This guide describes how to configure and use the Kaldi Speech Recognition (KaldiSR) plugin to the UniMRCP server. The document is intended for users having a certain knowledge of Kaldi GStreamer Server 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 KaldiSR 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 KaldiSR plugin.

2.1 MRCP Methods

ü DEFINE-GRAMMAR

ü RECOGNIZE

ü START-INPUT-TIMERS

ü STOP

ü SET-PARAMS

ü GET-PARAMS

2.2 MRCP Events

ü RECOGNITION-COMPLETE

ü START-OF-INPUT

2.3 MRCP Header Fields

ü Input-Type

ü No-Input-Timeout

ü Recognition-Timeout

ü Waveform-URI

ü Media-Type

ü Completion-Cause

ü Confidence-Threshold

ü Start-Input-Timers

ü DTMF-Interdigit-Timeout

ü DTMF-Term-Timeout

ü DTMF-Term-Char

ü Save-Waveform

ü Speech-Language

ü Cancel-If-Queue

ü Sensitivity-Level

2.4 Grammars

ü Built-in speech transcription grammar

ü Built-in/embedded DTMF grammar

ü SRGS XML (limited support)

2.5 Results

ü NLSML

3 Configuration Format

The configuration file of the KaldiSR plugin is located in /opt/unimrcp/conf/umskaldisr.xml. The configuration file is written in XML.

3.1 Document

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

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.

Parent

None.

Children

Name	Unit	Description
<kaldi-server-pool>	String	Specifies a pool of Kaldi servers.
<speech-dtmf-input-detector>	String	Specifies parameters of the speech and DTMF input detector.
<utterance-manager>	String	Specifies parameters of the utterance manager.
<rdr-manager>	String	Specifies parameters of the Recognition Details Record (RDR) manager.
<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.

< umskaldisr license-file="umskaldisr_*.lic">

</ umskaldisr>

3.2 Pool of Kaldi Servers

This element specifies a pool of Kaldi servers.

Attributes

None.

Parent

Children

<kaldi-server>

Example

This is an example of a pool of Kaldi servers.

<kaldi-server-pool>

<kaldi-server language="en-US" sampling-rate="16000" instance-count="auto" address="127.0.0.1" port="8080"/>

<kaldi-server language="en-US" sampling-rate="8000" instance-count="auto" address="127.0.0.1" port="8090"/>

</kaldi-server-pool>

3.3 Kaldi Server

This element specifies parameters a Kaldi server.

Attributes

Name	Unit	Description
language	String	Specifies the language supported by the Kaldi server.
sampling-rate	Integer	Specifies the sampling rate supported by the Kaldi server.
instance-count	Integer	Specifies a number of workers running on the Kaldi server. If set to "auto", then the number is determined implicitly.
address	String	Specifies the IP address of the Kaldi server.
port	Integer	Specifies the port number of the Kaldi server.
http-proxy	String	Specifies the URI of HTTP proxy, if used. Available since KaldiSR 1.4.0.

Parent

< kaldi-server-pool>

Children

None.

Example

This is an example of a Kaldi server.

<kaldi-server language="en-US" sampling-rate="16000" instance-count="auto" address="127.0.0.1" port="8080"/>

3.4 Speech and DTMF Input Detector

This element specifies parameters of the speech and DTMF input detector.

Attributes

Name	Unit	Description
vad-mode	Integer	Specifies an operating mode of VAD in the range of [0 ... 3]. Default is 1.
speech-start-timeout	Time interval [msec]	Specifies how long to wait in transition mode before triggering a start of speech input event.
speech-complete-timeout	Time interval [msec]	Specifies how long to wait in transition mode before triggering an end of speech input event.
noinput-timeout	Time interval [msec]	Specifies how long to wait before triggering a no-input event.
input-timeout	Time interval [msec]	Specifies how long to wait for input to complete.
dtmf-interdigit-timeout	Time interval [msec]	Specifies a DTMF inter-digit timeout.
dtmf-term-timeout	Time interval [msec]	Specifies a DTMF input termination timeout.
dtmf-term-char	Character	Specifies a DTMF input termination character.
speech-leading-silence	Time interval [msec]	Specifies desired silence interval preceding spoken input.
speech-trailing-silence	Time interval [msec]	Specifies desired silence interval following spoken input.
speech-output-period	Time interval [msec]	Specifies an interval used to send speech frames to the recognizer.

Parent

Children

None.

Example

The example below defines a typical speech and DTMF input detector having the default parameters set.

