Subject: [AVT] linking two streams in SDP

From: Dave Singer <[email-masked]>
Date: Wed, 28 Feb 2007 15:09:50 -0800

If I have one stream which carries optional 'repair' data for another 
stream, and I want to send them on two separate multicast groups, or 
two separate streams to an RTSP client, how would I indicate that 
'this media stream' is the repair data for 'that media stream' in SDP?

I guess this is somewhat like scalable coding, in which I would need 
to say 'this stream' is an enhancement, and builds on 'that stream'.

I have no idea how to write a stream reference in SDP, i.e. how to 
say 'that stream'.  The techniques for scalable coding seem to be 
confined to assigning consecutive port numbers or multicast 
addresses, neither of which seem to apply when RTSP/SDP is used.

Help?
-- 
David Singer
Apple Computer/QuickTime

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

---

From: Adam Li <[email-masked]>
Date: Wed, 28 Feb 2007 16:10:18 -0800

David,

For forward error correction, I think you can use RFC 4756 (FEC
Semantics)  with RFC 3388 (Media Line Grouping). There might be similar
semantics for scalable coding.

Adam

Dave Singer wrote:
> I have no idea how to write a stream reference in SDP, i.e. how to say
> 'that stream'.  The techniques for scalable coding seem to be confined
> to assigning consecutive port numbers or multicast addresses, neither
> of which seem to apply when RTSP/SDP is used.
>
> Help?