Subject: RE: [AVT] FEC draft

From: "White, Craig (Level 3)" <[email-masked]>
Date: Thu, 23 Oct 2003 14:32:10 -0600

Hi!

As a long time lurker (don't know if anyone remembers the sonet draft I proposed eons ago), I just wanted to say to the whole of the group. Not that there is anything special about this particular email (other than I'm interested in FEC) but this e-mail just prompted me to write this note, and I'd like to let you know that: 

YOU GUYS ROCK!!!! 

I have no technical content to add, just a word of encouragement! As you may or may not know, I've been working out of the PWE3 group and only wish we were beginning to work on issues like these, rather than what's going on over there (not saying that the work PWE3 is doing is not worthwhile...)

Carry on!
-craig

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of Magnus
Westerlund
Sent: Thursday, October 23, 2003 6:27 AM
To: Adam Li; IETF AVT WG
Subject: Re: [AVT] FEC draft

Hi Adam,

Why not, it should simplify the processing somewhat. However I think 
this should be discussed openly, so I CC the AVT list in this reply. So 
if someone else has any comments about this, please respond.

Cheers

Magnus

Adam Li wrote:

> Hi Magnus,
> 
> I shuffle the fields around a little bit more (since we have them moved
> already). What do you think about the following format along the line
> you proposed? It have a even closer resemblance of the RTP header.
> 
>  0                   1                   2                   3
>  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |E|L|P|X|  CC   |M| PT recovery |            SN base            |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |                          TS recovery                          |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |        length recovery        |             mask              |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> |              mask cont. (present only when L = 1)             |
> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> 
> Do you think this looks alright? Thanks a lot.
> 
> Adam
> 
> 
> 
>>-----Original Message-----
>>From: [email-masked] [mailto:[email-masked]] On Behalf Of
>>Magnus Westerlund
>>Sent: Wednesday, October 22, 2003 5:31 AM
>>To: Adam Li
>>Cc: [email-masked]
>>Subject: Re: [AVT] FEC draft
>>
>>Hi Adam,
>>
>>[chair hat of]
>>
>>I have actually thought this over and have a counter proposal that I
>>think is rather nice. First I would like to rearrange the header in
>>the
>>following way:
>>
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>|      SN base                  |        length recovery        |
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>|E|L|P|X|  CC   |M| PT recovery |             mask              |
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>|                          TS recovery                          |
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>
>>That way the 16 bits of fields matches the first 16 bits of the RTP
>>header. The sending part can simply XOR the headers of the packet as
>>is
>>and mask out the version bits.
>>
>>Secondly I would actually take the reserved bit and change it into a
>>"Long mask" indicator. When the L bit is set the header would then
>>actually look like this:
>>
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>|      SN base                  |        length recovery        |
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>|E|L|P|X|  CC   |M| PT recovery |             mask              |
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>|                         mask continued                        |
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>|                          TS recovery                          |
>>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>
>>That way one can allow for a 48 bit mask while still keeping the
>>number
>>of options low and keep the 32 bit alignment.
>>
>>What does you think about it?
>>
>>Cheers
>>
>>Magnus
>>
>>
-- 

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
----------------------------------------------------------------------
Ericsson AB                | Phone +46 8 4048287
Torshamsgatan 23           | Fax   +46 8 7575550
S-164 80 Stockholm, Sweden | mailto: [email-masked]

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt