[Live-devel] Get confused

[Ross Finlayson]

>         In the program "testMPEG1or2AudioVideoStreamer", it uses groupsock
>to send the video/audio packets to multicast address 239.255.42.42.
>Quicktime is required us to use the rtsp server IP address (i.e.
>rtsp://192.168.110.4) in order to watch the streamed video.
>
>         Then actually what type of packet do I get from the
>server ? Is it the multicast from the multicast group or unicast from the
>rtsp server ?

Both.  The player client first uses RTSP (over TCP) to contact the server, 
and issue RTSP commands (in particular "DESCRIBE", which asks the server 
for a SDP description for the stream).

However, the actual audio/video stream data is then sent using RTP (over 
UDP multicast).

>         Also, what is the function of creating RTSP server ? Is it
>necessary to create a RTSP server to stream the video out ?

No, not in this case.  That's why the RTSP server is an *option* (turned 
off by default) in "testMPEG1or2AudioVideoStreamer".  In general, RTSP is 
needed only for playing unicast streams to dynamic clients.  For multicast 
streams (such as those streamed by "testMPEG1or2AudioVideoStreamer") you 
could instead read the (static) SDP description, which (in this case) is 
stored in the file "testMPEG1or2AudioVideo.sdp".

To learn more about RTSP, and its relationship with RTP, I encourage you to 
visit <http://www.rtsp.org/>


	Ross Finlayson
	LIVE.COM
	<http://www.live.com/>