me_sgram.1

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.\" Copyright (c) 1988-1990 Entropic Speech, Inc.
.\" Copyright (c) 1990-1997 Entropic Research Laboratory, Inc. All rights reserved.
.\" @(#)me_sgram.1	1.10 27 Sep 1997 ESI/ERL
.ds ]W (c) 1997 Entropic Research Laboratory, Inc.
.TH ME_SGRAM 1\-ESPS 27 Sep 1997
.SH "NAME"
me_sgram - produces a maximum-entropy-based FEA_SPEC file suitable for displaying as a spectrogram
.SH "SYNOPSIS"
.B me_sgram 
[
.BI \-s " range
] [
.BI \-P " param_file
] [
.BI \-p " range
] [
.BI \-r " range"
] [
.BI \-m " method"
] [
.BI \-a " lpc_method"
] [
.BI \-w " window_len"
] [
.BI \-E " pre_emphasis"
] [
.BI \-o " analysis_order"
] [
.BI \-S " step_size"
] [
.BI \-d " data_window"
] [
.BI \-c " conv_test"
] [ 
.BI \-i " max_iter"
] [
.B \-D
]
.I " input.SD output.SPEC"
.SH "DESCRIPTION"
.PP
.I Me_sgram
reads an ESPS sampled data file, pre-emphasizes it, and produces an
ESPS FEA_SPEC(5\-ESPS) file, which qresults from maximum entropy spectral
analysis.  This file is suitable for displaying as a speech
spectrogram.  (See \fIplotsgram\fP (1\-\s-1ESPS\s+1).)  By default
(specifying no options) or by specifying \fIwb\fR for the \fB\-m\fR
option, \fIme_sgram\fR produces a FEA_SPEC file that simulates the
analysis done to produce a wide-band speech spectrogram.
Alternatively, by specifying \fInb\fR for the \fB\-m\fR option, a
FEA_SPEC file that simulates the analysis for a narrow-band
spectrogram is computed.  The \fB\-m\fP option simply defines
different defaults for the other options.  By specifying any of the
other options, in addition to \fB\-m\fP, the default values are
overridden by the specified option values.  This allows the user to
alter the basic display to highlight facets of the spectrogram that
are of particular interest.
.PP
.I me_sgram 
is a shell script that uses \fIfilter\fP(1\-\s-1ESPS\s+1),
\fIrefcof\fP(1\-\s-1ESPS\s+1), and \fIme_spec\fP(1\-\s-1ESPS\s+1);
the parameter file is processed using \fIgetparam\fP(1\-\s-1ESPS\s+1).
.PP
If "\-" is specified for the output file, standard output is used.
Note, standard input cannot be read by this script.
.SH OPTIONS
.PP
.TP
.BI \-s " start_time:end_time \fR[0.0:(end of file)]\fP"
.TP
.BI \-s " start_time:+duration"
Determines the range in seconds in the input file over which
the spectrogram values are to be computed.
In the first form, a pair of
real numbers gives the starting and ending times of the range.
The correspondence between samples and times is determined by two quantities:
the starting time of the file and the interval between samples.
The former is given by the generic header item
.I start_time
in the input file,
or 0.0 if the header item is not present.
The latter is the reciprocal of the sample frequency
.I sf
in the type-dependent part of the SD header.
If
.I start_time
is omitted, the starting time of the file is used.  If 
.I end_time 
is omitted, the range extends through the end of the file.
The second form of the option is equivalent to the first with 
.I "end = start + duration".
.TP
.BI \-p " starting_point:end_point \fR[1:(end of file)]\fP"
.TP
.BI \-p " starting_point:+incr"
Determines the range in points in the input file over which
the spectrogram values are to be computed.
In the first
form, a pair of unsigned integers gives the first and
last points of the range, counting from 1 for the first
point in the file.  If first is omitted, 1 is used.  If
last is omitted, the range extends to the end of the
file.  The second form is equivalent to the first with
last = first + incr . This option should not be
specified if -s is specified.  
.TP
.BI \-r " range"
\fB\-r\fP is a synonym for \fB\-p\fP.
