Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-data-channel - language indication
Gunnar Hellström <gunnar.hellstrom@omnitor.se> Mon, 26 August 2019 08:58 UTC
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To: Christer Holmberg <christer.holmberg@ericsson.com>, "mmusic@ietf.org" <mmusic@ietf.org>
References: <49749CEF-41E8-4E87-8CC6-938DBDA0CEE7@ericsson.com> <665185b6-c1e7-62c3-4e3b-e9374d23bfd5@omnitor.se> <DF010721-81CD-40DE-A848-DE4D36836FDA@ericsson.com> <ED158CF5-E059-482B-8D7E-934BA2C753A1@ericsson.com> <2201665d-5054-1872-d208-a0fe2d26095c@omnitor.se> <VI1PR07MB3167055C995D17D4BA9E36DE93A50@VI1PR07MB3167.eurprd07.prod.outlook.com> <8d14b055-8405-4a4f-174d-d7580bea348c@omnitor.se> <0DA1248C-41FC-4155-A578-29A19883857C@ericsson.com> <a91850b9-6e86-058f-dddd-3f856bcd6710@omnitor.se> <DBC532B8-38DC-4140-B7C4-0B6853F0EF77@ericsson.com> <6fcf46a6-544d-027c-97c7-5c0e08caa555@omnitor.se> <c8761f5d-f73b-8c94-9c5e-f378e262a7b1@omnitor.se> <HE1PR07MB3161354CC40B66BEA6E4CBC593A70@HE1PR07MB3161.eurprd07.prod.outlook.com> <57a01757-8a67-0f48-df63-4cd5e1584f37@omnitor.se> <HE1PR07MB3161BFE14DF8F1127ABF497093A60@HE1PR07MB3161.eurprd07.prod.outlook.com> <bb828fd1-3d97-7d2b-78fb-8cf44137b4c6@omnitor.se> <34A2F227-2C19-473B-A16E-C3546023CFB3@ericsson.com>
From: Gunnar Hellström <gunnar.hellstrom@omnitor.se>
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Subject: Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-data-channel - language indication
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Hi Christer, Den 2019-08-26 kl. 09:30, skrev Christer Holmberg: > Hi Gunnar, > > 12. At the end of 3.2, add the following about language negotiation > >>>>> The users may be interested to negotiate language to use during the >>>>> real-time text session. This is done by including specifications of >>>>> language capabilities in the media descriptors for the t140 data >>>>> channels by use of dsca attributes hlang-send and hlang-recv >>>>> according to RFC 8373 [RFC8373]. The format is as follows: >>>>> a=dsca:id hlang-send:language >>>>> a=dsca:id hlang-send:language >>>>> The negotiation is performed as indicated in RFC8373. >>>> Whoops, there was a copy-paste error there. the second dsca attribute was intended to be: >>>> >>>> a=dsca:id hlang-recv:language >>>> also, the value may be a list of space separated language tags, so it would be more correct to say: >>>> >>>> a=dsca:id hlang-send:language(s) >>>> a=dsca:id hlang-recv:language(s) >>>> >>>> This is a bit informal way to specify the format. Do you think it is acceptable? The reader should >>>> anyway look into RFC 8373 for the complete specification. >>> I don't think we need to say anything how to specify. draft-data-channel-sdpneg defines how to convey >>> SDP attributes in the dsca attribute, and 8873 defines the format of the hdland-send/recv attributes. >> We could include an example instead. > Yes. Proposal: Change 3.3. header from Example to Examples Add at the end of 3.3 the following: Another example is an offer for a T.140 data channel from an organisation offering real-time text conversation in Spanish and Esperanto, and an answer accepting Esperanto. Offer: m=application 911 UDP/DTLS/SCTP webrtc-datachannel c=IN IP6 2001:db8::3 a=max-message-size:1000 a=sctp-port 5000 a=dcmap:1 label="ACME customer service";subprotocol="t140" a=dcsa:1 fmtp:- a=dsca:1 hlang-send:es eo a=dsca:1 hlang-recv:es eo Answer: m=application 911 UDP/DTLS/SCTP webrtc-datachannel c=IN IP6 2001:db8::3 a=max-message-size:1000 a=sctp-port 5000 a=dcmap:1 label="ACME customer service";subprotocol="t140" a=dcsa:1 fmtp:- a=dsca:1 hlang-send:eo a=dsca:1 hlang-recv:eo (Christer, can you please insert the variations needed in the answer to make it a realistic example of offer - answer.) > > --- > > 12a: Allow use of hlang- attributes together with m=application media declarations > >>>>>> RFC 8373 has a statement in section 5.3 saying: >>>>>> "This document does not define the use of language tags in media >>>>>> other than interactive streams of audio, video, and text (such as "message" or "application"). >>>>>> Such use could be supported by future work or by application agreement." >>>>>> >>>>>> The reason for this limitation is that it must be clear for what >>>>>> modality (spoken or written or signed ) the language is intended to >>>>>> be used. For audio, text and video, RFC 8373 defines the implicit >>>>>> relation audio=spoken, text=written, video=signed, but for >>>>>> "application" there is no such implicit relation and it is in our case the subprotocol T140 that >>>>>> we can be sure carries written language modality. So, we just need to specify in the draft that >>>>>> for media "application / webrtc-datachannel" and subprotocol "t140", the language modality >>>>>> is "written". It may in fact be evident from the context. >>>>> I will look into it, but it seems like a useful clarification to make. >>>> Yes, it may be sufficient with a clear