Fix to avoid calling start twice.

MaKuEarth · MaKuEarth · commit 8eb58ca8a3cc · 2018-01-04T22:43:39.000+01:00
diff --git a/Source/SignalTracking/Units/InputSignalTracker.swift b/Source/SignalTracking/Units/InputSignalTracker.swift
@@ -66,9 +66,11 @@ final class InputSignalTracker: SignalTracker {
       }
     }
 
-    captureSession.startRunning()
-    audioEngine?.prepare()
     try audioEngine?.start()
+    captureSession.startRunning()
+    guard captureSession.isRunning == true else {
+        throw InputSignalTrackerError.inputNodeMissing
+    }
   }
 
   func stop() {

Original file line number	Diff line number	Diff line change
`@@ -66,9 +66,11 @@ final class InputSignalTracker: SignalTracker {`
`66`	`66`	`}`
`67`	`67`	`}`
`68`	`68`
`69`		`- captureSession.startRunning()`
`70`		`- audioEngine?.prepare()`
`71`	`69`	`try audioEngine?.start()`
	`70`	`+ captureSession.startRunning()`
	`71`	`+ guard captureSession.isRunning == true else {`
	`72`	`+ throw InputSignalTrackerError.inputNodeMissing`
	`73`	`+ }`
`72`	`74`	`}`
`73`	`75`
`74`	`76`	`func stop() {`