Flv and f4v player

Question

I'm writing On-demand player. This player need to play flv or f4v format videos.
Example: In that vod folder will available 1 video file (that is flv or f4v), I don't know what is that file format.
So first how can i check that the file format flv or f4v?
I'm trying to below like this.But this is not correct & not working. Can you suggest me how can i play or how to know video file extension?
var videoURL:String;
var videoFileName:String = "test";
var f4v:Boolean = true;
var prefix1:String = "mp4";
var prefix2:String = "f4v";
if(f4v == true)
          videoURL = prefix1 + ":" + videoFileName + "." + prefix2;
          trace("F4V OK");
    //  trace(videoURL);
else{
          videoURL = videoFileName;
          trace("FLV OK");
var serverURL:String = "rtmp://192.168.1.5/vod/";
var nConnection:NetConnection;
var ns:NetStream;
var video:Video = new Video();
nConnection = new NetConnection();
nConnection.addEventListener(NetStatusEvent.NET_STATUS, netStatusHandler);
nConnection.addEventListener(SecurityErrorEvent.SECURITY_ERROR, securityErrorHandler);
nConnection.addEventListener(AsyncErrorEvent.ASYNC_ERROR, ayncErrorHandler);
nConnection.connect(serverURL);
function netStatusHandler(event:NetStatusEvent):void
trace(event.info.code);
switch (event.info.code)
          case "NetConnection.Connect.Success" :
                    connectStream();
                    break;
          case "NetConnection.Connect.Failed" :
                    break;
          case "NetStream.Play.StreamNotFound" :
                    trace("Stream not found: ");
                    break;
          case "NetStream.Play.Start" :
                    trace("Play Started");
                    break;
          case "NetStream.Play.Stop" :
                    break;
          default :
function connectStream():void
     ns = new NetStream(nConnection);
     ns.addEventListener(NetStatusEvent.NET_STATUS, netStatusHandler);
     ns.addEventListener(AsyncErrorEvent.ASYNC_ERROR, ayncErrorHandler);
     ns.client = this;
     vidDisplay.attachNetStream(ns);
     ns.play(videoURL);
     vidDisplay.smoothing = true;
function securityErrorHandler(event:SecurityErrorEvent):void
     trace("securityErrorHandler: " + event);
function ayncErrorHandler(event: AsyncErrorEvent):void

Answer 1

What is setting videoFileName? Also you're setting a f4v:Boolean = true; assignment above and I don't see any logic to alter this in the case it's FLV so it will always assume the video is f4v unless "something else" is changing it.
To determine between F4V and FLV you really only need to look at the files extension. You can set your bool based on that.
var f4v:Boolean = videoFileURL.toUpperCase().indexOf('.F4V') != -1 ? true : false;
Then actually run your check
if (f4v)
     // handle f4v
else
     // handle FLV
Or use a switch if you're handling more than just these two.. Something like:
var sourceURL:String;
switch (videoFileURL.toUpperCase().substr(-3,3))
     case "MP4":
          // code to set sourceURL to MP4...
          break;
     case "FLV":
          // code to set sourceURL to FLV...
          break;
     case "F4V":
          // code to set sourceURL to F4V...
          break;
     default:
          // perhaps a default to one of the formats..
If you're actually trying to load the file and determine if the extension is incorrect then you'd have to use your errors during load and attempt alternate loads until you achieve a successful load. Metadata has an ID for the codec (audio/video) as well.