¶ 1 Overview
This guide describes how to configure and use the Nuance Speech Recognition (SR) plugin to the UniMRCP server. The document is intended for users having a certain knowledge of Nuance Mix ASRaaS, NLUaaS, NRaaS APIs and UniMRCP.
¶ 1.1 Installation
For installation of the packages, use one of the manuals below.
RPM Installation Manual Red Hat / CentOS
Deb Installation Manual Debian / Ubuntu¶ 1.2 Applicable Versions
Instructions provided in this guide are applicable to the following versions.
UniMRCP 1.7.0 and above
UniMRCP Nuance SR 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 Nuance SR plugin.
¶ 2.1 MRCP Methods
-
DEFINE-GRAMMAR
-
RECOGNIZE
-
START-INPUT-TIMERS
-
STOP
-
SET-PARAMS
-
GET-PARAMS
¶ 2.2 MRCP Events
-
RECOGNITION-COMPLETE
-
START-OF-INPUT
¶ 2.3 MRCP Header Fields
-
Input-Type
-
No-Input-Timeout
-
Recognition-Timeout
-
Speech-Complete-Timeout
-
Speech-Incomplete-Timeout
-
Waveform-URI
-
Media-Type
-
Completion-Cause
-
Confidence-Threshold
-
Start-Input-Timers
-
DTMF-Interdigit-Timeout
-
DTMF-Term-Timeout
-
DTMF-Term-Char
-
Save-Waveform
-
Speech-Language
-
Cancel-If-Queue
-
Sensitivity-Level
¶ 2.4 Grammars
-
Built-in and dynamic speech contexts
-
Built-in/embedded DTMF grammar
-
SRGS XML (limited support)
¶ 2.5 Results
- NLSML
¶ 3 Configuration Format
The configuration file of the Nuance SR plugin is located in /opt/unimrcp/conf/umsnuancesr.xml. The configuration file is written in XML.
¶ 3.1 Document
The root element of the XML document must be <umsnuancesr>.
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. |
| subscription-key-file | File path | Specifies the Nuance Mix credentials 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 |
|---|---|---|
| streaming-recognition | String | Specifies parameters of streaming recognition method employed via gRPC. |
| nlu | String | Specifies parameters of the NLU post-processing method employed via gRPC. Available since 1.1.0. |
| speech-contexts | String | Contains a list of speech contexts. |
| 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.
<umsnuancesr license-file="umsnuancesr_*.lic" subscription-key-file="nuance.subscription.key">
</umsnuancesr>
¶ 3.2 Streaming Recognition
This element specifies parameters of streaming recognition.
Attributes
| Name | Unit | Description |
|---|---|---|
| language | String | Specifies the default language to use, if not set by the client. |
| 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). |
| max-alternatives | Integer | Specifies the maximum number of speech recognition result alternatives to be returned. Can be overridden by client by means of the header field N-Best-List-Length. |
| alternatives-below-threshold | Boolean | Specifies whether to return speech recognition result alternatives with the confidence score below the confidence threshold. |
| sort-alternatives | Boolean | specifies whether to sort speech recognition result alternatives to ensure the order based on confidence score (the highest first). |
| confidence-format | String | Specifies the format of the confidence score to be returned (use "auto" for a format based on protocol version, "mrcpv2" for a float value in the range of 0..1, "mrcpv1" for an integer value in the range of 0..100). |
| single-utterance | Boolean | Specifies whether to detect a single spoken utterance or perform continuous recognition. |
| results-indent | Integer | Specifies the indentation used to compose NLSML results. |
| skip-unsupported-grammars | Boolean | Specifies whether to skip or raise an error while referencing a malformed or not supported grammar. |
| skip-empty-results | Boolean | Specifies whether to implicitly initiate a new gRPC request if the current one completes with an empty result. |
| transcription-grammar | String | Specifies the name of the built-in speech transcription grammar. The grammar can be referenced as builtin:speech/transcribe or builtin:grammar/transcribe, where transcribe is the default value of this parameter. |
| grammar-param-separator | String | specifies a separator of optional parameters passed to a built-in grammar. The separator defaults to ';'. |
| http-proxy | String | Specifies the URI of HTTP proxy, if used. |
