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<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2>I am sure Ross will comment from the live555 perspective
but from a TV perspective, and TV is a very common use for this, UDP is
used because this is a streaming application, if the media does not get there as
expected i.e. in time to display it in sequence for video playback, it is no
longer needed and therefore why bother retransmitting. Worse still is if the
system re-transmits and that delays or interferes with the next packet getting
to the display system in time now there is further interruption to the
stream.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2>Since the re-transmitting is not needed, TCP is not needed
(actually is sometimes considered detrimental). The bigger issue with UDP is
actually that there is unpredictable as to when it sends packets hence the use
of RTP which gives the server controls that helps regulate the flow of packets
and the receiving device to know when the frame is/was meant to be
presented/delivered. </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2>This is actually the area I was looking to live555 to help
with. I have found very little help on how to do this. In my application I get
transport stream data in large blocks that I can easily break up into 7 x TS
packets for sending on Ethernet but I have not found the method of regulating
the flow particularly clear either from the MPEG side or the live555
side.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2>If you ever dig into this I would be appreciate any
information you may come up with.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=059053918-23102009><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> live-devel-bounces@ns.live555.com
[mailto:live-devel-bounces@ns.live555.com] <B>On Behalf Of </B>Sharda
Murthi<BR><B>Sent:</B> Friday, October 23, 2009 10:22 AM<BR><B>To:</B>
live-devel@ns.live555.com<BR><B>Subject:</B> [Live-devel] Reliable UDP -- does
it make sense?<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=gmail_quote>Hi All,<BR><BR>We are trying to implement a
retransmission mechanism for the live555 server over UDP, as part of our
research work for a professor.<BR><BR>Well, we hit our first road block thinking
why would someone want to do it at all? We do understand that UDP doesnt provide
for reliable transmission. And that's the purpose! If retransmission is
provided, then the overhead increases, which UDP cant afford. <BR>So, why not
just use the existing TCP mechanism, given that the developers of live555 have
already done it?<BR><BR>Can someone point out as to why one would want to be
doing this at all? Probably we're not seeing the subtler side of the idea. We're
just too confused about this whole thing.<BR>And if someone has done this
before, could you please guide us as to where we can start from?<BR><BR>Thank
you!<BR><BR></DIV><BR><BR>
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