void prepareExtAudioFile()
        {
            // Opening Audio File
            _extAudioFile = ExtAudioFile.OpenUrl(_url);

            // Getting file data format
            _srcFormat = _extAudioFile.FileDataFormat;

            // Setting the channel number of the output format same to the input format
            _dstFormat = AudioUnitUtils.AUCanonicalASBD(_sampleRate, _srcFormat.ChannelsPerFrame);

            // setting reading format as audio unit cannonical format
            _extAudioFile.ClientDataFormat = _dstFormat;

            // getting total frame
            _totalFrames = _extAudioFile.FileLengthFrames;

            // Aloocating AudoBufferList
            _buffer = new MutableAudioBufferList(_srcFormat.ChannelsPerFrame, (int) (sizeof(uint) * _totalFrames));
            _numberOfChannels = _srcFormat.ChannelsPerFrame;

            // Reading all frame into the buffer
            _extAudioFile.Read((int) _totalFrames, _buffer);
        }
		void prepareExtAudioFile ()
		{
			// Opening Audio File
			_extAudioFile = ExtAudioFile.OpenUrl (_url);

			// Getting file data format
			_srcFormat = _extAudioFile.FileDataFormat;

			// Setting the channel number of the output format same to the input format
			_dstFormat = AudioStreamBasicDescription.CreateLinearPCM (channelsPerFrame: (uint)_srcFormat.ChannelsPerFrame, bitsPerChannel: 32);
			_dstFormat.FormatFlags |= AudioFormatFlags.IsNonInterleaved;

			// setting reading format as audio unit cannonical format
			_extAudioFile.ClientDataFormat = _dstFormat;

			// getting total frame
			_totalFrames = _extAudioFile.FileLengthFrames;

			// Allocating AudioBufferList
			_buffer = new AudioBuffers (_srcFormat.ChannelsPerFrame);
			for (int i = 0; i < _buffer.Count; ++i) {
				int size = (int)(sizeof(uint) * _totalFrames);
				_buffer.SetData (i, Marshal.AllocHGlobal (size), size);
			}
			_numberOfChannels = _srcFormat.ChannelsPerFrame;

			// Reading all frame into the buffer
			ExtAudioFileError status;
			_extAudioFile.Read ((uint)_totalFrames, _buffer, out status);
			if (status != ExtAudioFileError.OK)
				throw new ApplicationException ();
		}