<speech-dtmf-input-detector

vad-mode="1"

speech-start-timeout="300"

speech-complete-timeout="1000"

noinput-timeout="5000"

input-timeout="10000"

dtmf-interdigit-timeout="5000"

dtmf-term-timeout="10000"

dtmf-term-char=""

speech-leading-silence="300"

speech-trailing-silence="300"

speech-output-period="200"

3.5 Utterance Manager

This element specifies parameters of the utterance manager.

Attributes

Name	Unit	Description
save-waveforms	Boolean	Specifies whether to save waveforms or not.
purge-existing	Boolean	Specifies whether to delete existing records on start-up.
max-file-age	Time interval [min]	Specifies a time interval in minutes after expiration of which a waveform is deleted. Set 0 for infinite.
max-file-count	Integer	Specifies the max number of waveforms to store. If reached, the oldest waveform is deleted. Set 0 for infinite.
waveform-base-uri	String	Specifies the base URI used to compose an absolute waveform URI.
waveform-folder	Dir path	Specifies a folder the waveforms should be stored in.
file-prefix	String	Specifies a prefix used to compose the name of the file to be stored. Defaults to 'umskaldisr-', if not specified.
use-logging-tag	Boolean	Specifies whether to use the MRCP header field Logging-Tag, if present, to compose the name of the file to be stored. Available since 1.3.0.

Parent

Children

None.

Example

The example below defines a typical utterance manager having the default parameters set.

<utterance-manager

save-waveforms="false"

purge-existing="false"

max-file-age="60"

max-file-count="100"

waveform-base-uri="http://localhost/utterances/"

waveform-folder=""

3.6 RDR Manager

This element specifies parameters of the Recognition Details Record (RDR) manager.

Attributes

Name	Unit	Description
save-records	Boolean	Specifies whether to save recognition details records or not.
purge-existing	Boolean	Specifies whether to delete existing records on start-up.
max-file-age	Time interval [min]	Specifies a time interval in minutes after expiration of which a record is deleted. Set 0 for infinite.
max-file-count	Integer	Specifies the max number of records to store. If reached, the oldest record is deleted. Set 0 for infinite.
record-folder	Dir path	Specifies a folder to store recognition details records in. Defaults to ${UniMRCPInstallDir}/var.
file-prefix	String	Specifies a prefix used to compose the name of the file to be stored. Defaults to 'umskaldisr -', if not specified.
use-logging-tag	Boolean	Specifies whether to use the MRCP header field Logging-Tag, if present, to compose the name of the file to be stored. Available since 1.3.0.

Parent

Children

None.

Example

The example below defines a typical utterance manager having the default parameters set.

<rdr-manager

save-records="false"

purge-existing="false"

max-file-age="60"

max-file-count="100"

waveform-folder=""

3.7 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

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="umskaldisr-channels.status"/>

</usage-refresh-handler >

</monitoring-agent>

3.8 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="umskaldisr-usage.status"/>

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

</usage-change-handler>

3.9 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="umskaldisr-usage.status"/>

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

</usage-refresh-handler>

3.10 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.
http-proxy-address	String	Specifies the IP address or host name of the HTTP proxy server, if used. Available since 1.3.0.
http-proxy-port	Integer	Specifies the port number of the HTTP proxy server, if used. Available since 1.3.0.

Parent

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

4 Configuration Steps

This section outlines common configuration steps.

4.1 Specifying Pool of Kaldi GStreamer Servers

One or more Kaldi GStreamer servers can be specified in the configuration file umskaldisr.xml. Each instance of Kaldi GStreamer server may process a number of concurrent recognition requests for a given language and sampling rate.

In the following example, two Kaldi GStreamer servers are used: one for en-US/16 kHz, the other for en-US/8kHz audio data.

<kaldi-server-pool>

<kaldi-server language="en-US" sampling-rate="16000" instance-count="auto" address="127.0.0.1" port="8080"/>

<kaldi-server language="en-US" sampling-rate="8000" instance-count="auto" address="127.0.0.1" port="8090"/>

</kaldi-server-pool>

For evaluation purposes, Kaldi GStreamer servers may reside on the same host with UniMRCP server. However, in production, UniMRCP and Kaldi GStreamer servers should reside on different hosts in the same LAN.

Note that installation and configuration of the Kaldi GStreamer servers is not covered in this document.

4.2 Specifying Recognition Language

Recognition language can be specified by the client per MRCP session by means of the header field Speech-Language set in a SET-PARAMS or RECOGNIZE request.

