Streaming Media Properties
The following parameters are part of the MRCPv1 specification, and can be controlled via the
mrcp.config file, located in the config directory of the MRCPv1
installation folder. By default, this location is C:\Program Files\Lumenvox\MRCPServer\config\
They may also be set with the appropriate header as part of a RECOGNITION or SET-PARAMS method. Refer to the
MRCPv1 RFC, section 8.4,
for more information about changing the parameters using recognizer headers.
See Configuring Parameters for general information
about changing various MRCPv1 parameters.
dtmf_payload_type
This parameter may be used to customize the DTMF RTP payload type. Different vendors have used their own DTMF
payload types. We allow this to be configurable.
Default: 96
nbest_length
When the recognizer matches audio with a grammar, it may come up with more than one alternative match
because of confidence levels in certain words or conversation paths. By default, the Speech Engine will
only return the best match above the confidence threshold. The nbest_length parameter determines how many
different results to return. All alternatives must still be above the confidence-threshold. A value greater
than one does not guarantee that the recognizer will send the requested number of alternatives. The minimum
value for this field is 1.
Default: 1
confidence_thrsld
When a recognition resource recognizes an utterance with some portion of the grammar, it associates a
confidence level with that conclusion. The confidence-threshold parameter tells the recognizer resource what
confidence level should be considered a successful match. This is an integer from 0-100 indicating the
recognizer's confidence in the recognition. If the recognizer determines that its confidence in all its
recognition results is less than the confidence threshold, then it returns no-match as the recognition result.
Default: 20
sensitivity_lvl
Controls the sensitivity level for barge-in. It is set on a scale of 0 to 100; the higher the value, the more
easily the system will barge-in. For a similar value, see snr_sensitivity in our vendor-specific
Recognizer Properties.
Default: 50
speed_vs_accuracy
At this time, this parameter is unused.
speech_incomplete_timeout
At this time, this parameter is unused.
no_input_timeout
After recognition has started, if there is no speech detected for a certain period of time, the recognizer will
send a RECOGNITION-COMPLETE event to the client and terminate the recognition operation. The no-input-timeout
parameter controls the length of this time period. The value is in milliseconds.
Default: 20000
dtmf_term_char
This parameter specifies the terminating DTMF character for DTMF input recognition. When the specified character
is received, the system will immediately stop waiting for DTMF input.
Default: #
dtmf_termination_timeout
The terminating timeout to use when recognizing DTMF input. When no DTMF input has been detected for the length
of time set by this parameter, the system will stop waiting for DTMF input. The value is in milliseconds. The
value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. Refer to the
VoiceXML 2.0 specification, Appendix D
for detailed information.
Default: 10000
dtmf_inter_digit_timeout
This parameter specifies the inter-digit timeout value to use when recognizing DTMF input. The value is in
milliseconds. The value for this field ranges from 0 to MAXTIMEOUT, where MAXTIMEOUT is platform specific. Refer to the
VoiceXML 2.0 specification, Appendix D
for detailed information.
Default: 5000
recognizer_start_timers
If set, the recognizer will not start the timers until the client sends a RECOGNITION-START-TIMERS method to the
recognizer.
Default: false
recognition_timeout
After recognition has started and there is no match for a certain period of time, the recognizer can send a
RECOGNITION-COMPLETE event to the client and terminate the recognition operation. The recognition-timeout parameter
field sets this timeout value. The value is in milliseconds. The value for this field ranges from 0 to MAXTIMEOUT,
where MAXTIMEOUT is platform specific.
Default: 10000
save_waveform
The MRCP server can save the audio stream that was used for a recognition if the client sets this parameter to
true. The server records the audio and makes it available to the client in the form of a URI returned in the
waveform-uri header field in the RECOGNITION-COMPLETE event. If there is an error in recording the stream, the
recognizer returns a blank waveform-uri header field.
Default: false
waveform_url_location
This parameter is used in conjunction with the save-waveform parameter. This tells the MRCP server where to put
the recorded audio-stream. It is only used if the save_waveform parameter is set to true.
Default: "" (empty string)