 
 extension NextLevelSession {
     
-    internal func fileType() -> String {
-        return AVFileTypeAppleM4A
-    }
-    
-    internal func fileExtension(fileType: String) -> String {
-        return "m4a"
-    }
-    
     internal func nextFileURL() -> URL? {
-        let fileType = self.fileType()
-        let fileExtension = self.fileExtension(fileType: fileType)
-        let filename = "\(self.identifier)-NL-clip.\(self.sessionClipFilenameCount).\(fileExtension)"
+        let filename = "\(self.identifier)-NL-clip.\(self.sessionClipFilenameCount).\(self.fileExtension)"
         if let url = NextLevelClip.clipURL(withFilename: filename, directory: self.sessionDirectory) {
             self.removeFile(fileUrl: url)
             self.sessionClipFilenameCount += 1

    
    public func mergeClips(usingPreset preset: String, completionHandler: @escaping NextLevelSessionMergeClipsCompletionHandler) {
        self.executeClosureSyncOnSessionQueueIfNecessary {
            let fileType = self.fileType()
            let fileExtension = self.fileExtension(fileType: fileType)
            let filename = "\(self.identifier)-NL-merged.\(fileExtension)"

            let outputURL: URL? = NextLevelClip.clipURL(withFilename: filename, directory: self.sessionDirectory)

    
    override init() {
        self.sessionIdentifier = NSUUID().uuidString
        self.fileType = AVFileTypeMPEG4
        self.fileExtension = "mp4"
        
        self.sessionDirectory = NSTemporaryDirectory()
        self.sessionClips = []
        self.sessionClipFilenameCount = 0
