 
         // Note: AVAssetReaderOutput does not currently support compressed output
         if formatKey == kAudioFormatMPEG4AAC {
-
             if sampleRate > 48_000 {
                 sampleRate = 44_100
             }

    // Currently, as of 2017, if you want to convert from a compressed
    // format to a pcm one, you still have to hit CoreAudio
    private func convertToPCM(completionHandler: AKConverterCallback? = nil) {

        guard let inputURL = self.inputURL else {
            completionHandler?(createError(message: "Input file can't be nil."))
            return

        let asset = AVURLAsset(url: inputURL)
        guard let session = AVAssetExportSession(asset: asset, presetName: AVAssetExportPresetAppleM4A) else { return }

        // session.progress could be sent out via a delegate for this session
        session.outputURL = outputURL
        session.outputFileType = .m4a
        session.exportAsynchronously {