.TP
.BI \-m " method \fR[wb]\fP"
The basic method is specified here. There are two possible values:
\fIwb\fR for wide band and \fInb\fR for narrow band.  By specifying
\fIwb\fR, the following values are set: lpc_method = fburg,
pre-emphasis = .94, analysis_order = 10, window_len = 8 msec.,
step_size = 2 msec., and data_window = RECT.  By specifying
\fInb\fR, the following values are set: lpc_method = fburg,
pre-emphasis = .94, analysis_order = 10, window_len = 40 msec.,
step_size = 2 msec., and data_window = RECT.
.TP
.BI \-a " lpc_method \fR[fburg]\fP"
Specifies the spectrum analysis method.  The default is the fast
modified Burg ("fburg") method.  Also available are the
autocorrelation method "autoc"), covariance method ("cov"), Burg
method ("burg"), modified Burg method ("mburg"), stuctured covariance
("strcov" and "strcov1"), and vector Burg ("vburg", fast approximation
to structured covariance.  Of the two structured covariance methods,
the first ("strcov" is considerably faster and better behaved;
"strcov1" is older but included as it may prove useful on occasion.
**
If "strcov" is used, the \fB-c\fP and \fB-i\fP options become
relevant.  The \fB-m\fP option overrides the value that may be in the
parameter file.  
.TP
.BI \-c " conv_test\fR[1e-5]\fP"
Specifies, for the STRCOV method only (not including STRCOV1), 
a convergence test value.  The lower the value, the smaller the 
change required on each iteration before the estimator terminates, 
and the more iterations that normally will result.  
.TP
.BI \-i " max_iter\fR[20]\fP"
Specifies, for the STRCOV method only (not including STRCOV1), the 
maximum number of iterations that the estimator will run through 
before terminating.  A warning will indicate if the estimator
terminates because max_iter has been exceeded. 
.TP
.BI \-w " window_len"
The duration of data in milliseconds over which the the power spectrum
is computed for each column of the spectrogram. The analysis bandwidth
is inversely proportional to this value.
.TP
.BI \-E " pre_emphasis"
The coefficient \fIA\fR in the pre-emphasis filter: 1 \- \fIA\fR/z.
This filter is applied to the sampled data before computing
the power spectrum. A value of \fIA\fR = 1 provides a 6 dB/octave
boost to the high frequencies; a value of 0 provides no boost.
.TP
.BI \-o " analysis_order"
The number of parameters in the autoregressive
model that is used to compute the 
power spectrum. 
.TP
.BI \-S " step_size"
The time step in milliseconds between columns in the spectrogram.
The time resolution and horizontal magnification are
affected by this parameter.
.TP
.BI \-d " data_window"
The data window applied to the data before the computation
of the power spectrogram. Possible values include RECT (rectangular),
HAMMING, and TRIANG (triangular). See \fIwindow\fP (3\-\s-1ESPS\s+1) for
a complete list of supported data windows.
.TP
.B \-D
Include in the output records a field
.I dith_spec_val
containing 1s and 0s intended for display as a simulated gray-scale spectrogram
on a black-and-white monitor.
The \fIrefcof\fP (1\-\s-1ESPS\s+1) output is piped through the
.IR dither (1-ESPS)
program.
.SH "ESPS PARAMETERS"
.PP
The parameter file is not required to be present, as there are 
default parameter values that apply.  If the parameter file 
does exist, the following parameters are read:
.TP
.I "method \- string"
The spectrogram method to use.  This parameter is not read if the
\fB-m\fP option is used.  If the parameter is present and is read, it
determines default values for all other parameters as discussed under
the \fB-m\fP option.  The other parameters (or command line options),
if present, override these defaults.  The choice of "other" uses
defaults that are the same as "wb".  
.TP
.I "lpc_method \- string"
The analysis method used to compute reflection coefficients.  This
parameter is not read if the \fB-a\fP is used.  
.TP
.I "data_window \- string"
The data window to apply to the data.  This parameter is not read if
the \fB-d\fP option is specified or if \fImethod\fP is in the
parameter file and does not have the value "other".  Acceptable values
include "RECT" for a rectangular window, "HAMMING", for Hamming,
"HANNING" for Hanning, "COS4" for cosine 4th, and "TRIANG", for
triangular; see the
.IR window (3-ESPSsp)
manual page for the complete list.
