intro.vrme

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the file header the average rate of zero crossings, but applications
arise when it is convenient to do so.  To address such needs, ESPS
provides generic header items.
.lp 
Generic header items provide programmers with the
ability to create arbitrary named fields in the header of any ESPS
file.  Utility functions in the ESPS library facilitate the creation
and manipulation of generics.  For example, the function 
.i add_genhd_f 
(3\-\s-1ESPS\s+1) can be used to create a generic header comprising
one or more floats.  Here's one example of its use to create
and fill an item called "zero_cross_rate":  
.vS
.nf

    struct header *hd;
    float time;
    long nzeros;
    . . .
    *add_genhd_f("zero_cross_rate", NULL, 1L, hd) = nzeros / time;

.fi
.vE
.lp
Similarly, \fIget_genhd\fP (3\-\s-1ESPS\s+1) returns a pointer to
an existing generic and might be used as follows:
.vS
.nf

    struct header *hd;
    long estim_zeros;
    float time;
    . . .
    /*compute estimated number of zeros*/
    estim_zeros = time * (*(float *) get_genhd("zero_cross_rate", hd));

.fi
.vE
.lp
Generic header items can store any type of C variable values, including
characters (and strings).  Also provided are generic header items 
to store enumerated types (also called coded types).  These header
items store an integer value but allow those values to be expressed
symbolically via a set of pre-defined strings.	For example, this 
code creates and fills a generic header item called "filter_type":
.vS
.nf

    /*defined constants for filter_type*/
    #define MISC	0
    #define LOW_PASS	1
    #define HIGH_PASS	2
    #define BAND_PASS	3

    /*string array of filter_type values*/
    char * f_types[] = {"MISC", "LOW_PASS", "HIGH_PASS", "BAND_PASS", NULL};

    /*create generic header item and fill it*/
    *add_genhd_e("filt_type", NULL, 1L, f_types, hd) = MISC;
    . . .
    /*change filt_type item in header*/
    *(short *) get_genhd("filt_type", hd) = BAND_PASS;

.fi
.vE
.lp
The \fIpsps\fP (1\-\s-1ESPS\s+1) listing for a file processed as above
will show the item symbolically, i.e.:
.nf

    . . .
    filt_type: BAND_PASS
    . . .

.fi
.lp
Also, programs that read a file with such a generic item defined in
the header can refer to the contents symbolically, as in the
following:
.vS
.nf

    struct header *hd;
    short filter_class;
    . . .
    filter_class = *(short *) get_genhd("filt_type", hd);
    . . .
    switch (fitler_class) {	
	case LOW_PASS:
	    . . .
	    break;
	case HIGH_PASS:
	    . . .
	    break;
	case BAND_PASS:
	    . . .
	    break;
	case MISC:
	    . . .
	    break;
	default:
	    ERROR_EXIT("invalid filter type encountered");
    }

.fi
.vE
.lp
Note that one can also add generic header items to existing files 
by means of the user-level program \fIaddgen\fP (1\-\s-1ESPS\s+1).  
.sh 2 "ESPS Record Structures"
.lp
The ESPS header is followed by a set of fixed-length data records.
When any record is read into memory (through use of an ESPS library
routine), it is stored as a C structure that is documented in the
relevant Section 5 manual page of the ESPS Manual.  As is the case for
file headers, programmers need not be concerned with the actual
format of ESPS data records.  For example, suppose that the variable
scbkrec is pointer to a SCBK file record (each record contains a
scalar quantization codebook plus related design information).  Then
the final distortion value for that codebook and the population of
the \fIi\fPth codeword are referred to as
.vS
.nf

    scbkrec->final_dist

and

    scbkrec->final_pop[i]

.fi
.vE
respectively (see SCBK (5\-\s-1ESPS\s+1)).  
.lp
This symbolic form of
reference for ESPS data records also applies to FEA files.  
For example, if anarec is a pointer to a FEA_ANA file record, the 
\fIi\fPth filter pole in that record is referred to as 
.vS
.nf

    anarec->filt_poles[i]

