[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01

SLIM                                                        G. Hellstrom
Internet-Draft                                                   Omnitor
Intended status: Informational                              June 9, 2017
Expires: December 11, 2017


    Negotiating Simultaneous Modalities in Real-Time Communications
            draft-hellstrom-slim-simultaneous-modalities-01

Abstract

   In a real-time communication session, there may be a need or
   preference for receiving the same content in two or more simultaneous
   modalities.  This specification extends a mechanism for human
   language negotiation with a mechanism for indication of preference
   for, or the availability of, simultaneously provided transformations
   of original contents.  This indication enables negotiation of
   simultaneous modalities in real-time sessions.  Applications are for
   example provision of both spoken and written content in a real-time
   call (captioning), or provision of both spoken language original and
   sign language interpretation of the original language in a real-time
   session.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 11, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of



Hellstrom               Expires December 11, 2017               [Page 1]


Internet-Draft           Simultaneous Modalities               June 2017


   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Indication of Simutaneous Modalities  . . . . . . . . . . . .   3
   4.  Negotiation . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Limitations . . . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   6
     10.2.  Informative References . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   In certain applications it is of interest to indicate a need for, or
   the availability of, transformed version of the contents of a media
   stream in another media, while still also providing the original.

   The application of this indication may for example be for rapid
   subtitling of speech either manually or automatically.  It may also
   be sign language interpretation of speech, or spoken interpretation
   of sign language when both the original and the interpretation is
   delivered to the user.

   A mechanism for language negotiation in real-time communications is
   introduced in [I-D.ietf-slim-negotiating-human-language].

   This specification extends the mechanism with an indication that a
   transformation of language contents in one modality is desired in a
   different modality.  Negotition of transformations of the language
   contents simultaneously with the original contents can be
   accomplished by using this indication in the context of language
   negotiation in real-time communications
   [I-D.ietf-slim-negotiating-human-language].  The same indication is
   used for indication of preparedness to send language contents in one
   modality simultaneously with same content in a different modality




Hellstrom               Expires December 11, 2017               [Page 2]


Internet-Draft           Simultaneous Modalities               June 2017


   The indication is based on the "t" extension of [RFC5646], specified
   in RFC 6497 [RFC6497].

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  Indication of Simutaneous Modalities

   The mechanism specified here extends the language negotiation
   mechanism specified in [I-D.ietf-slim-negotiating-human-language]
   with a mechanism for indicating request for, or availability of,
   original content and transformed form of original language content in
   another modality in the same transmission direction.  The indication
   should be provided in language tags of the 'hlang-send' or 'hlang-
   recv' SDP attribute values specified in
   [I-D.ietf-slim-negotiating-human-language].

   When the transformed language is to be requested or provided
   simultaneously with the original, this condition should be indicated
   by using the "t" extension to BCP47 [RFC5646] as specified in RFC
   6497 [RFC6497], by attaching a "t" subtag on the language tag for the
   language that is expected to be provided in a transformed modality.

   Briefly, the 't' extension consists of the string "-t" followed by
   the source language subtag.

   Example: "en-t-en" is an English transform of an English source (in
   another modality).

   On reception of an indication in a 'hlang-recv' attribute, a language
   tag with the 't' extension and also a 'hang-recv' attribute for
   another modality with the same language without the "t" extension,
   the answering party should interpret this as a request to send both
   the original and the transformed content.

   On reception of an indication in a 'hlang-send' attribute a language
   tag with the 't' extension and also a 'hang-send' attribute for
   another modality with the same language without the "t" extension,
   the answering party should interpret this as the preparedness of the
   offering party to send both the original and the transformed content
   simultaneously.

   The media that the "t" extension is attached to should only be
   interpreted as an expectation for how the transformation will be
   made.  Conditions in the real established session MAY cause the



Hellstrom               Expires December 11, 2017               [Page 3]


Internet-Draft           Simultaneous Modalities               June 2017


   original and transformation to swap roles from what the subtags
   indicated.

4.  Negotiation

   Indication of a request for reception of multiple simultaneous
   modalities by the "t" extension in an offer by 'hlang-recv'
   attributes should be interpreted as a request to receive these
   modalities simultaneously.  The answering party MAY satisfy this
   request by providing the requested simultaneous modalities.  This
   should be indicated in the answer by the "t" extension in the 'hlang-
   send' SDP attributes.  If the answering party had no possibility to
   provide the simultaneous modalities, then no "t" extensions should be
   indicated in the 'hlang-send' attribute values with the same original
   language.

