Subject: [avtext] using tmbbr to pause a stream

From: "Roni Even" <[email-masked]>
Date: Wed, 7 Nov 2012 19:33:47 -0500

Hi,

Looking at RFC 5104 section 3.5.4.1 last paragraph

Obviously, in point-to-point cases, when there is only one media
   receiver, this receiver becomes "owner" once it receives the first
   TMMBN in response to its own TMMBR, and stays "owner" for the rest of
   the session.  Therefore, when it is known that there will always be
   only a single media receiver, the above algorithm is not required.
   Media receivers that are aware they are the only ones in a session
   can send TMMBR messages with bit rate limits both higher and lower
   than the previously notified limit, at any time (subject to the AVPF
   [RFC4585 <http://tools.ietf.org/html/rfc4585> ] RTCP RR send timing
rules).  However, it may be difficult
   for a session participant to determine if it is the only receiver in
   the session.  Because of this, any implementation of TMMBR is
   required to include the algorithm described in the next section or a
   stricter equivalent.

I got the impression that in the typical unicast cases (point to point and
MCUs) there is no problem with using tmbbr to pause and resume a stream 

Roni Even

---

From: Magnus Westerlund <[email-masked]>
Date: Wed, 7 Nov 2012 19:45:20 -0500

On 2012-11-07 19:33, Roni Even wrote:
>    Because of this, any implementation of TMMBR is
> 

The important part is the last sentence with the conclusion. Also this
section is informative. While the actual normative text is:

Section 4.2.1.2 which includes the following text:

   If the media sender concludes that it can increase the maximum total
   media bit rate value, it SHALL wait before actually doing so, for a
   period long enough to allow a media receiver to respond to the TMMBN
   if it determines that its tuple belongs in the bounding set.

There are no exception present in this text.

Cheers

Magnus Westerlund

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