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--></style><title>Re: [Live-devel] Help with
multicast</title></head><body>
<blockquote type="cite" cite><font face="Arial" size="-1">I have some
questions about multicast that hope someone can help me with.<br>
<br>
I need to transmit a mpeg4 video using multicast and for doing that
I'm using the "-m" option in wis-streamer.<br>
Doing that and using Wireshark I can see the multicast packets but if
I try to watch the video connecting to the multicast address using VLC
I see nothing, but, if I use the RTSP option in VLC then I can see the
video.</font></blockquote>
<div><br></div>
<div>So then what's the problem? If RTSP works for you, then why
not continue to use that?</div>
<div><br></div>
<div>Note that RTSP tells the client not only the multicast address
and port number to subscribe to, but also (in the SDP description)
important details about the codec that is being streamed. (Note,
in particular, the "config=" parameter, which contains
important information for the client's MPEG-4 decoder.)</div>
<div><br></div>
<div>Even though VLC (apparently) allows you to subscribe to a
multicast stream merely by specifying its address and port number,
this will work only for certain simple codecs that are 'hard wired'
into VLC. (However, I remind people yet again that VLC is not
our software, and questions about VLC should be posted to a VLC
mailing list.)</div>
<div><br></div>
<div><br></div>
<blockquote type="cite" cite><font face="Arial" size="-1">With RTSP
the SDP info is as following:</font><br>
<blockquote>v=0<br>
o=- 952047184189632 1 IN IP4 192.168.1.95<br>
s=RTSP/RTP stream<br>
i=mpeg4<br>
t=0 0<br>
a=tool:LIVE555 Streaming Media v2008.04.02<br>
a=type:broadcast<br>
a=control:*<br>
a=source-filter: incl IN IP4 * 192.168.1.95<br>
a=rtcp-unicast: reflection<br>
a=range:npt=0-<br>
a=x-qt-text-nam:RTSP/RTP stream from DaVinci EVM<br>
a=x-qt-text-inf:mpeg4<br>
m=audio 6002 RTP/AVP 96<br>
<b>c=IN IP4 232.36.244.217/255</b><br>
a=rtpmap:96 L16/8000<br>
a=control:track1<br>
m=video 6000 RTP/AVP 97<br>
c=IN IP4 232.36.244.217/255<br>
a=rtpmap:97 MP4V-ES/90000<br>
a=fmtp:97
profile-level-id=1;config=000001B001000001B50900000101000001200084400<span
></span>7A94022D0A21F<br>
a=control:track2<br>
</blockquote>
</blockquote>
<blockquote type="cite" cite>And the SETUP says:<br>
<blockquote>Transport:
RTP/AVP;<b>multicast</b
>;destination=232.36.244.217;source=192.168.1.95;port=6002-6003;ttl=2<span
></span>55<br>
</blockquote>
</blockquote>
<blockquote type="cite" cite>Does it mean I am really transmiting in
multicast?</blockquote>
<div><br>
Yes.<br>
</div>
<blockquote type="cite" cite> shouldn't I be able to connect
directly to the multicast address?</blockquote>
<div><br></div>
<div>Yes, but the way to do this is to use RTSP (see above).</div>
<x-sigsep><pre>--
</pre></x-sigsep>
<div><br>
Ross Finlayson<br>
Live Networks, Inc.<br>
http://www.live555.com/</div>
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