Re: [rtcweb] RTP Usage: Is RTP Retransmission REQUIRED or RECOMMENDED

["Roni Even" <[e-mail]>]

Hi,
My view is that retransmission have great value for content delivery or
streaming applications, when the communication is unidirectional. 
For conversional applications like we are defining in RTCweb, retransmission
has the lower value comparing to other loss recovery options like FEC or
receiver based recovery. The latency involved with the extra roundtrips
makes it not effective comparing to typical jitter buffer sizes at the
receiver, note that receiver will take correction actions even for late
arrival and will not try to dynamically change the jitter buffer to a larger
size beyond the maximum threshold of end to end delay. 
 If we look at the typical behavior of conversional applications, they will
add to audio on the sender side FEC or even send the media twice is
subsequent packets encoded in different encoders,( of course for the
conversation itself the listener can always ask the talker to repeat since
he did not hear it clearly). On the video FEC and receiver side recovery
like motion estimation is common.
I propose that retransmission can be recommended and in my view for
conversional usage even this is strong.

Roni

-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On Behalf Of
Magnus Westerlund
Sent: 27 June, 2012 9:37 AM
To: [e-mail]
Subject: [rtcweb] RTP Usage: Is RTP Retransmission REQUIRED or RECOMMENDED

WG,

We had a discussion at the interim if RTP Retransmission is to be considered
REQUIRED or RECOMMENDED to implement. I would like to see if we can first
have some discussion on this topic before moving on to see if we can get a
consensus here on the mailing list.

Please provide your views on this topic.

Cheers

Magnus Westerlund
(As Chair and document editor)


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