statement that for m=application / webrtc-datachannel >>>> subprotocol T140, language indications according to RFC 8373 are allowed and indicate written >>>> language media. But that is a kind of extension over what RFC 8373 specified because the use >>>> for a=application was excluded there. Do we need to make IANA aware of that extension in some way? >>> Not sure about IANA, but it might be an update to 8373. >>> >>> The problem is that we are not defining usage of the lang attributes, and modality, for the 'application/webrtc-datachannel' media type: >>> we are defining modality and usage of the attributes for a specific data channel. >>> >>> So, maybe something like: >>> >>> "This document updates RFC 8373, by defining how the SDP hlang-send and hlang-recv attributes are used for >>> the "application/webrtc-datachannel" media type. >>> >>> SDP endpoints MUST NOT include the attributes directly in the m= section associated with the >>> 'application/webrtc-datachannel' media type. Instead, the attributes MUST be associated with >>> individual data channels, using the SDP dcsa attribute. A specification that defines a subprotocol >>> that uses the attributes MUST specify the modality for that subprotocol. >>> >>> For T.140 data channels the modality is 'written'." >> >> This works for the T140 data channel, but another subprotocol may be >> able to carry more than one media type and therefore have some other >> indication of what media type is used. An example is the msrp data >> channel that can carry messages with different modalities. > > Sure, and the text says that each subprotocol specification need to define what the modality is. > > (Of course, it would have been great if 8373 would have defined a way to explicitly indicate the modality, instead of implicitly retrieve it from the media type.) Agreed. It was discussed but not included in the final result. > >> So, yes, it is tempting to say that we extend RFC 8373 in general, but >> we can do in in a fully specified way only for the T140 data channel. >> >> How would you express that? > Using the suggested text above :) > > - It updates 8373 by allowing usage of the lang attributes for application/webrtc-datachannel media types. > - It updates draft-data-channel-sdpneg, by indicating that the modality must be defined for each data channel that > uses the lang attributes. In draft-t140-data-channel we then define the modality for T.140 data channels. Yes, I agree, it can be read your way. But I read "A specification that defines a subprotocol that uses the attributes MUST specify the modality for that subprotocol." as if only one modality was tied to a specific subprotocol identity. Can we change the sentence to "A specification that defines a subprotocol that uses the attributes MUST specify how the modality is deducted for languages used with that subprotocol." Regards Gunnar > > Regards, > > Christer > > > > _______________________________________________ > mmusic mailing list > mmusic@ietf.org > https://www.ietf.org/mailman/listinfo/mmusic -- ----------------------------------------- Gunnar Hellström Omnitor gunnar.hellstrom@omnitor.se +46 708 204 288
- [MMUSIC] Draft new: draft-holmberg-mmusic-t140-us… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Belling, Thomas (Nokia - DE/Munich)
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Bernard Aboba
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… R.Jesske
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Bernard Aboba
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Gunnar Hellström
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Gunnar Hellström
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Gunnar Hellström
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Gunnar Hellström
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Paul Kyzivat
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Gunnar Hellström
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Paul Kyzivat
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] Draft new: draft-holmberg-mmusic-t14… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Paul Kyzivat
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Paul Kyzivat
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Paul Kyzivat
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Paul Kyzivat
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- [MMUSIC] draft-holmberg-mmusic-t140-usage-data-ch… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Roni Even (A)
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Roni Even (A)
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Roni Even (A)
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Gunnar Hellström
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Christer Holmberg
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Roni Even (A)
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Paul Kyzivat
- Re: [MMUSIC] draft-holmberg-mmusic-t140-usage-dat… Paul Kyzivat