| stream-creation-timeout | Time interval [msec] | Specifies how long to wait for gRPC stream creation. If timeout is set 0, no timer is used. Otherwise, if timeout is elapsed, gRPC stream creation is cancelled. |
| grpc-log-redirection | Boolean | Specifies whether to enable gRPC log redirection. |
| grpc-log-verbosity | String | Specifies gRPC logging verbosity. One of DEBUG, INFO, ERROR. See GRPC_VERBOSITY for more info. |
| grpc-log-trace | String | Specifies a comma separated list of tracers producing gRPC logs. Use 'all' to turn all tracers on. See GRPC_TRACE for more info. |
| inter-result-timeout | Time interval [msec] | Specifies a timeout between interim results containing transcribed speech. If the timeout is elapsed, input is considered complete. The timeout defaults to 0 (disabled). |
| tag-format | String | Specifies the format of the instance element to be returned. Use one of:
|
| auth-validation-period | Time interval [sec] | Specifies a period in seconds used to re-validate access token. |
| auth-request-timeout | Time interval [sec] | Specifies a timeout in seconds set on HTTP requests placed to re-validate access token. |
| topic | String | Specifies the topic field in RecognitionParameters. |
| speech-domain | String | Specifies the speech_domain field in RecognitionParameters. |
| formatting-scheme | String | Specifies the formatting scheme field in RecognitionParameters. |
| auto-punctuate | Boolean | Specifies whether to enable automatic punctuation. |
| filter-profanity | Boolean | Specifies whether to filter profanities in recognition result. |
| include-tokenization | Boolean | Specifies whether to include tokenized recognition result. |
| discard-speaker-adaptation | Boolean | Specifies whether to discard updated speaker data, if speaker profiles are used. By default, data is stored. |
| suppress-call-recording | Boolean | Specifies whether to redact transcription results in the call logs and disable audio capture. |
| mask-load-failures | Boolean | Specifies whether errors loading external resources shall not terminate recognition. |
| suppress-initial-capitalization | Boolean | Specifies whether to suppress automatic capitalization of the first word in a sentence. |
| allow-zero-base-lm-weight | Boolean | Specifies whether custom resources (DLMs, wordsets, and others) can use the entire weight space. |
| filter-wakeup-word | Boolean | Specifies whether to remove the wakeup word from the final result. |
| api | String | Specifies the API to use, including the version of the API. One of ASRv1 or NRv1. Available since 1.2.0. |
| result-format | String | Specifies the format the recognition result is returned by the NRaaS API. The parameter is observed if api is set to NRv1. Available since 1.2.0. |
| result-format-parameters | String | Specifies additional parameters of the format the recognition result is returned by the NRaaS API. The parameter is observed if api is set to NRv1. Available since 1.2.0. |
| secure-context-level | String | Specifies the level of security for the recognition performed by the NRaaS API. The parameter is observed if api is set to NRv1. Available since 1.2.0. |
Parent
<umsnuancesr>
Children
- None.
Example
This is an example of streaming recognition element.
<streaming-recognition
single-utterance="true"
start-of-input="service-originated"
language="en-US"
max-alternatives="1"
alternatives-below-threshold="false"
sort-alternatives="false"
confidence-format="auto"
results-indent="2"
skip-empty-results="true"
skip-unsupported-grammars="true"
transcription-grammar="transcribe"
grammar-param-separator=";"
stream-creation-timeout="0"
inter-result-timeout="2000"
grpc-log-redirection="false"
grpc-log-verbosity=""
grpc-log-trace=""
tag-format="default"
topic=""
speech-domain=""
auto-punctuate="false"
filter-profanity="false"
include-tokenization="false"
discard-speaker-adaptation="false"
suppress-call-recording="false"
mask-load-failures="false"
suppress-initial-capitalization="false"
allow-zero-base-lm-weight="false"
filter-wakeup-word="false"
auth-validation-period="600"
auth-request-timeout="30"
/>
¶ 3.3 NLU
This element specifies parameters of streaming recognition.
