rfc3351.txt

RFC 的详细文档！

     prejudice, while still being able to establish a SIP session.

5.3 Intelligent Gateways

   This requirement states:

   SIP SHOULD support a class of User Agents to perform as gateways for
   legacy systems designed for deaf, hard of hearing and speech-impaired
   people.

   For example, an individual could have a SIP User Agent acting as a
   gateway to a PSTN legacy textphone.






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5.4 Inclusive Design

   This requirement states:

   Where applicable, design concepts for communications (devices,
   applications, etc.) MUST include the abilities and preferences of
   deaf, hard of hearing and speech-impaired people.

   Transcoding services and User Agents MUST be able to connect with
   each other regardless of the provider or manufacturer.  This means
   that new User Agents MUST be able to support legacy protocols through
   appropriate gateways.

5.5 Resource Management

   This requirement states:

   User Agents SHOULD be able to identify the content of a media stream
   in order to obtain such information as the cost of the media stream,
   if a transcoding service can support it, etc.

   User Agents SHOULD be able to choose among transcoding services and
   similar services based on their capabilities (e.g., whether a
   transcoding service carries a particular media stream), and any
   policy constraints they impose (e.g., charging for use).  It SHOULD
   be possible for User Agents to discover the availability of
   alternative media streams and to choose from them.

5.6 Confidentiality and Security

   This requirement states:

   All third-party or intermediaries (transcoding services) employed in
   a session for deaf, hard of hearing and speech-impaired people MUST
   offer a confidentiality policy.  All information exchanged in this
   type of session SHOULD be secure, that is, erased before
   confidentiality is breached, unless otherwise required.

   This means that transcoding services (e.g., interpretation,
   translation) MUST publish their confidentiality and security
   policies.










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6. Some Real World Scenarios

   These scenarios are intended to show some of the various types of
   media streams that would be initiated, managed, directed, and
   terminated in a SIP-enabled network, and shows how some resources
   might be managed between SIP-enabled networks, transcoding services
   and service providers.

   To illustrate the communications dynamic of these kinds of scenarios,
   each one specifically mentions the kind of media streams transmitted,
   and whether User Agents and Transcoding Services are involved.

6.1 Transcoding Service

   In this scenario, a hearing person calls the household of a deaf
   person and a hearing person.

   1. A voice conversation is initiated between the hearing
      participants:

      ( Person A) <-----Voice ---> ( Person B)

   2. During the conversation, the hearing person asks to talk with the
      deaf person, while keeping the voice connection open so that voice
      to voice communications can continue if required.

   3. A Relay Service is invited into the conversation.

   4. The Relay Service transcodes the hearing person's words into text.

   5. Text from the hearing person's voice appears on the display of the
      deaf person's User Agent.

   6. The deaf person types a response.

   7. The Relay Service receives the text and reads it to the hearing
      person:

      (         ) <------------------Voice----------------> (         )
      (Person A ) -----Voice---> ( Voice To Text  ) -Text-> (Person B )
      (         ) <----Voice---- (Service Provider) <-Text- (         )

   8. The hearing person asks to talk with the hearing person in the
      deaf person's household.

   9. The Relay Service withdraws from the call.





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6.2 Media Service Provider

   In this scenario, a deaf person wishes to receive the content of a
   radio program through a text stream transcoded from the program's
   audio stream.

   1. The deaf person attempts to establish a connection to the radio
      broadcast, with User Agent preferences set to receiving audio
      stream as text.

   2. The User Agent of the deaf person queries the radio station User
      Agent on whether a text stream is available, other than the audio
      stream.

   3. However, the radio station has no text stream available for a deaf
      listener, and responds in the negative.

   4. As no text stream is available, the deaf person's User Agent
      requests a voice-to-text transcoding service (e.g., a real-time
      captioning service) to come into the conversation space.

   5. The transcoding service User Agent identifies the audio stream as
      a radio broadcast.  However, the policy of the transcoding service
      is that it does not accept radio broadcasts because it would
      overload their resources far too quickly.

   6. In this case, the connection fails.

   Alternatively, continuing from 2 above:

   3. The radio station does provide text with their audio streams.

   4. The deaf person receives a text stream of the radio program.

   Note:  To support deaf, hard of hearing and speech-impaired people,
   service providers are encouraged to provide text with audio streams.