   Indication of availability of providing simultaneous modality of an
   original language should be indicated by the "t" extension in the
   'hlang-send' attribute in the offer.  The answering party SHOULD
   indicate its interest to receive the offered simultaneous modalities
   by including the "t" extension in 'hlang-recv' attributes in the
   approriate media specifications in the answer.  If the answering
   party is only interested in receiving one of the offered modalities,
   then the language tag should only be provided in the corresponding
   'hlang-recv' attribute in the answer.

   If an answering party prefers to receive simultaneous modalities of
   an original language content that was not offered in the 'hlang-send'
   attribute in the offer, then the answering party MAY anyway include
   the preferred language and modality with the "t" extension in the
   answer.  The answering user may then observe in the language exchange
   in the beginning of the session if the request for simultaneous
   modalities could be satisfied.  For cases when a more formal
   indication of the satisfaction of the request, the answering party
   SHOULD request an update of the session and include the request for
   reception of multiple simultaneous modalities in the 'hlang-recv'
   attributes.

   The indications of multiple simultaneous modalities MAY be combined
   with other preference indications defined for the application of the
   'hlang-' attributes.

5.  Limitations

   It is not possible to use the "t" extention to indicate an
   alternative language for selection in a different modality than the
   original language that is also included in a 'hlang-' attribute.
   Implementations SHOULD always interpret such indications as



Hellstrom               Expires December 11, 2017               [Page 4]


Internet-Draft           Simultaneous Modalities               June 2017


   indications for simultaneous modality.  If interpretation as
   alternative languages to select from is desired, the "t" extension
   SHOULD be omitted.

6.  Examples

   A request for a written English subtitling to be received by the
   caller in the text stream created from a spoken English source in the
   audio stream.  The caller also indicates a preference to speak
   English:

      m=audio 49250 RTP/AVP 20

      a=hlang-recv:en

      a=hlang-send:en*

      m=text 45020 RTP/AVP 103 104

      a=hlang-recv:en-t-en

   An acknowledgement of the request:

      m=audio 49250 RTP/AVP 20

      a=hlang-send:en

      a=hlang-recv:en

      m=text 45020 RTP/AVP 103 104

      a=hlang-send:en-t-en

   In the session, the caller will receive both spoken English and
   written English.  The caller will send English speech.

   An alternative response from a party that cannot satisfy the request,
   but only provide spoken English:

      m=audio 49250 RTP/AVP 20

      a=hlang-send:en

      a=hlang-recv:en

      m=text 45020 RTP/AVP 103 104





Hellstrom               Expires December 11, 2017               [Page 5]


Internet-Draft           Simultaneous Modalities               June 2017


7.  Acknowledgements

8.  IANA Considerations

   No IANA considerations.  This specification reuses already registered
   entities.

9.  Security Considerations

   Some users may regard their language and modality preference details
   to be sensitive and requiring privacy and security measures.  This
   fact should be considered when implementing the mechanism specified
   in this document.  The security considerations are common with
   [I-D.ietf-slim-negotiating-human-language].

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5646]  Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
              Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
              September 2009, <http://www.rfc-editor.org/info/rfc5646>.

   [RFC6497]  Davis, M., Phillips, A., Umaoka, Y., and C. Falk, "BCP 47
              Extension T - Transformed Content", RFC 6497,
              DOI 10.17487/RFC6497, February 2012,
              <http://www.rfc-editor.org/info/rfc6497>.

10.2.  Informative References

   [I-D.ietf-slim-negotiating-human-language]
              Gellens, R., "Negotiating Human Language in Real-Time
              Communications", draft-ietf-slim-negotiating-human-
              language-10 (work in progress), May 2017.

Author's Address










Hellstrom               Expires December 11, 2017               [Page 6]


Internet-Draft           Simultaneous Modalities               June 2017


   Gunnar Hellstrom
   Omnitor
   Hammarby Fabriksvag 23
   Stockholm  120 30
   Sweden

   Phone: +46 708 204 288
   Email: gunnar.hellstrom@omnitor.se











































Hellstrom               Expires December 11, 2017               [Page 7]


Html markup produced by rfcmarkup 1.124, available from https://tools.ietf.org/tools/rfcmarkup/