Subject: Re: [AVT] Summary of 3GPP timed text draft

From: John Lazzaro <[email-masked]>
Date: Mon, 7 Jul 2003 12:55:44 -0700

>  "Jose Rey" <[email-masked]> writes:
>
> The open issues/TODO list includes:
>
> - resilient transport: repetition, fragmentation, retransmission, FEC
> (other?). It is our opinion that repetition should be included at the
> very least.

Is RTCP expected to be normally used with this payload format?  If so,
maybe the core idea behind the RTP MIDI resiliency -- a "recovery journal"
in every packet coding the recent past, whose contents grow and shrink
as the sender examines RTCP RR reports which indicate the highest 
sequence number the receiver has received -- could be the starting
point of a timed text resiliency scheme.  For the default 5 second
RTCP sending rate, and text that is not sent too frequently, one
could imagine a recovery journal approach would be more efficient
that simple repetition.  But you need RTCP to make it work ...

-------------------------------------------------------------------------
John Lazzaro -- Research Specialist -- CS Division -- EECS -- UC Berkeley
lazzaro [at] cs [dot] berkeley [dot] edu     www.cs.berkeley.edu/~lazzaro
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_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: "Jose Rey" <[email-masked]>
Date: Tue, 8 Jul 2003 13:57:20 +0200

Hi John,

thanks for the comments. Please see below.

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]On Behalf Of John
> Lazzaro
> Sent: Monday, July 07, 2003 9:56 PM
> To: [email-masked]
> Subject: Re: [AVT] Summary of 3GPP timed text draft
>
>
>
> Is RTCP expected to be normally used with this payload format?

Not necessarily. Yes for unicast, but there's no plan to use RTCP
feedback in a first stage of the MBMS Service, that's why repetition is
important as a base mechanism.

cheers,

José

> If so,