6.3 Sign Language Interface

   In this scenario, a deaf person enables a signing avatar (e.g.,
   ViSiCAST[6]) by setting up a User Agent to receive audio streams as
   XML data that will operate an avatar for sign-language.  For outgoing
   communications, the deaf person types text that is transcoded into an
   audio stream for the other conversation participant.







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For example:

(         )-Voice->(Voice To Avatar Commands) ----XMLData-->(        )
( hearing )                                                 (deaf    )
( Person A)<-Voice-( Text To Voice  ) <--------Text-------- (Person B)
(         )        (Service Provider)                       (        )

6.4 Synthetic Lip-speaking Support for Voice Calls

   In order to receive voice calls, a hard of hearing person uses lip-
   speaking avatar software (e.g., Synface[7]) on a PC.  The lip-
   speaking software processes voice (audio) stream data and displays a
   synthetic animated face that a hard of hearing person may be able to
   lip-read.  During a conversation, the hard of hearing person uses the
   lip-speaking software as support for understanding the audio stream.

   For example:

      (         ) <------------------Voice-------------->(         )
      ( hearing )                    ( PC with     )     ( hard of )
      ( Person A) -------Voice-----> ( lip-speaking)---->( hearing )
      (         )                    ( software    )     ( Person B)

6.5 Voice Activated Menu Systems

   In this scenario, a deaf person wishing to book cinema tickets with a
   credit card, uses a textphone to place the call.  The cinema employs
   a voice-activated menu system for film titles and showing times.

   1. The deaf person places a call to the cinema with a textphone:

         (Textphone) <-----Text ---> (Voice-activated System)

   2. The cinema's voice-activated menu requests an auditory response to
      continue.

   3. A Relay Service is invited into the conversation.

   4. The Relay Service transcodes the prompts of the voice-activated
      menu into text.

   5. Text from the voice-activated menu appears on the display of the
      deaf person's textphone.

   6. The deaf person types a response.






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   7. The Relay Service receives the text and reads it to the voice-
      activated system:

   (           )         (Relay Service   )          (               )
   ( deaf      ) -Text-> (Provider        ) -Voice-> (Voice-Activated)
   ( Person A  ) <-Text- (Text To Voice   ) <-Voice- (System         )

   8. The transaction is finalized with a confirmed booking time.

   9. The Relay Service withdraws from the call.

6.6 Conference Call

   A conference call is scheduled between five people:

   - Person A listens and types text (hearing, no speech)
   - Person B recognizes sign language and signs back (deaf, no speech)
   - Person C reads text and speaks (deaf or hearing impaired)
   - Person D listens and speaks
   - Person E recognizes sign language and reads text and signs

   A conference call server calls the five people and based on their
   preferences sets up the different transcoding services required.
   Assuming English is the base language for the call, the following
   intermediate transcoding services are invoked:

   - A transcoding service (English speech to English text)
   - An English text to sign language service
   - A sign language to English text service
   - An English text to English speech service

   Note:  In order to translate from English speech to sign language, a
   chain of intermediate transcoding services was used (transcoding and
   English text to sign language) because there was no speech-to-sign
   language available for direct translation.  Accordingly, the same
   applied for the translation from sign language to English speech.















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(Person A) ----- Text ----> (  Text-to-SL  ) --- Video ----> (Person B)
           ---------------------- Text --------------------> (Person C)
           ----- Text ----> (Text-to-Speech) --- Voice ----> (Person D)
           ---------------------- Text --------------------> (Person E)
           ----- Text ----> (  Text-to-SL  ) --- Video ----> (Person E)
(Person B) -Video-> (SL-to-Text) -Text-> (Text-to-Speech) -> (Person A)
           ---- Video ----> (  SL-to-Text  ) ---- Text ----> (Person C)
           -Video-> (SL-to-Text) -Text-> (Text-to-Speech) -> (Person D)
           --------------------- Video --------------------> (Person E)
           ---- Video ----> (  SL-to-Text  ) ---- Text ----> (Person E)
(Person C) --------------------- Voice --------------------> (Person A)
           Voice->(Speech-to-Text)-Text->(Text-to-SL)-Video->(Person B)
           --------------------- Voice --------------------> (Person D)
           ---- Voice ----> (Speech-to-Text) ---- Text ----> (Person E)
           Voice->(Speech-to-Text)-Text->(Text-to-SL)-Video->(Person E)
(Person D) --------------------- Voice --------------------> (Person A)