[Live-devel] Unicast and Multicast from a single source server?

[Ross Finlayson]

>I want to make a server that will stream from a single source to 
>multiple unicast clients and at least one multicast address.  To 
>further complicate matters I believe it will need to support ASM (I 
>haven't been able to convince Quicktime to supports SSM).
>
>Before I go too far down the wrong path I thought I'd pose the 
>problem to the mailing list for any suggestions.
>
>I see three options:
>
>1. Use two different server sessions one for unicast (OnDemand based 
>subsession) and a separate session for multicast (Passive based 
>subsession)

This is by far the best solution, because it doesn't require messing 
around with the existing RTSP/RTP implementation - which works well 
as is.  The RTSP protocol works differently for unicast and multicast 
streams, and I definitely don't recommend trying to hack the unicast 
implementation to support multicast, or vice versa.


>  then feed them from a single FramedSource.

No, each would need to read from a different "FramedSource" (because 
the implementation of "FramedSource" does not allow more than one 
object to read from a single "FramedSource").

However, is your input source accessible as a file (e.g., in /dev/)? 
If so, then you could probably just create two separate 
"ByteStreamFileSource" objects, each reading from this file.

If, however, your input source is not accessible as a file, then you 
would need to
	1/ Write a class (which would *not* be a "FramedSource" 
subclass to encapsulate it), and
	2/ Write a FramedSource subclass that encapsulates a single 
copy of data from the source.
This is nontrivial, but you could use the existing "MPEG1or2Demux" 
and "MPEG1or2DemuxedElementaryStream" code as a model, because this 
does something similar.


>   This has complications in the design of the FramedSource

Yes, but that's much simpler than hacking with the RTSP/RTP code.


>  and it duplicates the RTP framing and buffering.

That really doesn't matter at all.  You just create two "RTPSink" 
(subclass) objects instead of one.
-- 

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/
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