Availability
>= 1.1.0.
Attributes
| Name | Unit | Description |
|---|---|---|
| enable | Boolean | Specifies whether to enable the NLU service. |
| deadline | Time interval [msec] | Specifies the gRPC call deadline. The deadline is specified in ms and defaults to 0 (disabled). |
| interpretation-result-type | String | Specifies the interpretation_result_type field in InterpretationParameters. |
| interpretation-input-logging-mode | String | Specifies the interpretation_input_logging_mode field in InterpretationParameters. |
| resource-type | String | Specifies the type field in ResourceReference. |
| resource-uri | String | Specifies the uri field in ResourceReference. |
Parent
<umsnuancesr>
Children
- None.
Example
This is an example of nlu element.
<nlu
enable="true"
deadline="0"
interpretation-result-type=""
interpretation-input-logging-mode=""
resource-type=""
resource-uri=""
/>
¶ 3.4 Speech Contexts
This element specifies a list of speech contexts.
Attributes
- None.
Parent
<umsnuancesr>
Children
<speech-context>
Example
The example below defines two speech contexts booking and directory.
<speech-contexts>
<speech-context id="booking" enable="true">
<phrase>I would like to book a flight from New York to Rome with a ticket eligible for free cancellation</phrase>
<phrase>I would like to book a one-way flight from New York to Rome</phrase>
</speech-context>
<speech-context id="directory" enable="true">
<phrase>call Steve</phrase>
<phrase>call John</phrase>
<phrase>dial 5</phrase>
<phrase>dial 6</phrase>
</speech-context>
</speech-contexts>
¶ 3.5 Speech Context
This element specifies a speech context.
Attributes
| Name | Unit | Description |
|---|---|---|
| id | String | Specifies a unique string identifier of the speech context to be referenced by the MRCP client. |
| enable | Boolean | Specifies whether the speech context is enabled or disabled. |
| speech-complete | Boolean | Specifies whether to complete input as soon as an interim result matches one of the specified phrases. |
| language | String | The language the phrases are defined for. |
| scope | String | Specifies a scope of the speech context, which can be set to either hint or strict. |
Parent
<speech-contexts>
Children
<phrase>
Example
This is an example of speech context element.
<speech-context id="directory" enable="true">
<phrase>call Steve</phrase>
<phrase>call John</phrase>
<phrase>dial 5</phrase>
<phrase>dial 6</phrase>
</speech-context>
¶ 3.6 Phrase
This element specifies a phrase in the speech context.
Attributes
| Name | Unit | Description |
|---|---|---|
| tag | String | Specifies an optional arbitrary string identifier to be returned as an instance in the NLSML result, if the transcription result matches the phrase. |
Parent
<speech-context>
Children
- None.
This is an example of a speech context with phrases having tags specified.
