¶ 1 Overview
This guide describes how to configure and use the Deepgram Speech Synthesis (SS) plugin to the UniMRCP server. The document is intended for users having a certain knowledge of Deepgram Speech API and UniMRCP.
¶ 1.1 Installation
For installation instructions, use one of the guides 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 Deepgram 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 Deepgram 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
-
Logging-Tag
-
Cache-Control
¶ 2.3 Speech Data
-
Plain text (text/plain)
-
SSML (application/ssml+xml or application/synthesis+ssml)
¶ 3 Supported Voices
All the supported voices are stored in the configuration file umsdeepgramvoices.xml located in the directory /opt/unimrcp/conf. The configuration file is synched with the actual set of voices supported by Deepgram Speech API listed in the following page:
¶ 4 Configuration Format
The configuration file of the Deepgram SS plugin is located in /opt/unimrcp/conf/umsdeepgramss.xml. The configuration file is written in XML.
¶ 4.1 Document
The root element of the XML document must be <umsdeepgramss>.
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 Deepgram subscription key 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. |
| waveform-manager | String | Specifies parameters of the waveform manager. |
| sdr-manager | String | Specifies parameters of the Synthesis Details Record (SDR) manager. Available since Deepgram SS 1.4.0. |
| 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. |
| service-endpoints | String | Specifies service endpoints. |
Example
This is an example of a bare document.
<umsdeepgramss license-file="umsdeepgramss_*.lic" subscription-key-file="cognitive.subscription.key">
</umsdeepgramss>
¶ 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. |
| voice-gender | String | Specifies the default voice gender. Can be overridden by client. |
| prosody-pitch | String | Specifies the default prosody pitch. Use either labels (x-low, low, medium, high, x-high) or an absolute value (600 Hz) or relative changes from the default pitch (+80 Hz or -20 Hz). Can be overridden by client in SSML. |
| prosody-contour | String | Specifies the default prosody contour. Can be overridden by client in SSML. |
| prosody-range | String | Specifies the default prosody range. Use either labels (x-low, low, medium, high, x-high) or an absolute value (600 Hz) or relative changes from the default pitch (+80 Hz or -20 Hz). Can be overridden by client in SSML. |
| prosody-rate | String | Specifies the default prosody rate. Use either labels (x-slow, slow, medium, fast, x-fast) or relative changes from the default rate as a percentage (+10% or -20%) or numeric values as a multiplier where 1 indicates no change. Can be overridden by client. |
| prosody-duration | String | Specifies the default prosody duration. Can be overridden by client in SSML. |
| prosody-volume | String | Specifies the default prosody volume. Use either labels (silent, x-soft, soft, medium, loud, x-loud) or relative changes from the default volume as a percentage (+10% or -20%) or numeric values in the range from 0 to 100. Can be overridden by client. |
| bypass-ssml | Boolean | Specifies whether transparently bypass or normalize received SSML content before sending it to the service for synthesis. |
| http-proxy | String | Specifies the URI of HTTP proxy, if used. |
| caching | Boolean | Specifies whether to enable caching of synthesized waveforms. |
| request-timeout | Integer | Specifies a timeout in seconds set on HTTP requests placed for speech synthesis. |
| auth-request-timeout | Integer | Specifies a timeout in seconds set on HTTP requests placed re-validate access token. |
| persistent-connection | Boolean | Specifies whether to keep the connection alive and reuse it for subsequent requests placed in the scope of a single MRCP session or close the connection after a request completes. |
Parent
<umsdeepgramss>
Children
- None.
Example
This is an example of synthesis parameters.
<synth-settings
language="en-US"
bypass-ssml="false"
auth-validation-period="480"
/>
¶ 4.3 Waveform Manager
This element specifies parameters of the waveform 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-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 'umsdeepgramss-', 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
<umsdeepgramss>
Children
- None.
Example
The example below defines a typical utterance manager having the default parameters set.
<waveform-manager
save-waveforms="false"
purge-existing="false"
max-file-age="60"
max-file-count="100"
waveform-folder=""
/>
¶ 4.4 SDR Manager
This element specifies parameters of the Synthesis Details Record (SDR) 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 'umsdeepgramss-', 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
<umsdeepgramss>
Children
- None.
Example
The example below defines a typical utterance manager having the default parameters set.
<sdr-manager
save-records="false"
purge-existing="false"
max-file-age="60"
max-file-count="100"
waveform-folder=""
/>
¶ 4.5 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
<umsdeepgramss>
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="umsdeepgramss-channels.status"/>
</usage-refresh-handler >
</monitoring-agent>
¶ 4.6 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="umsdeepgramss-usage.status"/>
<dump-channels enable="false" status-file="umsdeepgramss-channels.status"/>
</usage-change-handler>
¶ 4.7 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="umsdeepgramss-usage.status"/>
<dump-channels enable="false" status-file="umsdeepgramss-channels.status"/>
</usage-refresh-handler>
¶ 4.8 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
<umsdeepgramss>
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
License Server Check out the concepts¶ 4.9 Service Endpoints
This element specifies service endpoints.
Attributes
| Name | Unit | Description |
|---|---|---|
| load-balancing | String | Specifies the load balancing method. One of "round-robin" or "sequential". |
| fail-over | Boolean | Specifies whether the fail-over functionality is enabled or disabled. |
Parent
<umsdeepgramss>
Children
<service-endpoint>.
Example
The example below defines a configuration with two service endpoints located, for example, at 10.0.0.1 and 10.0.0.2.
