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Stream Properties

Reference Number: AA-01056 Views: 2795 0 Rating/ Voters

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.

Properties

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

Deprecated or Non-Functinal Properties

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

See Also