.TP
.I "start \- integer"
.IP
The first point in the input sampled data file that is processed.  A
value of 1 denotes the first sample in the file.  This parameter is
not read if any of the range command line options are used.  If it is
not in the parameter file, and neither option is specified, a default
value of 1 is used.
.TP
.I "nan \- integer"
.IP
The total number of data points to process.
If
.I nan
is 0, processing continues through the end of the file.
This parameter is not read if any of the range command line 
options are used.
.TP
.I "window_len \- float"
.IP
The duration in milliseconds of each frame.  
This parameter not read if the \fB-w\fP option is specified of if
\fImethod\fP is in the file and does not have the value "other".
.TP
.I "pre_emphasis \- float"
The coefficient in the preemphasis filter (see
.B \-E
in the Options section).  
This parameter not read if the \fB-E\fP option is specified.
.TP
.I "step_size \- float"
Initial points of consecutive frames differ by this number of
milliseconds.  This parameter not read if the \fB-S\fP option is
specified.
.TP
.I "order - integer"
.IP
The number of reflection coefficients computed for each frame of input data.
If no value is given in the file, a default value of 15 is used.  This value 
is not read if the command line option \fB\-o\fP is used.  
.TP
.I "strcov_test - float"
.IP
If STRCOV is used, this is the convergence test value (the lower 
the value, the smaller the change per iteration before termination).  
This is not read if \fB-c\fP is used. 
.TP
.I "strcov_maxiter - int"
.IP
If STRCOV is used, this is the maximum number of iterations allowed
before the estimator terminates.  This is not read if \fB-i\fP is
used.
.PP
The values of parameters obtained from the parameter file are printed
if the environment variable ESPS_VERBOSE is 3 or greater.  The default
value is 3.
.SH ESPS COMMON
.PP
ESPS Common is read provided that Common processing is enabled and 
that the 
.I filename
entry in Common matches 
.I input.SD,
in which case parameters present in Common override values from the
parameter file, which in turn may be overriden by command line options
(see the discussion in ESPS PARAMETERS and under each option).
Common is not read if 
.I file.sd
is standard input.  
If 
.I file.rc
is not standard output and 
.I file.sd
is not standard input, the Common parameters 
\fIfilename\fP (= file.sd), \fIprog\fP (= refcof), 
.I start,
and
.I nan
are written to ESPS Common.
.PP
ESPS Common processing may be disabled by setting the environment
variable USE_ESPS_COMMON to "off".  The default ESPS Common file is
.espscom in the user's home directory.  This may be overidden by
setting the environment variable ESPSCOM to the desired path.  User
feedback of Common processing is determined by the environment
variable ESPS_VERBOSE, with 0 causing no feedback and increasing
levels causing increasingly detailed feedback.  If ESPS_VERBOSE is not
defined, a default value of 3 is assumed.
.SH ESPS HEADERS
.PP
The generic header item \fIstart_time\fP (type DOUBLE) is written in
the output file.  The value written is computed by taking the
\fIstart_time\fP value from the header of the input file (or zero, if
such a header item doesn't exist) and adding to it the offset time
(from the beginning of the input file) of the first point processed.
Also, the generic header item \fIrecord_freq\fP (type DOUBLE) is
written in the output file.  The value is the number of output records
per second of input data.  For details on the parameters used 
by all of the programs in the script, look at all of the intermediate
headers (e.g., via \fIpsps\fP \fB-a\fP).  
.SH "FUTURE CHANGES"
.PP
\fIme_sgram\fP will be re-implemented as a C program.  
.SH "SEE ALSO"
.PP
\fIsgram\fP (1\-\s-1ESPS\s+1),
\fIplotsgram\fP (1\-\s-1ESPS\s+1),
\fIfilter\fP (1\-\s-1ESPS\s+1), 
.br
\fIrefcof\fP (1\-\s-1ESPS\s+1),
\fIme_spec\fP (1\-\s-1ESPS\s+1), 
\fIcompute_rc\fP (3\-\s-1ESPS\s+1sp),
.br
\fIdither\fP (1\-\s-1ESPS\s+1), 
FEA_SPEC (5\-\s-1ESPS\s+1), 
FEA_SD (5\-\s-1ESPS\s+1)
.SH "BUGS"
.PP
This script cannot read standard input.
.SH "AUTHOR"
.PP
Manual page and program by David Burton. Revisions by John Shore.