Vendor-Specific Recognizer Properties
The following parameters are LumenVox-specific extensions to the MRCPv1 specification. They can be
controlled via the mrcp.config file, located in the config directory
of the MRCPv1 installation folder. By default, this location is
They may also be set with the appropriate header as part of a RECOGNITION or SET-PARAMS method; see
Specifying Vendor-Specific Properties via MRCP Headers below.
See Configuring Parameters for more
information about changing various MRCPv1 parameters.
If this property is set to 1, then the client will decide which acoustic model is most appropriate
for the server to use, based on a frequency analysis of the speaker's voice. Otherwise, two decodes
will be done simultaneously, and an answer will be selected based on which model had better "coverage"
for the speaker's voice.
The lattice-based confidence score is a slightly slower, but more accurate confidence score.
Deprecated in favor of speech_complete_timeout, the standard MRCP parameter that works
in the same way. See
Streaming Media Properties.
The length of audio wound back at the beginning of voice. It helps in the situation of weak speech onset.
The resolution of this parameter is 1/8 sec, i.e. 125 ms, which means setting this value to 249 ms is the
same as setting it to 125. It is specified in milliseconds.
This parameter tells the Engine's voice activity detection technology whether the audio stream contains
leading silence or not. By default, the Engine expects to receive an audio stream that contains silence
before speech. If your hardware is trimming the silence before sending the Engine audio, you should set
this to 1.
Barge-in will trigger only after it has detected speech for the period specified by this parameter. This
helps prevent burst noise from triggering barge-in. It is specified in milliseconds.
If no speech was detected in the time specified by this property, the recognition request is cancelled. It
is specified in milliseconds.
After barge-in, if end-of-speech is not detected in the time specified by this property, the recognition
request is cancelled. It is specified in milliseconds.
Specifying Vendor-Specific Properties via MRCP Headers
As mentioned previously, you may specify the above parameters in an MRCP header. You must use the following
format. Note that a semicolon (";" ) is used as the delimiter:
This header field may be specified in RECOGNIZE or SET-PARAMS method during an MRCP session. The following
header field names may be used: