decode.1

speech signal process tools

.\" Copyright (c) 1987 Entropic Speech, Inc.; All rights reserved
.\" @(#)decode.1	1.2	11/25/87 ESI
.TH DECODE 1\-ESPS 11/25/87
.ds ]W "\fI\s+4\ze\h'0.05'e\s-4\v'-0.4m'\fP\(*p\v'0.4m'\ Entropic Speech, Inc.
.ds ]Y "\fBESI INTERNAL\fP
.SH "NAME"
decode \- decode 2400 bps serial bitstream file, and generate file of
reconstructed quantization indices for LSFs, pitch, and power.
.SH "SYNOPSIS"
.B decode
[
.BI \-D " debug_file"
][
.BI \-d " "
][
.BI \-h " hist_file"
][
.BI \-x " debug_level"
]
.I " infile.fea huffile.fea outfile.fea"
.SH "DESCRIPTION"
.PP
\fIDecode\fR accepts a FEA_2KB serial bitstream file \fIinfile.fea\fR, and
creates an expanded FEA_ANA file \fIoutfile.fea\fR, which contains
reconstructed quantization indices for LSFs, pitch and power. The Huffman code
tables in the expanded FEA_QHIST file \fIhuffile.fea\fR are used to decode
the bitstream. The FEA_2KB file structure is defined in \fIfea_2kb\fR (5\-ESPS).
Descriptions of the auxiliary record fields in the expanded FEA_ANA and FEA_QHIST
files are given in \fIaux_ana\fR (5\-ESPS) and \fIaux_qhist\fR (5\-ESPS),
respectively.
.PP
\fIDecode\fR fills in the \fIraw_power_idx\fR, \fIpulse_len_idx\fR, and
\fIspec_param_idx\fR fields of the extended FEA_ANA output record. In
addition, several of the standard FEA_ANA record fields are filled in, as
described by the following: The \fIframe_type\fR field is written, and
the \fIvoiced_fraction\fR field is set accordingly. For a voiced frame, the
\fInum_pulses\fR field is filled in, and the \fIframe_len\fR field is set
to zero. For an unvoiced frame, the \fIframe_len\fR field is filled in, and
the \fInum_pulses\fR field is set to zero.
.PP
\fIOutfile.fea\fR can be further processed by \fIiqlsf\fR (1\-ESPS) to
produce an exact replica of the original output from \fIqlsf\fR (1\-ESPS).
The file thus created is suitable for input to the ESPS synthesis and listening
programs [\fIsynt\fR (1\-ESPS) or \fIdspsynt\fR (1\-ESPS), and \fIplay\fR (1\-ESPS)].
.PP
A detailed breakdown of the bits consumed while decoding various parameters
is written to a history file. The default name of this file is \fIdecode.his\fR,
but this can be overridden by the \fB\-h\fR option. In addition, a frame-by-frame
dump of decoding statistics to the history file can be initiated via the \fB\-d\fR
option.
.PP
A debug capability allows details of the decoding process to be monitored,
starting with bit unpacking operations at the codestream level, and proceeding
up to the speech frame level. This feature is controlled by the \fB\-x\fR option.
Debug output is normally written to \fIstderr\fR, but can be placed instead
in a file specified by the \fB\-D\fR option.
.PP
If \fIinfile.fea\fR is equal to "\-", standard input is used. Standard input
\fIcannot\fR be used for \fIhuffile.fea\fR. If \fIoutfile.fea\fR is equal to
"\-", standard output is used.
.SH OPTIONS
.TP
.BI \-D " debug_file"
Causes any debug output (see the \fB\-x\fR option) to be written to the
file \fIdebug_file\fR, rather than to the default file, which is \fIstderr\fR.
.TP
.BI \-d " "
Results in frame-by-frame details of the decoder bandwidth consumption
being output to the history file prior to the statistical summary. These
detailed items include: frame number, number of samples, number of bits
used to decode spectral parameters, power, and pulse/frame length, and
total number of bits. In transition frames, the frame number is tagged
with a '*', followed by a 'U' or 'V', denoting an unvoiced or voiced frame.
The number of samples is significant only for unvoiced frames; for voiced
frames, a value of zero is written.
.TP
.BI \-h " hist_file"
Causes the statistical summary and frame-by-frame details to be placed
in the file \fIhist_file\fR, instead of in the default file, which is
\fIdecode.his\fR.
.TP
.BI \-x " debug_level"
Causes details of the decoding process to be written to \fIstderr\fR, or
to the file specified by the \fB\-D\fR option. Values of \fIdebug_level\fR
in the range from 1 to 4 are currently supported, with the higher values
corresponding to greater levels of detail.
.SH "ESPS PARAMETERS"
.PP
The parameter file is not accessed by \fIdecode\fR.
.SH ESPS COMMON
.PP
ESPS Common is not used.
.SH ESPS HEADERS
.PP
The values of \fIcomb_vcg\fR, \fIcomb_frq\fR, \fIcont_pwr\fR, \fIcont_spc\fR,
\fIlsf_quant\fR, \fImax_steps\fR, \fIpitch_quant\fR, \fIpower_quant\fR,
\fIunvoiced_steps\fR, \fIvoiced_steps\fR, \fIu_avg\fR, and \fIv_avg\fR
are read from the generic header of \fIhuffile.fea\fR. For a description
of these quantities, see \fIfea_qhist\fR (5\-ESPS).
.PP
The values of \fIlsf_quant\fR, \fIpitch_quant\fR, \fIpower_quant\fR,
\fIunvoiced_steps\fR and \fIvoiced_steps\fR are read from the generic
header of \fIinfile.fea\fR. These are used to verify that the quantization
of the file from which \fIinfile.fea\fR was created is consistent with
\fIhuffile.fea\fR. If the \fI1.5_dB\fR power quantization has been used,
the values of \fImax_steps\fR are also checked for consistency between these
two files. The generic header items \fIcomb_vcg\fR, \fIcomb_frq\fR, \fIcont_pwr\fR,
\fIcont_spc\fR, \fIu_avg\fR, and \fIv_avg\fR are then read and compared with their
counterparts from \fIhuffile.fea\fR. This is done to ensure that consistent
Huffman tables are used for encoding and decoding. Finally, the values of
\fIchan_rate\fR, \fIorder_unvcd\fR, \fIorder_vcd\fR, \fIsync_intv\fR, \fIsync_len\fR,
and \fIuvced_frmlen\fR are are read for internal use by \fIdecode\fR.
.PP
A new file header is created for the output file. The header of \fIinfile.fea\fR
is added as a source in the output header, and the command line is added to the
comment field. The following generic header items are created, in addition to
those in the standard FEA_ANA header: \fIavg_pitch\fR, \fIavg_power\fR, \fIchan_rate\fR,
\fIlsf_quant\fR, \fIn_uv_pieces\fR, \fIpitch_quant\fR, \fIpower_quant\fR, \fIpre_poles\fR,
\fIpre_siz\fR, \fIpre_zeros\fR, \fIpreemp_uv\fR, \fIpsynch\fR, \fIsinc_flg\fR,
\fIunvoiced_steps\fR, and \fIvoiced_steps\fR.
.SH "EXAMPLES"
.PP
The following example gives a model shell script which shows all the steps
required to reconstruct, synthesize, and play back a speech file, starting
with a FEA_2KB bitstream file. [See \fIencode\fR (1\-ESPS) for examples of how
the files \fIbits.f2kb\fR and \fIhuff.xfqhist\fR are created.] \fIDecode\fR
currently has no mechanism for recovery from bit errors. Therefore, the
FEA_2KB file should be taken directly from \fIencode\fR (1\-ESPS); it should
not be processed by \fIcorrupt\fR (1\-ESPS).
.nf