.fi
.vE
(see FEA_ANA (5\-\s-1ESPS\s+1). As mentioned earlier, users can 
define their own FEA file sub-types and extend existing subtypes.  
New fields in FEA file records are defined through use 
of \fIadd_fea_fld\fP (3\-\s-1ESPS\s+1), which creates a new field 
with a given name size, numerical type, etc.  The new fields are 
accessed by means of of \fIget_fea_ptr\fP (3\-\s-1ESPS\s+1), which 
returns a pointer to a field with a given name from a given record.  
.sh 2 "The ESPS Library"
.lp
To support the writing of new user-level ESPS programs, the ESPS
library contains various routines for processing ESPS headers, for
processing ESPS data records, and for performing various signal
processing functions.  At present, there are over 110 routines in the
library.  
.lp
A full ESPS lint library is included so that ESPS programs can be fully
checked with the standard \s-1UNIX\s+1 \fIlint\fP(1) utility for C program
checking.  As a further aid to programmers, \fIecheck\fP (3\-\s-1ESPS\s+1)
looks up entries in the ESPS lint library and prints the proper calling
sequence.  For emacs users, a mock-lisp file provides for \fIecheck\fP use
from within emacs.  The scripts \fIemake\fP (1\-\s-1ESPS\s+1), \fIecc\fP
(1\-\s-1ESPS\s+1), and \fIelint\fP (1\-\s-1ESPS\s+1) facilitate compiling
and checking programs under ESPS (for details, see.
.[[
ESPS programming
.]])
.lp
Here are a few examples of functions in the ESPS library:
.sh 3 "Signal Processing Support Library Functions"
.ta .1i 1i 
.nf

	\fIanalyze\fP	compute prediction error filter and reflection coefficients
	\fIblock-filter\fP	filter a data array
	\fIconvolv\fP	convolution of polynomials or auto-correlations
	\fIcovar\fP	compute reflection coefficients with covariance method 
	\fIfdbk_latic\fP	feedback filtering with lattice form
	\fIfeedbk_fil\fP	feedback filtering with transversal form
	\fIgauss\fP	compute Gaussian random numbers
	\fIget_auto\fP	compute auto-correlation coefficients
	\fIget_burg\fP	compute reflection coefficients with Burg or modified
		Burg method
	\fIget_fft\fP	compute fast Fourier transform
	\fIhamm_dec\fP	decode (8,4) Hamming code
	\fIhamm_enc\fP	encode with (8,4) Hamming code
	\fIinterp_filt\fP	perform interpolation filtering
	\fIis_dist_td\fP	compute Itakura-Saito distortion
	\fIpc_to_lsf\fP	convert prediction coefficients to line spectrum frequencies
	\fIrand_intnr\fP	sample without replacement from uniformly
		distributed integers
	\fIrefl_to_filt\fP	convert reflection coefficients to filter coefficients
	\fIremove_dc\fP	remove DC, using exponential weighting
	\fIvqdesign\fP	design a full-search vector quantization codebook

.fi
.sh 3 "File Support Library Functions"
.ta
.nf
.ta .1i 1.4i

	\fIadd_comment\fP	adds a string to the comment field of an ESPS header
	\fIadd_fea_fld\fP	add a new field to data record in a FEA file
	\fIadd_genhd\fP	adds a generic header item to a ESPS header
	\fIadd_source_file\fP	add the header of a source file to an ESPS header
	\fIcopy_header\fP	copies an ESPS header to a new header
	\fIgenhd_list\fP	returns a list of defined generic header items
	\fIget_cmd_line\fP	returns pointer to string containing program's command line
	\fIget_fea_fld\fP	returns pointer to named field in a FEA record
	\fIget_genhd\fP	returns pointer to named generic header item
	\fIget_spec_rec\fP	get next spectral record from ESPS SPEC file
	\fIget_sym\fP	get a parameter value after read_params called
	\fInew_header\fP	create new ESPS file header
	\fIprint_fea_rec\fP	prints a FEA file record
	\fIput_fea_rec\fP	writes a FEA file record
	\fIput_sym\fP	put value in ESPS common file
	\fIrange_switch\fP	parse the argument to a command-line range switch
	\fIread_header\fP	read an ESPS file header
	\fIread_params\fP	read the parameters in ESPS parameter or common file
	\fIskiprec\fP	skip records in ESPS file
	\fIwrite_header\fP	write an ESPS file header

.fi
.sh 1 "EXAMPLE USER-LEVEL ESPS PROGRAMS"
.lp
This section lists some user-level ESPS programs of general interest.
Note that the entire ESPS Manual is stored on-line.  The manual pages
can be viewed with the 
.i eman
(1\-\s-1ESPS\s+1) command, which is an ESPS version of the \s-1UNIX\s+1 
.i man 
command.  
.i Eman
includes the \fB\-k\fP option to search the manual for programs
whose one-line descriptions include a given keyword. 
.sh 2 "Conversion and Related Support Programs"
.ta .1i 1i 
.nf

