RESPITE: The CASA Toolkit Page: Documentation: Block Library Index:HMMDecoderStandard


The HMMDecoderStandard block performs HMM Viterbi decoding on a stream of input feature vectors given a set of HMM models.

As a by-product the decoder outputs a stream of state-likelihood frames (out1. Each frame consists of the likelihood of each model state having generated the corresponding input feature frame. Within these frames the state likelihoods occur in the same order in which the states are defined in the HMM definition file.

The operation of the decoder is specified by the following set of parameters:

Inputs Meaning Sample 1-D frame $\ge$2-D frame
in1 feature vectors No Yes No

Outputs Meaning
out1state likelihoods
out2state max mixture label

Parameters Type Default Meaning
LOG_FILE String - Name of an optional log file
LOG_FILE_2 String - Name of additional detailed log file
WORD_PENALTY Float 0.0 The creation penalty
HMM_FILE String - Name of the HMM file list
GRAMMAR_FILE String - File storing the grammar
LABEL_FILE String - File storing HMM NAME-> HMM LABEL mapping
FIRST_TOKEN String - Label of a fixed first token
FINAL_TOKEN String - Label of a fixed final token
TRANSCRIPTION String - The correct transcription
SILENCE String "" The silence label(s)
MAX_APPROX Boolean False Use max mixture approximation
NBEST Int 1 Return best N hypotheses
STATE_PATH Boolean False Record HMM state path
HAS_DELTAS Boolean False Models have delta parameters
USE_DELTAS Boolean - Models have delta parameters
HYPOTHESIS FILTER String "" Regular expression for filtering hypotheses
OUTPUT_CONFUSIONS Boolean False Output confusion matrix
DUMP_PARAMETERS Boolean False Write parameters to log file

Documentation for CTKv1.1.4 - Last modified: Mon Jul 2 18:15:59 BST 2001