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|
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.\"
|
||||
.\" Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
|
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.\" Universitaet Berlin. See the accompanying file "COPYRIGHT" for
|
||||
.\" details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
|
||||
.\"
|
||||
.PU
|
||||
.TH BITTER 1
|
||||
.SH NAME
|
||||
bitter, sweet \(em code-generators for packing bits
|
||||
.SH SYNOPSIS
|
||||
bitter < input > output
|
||||
.br
|
||||
sweet < input > output
|
||||
.SH "DESCRIPTION"
|
||||
Bitter and sweet are two filters which turn a description of the
|
||||
form
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||||
.nf
|
||||
name number-of-bits
|
||||
name number-of-bits
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||||
...
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||||
.nf
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||||
into code.
|
||||
.PP
|
||||
Bitter generates code that packs the specified bits from their
|
||||
variables into an array of unsigned char referenced by an
|
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advancing pointer c.
|
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.PP
|
||||
Sweet generates code that unpacks the specified bits from an array
|
||||
of unsigned char referenced by a mutable pointer c into the
|
||||
named variables.
|
||||
.\" .SH OPTIONS
|
||||
.\" .SH "RETURN VALUE"
|
||||
.\" .SH ERRORS
|
||||
.SH EXAMPLES
|
||||
.nf
|
||||
% cat in
|
||||
amaretto 1
|
||||
banana 2
|
||||
cherry 3
|
||||
strawberry 4
|
||||
vanilla 15
|
||||
walnut 15
|
||||
|
||||
% bitter < in
|
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*c++ = ((amaretto & 0x1) << 7)
|
||||
| ((banana & 0x3) << 5)
|
||||
| ((cherry & 0x7) << 2)
|
||||
| ((strawberry >> 2) & 0x3);
|
||||
*c++ = ((strawberry & 0x3) << 6)
|
||||
| ((vanilla >> 9) & 0x3F);
|
||||
*c++ = ((vanilla >> 1) & 0xFF);
|
||||
*c++ = ((vanilla & 0x1) << 7)
|
||||
| ((walnut >> 8) & 0x7F);
|
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*c++ = walnut & 0xFF;
|
||||
|
||||
% sweet < in
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amaretto = (*c >> 7) & 0x1;
|
||||
banana = (*c >> 5) & 0x3;
|
||||
cherry = (*c >> 2) & 0x7;
|
||||
strawberry = (*c++ & 0x3) << 2;
|
||||
strawberry |= (*c >> 6) & 0x3;
|
||||
vanilla = (*c++ & 0x3F) << 9;
|
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vanilla |= (*c++ & 0xFF) << 1;
|
||||
vanilla |= (*c >> 7) & 0x1;
|
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walnut = (*c++ & 0x7F) << 8;
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walnut |= *c++;
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.SH NOTES
|
||||
This is a quick hack for the gsm_encode() and gsm_decode() routines.
|
||||
.SH BUGS
|
||||
Please direct bug reports to jutta@cs.tu-berlin.de and cabo@cs.tu-berlin.de.
|
||||
+105
@@ -0,0 +1,105 @@
|
||||
.\"
|
||||
.\" Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
|
||||
.\" Universitaet Berlin. See the accompanying file "COPYRIGHT" for
|
||||
.\" details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
|
||||
.\"
|
||||
.PU
|
||||
.TH GSM 3
|
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.SH NAME
|
||||
gsm_create, gsm_destroy, gsm_encode, gsm_decode \(em GSM\ 06.10 lossy sound compression
|
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.SH SYNOPSIS
|
||||
.PP
|
||||
#include "gsm.h"
|
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.PP
|
||||
gsm gsm_create();
|
||||
.PP
|
||||
void gsm_encode(handle, src, dst)
|
||||
.br
|
||||
gsm handle;
|
||||
.br
|
||||
gsm_signal src[160];
|
||||
.br
|
||||
gsm_frame dst;
|
||||
.PP
|
||||
int gsm_decode(handle, src, dst)
|
||||
.br
|
||||
gsm handle;
|
||||
.br
|
||||
gsm_frame src;
|
||||
.br
|
||||
gsm_signal dst[160];
|
||||
.PP
|
||||
void gsm_destroy(handle)
|
||||
.br
|
||||
gsm handle;
|
||||
.br
|
||||
.SH "DESCRIPTION"
|
||||
Gsm is an implementation of the final draft GSM 06.10
|
||||
standard for full-rate speech transcoding.
