Re: [AVT] Working Group Last Call for draft-ietf-avt-forward-shifted-red-03.txt

[Qiaobing Xie <[e-mail]>]

Hi, Colin,

Thanks for the comments. Please see my response in-line.

Colin Perkins wrote:
> On 5 Jan 2010, at 01:19, Tom Taylor wrote:
>> This is to announce Working Group Last call for 
>> draft-ietf-avt-forward-shifted-red-03.txt. Subject to comments 
>> received, the Last Call period will expire on 18 January 2010.
> 
> 
> I have some minor comments.
> 
> What are the units of the "forwardshift" media type parameter? Section 3 
> implies that it's RTP timestamp units, whereas the appendix suggests 
> that it counts codec frames; section 4 doesn't specify a unit.

It is in RTP timestamp units. Appendix text is meant to be conceptual 
and thus using codec frames. I will improve the wording to remove the 
confusion.

> 
> Is the intent to define this only for audio, or for other top-level 
> media types? RFC 4102 defines text/red, but this draft has no 
> equivalent. This draft should probably register text/fwdred and updated 
> RFC4102, however if there's a good reason for only registering 
> audio/fwdred, then the draft title should change to "Forward-shifted RTP 
> Payload for Redundant Audio Data".

Good point! I think it is a good idea to be consistent with red media 
types and the same benefits also apply to text redundant. I will add 
wording for registering text/fwdred and updating RFC4102.

> 
> For the security considerations, this draft introduces an additional 
> issue where an excessive forward shift can be signalled, as a denial of 
> service. Section 8 should mention this issue, and presumably suggest 
> that a receive be prepared to ignore outrageous values.
> 

Agreed. Will add wording to that effect.

regards,
-Qiaobing

> 
>