Summary

This section summarises the various file formats, parameter kinds, qualifiers and configuration parameters used by HTK. Table  lists the audio speech file formats which can be read by the HWAVE module. Table  lists the basic parameter kinds supported by the HPARM module and Fig.  shows the various automatic conversions that can be performed by appropriate choice of source and target parameter kinds. Table  lists the available qualifiers for parameter kinds. The first 6 of these are used to describe the target kind. The source kind may already have some of these, HPARM adds the rest as needed. Note that HPARM can also delete qualifiers when converting from source to target. The final two qualifiers in Table  are only used in external files to indicate compression and an attached checksum. HPARM adds these qualifiers to the target form during output and only in response to setting the configuration parameters SAVECOMPRESSED and SAVEWITHCRC. Adding the _C or _K qualifiers to the target kind simply causes an error. Finally, Tables and lists all of the configuration parameters along with their meaning and default values.

Name	Description
HTK	The standard HTK file format
TIMIT	As used in the original prototype TIMIT CD-ROM
NIST	The standard SPHERE format used by the US NIST
SCRIBE	Subset of the European SAM standard used in the SCRIBE CD-ROM
SDES1	The Sound Designer 1 format defined by Digidesign Inc.
AIFF	Audio interchange file format
SUNAU8	Subset of 8bit ".au" and ".snd" formats used by Sun and NeXT
OGI	Format used by Oregan Graduate Institute similar to TIMIT
WAV	Microsoft WAVE files used on PCs
ESIG	Entropic Esignal file format
AUDIO	Pseudo format to indicate direct audio input
ALIEN	Pseudo format to indicate unsupported file, the alien header size must be set via the environment variable HDSIZE
NOHEAD	As for the ALIEN format but header size is zero

Table. 5..1 Supported File Formats

Kind	Meaning
WAVEFORM	scalar samples (usually raw speech data)
LPC	linear prediction coefficients
LPREFC	linear prediction reflection coefficients
LPCEPSTRA	LP derived cepstral coefficients
LPDELCEP	LP cepstra + delta coef (obsolete)
IREFC	LPREFC stored as 16bit (short) integers
MFCC	mel-frequency cepstral coefficients
FBANK	log filter-bank parameters
MELSPEC	linear filter-bank parameters
USER	user defined parameters
DISCRETE	vector quantised codebook symbols
PLP	perceptual linear prediction coefficients
ANON	matches actual parameter kind

Table. 5..2 Supported Parameter Kinds

Qualifier	Meaning
_A	Acceleration coefficients appended
_C	External form is compressed
_D	Delta coefficients appended
_E	Log energy appended
_K	External form has checksum appended
_N	Absolute log energy suppressed
_T	Third differential coefficients appended
_V	VQ index appended
_Z	Cepstral mean subtracted
_0	Cepstral C0 coefficient appended

Table. 5..3 Parameter Kind Qualifiers

Module	Name	Default	Description
HAUDIO	LINEIN	T	Select line input for audio
HAUDIO	MICIN	F	Select microphone input for audio
HAUDIO	LINEOUT	T	Select line output for audio
HAUDIO	SPEAKEROUT	F	Select speaker output for audio
HAUDIO	PHONESOUT	T	Select headphones output for audio
	SOURCEKIND	ANON	Parameter kind of source
	SOURCEFORMAT	HTK	File format of source
	SOURCERATE	0.0	Sample period of source in 100ns units
HWAVE	NSAMPLES		Num samples in alien file input via a pipe
HWAVE	HEADERSIZE		Size of header in an alien file
HWAVE	STEREOMODE		Select channel: RIGHT or LEFT
HWAVE	BYTEORDER		Define byte order VAX or other
	NATURALREADORDER	F	Enable natural read order for HTK files
	NATURALWRITEORDER	F	Enable natural write order for HTK files
	TARGETKIND	ANON	Parameter kind of target
	TARGETFORMAT	HTK	File format of target
	TARGETRATE	0.0	Sample period of target in 100ns units
HPARM	SAVECOMPRESSED	F	Save the output file in compressed form
HPARM	SAVEWITHCRC	T	Attach a checksum to output parameter file
HPARM	ADDDITHER	0.0	Level of noise added to input signal
HPARM	ZMEANSOURCE	F	Zero mean source waveform before analysis
HPARM	WINDOWSIZE	256000.0	Analysis window size in 100ns units
HPARM	USEHAMMING	T	Use a Hamming window
HPARM	PREEMCOEF	0.97	Set pre-emphasis coefficient
HPARM	LPCORDER	12	Order of LPC analysis
HPARM	NUMCHANS	20	Number of filterbank channels
HPARM	LOFREQ	-1.0	Low frequency cut-off in fbank analysis
HPARM	HIFREQ	-1.0	High frequency cut-off in fbank analysis
HPARM	USEPOWER	F	Use power not magnitude in fbank analysis
HPARM	NUMCEPS	12	Number of cepstral parameters
HPARM	CEPLIFTER	22	Cepstral liftering coefficient
HPARM	ENORMALISE	T	Normalise log energy
HPARM	ESCALE	0.1	Scale log energy
HPARM	SILFLOOR	50.0	Energy silence floor (dB)
HPARM	DELTAWINDOW	2	Delta window size
HPARM	ACCWINDOW	2	Acceleration window size
HPARM	VQTABLE	NULL	Name of VQ table
HPARM	SAVEASVQ	F	Save only the VQ indices
HPARM	AUDIOSIG	0	Audio signal number for remote control

Table. 5..4 Configuration Parameters

Module	Name	Default	Description
HPARM	USESILDET	F	Enable speech/silence detector
HPARM	MEASURESIL	T	Measure background noise level prior to sampling
HPARM	OUTSILWARN	T	Print a warning message to stdout before measuring audio levels
HPARM	SPEECHTHRESH	9.0	Threshold for speech above silence level (dB)
HPARM	SILENERGY	0.0	Average background noise level (dB)
HPARM	SPCSEQCOUNT	10	Window over which speech/silence decision reached
HPARM	SPCGLCHCOUNT	0	Maximum number of frames marked as silence in window which is classified as speech whilst expecting start of speech
HPARM	SILSEQCOUNT	100	Number of frames classified as silence needed to mark end of utterance
HPARM	SILGLCHCOUNT	2	Maximum number of frames marked as silence in window which is classified as speech whilst expecting silence
HPARM	SILMARGIN	40	Number of extra frames included before and after start and end of speech marks from the speech/silence detector
HPARM	V1COMPAT	F	Set Version 1.5 compatibility mode
	TRACE	0	Trace setting

Table. 5..5 Configuration Parameters (cont)