Voip Blog
MRCP and Text-To-Speech
Wednesday, April 30, 2008
I recently got a press release from a company that does text-to-speech services. The press release proclaimed that the solution supports Media Resource Control Protocol, or MRCP. In theory, the press release says, it should make it easy to integrate text-to-speech into the largest call center/contact center solutions.
What is MRCP? It is defined by RFC 4463 and is described as follows:
The Media Resource Control Protocol (MRCP) is designed to provide a mechanism for a client device requiring audio/video stream processing to control processing resources on the network. These media processing resources may be speech recognizers (a.k.a. Automatic-Speech-Recognition (ASR) engines), speech synthesizers (a.k.a. Text-To-Speech (TTS) engines), fax, signal detectors, etc. MRCP allows implementation of distributed Interactive Voice Response platforms, for example VoiceXML interpreters. The MRCP protocol defines the requests, responses, and events needed to control the media processing resources. The MRCP protocol defines the state machine for each resource and the required state transitions for each request and server-generated event.
In short, MRCP makes it possible to distribute the various functions necessary for audio processing in order to implement things like text-to-speech in a scalable way. This is certainly the kind of technology necessary in large call centers!
What is interesting about this protocol is how "transparent" this protocol is. Much like SIP, the lingua franca of voice over IP, and the HTTP protocol used for web pages, the control aspects of the protocol are communicated in plain text that is human readable.
MRCP is built with the assumption that VoIP protocols like SIP and RTSP will be used. In fact, the RFC explicitly states that some functions are not addressed by MRCP and that SIP or RTSP should be used instead.
Even though this has been assigned an Internet RFC, the IETF cautions that the RFC is not a candidate for any level of Internet Standard. That being said, it will be interesting to see what other situations where MRCP will crop up. There are a lot of interesting possibilities here.