4.3 Specifying Sampling Rate

In order to support audio data sampled at 16 kHz, the corresponding codecs needs to be specified in the configuration file unimrcpserver.xml under the XML element <rtp-settings> as follows.

<rtp-settings id="RTP-Settings-1">

<codecs own-preference="false"> PCMU PCMA L16/96/8000 telephone-event/101/8000 PCMU/97/16000 PCMA/98/16000 L16/99/16000 telephone-event/102/16000</codecs>

</rtp-settings>

4.4 Specifying Speech Input Parameters

While the default parameters specified for the speech input detector are sufficient for the general use, various parameters can be adjusted to better suit a particular requirement.

· speech-start-timeout

This parameter is used to trigger a start of speech input. The shorter is the timeout, the sooner a START-OF-INPUT event is delivered to the client. However, a short timeout may also lead to a false positive.

· speech-complete-timeout

This parameter is used to trigger an end of speech input. The shorter is the timeout, the shorter is the response time. However, a short timeout may also lead to a false positive.

· vad-mode

This parameter is used to specify an operating mode of the Voice Activity Detector (VAD) within an integer range of [0 … 3]. A higher mode is more aggressive and, as a result, is more restrictive in reporting speech. The parameter can be overridden per MRCP session by setting the header field Sensitivity-Level in a SET-PARAMS or RECOGNIZE request. The following table shows how the Sensitivity-Level is mapped to the vad-mode.

Sensitivity-Level	Vad-Mode
[0.00 ... 0.25)	0
[0.25 … 0.50)	1
[0.50 ... 0.75)	2
[0.75 ... 1.00]	3

4.5 Specifying DTMF Input Parameters

While the default parameters specified for the DTMF input detector are sufficient for the general use, various parameters can be adjusted to better suit a particular requirement.

· dtmf-interdigit-timeout

This parameter is used to set an inter-digit timeout on DTMF input. The parameter can be overridden per MRCP session by setting the header field DTMF-Interdigit-Timeout in a SET-PARAMS or RECOGNIZE request.

· dtmf-term-timeout

This parameter is used to set a termination timeout on DTMF input and is in effect when dtmf-term-char is set and there is a match for an input grammar. The parameter can be overridden per MRCP session by setting the header field DTMF-Term-Timeout in a SET-PARAMS or RECOGNIZE request.

· dtmf-term-char

This parameter is used to set a character terminating DTMF input. The parameter can be overridden per MRCP session by setting the header field DTMF-Term-Char in a SET-PARAMS or RECOGNIZE request.

4.6 Specifying No-Input and Recognition Timeouts

· noinput-timeout

This parameter is used to trigger a no-input event. The parameter can be overridden per MRCP session by setting the header field No-Input-Timeout in a SET-PARAMS or RECOGNIZE request.

· input-timeout

This parameter is used to limit input (recognition) time. The parameter can be overridden per MRCP session by setting the header field Recognition-Timeout in a SET-PARAMS or RECOGNIZE request.

4.7 Specifying Vendor-Specific Parameters

The following parameters can optionally be specified by the MRCP client in SET-PARAMS, DEFINE-GRAMMAR and RECOGNIZE requests via the MRCP header field Vendor-Specific-Parameters.

Name	Unit	Description
start-of-input	String	Specifies the source of start of input event sent to the client (use "service-originated" for an event originated based on a first-received interim result and "internal" for an event determined by plugin). Available since 1.2.0.
alternatives-below-threshold	Boolean	Specifies whether to return speech recognition result alternatives with the confidence score below the confidence threshold. Available since 1.2.0.
speech-start-timeout	Time interval [msec]	Specifies how long to wait in transition mode before triggering a start of speech input event. Available since 1.2.0.

All the vendor-specific parameters can also be specified at the grammar-level via a built-in or SRGS XML grammar.

The following example demonstrates the use of a built-in grammar with the vendor-specific parameters alternatives-below-threshold and speech-start-timeout set to true and 100 correspondingly.

builtin:speech/transcribe?alternatives-below-threshold=true;speech-start-timeout=100

The following example demonstrates the use of an SRGS XML grammar with the vendor-specific parameters alternatives-below-threshold and speech-start-timeout set to true and 100 correspondingly.

<one-of ><item>blank</item></one-of>

</rule>

</grammar>

4.8 Maintaining Utterances

Saving of utterances is not required for regular operation and is disabled by default. However, enabling this functionality allows to save utterances sent to the Kaldi server and later listen to them offline.

The relevant settings can be specified via the element utterance-manager.

