Re: [Slim] SDP limitations

[Christian Groves <[e-mail]>]

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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