Re: [MMUSIC] New draft: multiple times problem description:draft-garcia-mmusic-multiple-ptimes-problem-00.txt

[Miguel Garcia <[e-mail]>]

Hi Dan:

Thanks for the reaction. Some inline discussion.

Dan Wing wrote:
> Would a solution that meets REQ-10 and REQ-20 from
> draft-ietf-mmusic-sdp-capability-negotiation-reqts also resolve the ptime
> problem?
> 
>    REQ-10: It MUST be possible to indicate and negotiate alternative 
>    media formats on a per media stream basis. 

No, this isn't the problem we are trying to tackle, because this 
requirement speaks about "alternative media formats" and speaks "on a 
per media stream basis".

However, our problem is not about alternative media formats, but about 
"specific parameters" and is not "on a per media stream basis" but "on a 
per media format (or codec) basis".

> 
>       For example, many implementations support multiple codecs, but 
>       only one at a time.  Changes between codecs cannot be done on-
>       the-fly, e.g. when receiving a simple RTP payload type change. 

Right... but this seems to be a different problem than the one we 
describe in the draft.

> 
>    REQ-20: It MUST be possible to indicate and negotiate alternative 
>    attribute values ("a=") on a per media stream basis.  

Again, the "on a per media stream basis" does not fulfill the 
requirement of the draft. It should say "on a per media type basis".

> 
>       For example, T.38 [T38] defines new attributes that may need to 
>       be conveyed as part of a capability. Also, alternative SRTP 
>       keying mechanisms (e.g. [SDES] and [KMGMT]) may use SDP 
>       attributes to negotiate SRTP keying material. 
> 
> I noticed your document didn't reference
> draft-ietf-mmusic-sdp-capability-negotiation-reqts, but I think there is an
> overlap of a requirement you have and the solution proposed in
> draft-ietf-mmusic-sdp-capability-negotiation-05.txt.

At this stage, the goal of the draft is just to highlight the problem 
and serve for deriving requirements, which we are doing in this thread. 
I am not sure how to reference your requirements...

As for the solution, the solution is space is quite broad, ranging from 
any of the proprietary solutions that have been specified elsewhere to 
the SDP capability negotiation, to SDP grouping of media, or perhaps 
others.

I would prefer that we don't derive the discussion to discuss a solution 
until we agree that there is a problem to be solved.

BR,

       Miguel
> 
> -d
> 
> 
>> -----Original Message-----
>> From: Miguel Garcia [mailto:[e-mail]] 
>> Sent: Tuesday, May 29, 2007 3:41 AM
>> To: mmusic
>> Cc: Willekens, Marc
>> Subject: [MMUSIC] New draft: multiple times problem 
>> description:draft-garcia-mmusic-multiple-ptimes-problem-00.txt
>>
>> Hi:
>>
>> We have just submitted a new short draft that describes the 
>> problem with 
>> the lack of multiple packetization times in SDP.
>>
>> The draft should be soon available in the traditional repositories. 
>> Until that time, you can fetch a copy from:
>>
>> http://people.nokia.net/~miguel/drafts/draft-garcia-mmusic-mul
>> tiple-ptimes-problem-00.txt
>> http://people.nokia.net/~miguel/drafts/draft-garcia-mmusic-mul
>> tiple-ptimes-problem-00.html
>>
>> We are aware that the issue has been discussed in the past, without a 
>> clear conclusion on whether a problem exists. We believe there is an 
>> interoperability problem, and thus, we are soliciting 
>> comments about it. 
>> At this stage, we are not discussing solutions yet, we rather agree 
>> first that there is a problem that needs to be solved.
>>
>> /Miguel
>> -- 
>> Miguel A. Garcia           tel:[phone]
>> Nokia Siemens Networks     Espoo, Finland
>>
>>
>> _______________________________________________
>> mmusic mailing list
>> [e-mail]
>> https://www1.ietf.org/mailman/listinfo/mmusic

-- 
Miguel A. Garcia           tel:[phone]
Nokia Siemens Networks     Espoo, Finland


_______________________________________________
mmusic mailing list
[e-mail]
https://www1.ietf.org/mailman/listinfo/mmusic