	\fIaddfea\fP	adds a FEA file field from ASCII data
	\fIaddfeahd\fP	adds a FEA file header to binary data
	\fIaddgen\fP	adds generic header item to ESPS file header
	\fIatofilt\fP	convert ASCII file to FILT file
	\fIatosps\fP	converts ASCII output to ESPS file (see spstoa)
	\fIbhd\fP	behead an ESPS file
	\fIeitem\fP	prints item from ESPS file header
	\fIils_sps\fP	converts ILS sampled data file to ESPS SD file
	\fIpplain\fP	print values from ESPS files in "plain" ASCII format 
	\fIspstoa\fP	convert ESPS file to machine-independent ASCII format
	\fItestsd\fP	make SD file with sine wave, pulses, Gaussian noise, or from ASCII data

.fi
.sh 2 "Signal I/O and Processing"
.ta .1i 1i 
.nf

	\fIaddsd\fP	adds SD files with scaling
	\fIana\fP	perform speech analysis from SD file
	\fIme_spec\fP	compute spectra (FEA_SPEC file) from FEA_ANA file
	\fIdistort\fP	compute distortion measures between ESPS files
	\fIclassify\fP	classify records in FEA files
	\fIfea_stats\fP	compute statistics from FEA files
	\fIfft\fP	produces FEA_SPEC file by doing fft on SD file
	\fIfilter\fP	performs digital filtering on SD file
	\fIlloydcbk\fP	design a scalar quantizer using Lloyd's algorithm
	\fInotch_filt\fP	design a notch filter
	\fIplay\fP	play portions of SD files
	\fIplaytest\fP	step through an "A-B" listening test with control options
	\fIrandplay\fP	create play scripts for randomized "A-B" listening comparisons
	\fIrecord\fP	digitize data using Masscomp EF-12M
	\fIrefcof\fP	compute reflection coefficients from sampled data (FEA_ANA output)
	\fIrem_dc\fP	remove DC component from SD file
	\fIsdcomp\fP	listening program for detailed comparison of two sampled data files
	\fIspectrans\fP	transform FEA_ANA from one spectral representation to another
	\fIstats\fP	computes statistics from ESPS files
	\fIsynt\fP	synthesize speech from ANA file
	\fItestsd\fP	make SD file with sine wave, pulses, Gaussian noise, or from ASCII data
	\fIvqdes\fP		design a vector quantization codebook from a FEA file
	\fIvq\fP		encode FEA file with a vector quantization codebook
	\fIwmse_filt\fP	design FIR filter using weighted mean square error criterion
	\fIiir_filt\fP	design recursive filter

.fi
.sh 2 "File Manipulation and Plotting"
.nf

	\fIaplot\fP	plot an array of ASCII data
	\fIcomment\fP	displays or adds comments in the header of an ESPS file
	\fIcopysd\fP	copy selected portions of SD files to a new file
	\fIfea_edit\fP	edit a FEA file in ASCII form
	\fIgenplot\fP	plot elements from any ESPS file in precise, multiline format 
	\fIhistogram\fP	sort data into bins for plotting histograms
			(screen, Imagen, or Tektronix) 
	\fImlplot\fP	plot SD file in precise, multiline format 
			(screen, Imagen, or Tektronix) 
	\fIplotsd\fP	plot sampled data (screen, Imagen, or Tektronix) 
	\fIplotspec\fP	plot spectra from FEA_SPEC file (screen, Imagen, or Tektronix) 
	\fIpsps\fP	print ESPS file headers and records
	\fIrange\fP	select a range from a graphics plot
	\fIselect\fP	select FEA records that satisfy queries
	\fIscatplot\fP	make a scatter plot

.fi
.sh 1 "FUTURE CHANGES"
.lp
Everything discussed in the foregoing is available in ESPS Version
3.3.  In this section, we mention some of the things that will added
in later versions.  
.lp
Current ESPS FEA files are restricted to fixed length records, 
one record type per file, with record fields containing only the machine
primitive data types (integer, float, double, character).  All of these
restrictions should be relaxed.  
.lp
We will provide support for engineering units, so that plotting 
and printing programs can display data in terms of externally 
relevant units (volts, pressure, etc.).  
.lp
We will provide some additional facilities to support ESPS
programming.  For example, there will be a program for the
semi-automatic generation of new FEA file sub-types, and there will
be a program for the automatic generation of C skeletons for
user-level programs.
.lp
The ESPS parameter file format might be simplified so that users didn't
have to specify types (they don't on command lines).  Also, ESPS user-level
programs will be modified to take all parameters from the parameter file
(with possible command-line overrides) so that every program can be run
interactively using \fIeparam\fP (1\-\s-1ESPS\s+1) (some programs in
Version 3.3 require command line arguments for some or all parameters).
.lp
Another significant enhancement will be provided by an interface
between ESPS and a \s-1UNIX\s+1 relational data base system.  This
interface will create data base records from ESPS file headers so
that the data base system can be used to manage sets of ESPS files.
.sh 1 "REFERENCES"
.lp
.[
$LIST$
.]