<speech-context id="boolean" speech-complete="true" scope="strict" enable="true">
<phrase tag="true">yes</phrase>
<phrase tag="true">sure</phrase>
<phrase tag="true">correct</phrase>
<phrase tag="false">no</phrase>
<phrase tag="false">not sure</phrase>
<phrase tag="false">incorrect </phrase>
</speech-context>
¶ 3.7 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. The complete timeout is used when there is an interim result available. |
| speech-incomplete-timeout | Time interval [msec] | Specifies how long to wait in transition mode before triggering an end of speech input event. The incomplete timeout is used as long as there is no interim result available. Afterwards, the complete timeout is used. |
| 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
<umsnuancesr>
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="2"
speech-start-timeout="300"
speech-complete-timeout="1000"
speech-incomplete-timeout="15000"
noinput-timeout="5000"
input-timeout="30000"
dtmf-interdigit-timeout="5000"
dtmf-term-timeout="10000"
dtmf-term-char=""
speech-leading-silence="300"
speech-trailing-silence="300"
speech-output-period="200"
/>
¶ 3.8 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 'umsnuancesr-', 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. |
Parent
<umsnuancesr>
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=""
/>
¶ 3.9 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 'umsnuancesr-', 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. |
Parent
<umsnuancesr>
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=""
/>
¶ 3.10 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
<umsnuancesr>
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="umsnuancesr-channels.status"/>
</usage-refresh-handler >
</monitoring-agent>
¶ 3.11 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="umsnuancesr-usage.status"/>
<dump-channels enable="false" status-file="umsnuancesr-channels.status"/>
</usage-change-handler>
¶ 3.12 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="umsnuancesr-usage.status"/>
<dump-channels enable="false" status-file="umsnuancesr-channels.status"/>
</usage-refresh-handler>
¶ 3.13 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. |
| http-proxy-port | Integer | Specifies the port number of the HTTP proxy server, if used. |
| security-level | Integer | Specifies the SSL security level, which defaults to 1. Applicable since OpenSSL 1.1.0. |
Parent
<umsnuancesr>
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"
/>
License Server Check out the concepts¶ 4 Configuration Steps
This section outlines common configuration steps.
¶ 4.1 Using Default Configuration
The default configuration should be sufficient for the general use.
¶ 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. Otherwise, the parameter language set in the configuration file umsnuancesr.xml is used. The parameter defaults to en-US.
The recognition language can be set by the attribute xml:lang specified in the SRGS grammar.
<?xml version="1.0" encoding="UTF-8"?>
<grammar mode="voice" root="transcribe" version="1.0"
xml:lang="es-ES"
xmlns="http://www.w3.org/2001/06/grammar">
<meta name="scope" content="builtin"/>
<rule id="transcribe"><one-of/></rule>
</grammar>
The recognition language can also be set by the optional parameter language passed to a built-in grammar.
builtin:speech/transcribe?language=es-ES
¶ 4.3 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.
The native sampling rate with the linear16 audio encoding is used in gRPC streaming to the service endpoint.
¶ 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.
Note that both events, an expiration of the speech complete timeout and a final response delivered from the service endpoint, are monitored to trigger an end of speech input, on whichever comes first basis. In order to rely solely on an event delivered from the speech service, the parameter speech-complete-timeout needs to be set to a higher value.
- 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. Since 1.4.0 release, the parameter can be overridden per MRCP session via the vendor-specific parameters.
¶ 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 Speech Recognition Mode
Single Utterance Mode
By default, if the configuration parameter single-utterance is set to true, recognition is performed in the single utterance mode and is terminated upon an expiration of the speech complete timeout or a final response delivered from the service endpoint.
Continuous Recognition Mode
In the continuous speech recognition mode, when the configuration parameter single-utterance is set to false, recognition is terminated upon an expiration of the speech complete timeout, which is recommended to be set in the range of 1500 msec to 3000 msec. The service endpoint may return multiple results (sub utterances), which are concatenated and sent back to the MRCP client in a single RECOGNITION-COMPLETE event.
The parameter single-utterance can be overridden per MRCP session by setting the header field Vendor-Specific-Parameters in a SET-PARAMS or RECOGNIZE request, where the parameter name is single-utterance and acceptable values are true and false.
