Subject: [rmcat] comments on draft-alvestrand-rmcat-remb-02

From: "Alfred E. Heggestad" <[email-masked]>
Date: Sun, 06 Oct 2013 14:16:28 +0200

Hi,

I have some comments/questions about draft-alvestrand-rmcat-remb-02

- is the new RTCP AFB message valid for all kinds of streams ?
   audio, video etc ?

- the maximum bitrate, is it defined as the maximum bitrate for
   a particular stream, or the maximum bitrate for the whole "Session" ?

- the message is using a unique identifier "REMB" to de-multiplex incoming
   AFB messages, is this method defined in a spec somewhere, and is there
   a central registry of other types of AFB messages?

- section 2.3 OPEN ISSUE, I dont think explicit signaling is needed.

/alfred

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From: Varun Singh <[email-masked]>
Date: Sun, 6 Oct 2013 19:45:58 +0300

Hi Alfred,

Some comment inline.

-Varun

> - is the new RTCP AFB message valid for all kinds of streams ?

It depends on how many and which SSRCs are reported in the feedback message.
As per the draft, it is up to the implementation (or the congestion
control algorithm)
to choose which SSRCs, i.e., it could report just the SSRCs of audio
or video or a combination.

>   a particular stream, or the maximum bitrate for the whole "Session" ?

One method of calculating the receiver's maximum estimate is defined by
Google's congestion control (GCC) in
http://tools.ietf.org/html/draft-alvestrand-rtcweb-congestion

As per GCC, REMB can be used for reporting the sum of the receiver
estimate across all media streams that share the same end-to-end path.
I supposed the SSRCs of the multiple media streams that make up the
aggregate estimate
are reported in the block.

>   AFB messages, is this method defined in a spec somewhere, and is there

The demultiplexing is defined in Section 6.4 of RFC4585,
https://tools.ietf.org/html/rfc4585#section-6.4

-- 
http://www.netlab.tkk.fi/~varun/

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From: "Alfred E. Heggestad" <[email-masked]>
Date: Tue, 08 Oct 2013 20:41:00 +0200

Hi Varun,

okay, thanks for the info!

/alfred