How can I create .wav file in c# with base64 /blob data?

See more:

C#

C#4.0

MVC4

recorder

Hi ,
I am creating an audio file in the server with exported blob data from Recorder.js
steps I have done:
1. recorded audio in chrome using recorder.js and recorderWorker.js
2.blob data is converted to base64 data.
3.I created .wav file in the controller with data .
Here data is added to file successfully , but audio play time is 2 seconds only.

byte[] dummyAudioData= Convert.FromBase64String(audioData);
var fname = "D:\\suri\\UseEveryTime.wav";
FileStream stream = new FileStream(fname, FileMode.Append, FileAccess.Write);
System.IO.BinaryWriter br = new System.IO.BinaryWriter(stream);
br.Write(dummyAudioData);
 br.Close();

Please help me .