A Media Resource Control Protocol (MRCP) Developed by Cisco, Nuance, and Speechworks
RFC 4463

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Network Working Group                                      S. Shanmugham
Request for Comments: 4463                           Cisco Systems, Inc.
Category: Informational                                        P. Monaco
                                                   Nuance Communications
                                                              B. Eberman
                                                        Speechworks Inc.
                                                              April 2006

                A Media Resource Control Protocol (MRCP)
              Developed by Cisco, Nuance, and Speechworks

Status of This Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

IESG Note

   This RFC is not a candidate for any level of Internet Standard.  The
   IETF disclaims any knowledge of the fitness of this RFC for any
   purpose and in particular notes that the decision to publish is not
   based on IETF review for such things as security, congestion control,
   or inappropriate interaction with deployed protocols.  The RFC Editor
   has chosen to publish this document at its discretion.  Readers of
   this document should exercise caution in evaluating its value for
   implementation and deployment.  See RFC 3932 for more information.

   Note that this document uses a MIME type 'application/mrcp' which has
   not been registered with the IANA, and is therefore not recognized as
   a standard IETF MIME type.  The historical value of this document as
   an ancestor to ongoing standardization in this space, however, makes
   the publication of this document meaningful.

Shanmugham, et al.           Informational                      [Page 1]
RFC 4463         MRCP by Cisco, Nuance, and Speechworks       April 2006

Abstract

   This document describes a Media Resource Control Protocol (MRCP) that
   was developed jointly by Cisco Systems, Inc., Nuance Communications,
   and Speechworks, Inc.  It is published as an RFC as input for further
   IETF development in this area.

   MRCP controls media service resources like speech synthesizers,
   recognizers, signal generators, signal detectors, fax servers, etc.,
   over a network.  This protocol is designed to work with streaming
   protocols like RTSP (Real Time Streaming Protocol) or SIP (Session
   Initiation Protocol), which help establish control connections to
   external media streaming devices, and media delivery mechanisms like
   RTP (Real Time Protocol).

Table of Contents

   1. Introduction ....................................................3
   2. Architecture ....................................................4
      2.1. Resources and Services .....................................4
      2.2. Server and Resource Addressing .............................5
   3. MRCP Protocol Basics ............................................5
      3.1. Establishing Control Session and Media Streams .............5
      3.2. MRCP over RTSP .............................................6
      3.3. Media Streams and RTP Ports ................................8
   4. Notational Conventions ..........................................8
   5. MRCP Specification ..............................................9
      5.1. Request ...................................................10
      5.2. Response ..................................................10
      5.3. Event .....................................................12
      5.4. Message Headers ...........................................12
   6. Media Server ...................................................19
      6.1. Media Server Session ......................................19
   7. Speech Synthesizer Resource ....................................21
      7.1. Synthesizer State Machine .................................22
      7.2. Synthesizer Methods .......................................22
      7.3. Synthesizer Events ........................................23
      7.4. Synthesizer Header Fields .................................23
      7.5. Synthesizer Message Body ..................................29
      7.6. SET-PARAMS ................................................32
      7.7. GET-PARAMS ................................................32
      7.8. SPEAK .....................................................33
      7.9. STOP ......................................................34
      7.10. BARGE-IN-OCCURRED ........................................35
      7.11. PAUSE ....................................................37
      7.12. RESUME ...................................................37
      7.13. CONTROL ..................................................38
      7.14. SPEAK-COMPLETE ...........................................40

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