readme

ears-0.32, linux下有用的语音信号处理工具包

$Header: /u/drspeech/src/rasta/RCS/README,v 1.9 1995/07/03 22:38:01 bedk Exp $
****************************************************
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        RASTA 2.2 - July 3, 1995 Release
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Changes from 2.1:

1) lpccep.c now has a more accurate routine for converting lpc
   coefficients to autoregressive coefficients.  This means that
   rasta2_2 will give different results than previous versions
   of the program; however, they are better results, so it is
   OK.

2) rasta2_2 does matlab MAT file I/O.  Use the -b/-B options to
   do this.  You'll need to build rasta with MATLAB=1 and a
   correct value of MATLAB_BASE to get this to work.  You'll
   also need matlab.

3) The input waveform can be filtered with an IIR highpass
   filter (cutoff at 45 Hz) to reduce DC offset.  The -F option
   enables the filter.

4) rasta2_2 can use a previously-stored estimate of the noise
   level and rasta filter history for initialization.  This
   option is recommended for use with Jah-RASTA processing if
   the input can have less than 100--200 ms. of silence at the
   beginning.  The -h and -H options control history
   maintenance.

5) The calls to irint() and log2() have been eliminated to
   improve code portability.

6) Several unused variables in the fvec and svec structures have
   been eliminated.

7) The fmat_x_fvec routine was changed to run faster.
   Thanks to Ralf W. Stephan (<[e-mail]>) for
   suggesting changes (6) and (7).

8) rasta now has a man page!

9) Some minor bug fixes and code cleaning, including the
   reduction of a statically allocated 60 MB (!) table.

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        RASTA 2.1 - Changes from 2.0
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1) Can now output the critical-band filter bank trajectories
   after the cube-root compression and loundess equalization.
   Enabled by the -P option.

2) Can byte-swap input when reading binary data (either on or   
   off-line).  Enabled by the -T option.

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        RASTA 2.0 - May 30, 1994 Release
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	RASTA 2.0 is an update version for RASTA 1.0. 
RASTA1.0 is a program for the rasta-plp processing and
it supports the following front-end techniques: PLP,
RASTA, and Jah-RASTA with fixed Jah-value. The Jah-Rasta
technique handles two different types of harmful effects
for speech recognition systems, namely additive noise and
spectral distortion, simultaneously, by bandpass filtering
the temporal trajectories of a non-linearly transformed
critical band spectrum. Since the optimal form of the
nonlinearity used in Jah-Rasta is dependent on the noise
level, this non-constant nonlinearity introduces a new
source of variability into the speech recognition system.
An approach was developed for compensating for this new
source of variability by Joachim Koehler and Grace Tong.
It will be referred as the spectral mapping method from
now on. RASTA 2.0 is an update version for RASTA 1.0 with
the spectral mapping method included. The spectral mapping
method will be further discussed in the file rasta.c.
	The J factor depends on the SNR. The J that we have
found to work well is something like 1/(3 * noisepower). 
In order to calculate the J factor adaptively, a noise 
estimation subroutine is also included in RASTA 2.0.
In the current version, the J factor can be either kept as
a constant by entering the value at the command line or
calculated adaptively using the formula J = 1/(3 * noisepower).
	There are two new files, mapping.c and noise_est.c 
added to RASTA 2.0. These two files handle the spectral 
mapping and noise_estimation respectively. Besides these
two files, a number of files from RASTA 1.0 were also 
slightly modified. They were modified to incorporate the 
Jah-Rasta spectral mapping and to correct some newly found
bugs in RASTA 1.0. The files that were modified are listed
below:

1) anal.c
2) debug.c 
3) init.c  
4) io.c
5) rasta.c
6) rasta_filt.c
7) Makefile
8) functions.h
9) rasta.h

The bugs that were corrected are:

1) In init.c, get_comline(),
    the following is added:
        case 'd':/* flag for debug output */
                pptr->debug = TRUE;
                break;

2) In init.c check_arg()
    the following is added:
        if((pptr->lrasta == TRUE) && (pptr->jrasta == TRUE))
        {
                fprintf(stderr,"Can't do log rasta and jah rasta at the same tim
e\n");
                exit(-1);
        }

3) In rasta_filt.c   struct fvec *rasta_filt()

   if(pptr->rfrac != 1.0)
   {
      outptr->values[i] =
                 pptr->rfrac * outptr->values[i]
                + (1-pptr->rfrac) * nl_audspec->values[i];
   }


4) Previously, for doing partial rasta and partial PLP, there
   were 2 switches; one as a flag to indicate that we are doing
   partial rasta, and the other to say what fraction of the output
   comes from the rasta part. Some users were complaining that
   the 2 switches are sort of confusing. Now, we just have the
   latter switches. It makes more sense since if you want it to
   be blended you will need to give a fractional amount.
  
5) The two makefiles have been merged to form one. Use e.g. "make
   ESPS=1 ESPS_BASE=/usr/local/esps" to build the version with ESPS
   IO.

Listed below is the old README file from RASTA 1.0 : 








****************************************************
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	RASTA 1.0 - August 13, 1993 Release
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	This directory holds the current debugged (at least we think so) 
release materials for the rasta-plp program. This code comes from 
(in ancient history) a Fortran source written by Hynek Hermansky to 
implement PLP.  Later versions done by H. Hermansky and C. Wooters used 
automatically translated C code and hand modifications to add in the 
RASTA processing.  This version (by N. Morgan) is pretty much 
a complete rewrite, splitting up analysis elements into reasonably-sized 
modules. A few routines from the past linger on with little change,
(e.g., the fft and the Durbin recursion)
because they work fine and suspect data structures (e.g. most arrays
with short fixed lengths) have been changed to dynamically allocate
what is needed and to check for array bounds.

In this directory you will find 2 sub-directories, one for
source files and one for the binary. 

See the front of "rasta.c" for a description of the algorithm.

**************************************************
	WHAT IS AND ISN'T HERE
**************************************************
	What is frozen here in reasonable form
is the most debugged version of the rasta algorithm.
Some of the things that we are currently experimenting with
are not yet included, since they are not yet sufficiently
mature for release (although we will be happy to talk
about them with you). However, it should be relatively easy
for you to modify the program to play with some of these ideas.
Some of the unimplemented pieces are:

	1) General linear filters - what we have implemented is
a ``standard'' rasta filter, which consists of a delta
calculation followed by a single-pole integration.
We have used data structures in the core filtering
routine that permit a more general filtering function
consisting of numerator and denominator polynomials,
but as of this release we don't read in such files
or allow for general polynomials in the routine that calls
the filt() function. 

	2) Similarly, we currently use the same rasta
filter for each band. Putting in the modifications for (1)
will also permit more flexibility in this regard.

	3) Nonlinear modifications within the filtering
are potentially possible (such as suppression of small
changes, or median filtering) but have not yet been tested.