¶ 4.8 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). |
| alternatives-below-threshold | Boolean | Specifies whether to return speech recognition result alternatives with the confidence score below the confidence threshold. |
| speech-start-timeout | Time interval [msec] | Specifies how long to wait in transition mode before triggering a start of speech input event. |
| skip-empty-results | Boolean | Specifies whether to implicitly initiate a new gRPC request if the current one completes with an empty result. |
| interim-result-timeout | Time interval [msec] | Specifies a timeout between interim results containing transcribed speech. If the timeout is elapsed, input is considered complete. |
| logging-tag | String | Specifies the logging tag. |
| tag-format | String | Specifies the format of the instance element to be returned. |
| service-uri | String | Specifies the service endpoint uri. |
| topic | String | Specifies the topic field in RecognitionParameters. |
| speech-domain | String | Specifies the speech_domain field in RecognitionParameters. |
| formatting-scheme | String | Specifies the formatting scheme field in RecognitionParameters. |
| auto-punctuate | Boolean | Specifies whether to enable automatic punctuation. |
| filter-profanity | Boolean | Specifies whether to filter profanities in recognition result. |
| include-tokenization | Boolean | Specifies whether to include tokenized recognition result. |
| discard-speaker-adaptation | Boolean | Specifies whether to discard updated speaker data, if speaker profiles are used. By default, data is stored. |
| suppress-call-recording | Boolean | Specifies whether to redact transcription results in the call logs and disable audio capture. |
| mask-load-failures | Boolean | Specifies whether errors loading external resources shall not terminate recognition. |
| suppress-initial-capitalization | Boolean | Specifies whether to suppress automatic capitalization of the first word in a sentence. |
| allow-zero-base-lm-weight | Boolean | Specifies whether custom resources (DLMs, wordsets, and others) can use the entire weight space. |
| filter-wakeup-word | Boolean | Specifies whether to remove the wakeup word from the final result. |
| recognition-resources-json | String | Specifies the resources field set in RecognitionInitMessage. The value of this parameter must transparently be specified in JSON. |
| client-data.* | String | Specifies transparent name/value parameters set in the client_data field in RecognitionInitMessage. The name must start with a prefix "client-data.". |
| user-id | String | Specifies the user_id field set in RecognitionInitMessage. |
| nlu-service-uri | String | Specifies the NLU service endpoint uri. Available since 1.1.0. |
| nlu-deadline | Time interval [msec] | Specifies the gRPC call deadline. Available since 1.1.0. |
| nlu-interpretation-result-type | String | Specifies the interpretation_result_type field in InterpretationParameters. Available since 1.1.0. |
| nlu-interpretation-input-logging-mode | String | Specifies the interpretation_input_logging_mode field in InterpretationParameters. Available since 1.1.0. |
| nlu-resource-type | String | Specifies the type field in ResourceReference. Available since 1.1.0. |
| nlu-resource-uri | String | Specifies the uri field in ResourceReference. Available since 1.1.0. |
| nlu-resources-json | String | Specifies the resources field in InterpretRequest in JSON. Available since 1.1.0. |
| nlu-model-json | String | Specifies the model field in InterpretRequest in JSON. Available since 1.1.0. |
| nlu-parameters-json | String | Specifies the parameters field in InterpretRequest in JSON. Available since 1.1.0. |
| api | String | Specifies the API to use, including the version of the API. One of ASRv1 or NRv1. Available since 1.2.0. |
| result-format | String | Specifies the format the recognition result is returned by the NRaaS API. The parameter is observed if api is set to NRv1. Available since 1.2.0. |
| result-format-parameters | String | Specifies additional parameters of the format the recognition result is returned by the NRaaS API. The parameter is observed if api is set to NRv1. Available since 1.2.0. |
| secure-context-level | String | Specifies the level of security for the recognition performed by the NRaaS API. The parameter is observed if api is set to NRv1. Available since 1.2.0. |
| vad-mode | Integer | Specifies an operating mode of VAD in the range of [0 ... 3]. Default is 1. Available since 1.4.0. |
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.
<grammar mode="voice" root="transcribe" version="1.0" xml:lang="en-US" xmlns="http://www.w3.org/2001/06/grammar">
<meta name="scope" content="builtin"/>
<meta name="alternatives-below-threshold" content="true"/>
<meta name="speech-start-timeout" content="100"/>
<rule id="transcribe">
<one-of ><item>blank</item></one-of>
</rule>
</grammar>
¶ 4.9 Specifying Recognition Resources
The resources field in RecognitionInitMessage can transparently be specified in JSON by means of the vendor-specific parameter recognition-resources-json.
