Re: [Slim] SDP limitations

Hello Albrecht,

Thanks must go to Paul for catching the fmtp one.

Christian

On 6/10/2015 6:34 PM, Schwarz, Albrecht (Albrecht) wrote:
> Thanks for spotting the "a=dcsa" issue Christian!
>
> Will request MMUSIC to adopt
> draft-schwarz-mmusic-t140-usage-data-channel
> as WG draft and reply on the question below at MMUSIC.
> Its an MMUSIC item and not SLIM in my understanding.
>
> Regards,
> Albrecht
>
>
> -----Original Message-----
> From: Christian Groves [mailto:Christian.Groves@nteczone.com]
> Sent: Dienstag, 6. Oktober 2015 01:40
> To: slim@ietf.org
> Cc: Schwarz, Albrecht (Albrecht)
> Subject: Re: [Slim] SDP limitations
>
> Hello Paul,
>
> On 6/10/2015 9:39 AM, Gunnar Hellström wrote:
>> Den 2015-10-05 kl. 18:45, skrev Paul Kyzivat:
>>> Christian,
>>>
>>>> Den 2015-10-05 kl. 01:44, skrev Christian Groves:
>>>>> Hello Gunnar,
>>>>>
>>>>> It would be possible to "hook" the humanlang attributes to the
>>>>> specific instance of the datachannel. You simply use the humanlang
>>>>> tags in the dcsa attribute. The protocol is indicated via the
>>>>> subprotocol element in the dcmap attribute. E.g.
>>>>>
>>>>>           m=application 911 <L4>/DTLS/SCTP webrtc-datachannel
>>>>>           c=IN IP4 11.9.19.65
>>>>>           a=max-message-size:1000 ;
>>>>>           a=sctp-port 5000
>>>>>           a=dcmap:1 label="text conversation";subprotocol="t140"
>>>>>           a=dcsa:1 cps=30  ; "the RFC4103 default value as example"
>>> The above line can't be right. 'cps=30' doesn't conform to syntax of
>>> an attribute.
>> Right, it is a subparameter in an fmtp attribute.  fmtp is not of
>> interest to carry over to the WebRTC side. So it likely needs to be
>> specifically specified as a native attribute in the dat channel
>> subprotocol.
>>
>>
>> But that was not the point. It was that mapping of humintlang
>> attributes to WebRTC RTT stream seem possible but it is no
>> straightforward m=text to hook it on to on the WebRTC side.
> [CNG] It was a cut and paste from
> draft-schwarz-mmusic-t140-usage-data-channel. I didn't look at that part of the syntax. As Gunnar said I was just illustrating the concept of using attributes associated with a data channel.
>
> You're right though it doesn't conform. It probably should be something like a=dcsa:1 fmtp:- cps=30. I've cc'd Albrecht on this.
>
> Regards, Christian
>>>>>           a=dcsa:1 humintlang-send:<language tag>
>>>>>           a=dcsa:1 humintlang-recv:<language tag>
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