Media Resource Control Protocol (MRCP) is a communication protocol used by speech servers to provide various services (such as speech recognition and

speech synthesis Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech synthesizer, and can be implemented in software or hardware products. A text-to-speech (TTS) system converts normal languag ...

) to their clients. MRCP relies on another protocol, such as Real Time Streaming Protocol (RTSP) or

Session Initiation Protocol The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telepho ...

( SIP) for establishing a control session and audio streams between the client and the server. MRCP uses a similar style of clear-text signaling as HTTP and many other Internet protocols, in which each message contains 3 sections: a first-line, a header and a body. The first line indicates the type of message as well as information such as response codes. The header contains a number of lines, each in the format

: . The body, whose length is specified by the header, contains the details of the message. Like HTTP, MRCP uses a request (usually issued by the client) and response model. Responses may simply acknowledge receipt of the request or give other information regarding its processing. For example, an MRCP client may request to send some audio data for processing (say, for speech recognition), to which the server could respond with a message containing a suitable port number to send the data, since MRCP does not have support for audio data specifically as this would have to be handled by some other protocol, such as Real-time Transport Protocol (RTP). MRCP protocol version 2 has been approved as an

RFC RFC may refer to: Computing * Request for Comments, a memorandum on Internet standards * Request for change, change management * Remote Function Call, in SAP computer systems * Rhye's and Fall of Civilization, a modification for Sid Meier's Civ ...

. Version 2 uses SIP for managing sessions and audio streams between the server and the clients, whereas version 1 did not specify the underlying protocol. MRCP has been adopted by a wide range of commercial speech servers, such as

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Skit.ai's VIVA
Microsoft Speech Server,

LumenVox Speech Engine LumenVox is a privately held speech recognition software company based in San Diego, California. LumenVox has been described as one of the market leaders in the speech recognition software industry. History LumenVox was founded in 2001 as subs ...

, ReadSpeaker speechServer MRCP,

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Recognizer and Vocalizer, Sestek TTS, Sestek Call Steering as well as commercial Interactive Voice Response software such as Blueworx Voice Response..

External links

* , A Media Resource Control Protocol (MRCP) * , Media Resource Control Protocol version 2 (MRCPv2)
UniMRCP
An open source cross-platform MRCP implementation Internet protocols Application layer protocols {{multimedia-software-stub