¶ External Reference
The following example demonstrates the use of an external reference passed to a built-in grammar.
builtin:speech/transcribe?recognition-resources-json=[{"external_reference": {"type": "DOMAIN_LM", "uri": "urn:nuance-mix:tag:model/names-places/mix.asr?=language=eng-USA"}}]
¶ Inline Wordset
The following example demonstrates the use of an inline wordset passed to a built-in grammar.
builtin:speech/transcribe?recognition-resources-json=[{"inline_wordset": "{\"PLACES\":[{\"literal\":\"La Jolla\",\"spoken\":[\"la hoya\",\"la jolla\"]},{\"literal\":\"Llanfairpwllgwyngyll\",\"spoken\":[\"lan vire pool guin gill\"]},{\"literal\":\"Abington Pigotts\"},{\"literal\":\"Steeple Morden\"},{\"literal\":\"Hoyland Common\"},{\"literal\":\"Cogenhoe\",\"spoken\":[\"cook no\"]},{\"literal\":\"Fordoun\",\"spoken\":[\"forden\",\"fordoun\"]},{\"literal\":\"Llangollen\",\"spoken\":[\"lan goth lin\",\"lan gollen\"]},{\"literal\":\"Auchenblae\"}]}", "weight_value": "0.2"}]
¶ Builtin
The following example demonstrates the use of a builtin resource in the data pack passed to a built-in grammar.
builtin:speech/transcribe?recognition-resources-json=[{"builtin": "CALENDARX", "weight_value": "0.2"}, {"builtin": "DISTANCE", "weight_value": "0.2"}]
¶ Wakeup Word
The following example demonstrates the use of wakeup words passed to a built-in grammar.
builtin:speech/transcribe?recognition-resources-json=[{"wakeup_word ": {"words": ["Hi Dragon", "Hey Dragon", "Yo Dragon"]}}]
¶ 4.10 Specifying Client Data
The following example demonstrates the use of client data passed to a built-in grammar.
builtin:speech/transcribe?client-data.call-id=22abe481329346518d11a3b2b599fe00;client-data.called-number=2876001223
As a result, the call-id and called-number parameters will be set in the client_data field in RecognitionInitMessage.
¶ 4.11 Specifying User ID
The following example demonstrates the use of user id passed to a built-in grammar.
builtin:speech/transcribe?user-id=126673
As a result, the user-d parameter will be set in the user_id field in RecognitionInitMessage.
¶ 4.12 Using NLU
Since 1.1.0, it is possible to place a follow-up request to the NLUaaS API after the request to the ASRaaS API completes.
- The use of NLU API must be enabled first. See the configuration parameter 'enable' in the 'nlu' element (enabled by default).
- A semantic model must be specified either globally (the configuration parameter 'resource-uri' in the 'nlu' element) or dynamically in a recognition request via vendor-specific parameters ('nlu-resource-uri' or 'nlu-model-json').
The following example demonstrates how to set the NLU resource uri via a built-in grammar.
builtin:speech/transcribe?nlu-resource-uri=urn:nuance-mix:tag:model/A5315_C1/mix.nlu?=language=eng-USA
The following example demonstrates how to set the NLU parameters and model via a built-in grammar.
builtin:speech/transcribe?nlu-parameters-json={"maxInterpretations":3};nlu-model-json={"uri":"urn:nuance-mix:tag:model/A5315_C1/mix.nlu?=language=eng-USA"}
¶ 4.13 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 service endpoint 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.
¶ 4.14 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 ${UniMRCPInstallDir}/var.
¶ 5 Recognition Grammars and Results
¶ 5.1 Using Built-in Speech Contexts
Pre-set built-in speech contexts can be referenced by the MRCP client in a RECOGNIZE request as follows:
builtin:speech/$id
Where $id is a unique string identifier of built-in speech context.
Speech contexts are defined in the configuration file umsnuancesr.xml. A speech context is assigned a unique string identifier and holds a list of phrases which can optionally be passed to the service endpoint to improve the recognition accuracy.
