Re: [rtcweb] Add, remove, add, remove, add, remove a media stream (lines in SDP)

[Randell Jesup <[e-mail]>]

On 4/23/2012 2:40 AM, Christer Holmberg wrote:
> Hi,
>
> I see no reason why you couldn't release resources when you disable media (read:
> set port to zero), but still re-use the associated m- line later.

Exactly - m-lines can't be removed, but they can be re-used - and the 
critical point is that the port doesn't have to match the previous port. 
  So generally they should be no worse than a high-water-mark of the 
number of audio and video streams in use at any one time.

Of course with bundle the port issue is simpler.

> From: [e-mail] [[e-mail]] On Behalf Of Iñaki Baz Castillo [[e-mail]]
>
> Hi, a stream in an SDP cannot be removed but just "disabled" (by
> setting its port to 0). In the same media session a participant could
> add a video stream and "disable" it later multiple times.
>
> Let's assume a media session initiated with just an audio stream:
>
> 1) A participant adds a video stream and the remote accepts it. This
> involves a new media section in the SDP.
> 2) Later the same participant removes the video stream which means
> setting its port to 0 in the SDP.
> 3) Later he adds video again.
> 4) ...and so on.
>
> AFAIK there are two choices for step 2 and 3:
>
> a) Releasing video resources and the UDP socket so when video is
> enabled again a new line should be added to the SDP and new resources
> (ICE, UDP socket) required.
>
> b) Not releasing all the resources (keep the UDP socket but stop
> sending/receiving data on it), and re-enabling it when video is added
> again, so the same SDP line would be reused by setting its port to the
> previous value.
>
>
> Choice a) means more and more lines in the SDP for each video
> activation. Option b) means not releasing resources after disabling a
> media stream.
>
> If I'm not wrong in the above text, which would be the WebRTC approach
> for this topic?

-- 
Randell Jesup
[e-mail]