decode bits.f2kb huff.xfqhist qidx.xfana
iqlsf qidx.xfana qlsf.xfana
spectrans \-p RC qlsf.xfana qrc.xfana
fea2ana qrc.xfana qrc.ana
dspsynt qrc.ana qrc.syn
play [\-opt ... ] qrc.syn

.fi
.SH "FUTURE CHANGES"
.PP
A number of modifications to \fIdecode\fR will be required to complete the
design of the 2400 bps bitstream. Details are given in [1].
.SH WARNINGS
.PP
\fIDecode\fR issues a warning and exits if \fIinfile.fea\fR is not a
FEA_2KB file, or if the quantization methods or coding techniques used to
generate \fIinfile.fea\fR are inconsistent with \fIhuffile.fea\fR.
The same actions are taken if \fIhuffile.fea\fR is not a FEA_QHIST file.
.SH "SEE ALSO"
.PP
corrupt (1\-ESPS), encode (1\-ESPS), huffgen (1\-ESPS), iqlsf (1\-ESPS), qlsf (1\-ESPS),
aux_ana (5\-ESPS), aux_qhist (5\-ESPS), fea_2kb (5\-ESPS), fea_qhist (5\-ESPS).
.SH "BUGS"
.PP
None known.
.SH REFERENCES
.PP
[1] ETM-S-87-08:jpe, \fIRemaining Tasks in the 2400 bps Coding Development\fR,
Version 1.0, 07/13/87.
.SH "AUTHOR"
.PP
Program and manual page by Jim Elliott.