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Decoder Flags

Reference Number: AA-01050 Views: 7689 0 Rating/ Voters

The engine accepts flags for use when calling LV_SRE_Decode and Decode.

In streaming mode, if Auto Decode mode is set by enabling STREAM_PARM_AUTO_DECODE using LV_SRE_StreamSetParameter or StreamSetParameter, the Decode function is internally called with the flags set for STREAM_PARM_DECODE_FLAGS.

In Auto Decode mode, LV_DECODE_BLOCK is ignored.

The flags can be bitwise OR'd ( "|" ) to customize behavior.

List of Flags


Description: Normally, calls to the decode function/method will return immediately to allow the client application to continue working on other tasks while the engine processes the data. This flag blocks the client application until the engine has finished.


Description: Specifies that the decode on the given port is for the same phone call / line as the last decode. This allows for certain settings such as noise estimates to be retained for consecutive decodes on the same call. This flag needs to be set through LV_SRE_StreamSetParameter (C API) or StreamSetParameter (C++ API) when in streaming mode.

Deprecated or Non-Functional Flags


Description: This flag tells the decoder to process the parse tree return type for semantic information in the tree's tags.

Status: Deprecated since 10.0.


Description: Identifies which gender acoustic model to use during decode. If these flags are not specified, the engine automatically decodes each audio file against both gender models. While this slows the engine by requiring two decodes, evaluating against both models has a very significant positive effect on recognition accuracy. Since the engine is multit-hreaded, unless CPU loads are a serious issue, do not use these flags.

Status: Deprecated since 9.0.


Description: Reset caller weights in Recognition Engine.

Status: Deprecated since 9.0.


Description: Use the Out-Of-Vocabulary filter (OOV) during decode. The OOV filter, when set, processes each audio file against both the grammar specified by the client application, and a special grammar which detects words not in the grammar. If the engine detects these OOV words, it will not return them. Generally, the OOV filter slows the engine down without a large gain in accuracy, so client applications should use the filter only if OOV words seem to be a problem.

Status: Deprecated since 9.0.


Description: When using standard grammars, a string of digits, monetary value etc. is passed back as a single concept. If this flag is used, each digit comes back as a separate concept. (Since each concept has a confidence score, this can be useful for determining poorly recognized individual digits.)

Status: Deprecated since 9.0.


Description: Normally, you do not need to use this flag. But if you want to use a concept-phrase grammar as an SRGS grammar, and are not using the LV_ACTIVE_GRAMMAR_SET, this flag is necessary.

Status: Deprecated since 10.0.

See Also