetector/ViewControllerMenu.swift b/SyllableDetector/ViewControllerMenu.swift
@@ -24,10 +24,10 @@ class ViewControllerMenu: NSViewController, WindowControllerProcessorDelegate {
         reloadDevices()
     }
 
-    override func viewDidDisappear() {
-        // terminate
-        NSApp.terminate(nil)
-    }
+//    override func viewDidDisappear() {
+//        // terminate
+//        NSApp.terminate(nil)
+//    }
 
     func reloadDevices() {
         // fetch list of devices
@@ -106,6 +106,11 @@ class ViewControllerMenu: NSViewController, WindowControllerProcessorDelegate {
         controller.delegate = self // custom delegate used to clean up open processor list when windows are closed
         controller.showWindow(sender)
         openProcessors.append(controller)
+
+        // reset selector
+        selectInput.selectItemAtIndex(0)
+        selectOutput.selectItemAtIndex(0)
+        buttonLaunch.enabled = false
     }
 
     func windowControllerDone(controller: WindowControllerProcessor) {

diff --git a/SyllableDetector/ViewControllerProcessor.swift b/SyllableDetector/ViewControllerProcessor.swift
@@ -62,18 +62,19 @@ class Processor: AudioInputInterfaceDelegate {
         // create queue
         queueProcessing = dispatch_queue_create("ProcessorQueue", DISPATCH_QUEUE_SERIAL)
 
-        // set self as delegate
-        interfaceInput.delegate = self
-
         try interfaceOutput.initializeAudio()
         try interfaceInput.initializeAudio()
 
         // check sampling rates
         for d in self.detectors {
             if (1 < abs(d.config.samplingRate - interfaceInput.inputFormat.mSampleRate)) {
-                DLog("Mismatched sampling rates.")
+                DLog("Mismatched sampling rates. Expecting: \(d.config.samplingRate). Device: \(interfaceInput.inputFormat.mSampleRate).")
+                d.config.modifySamplingRate(interfaceInput.inputFormat.mSampleRate)
             }
         }
+
+        // set self as delegate
+        interfaceInput.delegate = self
     }
 
     deinit {

diff --git a/sample.txt b/sample.txt
@@ -1,7 +1,7 @@
 # AUTOMATICALLY GENERATED SYLLABLE DETECTOR CONFIGURATION
-samplingRate = 44100.0
-fourierLength = 512
-fourierOverlap = 380
+samplingRate = 20000.0
+fourierLength = 256
+fourierOverlap = 196
 freqRange = 1992.0, 6992.0
 timeRange = 9
 threshold = 0.351351351351351