NCast PR720 - Manual (Page 75)

NCast Presentation Recorder Reference Manual
In all cases these files contain parameters such as the address of the server, media stream types, multicast
groups, etc. To view samples of these files, right-click and “Save Target As …” to a directory on your desktop.
The graphics, overlays and PIP video are in one media stream, inseparable.
The file extension will determine which media player to launch. Each web browser keeps a list of file
extensions and the appropriate application to process a file with that extension.
The most generic of these files, the SDP file, might be associated with any number of different players on
different operating systems. The sequence of events for getting a successful playback with an SDP file works
like this:
1. At installation the client player informs the web browser that “If you see an SDP file, launch me and
pass the file information to me”.
2. On the web page, when the playback link is clicked, the browser sends a request to the server to
retrieve the requested SDP file.
3. The server, upon receiving this request, dynamically generates an SDP file based on the current
channel and media parameters in use. This SDP file is returned to the browser.
4. When the browser get the SDP file requested it launches the application currently associated with
the “SDP” extension. This application must be the client media player.
5. The browser passes the file information to the application by giving the application the filename or
the location of the file.
6. The application (the client media player) reads the contents of the SDP file and determines how
many media streams must be requested, what types of audio/video codecs are required to process
the media, and what type of connection (multicast, RTSP) is required.
7. When all the appropriate components have been loaded, the client player opens up the Internet
connections required to play the media streams, and starts buffering media for playback.
8. After a few seconds of initial buffering the viewer sees the media playback.
7.4. VLC M
EDIA
P
LAYER
A popular cross-platform media player with low latency is called “VLC” (Video Lan Client). There are several
ways to launch VLC for use with a Presentation Recorder:
1. Associate the file extension “.sdp” with the VLC application. Under Windows this can be done using:
My Documents  Tools  Folder Options
and associating a .sdp extension with the vlc.exe application.
2. Download (Right click and Save as …) the .sdp file, and then drag it onto the VLC client. This
method works only for multicast connectivity.
3. For an RTSP connection, use File  Open Network Stream  RTSP and enter the proper RTSP
URL: rtsp://Presentation Recorder.ncast.com/live.sdp
NCast Corporation Revision 1.1
Page 75