Below is a definition of a sample speech context directory:
<speech-context id="directory">
<phrase>call Steve</phrase>
<phrase>call John</phrase>
<phrase>dial 5</phrase>
<phrase>dial 6</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
For generic speech transcription, having no speech contexts defined, a pre-set identifier transcribe must be used.
builtin:speech/transcribe
The name of the identifier transcribe can be changed from the configuration file umsnuancesr.xml.
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">
<meta name="scope" content="builtin"/>
<rule id="directory"><one-of/></rule>
</grammar>
Where the root rule name identifies a speech context.
¶ 5.2 Using Dynamic Speech Contexts
The MRCP client can also dynamically specify a speech context either
-
in a DEFINE-GRAMMAR request by further referencing the defined speech context in a RECOGNIZE request using the session URI scheme
-
or inline in a RECOGNIZE request
While composing a DEFINE-GRAMMAR or RECOGNIZE request containing speech context definition, the following should be considered.
-
The value of the header field Content-Id must be used as a unique string identifier of the speech context being defined.
-
The value of the header field Content-Type must be set to application/xml.
-
The message body must contain a definition of the speech context, composed based on the XML format of the element <speech-context>, specified in the configuration file umsnuancesr.xml. Note that the unique identifier of the speech context is set based on the header field Content-Id, as opposed to the attribute Id when loading from configuration.
A dynamic speech context can be specified by means of the <one-of> construct in SRGS XML grammar. For example:
<grammar mode="voice" root="booking" version="1.0"
xml:lang="en-US"
xmlns="http://www.w3.org/2001/06/grammar">
<meta name="scope" content="hint"/>
<rule id="booking">
<one-of>
<item> I would like to book a flight from New York to Rome with a ticket eligible for free cancellation</item>
<item> I would like to book a one-way flight from New York to Rome</item>
<one-of>
</rule>
</grammar>
¶ 5.3 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. For example:
builtin:dtmf/digits
Note that only a DTMF grammar identifier digits is currently supported.
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">
<meta name="scope" content="builtin"/>
<rule id="digits"><one-of/></rule>
</grammar>
Where the root rule name identifies a built-in DTMF grammar.
¶ 5.4 Using HTTP Grammars
External HTTP grammars can be used with the NRaaS API. For example:
https://www.example.com/sample_grammar.xml
Since 1.4.0, to use an extrenal HTTP grammar for DTMFs, the 'grammar-mode' should be set to 'dtmf' to explitly indicate that the referenced grammar is for DTMFs. The parameter defaults to 'speech' if not specified. For example:
https://www.example.com/sample_speech_grammar.xml
https://www.example.com/sample_dtmf_grammar.xml?grammar-mode=dtmf
¶ 5.5 Retrieving Results
Results received from the service endpoint are transformed to the NLSML format with no semantic interpretation performed and sent to the MRCP client in a RECOGNITION-COMPLETE event.
Limited support for semantic interpretation is added to processing of SRGS XML grammars. Only <one-of> construct and literal tags are currently supported.
¶ 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.
-
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] NUANCESR Usage: 0/0/2
¶ 6.2 Update Usage
The action update-usage writes the following data to a status file umsnuancesr-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.
- 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.
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 umsnuancesr-channels.status, located by default in the directory ${UniMRCPInstallDir}/var/status.
¶ 7 Usage Examples
¶ 7.1 Speech Recognition without Speech Context
This example demonstrates how to perform speech recognition by using a RECOGNIZE request, having no speech contexts defined.
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"?>
<result>
<interpretation grammar="builtin:speech/transcribe" confidence="0.88">
<instance>call Steve</instance>
<input mode="speech">call Steve</input>
</interpretation>
</result>
¶ 7.2 Speech Recognition with Built-in Speech Context
This example demonstrates how to perform speech recognition by using a RECOGNIZE request to reference a pre-set built-in speech context directory on the server.
