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Re: [Slim] SDP limitations

Bernard Aboba <bernard.aboba@gmail.com> Sun, 04 October 2015 03:37 UTC

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From: Bernard Aboba <bernard.aboba@gmail.com>
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Date: Sat, 03 Oct 2015 20:37:02 -0700
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Subject: Re: [Slim] SDP limitations
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>> I got a reminder from reviewing the latest specification of real-time
>> text in WebRTC.
>> https://tools.ietf.org/html/draft-schwarz-mmusic-t140-usage-data-channel-02
>> 
>> There, the real-time text stream is a subchannel multiplexed in the
>> WebRTC data channel, with sdp-specification m=application.
>> So, there is no m=text to hook our humintlang attributes on.

>> It is quite likely that WebRTC terminals will be used in situations
>> where language negotiation is desirable.

[BA] If we are talking about a WEBRTC application talking over the data channel to a gateway that translates to RTT, the gateway can compose the m=text line to hang the humintlang attributes on.  The WEBRTC application need not speak SDP to the gateway to accomplish this, it just needs to provide the information the gateway needs to compose the m=text line and humintlang attributes. This could be in any desired format: JSON, XML, etc.

>> If we keep it under SDP, we would then need to define some mapping rules
>> between languages for media not appearing under their original m= names.

[BA] The gateway would need such a mapping, but it is not clear to me why this application-specific signaling would need to be standardized.

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