---
name: "sphinx_fe"
section: "1"
platform: "linux"
package: "sphinxbase-utils"
version: "0.8+5prealpha+1-21+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/sphinx_fe"
---

# sphinx\_fe(1)

Convert audio files to acoustic feature files

## NAME

sphinx\_fe - Convert audio files to acoustic feature files

## SYNOPSIS

**sphinx\_fe** \[ *options* \]...

## DESCRIPTION

This program converts audio files (in either Microsoft WAV, NIST Sphere, or raw format) to acoustic feature files for input to batch-mode speech recognition.  The resulting files are also useful for various other things.  A list of options follows:

- **-alpha**

  Preemphasis parameter

- **-argfile**

  file (e.g. feat.params from an acoustic model) to read parameters from.  This will override anything set in other command line arguments.

- **-blocksize**

  Number of samples to read at a time.

- **-build\_outdirs**

  Create missing subdirectories in output directory

- **-c**

  file for batch processing

- **-cep2spec**

  Input is cepstral files, output is log spectral files

- **-di**

  directory, input file names are relative to this, if defined

- **-dither**

  Add 1/2-bit noise

- **-do**

  directory, output files are relative to this

- **-doublebw**

  Use double bandwidth filters (same center freq)

- **-ei**

  extension to be applied to all input files

- **-eo**

  extension to be applied to all output files

- **-example**

  Shows example of how to use the tool

- **-frate**

  Frame rate

- **-help**

  Shows the usage of the tool

- **-i**

  audio input file

- **-input\_endian**

  Endianness of input data, big or little, ignored if NIST or MS Wav

- **-lifter**

  Length of sin-curve for liftering, or 0 for no liftering.

- **-logspec**

  Write out logspectral files instead of cepstra

- **-lowerf**

  Lower edge of filters

- **-mach\_endian**

  Endianness of machine, big or little

- **-mswav**

  Defines input format as Microsoft Wav (RIFF)

- **-ncep**

  Number of cep coefficients

- **-nchans**

  Number of channels of data (interlaced samples assumed)

- **-nfft**

  Size of FFT

- **-nfilt**

  Number of filter banks

- **-nist**

  Defines input format as NIST sphere

- **-npart**

  Number of parts to run in (supersedes **-nskip** and **-runlen** if non-zero)

- **-nskip**

  If a control file was specified, the number of utterances to skip at the head of the file

- **-o**

  cepstral output file

- **-ofmt**

  Format of output files - one of sphinx, htk, text.

- **-part**

  Index of the part to run (supersedes **-nskip** and **-runlen** if non-zero)

- **-raw**

  Defines input format as raw binary data

- **-remove\_dc**

  Remove DC offset from each frame

- **-remove\_noise**

  Remove noise with spectral subtraction in mel-energies

- **-remove\_silence**

  Enables VAD, removes silence frames from processing

- **-round\_filters**

  Round mel filter frequencies to DFT points

- **-runlen**

  If a control file was specified, the number of utterances to process, or **-1** for all

- **-samprate**

  Sampling rate

- **-seed**

  Seed for random number generator; if less than zero, pick our own

- **-smoothspec**

  Write out cepstral-smoothed logspectral files

- **-spec2cep**

  Input is log spectral files, output is cepstral files

- **-sph2pipe**

  Input is NIST sphere (possibly with Shorten), use sph2pipe to convert

- **-transform**

  Which type of transform to use to calculate cepstra (legacy, dct, or htk)

- **-unit\_area**

  Normalize mel filters to unit area

- **-upperf**

  Upper edge of filters

- **-vad\_postspeech**

  Num of silence frames to keep after from speech to silence.

- **-vad\_prespeech**

  Num of speech frames to keep before silence to speech.

- **-vad\_startspeech**

  Num of speech frames to trigger vad from silence to speech.

- **-vad\_threshold**

  Threshold for decision between noise and silence frames. Log-ratio between signal level and noise level.

- **-verbose**

  Show input filenames

- **-warp\_params**

  defining the warping function

- **-warp\_type**

  Warping function type (or shape)

- **-whichchan**

  Channel to process (numbered from 1), or 0 to mix all channels

- **-wlen**

  Hamming window length

Currently the only kind of features supported are MFCCs (mel-frequency cepstral coefficients).  There are numerous options which control the properties of the output features.  It is **VERY** important that you document the specific set of flags used to create any given set of feature files, since this information is **NOT** recorded in the files themselves, and any mismatch between the parameters used to extract features for recognition and those used to extract features for training will cause recognition to fail.

## AUTHOR

Written by numerous people at CMU from 1994 onwards.  This manual page by David Huggins-Daines \<dhuggins@cs.cmu.edu\>

## COPYRIGHT

Copyright © 1994-2007 Carnegie Mellon University.  See the file *COPYING* included with this package for more information.\