C->S:
MRCP/2.0 335 RECOGNIZE 1
Channel-Identifier: 3ea18b9854af11e7@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: 24
builtin:speech/directory
S->C:
MRCP/2.0 83 1 200 IN-PROGRESS
Channel-Identifier: 3ea18b9854af11e7@speechrecog
S->C:
MRCP/2.0 115 START-OF-INPUT 1 IN-PROGRESS
Channel-Identifier: 3ea18b9854af11e7@speechrecog
Input-Type: speech
S->C:
MRCP/2.0 497 RECOGNITION-COMPLETE 1 COMPLETE
Channel-Identifier: 3ea18b9854af11e7@speechrecog
Completion-Cause: 000 success
Waveform-Uri: <http://localhost/utterances/utter-3ea18b9854af11e7-1.wav>;size=20480;duration=1280
Content-Type: application/x-nlsml
Content-Length: 213
<?xml version="1.0"?>
<result>
<interpretation grammar="builtin:speech/directory" confidence="0.88">
<instance>call Steve</instance>
<input mode="speech">call Steve</input>
</interpretation>
</result>
¶ 7.3 Speech Recognition with Dynamic Speech Context
This example demonstrates how to perform speech recognition, by using a DEFINE-GRAMMAR request to specify a speech context and further reference the defined speech context in a RECOGNIZE request.
C->S:
MRCP/2.0 314 DEFINE-GRAMMAR 1
Channel-Identifier: 25902c3a54b011e7@speechrecog
Content-Type: application/xml
Content-Id: request1@form-level
Content-Length: 146
<speech-context>
<phrase>call Steve</phrase>
<phrase>call John</phrase>
<phrase>dial 5</phrase>
<phrase>dial 6</phrase>
</speech-context>
S->C:
MRCP/2.0 112 1 200 COMPLETE
Channel-Identifier: 25902c3a54b011e7@speechrecog
Completion-Cause: 000 success
C->S:
MRCP/2.0 305 RECOGNIZE 2
Channel-Identifier: 25902c3a54b011e7@speechrecog
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: 27
session:request1@form-level
S->C:
MRCP/2.0 83 2 200 IN-PROGRESS
Channel-Identifier: 25902c3a54b011e7@speechrecog
S->C:
MRCP/2.0 115 START-OF-INPUT 2 IN-PROGRESS
Channel-Identifier: 25902c3a54b011e7@speechrecog
Input-Type: speech
S->C:
MRCP/2.0 500 RECOGNITION-COMPLETE 2 COMPLETE
Channel-Identifier: 25902c3a54b011e7@speechrecog
Completion-Cause: 000 success
Waveform-Uri: <http://localhost/utterances/utter-25902c3a54b011e7-2.wav>;size=20480;duration=1280
Content-Type: application/x-nlsml
Content-Length: 216
<?xml version="1.0"?>
<result>
<interpretation grammar="session:request1@form-level" confidence="0.88">
<instance>call Steve</instance>
<input mode="speech">call Steve</input>
</interpretation>
</result>
¶ 7.4 DTMF Recognition with Built-in Grammar
This example 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"?>
<result>
<interpretation grammar="builtin:dtmf/digits" confidence="1.00">
<input mode="dtmf">1 2 3 4</input>
<instance>1234</instance>
</interpretation>
</result>
¶ 7.5 Speech and DTMF Recognition
This example 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"?>
<result>
<interpretation grammar=" builtin:speech/pin" confidence="1.00">
<instance>one two three four</instance>
<input mode="speech">one two three four</input>
</interpretation>
</result>
¶ 8 Sequence Diagrams
The following sequence diagrams outline common interactions between all the main components involved in a typical recognition session performed over MRCPv1 and MRCPv2 respectively.
¶ 8.1 MRCPv1
¶ 8.2 MRCPv2
¶ 9 Security Considerations
¶ 9.1 Network Connection
All the data is carried over an HTTP/2 connection via the gRPC streaming.