· save-waveforms

Utterances can optionally be recorded and stored if the configuration parameter save-waveforms is set to true. The parameter can be overridden per MRCP session by setting the header field Save-Waveforms in a SET-PARAMS or RECOGNIZE request.

· purge-existing

This parameter specifies whether to delete existing waveforms on start-up.

· max-file-age

This parameter specifies a time interval in minutes after expiration of which a waveform is deleted. If set to 0, there is no expiration time specified.

· max-file-count

This parameter specifies the maximum number of waveforms to store. If the specified number is reached, the oldest waveform is deleted. If set to 0, there is no limit specified.

· waveform-base-uri

This parameter specifies the base URI used to compose an absolute waveform URI returned in the header field Waveform-Uri in response to a RECOGNIZE request.

· waveform-folder

This parameter specifies a path to the directory used to store waveforms in. The directory defaults to ${UniMRCPInstallDir}/var.

4.9 Maintaining Recognition Details Records

Producing of recognition details records (RDR) is not required for regular operation and is disabled by default. However, enabling this functionality allows to store details of each recognition attempt in a separate file and analyze them later offline. The RDRs ate stored in the JSON format.

The relevant settings can be specified via the element rdr-manager.

· save-records

This parameter specifies whether to save recognition details records or not.

· purge-existing

This parameter specifies whether to delete existing records on start-up.

· max-file-age

This parameter specifies a time interval in minutes after expiration of which a record is deleted. If set to 0, there is no expiration time specified.

· max-file-count

This parameter specifies the maximum number of records to store. If the specified number is reached, the oldest record is deleted. If set to 0, there is no limit specified.

· record-folder

This parameter specifies a path to the directory used to store records in. The directory defaults to ${UniMRCPInstallDir}/var.

5 Recognition Grammars and Results

5.1 Using Built-in Speech Transcription

For generic speech transcription, having no speech contexts defined, a pre-set identifier transcribe must be used by the MRCP client in a RECOGNIZE request as follows:

builtin:speech/transcribe

The name of the identifier transcribe can be changed from the configuration file umskaldisr.xml, since KaldiSR 1.1.0.

Speech contexts are defined in the configuration file umskaldisr.xml and available since KaldiSR 1.2.0. A speech context is assigned a unique string identifier and holds a list of phrases.

Below is a definition of a sample speech context directory:

<speech-context id="directory" speech-complete="true">

<phrase>call Steve</phrase>

</speech-context>

Which can be referenced in a RECOGNIZE request as follows:

builtin:speech/directory

The prefixes builtin:speech and builtin:grammar can be used interchangeably as follows:

builtin:grammar/directory

Since KaldiSR 1.2.0, a speech context can be referenced by means metadata in SRGS XML grammar. For example, the following SRGS grammar references a built-in speech context directory.

<grammar mode="voice" root="directory" version="1.0"

xml:lang="en-US"

xmlns="http://www.w3.org/2001/06/grammar">

</grammar>

Where the root rule name identifies a speech context.

5.2 Using Built-in DTMF Grammars

Pre-set built-in DTMF grammars can be referenced by the MRCP client in a RECOGNIZE request as follows:

builtin:dtmf/$id

Where $id is a unique string identifier of the built-in DTMF grammar.

Note that only a DTMF grammar identifier digits is currently supported.

Since KaldiSR 1.2.0, built-in DTMF digits can also be referenced by metadata in SRGS XML grammar. The following example is equivalent to the built-in grammar above.

<grammar mode="dtmf" root="digits" version="1.0"

xml:lang="en-US"

xmlns="http://www.w3.org/2001/06/grammar">

</grammar>

Where the root rule name identifies a built-in DTMF grammar.

5.3 Retrieving Results

Results received from the Kaldi GStreamer server are transformed to the NLSML format.

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.

6.1 Log Usage

The action log-usage logs the following data in the order specified.

· The number of currently in-use channels.

· The maximum number of channels used concurrently. Available since KaldiSR 1.2.0.

· The total number of licensed channels.

The following is a sample log statement, indicating 0 in-use, 0 max-used and 2 total channels.

[NOTICE] KALDISR Usage: 0/0/2

6.2 Update Usage

The action update-usage writes the following data to a status file umskaldisr-usage.status, located by default in the directory ${UniMRCPInstallDir}/var/status.

· The number of currently in-use channels.

· The maximum number of channels used concurrently. Available since KaldiSR 1.2.0.

· The total number of licensed channels.

· The current status of the license permit.