<service-endpoints load-balancing="round-robin" fail-over="true">
<service-endpoint enable="true" service-uri="http://10.0.0.1:5000/speech/synthesize/cognitiveservices/v1"/>
<service-endpoint enable="true" service-uri="http://10.0.0.2:5000/speech/synthesize/cognitiveservices/v1"/>
</service-endpoints>
¶ 4.10 Service Endpoint
This element specifies a service endpoint.
Attributes
| Name | Unit | Description |
|---|---|---|
| enable | Boolean | Specifies whether the service endpoint is enabled or disabled. |
| service-uri | String | Specifies the URI of the service endpoint. |
Parent
<service-endpoints>
Children
- None.
Example
The example below defines a configuration of a service endpoint located, for example, at 10.0.0.1.
<service-endpoint enable="true" service-uri="http://10.0.0.1:5000/speech/synthesize/cognitiveservices/v1"/>
¶ 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 umsdeepgramss.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 Deepgram Speech API for synthesis.
¶ 5.4 Specifying Voice Parameters
Global Settings
The default voice name and gender can be specified from the configuration file umsdeepgramss.xml using the voice-name and voice-gender attributes of the synth-settings element. This functionality is available since Deepgram SS 1.3.0 release.
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. -
Voice-Gender
This is an optional parameter indicating the preferred gender of the voice to use for synthesis, which can be set to either male or female.
The voice name and gender can also be specified via the header field Vendor-Specific-Parameters.
¶ 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 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 |
|---|---|---|
| service-uri | String | Specifies the URI of the service endpoint. |
| voice-name | String | Specifies the voice name. |
| voice-gender | String | Specifies the default voice gender. |
| logging-tag | String | Specifies the logging tag. |
| guid | String | Specifies the GUID to be set on synthesis request. |
| subscription-key-file | String | Specifies the Deepgram subscription key file to use. |
All the vendor-specific parameters can also be specified via query parameters of the 'xml:base' attribute in SSML. The following example demonstrates the use of an SSML content with the vendor-specific parameter subsccription-key-file set to custom.subscription.key.
<speak version="1.0"
xml:lang="en-US"
xml:base="http://localhost/settings?subscription-key-file=cognitive.subscription.key"
xmlns="http://www.w3.org/2001/10/synthesis">
Your reservation is confirmed.
</speak>
¶ 5.7 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)
¶ 5.8 Maintaining Waveforms
Collection of waveforms is not required for regular operation and is disabled by default. However, enabling this functionality allows to save synthesized speech received from the Deepgram Speech service and later listen to them offline.
The relevant settings can be specified via the element waveform-manager.
-
save-waveforms
Utterances can optionally be recorded and stored if the configuration parameter save-waveforms is set to true. -
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-folder
This parameter specifies a path to the directory used to store waveforms in. The directory defaults to ${UniMRCPInstallDir}/var.
¶ 5.9 Maintaining Synthesis Details Records
Collection of synthesis details records (SDR) is not required for regular operation and is disabled by default. However, enabling this functionality allows to store details of each synthesis attempt in a separate file and analyze them later offline. The SDRs ate stored in the JSON format.
The relevant settings can be specified via the element sdr-manager.
-
save-records
This parameter specifies whether to save synthesis 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.
The following is the content of a sample SDR.
{"synth-details-record": {
"datetime": "2024-06-20 12:57:44",
"language": "en-US",
"voice-name": "",
"sampling-rate": "8000 Hz",
"codec": "PCMU",
"data-length": "18150 bytes",
"start-of-streaming-ts": "282 ms"
"completion-ts": "2550 ms"
"completion-cause": "normal",
}}
where the stored attributes are:
-
datetime
This attribute denotes the date and time captured when the corresponding MRCP SPEAK request is received. -
language
This attribute denotes the speech language used with the request. -
voice-name
This attribute denotes the voice name used with the request. -
sampling-rate
This attribute denotes the sampling rate used with the request. -
codec
This attribute denotes the codec of synthesized speech received from the service. -
data-length
This attribute denotes the number of bytes of synthesized speech received from the service. -
start-of-streaming-ts
This attribute denotes a time interval in milliseconds, elapsed since initiation of the request, captured when streaming to the MRCP client is started. This attribute also denotes the HTTP response time of the service. -
completion-ts
This attribute denotes a time interval in milliseconds, elapsed since initiation of the request, captured upon completion of the request (SPEAK-COMPLETE is sent). -
completion-cause
This attribute denotes the completion cause of the request.
¶ 5.10 Using Cache
Synthesized waveforms can be stored and re-used for consecutive speech synthesis requests, when applicable. In order to use this functionality, the attribute caching of the element synth-settings must be set to true. The attribute defaults to false.
The lifetime and size of cached records are controlled by the attributes max-file-age and max-file-count of the element waveform-manager.
The cached records are persistent and populated on initial loading, unless the attribute purge-existing of the element waveform-manager is set to true.
The following speech synthesis parameters are observed while searching for a cached record.
-
language
-
voice-name
-
voice-gender
-
sampling-rate
-
prosody-pitch
-
prosody-contour
-
prosody-range
-
prosody-rate
-
prosody-duration
-
prosody-volume
-
content
The following cache control directives are observed while searching for a cached record.
-
max-age
-
min-fresh
The cache control directives can be specified by the client per individual speech synthesis request via the MRCP header field Cache-Control. By default, no cache control directives are applied.
¶ 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] DEEPGRAMSS Usage: 0/0/2
¶ 6.2 Update Usage
The action update-usage writes the following data to a status file umsdeepgramss-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-channel writes the identifiers of in-use channels to a status file umsdeepgramss-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 MRCPv1 and MRCPv2 respectively.
¶ 8.1 MRCPv1
¶ 8.2 MRCPv2
