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Various stream properties can be set via LV_SRE_StreamSetParameter and StreamSetParameter. These parameter can later be queried with LV_SRE_StreamGetParameter or StreamGetParameter. The Stream parameters can be returned to their default values with LV_SRE_StreamSetParameterToDefault or StreamSetParameterToDefault. All stream properties are set at the Scope of a single Port.
STREAM_PARM_AUTO_DECODE
Description: If active, the decode will start immediately on end-of-speech detection or a call to StopStream. Otherwise, the application needs to call LV_SRE_Decode to begin a decode.
Scope: Port
Possible Values: 0 or 1
Default Value: 0 (off)
STREAM_PARM_BARGE_IN_TIMEOUT
Description: The streaming interface will flag STREAM_STATUS_BARGE_IN_TIMEOUT, if no speech was detected in the time frame specify by this property.
Scope: Port
Possible Values: Time in milliseconds
Default Value: -1 (infinite)
STREAM_PARM_DECODE_FLAGS
Description: Allows for the setting of multiple flags. These are the same flags that would be entered in to the system via the Decode method / function. Currently, the only flag that can be set is LV_DECODE_SEMANTIC_INTERPRETATION, which tells the Engine to return a semantic interpretation. Without this tag the engine will ignore what is contained in SISR tag elements.
Scope: Port
Possible Values: LV_DECODE_SEMANTIC_INTERPRETATION
Default Value: NULL
STREAM_PARM_DETECT_BARGE_IN
Description: The SRE will monitor the audio stream for start-of-speech. Once barge in has been detected that state will be announced
Scope: Port
Possible Values: TRUE, FALSE
Default Value: 0
STREAM_PARM_DETECT_END_OF_SPEECH
Description: Specifies if the stream interface will start discarding sound data once silence has been detected.
Scope: Port
Possible Values: 0 or 1
Default Value: 0 (off)
STREAM_PARM_END_OF_SPEECH_DETECTION
Description: Changes voice activity detection delay for end of speech detection based to one of four modes.
Scope: Port
Possible Values: Possible values are STREAM_END_OF_SPEECH_DETECTION_SINGLE_WORDS (500ms) STREAM_END_OF_SPEECH_DETECTION_PHRASES_NO_PAUSES (800ms), STREAM_END_OF_SPEECH_DETECTION_PHRASES_WITH_PAUSES (1200ms), and STREAM_END_OF_SPEECH_DETECTION_NORMAL (800ms).
Default Value: STREAM_END_OF_SPEECH_DETECTION_NORMAL
STREAM_PARM_END_OF_SPEECH_TIMEOUT
Description: After barge-in, the streaming interface will flag STREAM_STATUS_END_SPEECH_TIMEOUT, if it did detect end-of-speech in the time specified by this property. This is different from the end of speech delay; STREAM_PARM_END_OF_SPEECH_TIMEOUT represents the total amount of time a caller has to speak after barge-in is detected.
Scope: Port
Possible Values: Time in milliseconds
Default Value: -1 (infinite)
STREAM_PARM_GRAMMAR_SET
Description: The grammar set to use with auto decode streams
Scope: Port
Possible Values: LV_ACTIVE_GRAMMAR_SET
Default Value: 0
STREAM_PARM_SOUND_FORMAT
Description: The sound format handled by the stream.
Scope: Port
Possible Values: ULAW_8KHZ, PCM_8KHZ, PCM_16KHZ, ALAW_8KHZ
Default Value: ULAW_8KHZ
STREAM_PARM_VAD_BARGEIN_THRESHOLD
Description: A higher value makes the VAD more sensitive to speech which means that the VAD is very sure the data is speech before barge in. Raising the value will reject more false positives/noises. However, it may mean that some speech that is on the borderline may be rejected. This value should not be changed from the default without significant tuning and verification
Scope: Port
Possible Values: Range [0 - 100]
Default Value: 50
STREAM_PARM_VAD_EOS_DELAY
Description: This is the amount of time, specified in milliseconds, that the Engine must detect silence after speech before it begins processing the utterance.
