Re: [rtcweb] A problem with both A and B

Hi,

>Clearly adding a new m= line needs a SDP O/A.

Correct. 

>So in the multiplex case I would think that adding another m= line equivalent to a bundle would also need a SDP O/A.

Yes. In my opinion, adding a new m- line requires an SDP O/A - bundle or no bundle.

> In the non multiplex case changing to a different source doesn't require a SDP O/A. However,  unless there is 
> some identifier in the RTP packets that the receiver knows already, such a change would need to be signalled in the multiplex case.

What do you mean by "non-multiplex"?

1) No bundle, but possibly multiple SSRCs per m- line; or

2) No bundle, and only one SSRC per m- line

Regards,

Christer

> 
On 21 May 2013 09:57, Christer Holmberg <christer.holmberg@ericsson.com> wrote:
Hi,

> In cases where each m= line has a different port, when a new SSRC is received usually it is either discarded (when latched to a pre exisiting SSRC stream that does not stop) or is treated as replacing the previous SSRC.
>
> When multiplexing is being used it is not obvious whether the new SSRC is replacing a previous one, or is another separate stream.
>
> I think that in the multiplex case we need something like a virtual destination port in each RTP packet, such as a RTP header extension or even UDP over UDP!
Perhaps.

But, then we talk more about how to identify/demux a stream, once it has been added.

We would still need to answer whether the actual addition of a new stream requires a SDP O/A transaction :)

Regards,

Christer

On 21.05.13, 10:38, Christer Holmberg wrote:
> Hi,
>
>>> If adding a new stream means adding a new SSRC, within an
>>> existing m-, then it is also an SDP O/A issue - bundle or no
>>> bundle.
>>
>> Why is that?
>
> Because, even WITHOUT bundle, you have to answer whether adding a new
> SSRC (or, whatever mechanism we use to identify a stream) within an
> existing m- line requires an SDP O/A transaction or not.
OK, I guess I took your statement to mean that adding and removing SSRCs
to m= lines is a matter that cannot be handled without SDP O/A which I
think it isn't (and which is what this thread started with).

I obviously agree that it is not a bundle-specific issue.

Emil

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