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MRCP

Watson SS Plugin

Usage Guide

 

Revision: 1

Created: June 28, 2018

Last updated: June 28, 2018

Author: Arsen Chaloyan


 

Table of Contents

 

1 Overview.. 3

1.1 Installation. 3

1.2 Applicable Versions. 3

2 Supported Features. 4

2.1 MRCP Methods. 4

2.2 MRCP Events. 4

2.3 MRCP Header Fields. 4

2.4 Speech Data. 4

3 Supported Voices. 5

4 Configuration Format 6

4.1 Document 6

4.2 Synthesis Settings. 7

4.3 Monitoring Agent 8

4.4 Usage Change Handler 8

4.5 Usage Refresh Handler 9

4.6 License Server 10

5 Configuration Steps. 12

5.1 Using Default Configuration. 12

5.2 Specifying Synthesis Language. 12

5.3 Specifying Sampling Rate. 12

5.4 Specifying Voice Parameters. 12

5.5 Specifying Prosody Parameters. 12

5.6 Specifying Speech Data. 13

6 Monitoring Usage Details. 14

7 Usage Examples. 15

7.1 SSML. 15

7.2 Plain Text 15

8 Sequence Diagram.. 17

9 References. 18

9.1 IBM Watson. 18

9.2 Specifications. 18

 

 

1       Overview

This guide describes how to configure and use the IBM Watson Speech Synthesis (SS) plugin to the UniMRCP server. The document is intended for users having a certain knowledge of IBM Watson Text-to-Speech API and UniMRCP.

Asterisk / FreeSWITCH

1.1      Installation

For installation instructions, use one of the guides below.

         RPM Package Installation (Red Hat / Cent OS)

         Deb Package Installation (Debian / Ubuntu)

1.2      Applicable Versions

Instructions provided in this guide are applicable to the following versions.

 

UniMRCP 1.5.0 and above

UniMRCP Watson SS Plugin 1.0.0 and above

 

2       Supported Features

This is a brief check list of the features currently supported by the UniMRCP server running with the Watson SS plugin.

2.1      MRCP Methods

  SPEAK

  STOP

  PAUSE

  RESUME

  BARGE-IN-OCCURRED

  SET-PARAMS

  GET-PARAMS

2.2      MRCP Events

  SPEECH-MARKER

  SPEAK-COMPLETE

2.3      MRCP Header Fields

  Kill-On-Barge-In

  Completion-Cause

  Voice-Gender

  Voice-Name

  Prosody-Rate

  Prosody-Volume

  Speech-Language

2.4      Speech Data

  Plain text (text/plain)

  SSML (application/ssml+xml or application/synthesis+ssml)

3       Supported Voices

All the voices supported by IBM Watson Text-to-Speech API are listed in the following page:

 

https://www.ibm.com/watson/developercloud/text-to-speech/api/v1/curl.html?curl#get-voice

 

4       Configuration Format

The configuration file of the Watson SS plugin is located in /opt/unimrcp/conf/umswatsonss.xml. The configuration file is written in XML.

4.1      Document

The root element of the XML document must be <umswatsonss>.

Attributes

 

Name

Unit

Description

license-file

File path

Specifies the license file. File name may include patterns containing '*' sign. If multiple files match the pattern, the most recent one gets used.

credentials-file

File path

Specifies the IBM Watson credentials file to use. File name may include patterns containing '*' sign. If multiple files match the pattern, the most recent one gets used.

 

Parent

None.

Children

 

Name

Unit

Description

<synth-settings>

String

Specifies synthesis parameters.

<monitoring-agent>

String

Specifies parameters of the monitoring manager.

<license-server>

String

Specifies parameters used to connect to the license server. The use of the license server is optional.

 

Example

This is an example of a bare document.

 

<umswatsonss license-file="umswatsonss_*.lic" credentials-file="watson.credentials">

</ umswatsonss>

 

4.2      Synthesis Settings

This element specifies synthesis parameters.

Attributes

 

Name

Unit

Description

language

String

Specifies the default language to use, if not set by the client.

voice-name

String

Specifies the default voice name. Can be overridden by client.

bypass-ssml

Boolean

Specifies whether transparently bypass or normalize received SSML content before sending it to the speech service for synthesis.

escape-characters

Boolean

Specifies whether to escape special characters in plain text or SSML content.

auth-validation-period

Integer

Specifies a period in seconds used to re-validate access token based on credentials.