· The license server alarm. Set to on, if the license server is not available for more than one hour; otherwise, set to off. This parameter is maintained only if the license server is used. Available since KaldiSR 1.3.0.

The following is a sample content of the status file.

in-use channels: 0

max used channels: 0

total channels: 2

license permit: true

licserver alarm: off

6.3 Dump Channels

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

7 Usage Examples

7.1 Speech Transcription

This examples demonstrates how to perform speech recognition by using a RECOGNIZE request.

C->S:

MRCP/2.0 336 RECOGNIZE 1

Channel-Identifier: 6e1a2e4e54ae11e7@speechrecog

Content-Id: request1@form-level

Content-Type: text/uri-list

Cancel-If-Queue: false

No-Input-Timeout: 5000

Recognition-Timeout: 10000

Start-Input-Timers: true

Confidence-Threshold: 0.87

Save-Waveform: true

Content-Length: 25

builtin:speech/transcribe

S->C:

MRCP/2.0 83 1 200 IN-PROGRESS

Channel-Identifier: 6e1a2e4e54ae11e7@speechrecog

S->C:

MRCP/2.0 115 START-OF-INPUT 1 IN-PROGRESS

Channel-Identifier: 6e1a2e4e54ae11e7@speechrecog

Input-Type: speech

S->C:

MRCP/2.0 498 RECOGNITION-COMPLETE 1 COMPLETE

Channel-Identifier: 6e1a2e4e54ae11e7@speechrecog

Completion-Cause: 000 success

Waveform-Uri: <http://localhost/utterances/utter-6e1a2e4e54ae11e7-1.wav>;size=20480;duration=1280

Content-Type: application/x-nlsml

Content-Length: 214

<?xml version="1.0"?>

<instance>what's the weather like</instance>

<input mode="speech">what's the weather like</input>

</interpretation>

</result>

7.2 DTMF Recognition

This examples demonstrates how to reference a built-in DTMF grammar in a RECOGNIZE request.

C->S:

MRCP/2.0 266 RECOGNIZE 1

Channel-Identifier: d26bef74091a174c@speechrecog

Content-Type: text/uri-list

Cancel-If-Queue: false

Start-Input-Timers: true

Confidence-Threshold: 0.7

Speech-Language: en-US

Dtmf-Term-Char: #

Content-Length: 19

builtin:dtmf/digits

S->C:

MRCP/2.0 83 1 200 IN-PROGRESS

Channel-Identifier: d26bef74091a174c@speechrecog

S->C:

MRCP/2.0 113 START-OF-INPUT 1 IN-PROGRESS

Channel-Identifier: d26bef74091a174c@speechrecog

Input-Type: dtmf

S->C:

MRCP/2.0 382 RECOGNITION-COMPLETE 1 COMPLETE

Channel-Identifier: d26bef74091a174c@speechrecog

Completion-Cause: 000 success

Content-Type: application/x-nlsml

Content-Length: 197

<?xml version="1.0"?>

</interpretation>

</result>

7.3 Speech and DTMF Recognition

This examples demonstrates how to perform recognition by activating both speech and DTMF grammars. In this example, the user is expected to input a 4-digit pin.

C->S:

MRCP/2.0 275 RECOGNIZE 1

Channel-Identifier: 6ae0f23e1b1e3d42@speechrecog

Content-Type: text/uri-list

Cancel-If-Queue: false

Start-Input-Timers: true

Confidence-Threshold: 0.7

Speech-Language: en-US

Content-Length: 47

builtin:dtmf/digits?length=4

builtin:speech/pin

S->C:

MRCP/2.0 83 2 200 IN-PROGRESS

Channel-Identifier: 6ae0f23e1b1e3d42@speechrecog

S->C:

MRCP/2.0 115 START-OF-INPUT 2 IN-PROGRESS

Channel-Identifier: 6ae0f23e1b1e3d42@speechrecog

Input-Type: speech

S->C:

MRCP/2.0 399 RECOGNITION-COMPLETE 2 COMPLETE

Channel-Identifier: 6ae0f23e1b1e3d42@speechrecog

Completion-Cause: 000 success

Content-Type: application/x-nlsml

Content-Length: 214

<?xml version="1.0"?>

<instance>one two three four</instance>

<input mode="speech">one two three four</input>

</interpretation>

</result>

8 Sequence Diagram

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

9 References

9.1 Kaldi

· Kaldi Speech Recognition Toolkit

· Kaldi GStreamer Server

· Docker Kaldi GStreamer Server

9.2 Specifications

· Speech Recognizer Resource

· NLSML Results