Scope: Port
Possible Values: Time (in milliseconds)
Default Value: 500ms
STREAM_PARM_VAD_SNR_SENSITIVITY
Description:Determines how much louder the speaker must be than the background noise in order to trigger barge-in. The smaller this value, the easier it will be to trigger barge-in.
Scope: Port
Possible Values: 1 to 100.
Default Value: 50.
STREAM_PARM_VAD_STREAM_INIT_DELAY
Description: Accurate VAD depends on good estimation of acoustic environment. The VAD module uses the first a couple of frames of audio to estimate the acoustic environment, such as noise level. The length of this period is defined by this parameter.
Scope: Port
Possible Values: >0
Default Value: 100ms
STREAM_PARM_VAD_VOLUME_SENSITIVITY
Description: The volume required to trigger barge-in. The smaller the value, the more sensitive barge-in will be. This is primarily used to deal with poor echo cancellation. By setting this value higher (less sensitive) prompts that are not properly cancelled will be less likely to falsely cancel barge-in.
Scope: Port
Possible Values: 1 to 100.
Default Value: 50.
STREAM_PARM_VAD_WIND_BACK
Description: The length of audio to be wound back at the beginning of voice activity. This is used primarily to counter instances where barge-in does not accurately capture the very start of speech. The resolution of this parameter is 1/8 of a second.
Scope: Port
Possible Values: Time (milliseconds).
Default Value: 480ms
STREAM_PARM_VOICE_CHANNEL
Description: The voice channel for decode to load the sound data to once end pointing is done.
Scope: Port
Possible Values: Range [0 - 63]
Default Value: 0
STREAM_PARM_BARGE_IN_NOISE_COUNT_LOW_THRESHOLD
Status: Deprecated since 9.0
STREAM_PARM_BARGE_IN_DYNAMIC_ADJUST
Status: Deprecated since 9.0
STREAM_PARM_NOISE_REDUCTION
Status: Deprecated since 9.0
STREAM_PARM_NOTIFY_OF_BEEPS
Status: Deprecated since 9.0
STREAM_PARM_STORE_PROMPT
Status: Deprecated since 9.0
STREAM_PARM_USE_COMPRESSION
Status: Deprecated since 9.0
STREAM_PARM_RECOGNITION_MODE
Status: Deprecated since 9.0
STREAM_PARM_RECOGNITION_MODE_HOTWORD
Status: Deprecated since 9.0
STREAM_PARM_HOTWORD_MODE_CALLBACK_TRIGGER_SCORETHLD
Status: Deprecated since 9.0
STREAM_PARM_ECHO_CANCELLATION_CONVERGERNCE
Status: Not Implemented yet
STREAM_PARM_MAX_ECHO_DELAY
Status: Not Implemented yet
STREAM_PARM_USE_ECHO_CANCELLATION
Status: Not Implemented yet
STREAM_PARM_USE_FREQ_VAD
Status: Deprecated since 9.0
STREAM_PARM_VAD_BARGEIN_LVL
Status: Deprecated since 9.0
STREAM_PARM_VAD_NOISE_FLOOR
Status: Deprecated since 9.0
STREAM_PARM_VAD_P2A_THLD
Status: Deprecated since 9.0
STREAM_PARM_VAD_BURST_THLD
Status: Deprecated since 9.0
STREAM_PARM_VAD_USE_ZERO_CROSSING
Status: Deprecated since 9.0
STREAM_PARM_VAD_USE_BAND_PASS
Status: Deprecated since 9.0
STREAM_PARM_VAD_INIT_MODE
Description: 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 and sending audio data that just includes voice, you need to set this to SILENCE_TRIMMED.
Scope: Port
Possible Values: SILENCE_TRIMMED or SILENCE_UNTRIMMED.
Default Value:SILENCE_UNTRIMMED
Status: Deprecated since 10.1