 

Parent

<umswatsonss>

Children

None.

Example

This is an example of synthesis parameters.

 

<synth-settings

language="en-US"

voice-name=""

bypass-ssml="false"

escape-characters="false"

auth-validation-period="480"

/>

 

4.3      Monitoring Agent

This element specifies parameters of the monitoring agent.

Attributes

 

Name

Unit

Description

refresh-period

Time interval [sec]

Specifies a time interval in seconds used to periodically refresh usage details. See <usage-refresh-handler>.

 

Parent

<umswatsonss>

Children

<usage-change-handler>

<usage-refresh-handler>

Example

The example below defines a monitoring agent with usage change and refresh handlers.

 

<monitoring-agent refresh-period="60">

 

<usage-change-handler>

<log-usage enable="true" priority="NOTICE"/>

</usage-change-handler>

 

<usage-refresh-handler>

<dump-channels enable="true" status-file="umswatsonss-channels.status"/>

</usage-refresh-handler >

 

</monitoring-agent>

 

4.4      Usage Change Handler

This element specifies an event handler called on every usage change.

Attributes

None.

Parent

<monitoring-agent>

Children

<log-usage>

<update-usage>

<dump-channels>

Example

This is an example of the usage change event handler.

 

<usage-change-handler>

<log-usage enable="true" priority="NOTICE"/>

<update-usage enable="false" status-file="umswatsonss-usage.status"/>

<dump-channels enable="false" status-file="umswatsonss-channels.status"/>

</usage-change-handler>

4.5      Usage Refresh Handler

This element specifies an event handler called periodically to update usage details.

Attributes

None.

Parent

<monitoring-agent>

Children

<log-usage>

<update-usage>

<dump-channels>

Example

This is an example of the usage change event handler.

 

<usage-refresh-handler>

<log-usage enable="true" priority="NOTICE"/>

<update-usage enable="false" status-file="umswatsonss-usage.status"/>

<dump-channels enable="false" status-file="umswatsonss-channels.status"/>

</usage-refresh-handler>

 

4.6      License Server

This element specifies parameters used to connect to the license server.

Attributes

 

Name

Unit

Description

enable

Boolean

Specifies whether the use of license server is enabled or not. If enabled, the license-file attribute is not honored.

server-address

String

Specifies the IP address or host name of the license server.

certificate-file

File path

Specifies the client certificate used to connect to the license server. File name may include patterns containing a '*' sign. If multiple files match the pattern, the most recent one gets used.

ca-file

File path

Specifies the certificate authority used to validate the license server.

channel-count

Integer

Specifies the number of channels to check out from the license server. If not specified or set to 0, either all available channels or a pool of channels will be checked based on the configuration of the license server.

 

Parent

<umswatsonss>

Children

None.

Example

The example below defines a typical configuration which can be used to connect to a license server located, for example, at 10.0.0.1.

 

<license-server

enable="true"

server-address="10.0.0.1"

certificate-file="unilic_client_*.crt"

ca-file="unilic_ca.crt"

/>

 

For further reference to the license server, visit

 

http://unimrcp.org/licserver

 

 

5       Configuration Steps

This section outlines common configuration steps.

5.1      Using Default Configuration

The default configuration should be sufficient for the general use.

5.2      Specifying Synthesis Language

Synthesis language can be specified by the client per MRCP session by means of the header field Speech-Language set in a SET-PARAMS or SPEAK request, or inline in the SSML data. Otherwise, the parameter language set in the configuration file umswatsonss.xml is used. The parameter defaults to en-US.

5.3      Specifying Sampling Rate

Sampling rate is determined based on the SDP negotiation. Refer to the configuration guide of the UniMRCP server on how to specify supported encodings and sampling rates to be used in communication between the client and server. Either 8 or 16 kHz can be used by IBM Watson Text-to-Speech API.

5.4      Specifying Voice Parameters

Global Settings

The default voice name can be specified from the configuration file umswatsonss.xml using the voice-name attribute of the synth-settings element.

MRCP Header Fields

The voice name and gender can be specified by the MRCP client in SET-PARAMS and SPEAK requests.

         Voice-Name

This is an optional parameter indicating the name of the voice to use for synthesis.

SSML Content

The voice name can also be specified using the corresponding attributes of the voice element in SSML content. In order to parse and determine the parameter and pass it forward to IBM Watson Text-to-Speech API accordingly, the bypass-ssml attribute of the synth-settings element must be set to false in the configuration file umswatson.xml.

5.5      Specifying Prosody Parameters

The following prosody parameters can be specified by the MRCP client in SET-PARAMS and SPEAK requests.

         Prosody-Rate

This is an optional parameter indicating the speaking rate, which can be set to one of the following labels: x-slow, slow, medium, fast, x-fast, default.

         Prosody-Volume

This is an optional parameter indicating the speaking volume, which can be set to one of the following labels: silent, x-soft, soft, medium, loud, x-loud, default.

5.6      Specifying Speech Data

Speech data can be specified by the MRCP client in SPEAK requests using one of the following content types:

         plain/text

         application/ssml+xml (or application/synthesis+ssml)

 

6       Monitoring Usage Details

The number of in-use and total licensed channels can be monitored in several alternate ways. There is a set of actions which can take place on certain events. The behavior is configurable via the element monitoring-agent, which contains two event handlers: usage-change-handler and usage-refresh-handler.

 

While the usage-change-handler is invoked on every acquisition and release of a licensed channel, the usage-refresh-handler is invoked periodically on expiration of a timeout specified by the attribute refresh-period.

 

The following actions can be specified for either of the two handlers.

         log-usage

This action logs the number of in-use and total licensed channels. The following is a sample log statement, indicating 0 in-use and 2 total channels.

 

[NOTICE] WSS Usage: 0/2

 

         update-usage

This action writes the number of in-use and total licensed channels to a status file umswatsonss-usage.status, located by default in the directory ${UniMRCPInstallDir}/var/status. The following is a sample content of the status file.

 

in-use channels: 0

total channels: 2

 

         dump-channels

This action writes the identifiers of in-use channels to a status file umswatsonss-channels.status, located by default in the directory ${UniMRCPInstallDir}/var/status.

 

 

7       Usage Examples

7.1      SSML

This examples demonstrates how to perform speech synthesis by using a SPEAK request with an SSML content.

 

C->S:

 

MRCP/2.0 309 SPEAK 1

Channel-Identifier: 4dde51f37d1a9546@speechsynth

Content-Type: application/ssml+xml

Voice-Age: 28

Content-Length: 163

 

<?xml version="1.0"?>

<speak version="1.0" xml:lang="en-US" xmlns="http://www.w3.org/2001/10/synthesis">

<p>

<s>Welcome to Uni MRCP.</s>

</p>

</speak>

 

S->C:

 

MRCP/2.0 83 1 200 IN-PROGRESS

Channel-Identifier: 4dde51f37d1a9546@speechsynth

 

 

S->C:

 

MRCP/2.0 122 SPEAK-COMPLETE 1 COMPLETE

Channel-Identifier: 4dde51f37d1a9546@speechsynth

Completion-Cause: 000 normal

 

 

7.2      Plain Text

This examples demonstrates how to perform speech synthesis by using a SPEAK request with a plain text content.

 

C->S:

 

MRCP/2.0 155 SPEAK 1

Channel-Identifier: 85667d0efbf95345@speechsynth

Content-Type: text/plain

Voice-Age: 28

Content-Length: 20

 

Welcome to Uni MRCP.

 

S->C:

 

MRCP/2.0 83 1 200 IN-PROGRESS

Channel-Identifier: 85667d0efbf95345@speechsynth

 

 

S->C:

 

MRCP/2.0 122 SPEAK-COMPLETE 1 COMPLETE

Channel-Identifier: 85667d0efbf95345@speechsynth

Completion-Cause: 000 normal

 

8       Sequence Diagram

The following sequence diagram outlines common interactions between all the main components involved in a typical synthesis session performed over MRCPv2.

9       References

9.1      IBM Watson

         Text to Speech API

         Credentials

9.2      Specifications

         Speech Synthesizer Resource

         SSML