     
     public var url: URL? {
         get {
-            let fileType = self.fileType()
-            let fileExtension = self.fileExtension(fileType: fileType)
-            let filename = "\(self.identifier)-NL-merged.\(fileExtension)"
+            let filename = "\(self.identifier)-NL-merged.\(self.fileExtension)"
             if let url = NextLevelClip.clipURL(withFilename: filename, directory: self.sessionDirectory) {
                 return url
             } else {

    internal func setupWriter() {
        if let url = self.nextFileURL() {
            do {
                self.writer = try AVAssetWriter(url: url, fileType: self.fileType())
                if let writer = self.writer {
                    writer.shouldOptimizeForNetworkUse = true
                    writer.metadata = NextLevel.assetWriterMetadata()

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

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