|
||||
.PP
|
||||
gsm_create() initializes a gsm pass and returns a 'gsm' object
|
||||
which can be used as a handle in subsequent calls to gsm_decode(),
|
||||
gsm_encode() or gsm_destroy().
|
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.PP
|
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gsm_encode() encodes an array of 160 13-bit samples (given as
|
||||
gsm_signal's, signed integral values of at least 16 bits) into
|
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a gsm_frame of 33 bytes.
|
||||
(gsm_frame is a type defined as an array of 33 gsm_bytes in gsm.h.)
|
||||
.PP
|
||||
gsm_decode() decodes a gsm_frame into an array of 160 13-bit samples
|
||||
(given as gsm_signals), which sound rather like what you handed to
|
||||
gsm_encode() on the other side of the wire.
|
||||
.PP
|
||||
gsm_destroy() finishes a gsm pass and frees all storage associated
|
||||
with it.
|
||||
.SS "Sample format"
|
||||
The following scaling is assumed for input to the algorithm:
|
||||
.br
|
||||
.nf
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||||
0 1 11 12
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||||
S..v..v..v..v..v..v..v..v..v..v..v..v..*..*..*
|
||||
.nf
|
||||
.br
|
||||
Only the top 13 bits are used as a signed input value.
|
||||
The output of gsm_decode() has the three lower bits set to zero.
|
||||
.\" .SH OPTIONS
|
||||
.SH "RETURN VALUE"
|
||||
gsm_create() returns an opaque handle object of type gsm, or 0 on error.
|
||||
gsm_decode() returns -1 if the passed frame is invalid, else 0.
|
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.SH EXAMPLE
|
||||
.nf
|
||||
#include "gsm.h"
|
||||
|
||||
gsm handle;
|
||||
gsm_frame buf;
|
||||
gsm_signal sample[160];
|
||||
int cc, soundfd;
|
||||
|
||||
play() { /* read compressed data from standard input, write to soundfd */
|
||||
|
||||
if (!(handle = gsm_create())) error...
|
||||
while (cc = read(0, (char *)buf, sizeof buf)) {
|
||||
if (cc != sizeof buf) error...
|
||||
if (gsm_decode(handle, buf, sample) < 0) error...
|
||||
if (write(soundfd, sample, sizeof sample) != sizeof sample)
|
||||
error...
|
||||
}
|
||||
gsm_destroy(handle);
|
||||
}
|
||||
|
||||
record() { /* read from soundfd, write compressed to standard output */
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||||
|
||||
if (!(handle = gsm_create())) error...
|
||||
while (cc = read(soundfd, sample, sizeof sample)) {
|
||||
if (cc != sizeof sample) error...
|
||||
gsm_encode(handle, sample, buf);
|
||||
if (write(1, (char *)buf, sizeof buf) != sizeof sample)
|
||||
error...
|
||||
}
|
||||
gsm_destroy(handle);
|
||||
}
|
||||
.nf
|
||||
.SH BUGS
|
||||
Please direct bug reports to jutta@cs.tu-berlin.de and cabo@cs.tu-berlin.de.
|
||||
.SH "SEE ALSO"
|
||||
toast(1), gsm_print(3), gsm_explode(3), gsm_option(3)
|
||||
@@ -0,0 +1,47 @@
|
||||
.\"
|
||||
.\" Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
|
||||
.\" Universitaet Berlin. See the accompanying file "COPYRIGHT" for
|
||||
.\" details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
|
||||
.\"
|
||||
.PU
|
||||
.TH GSM_EXPLODE 3
|
||||
.SH NAME
|
||||
gsm_explode, gsm_implode \(em GSM\ 06.10 supplementary
|
||||
functions for testing
|
||||
.SH SYNOPSIS
|
||||
#include "gsm.h"
|
||||
.PP
|
||||
void gsm_explode(g, frame, xframe)
|
||||
.br
|
||||
gsm g;
|
||||
.br
|
||||
gsm_frame frame;
|
||||
.br
|
||||
gsm_signal xframe[ 76 ];
|
||||
.PP
|
||||
void gsm_implode(g, xframe, frame)
|
||||
.br
|
||||
gsm g;
|
||||
.br
|
||||
gsm_signal xframe[ 76 ];
|
||||
.br
|
||||
gsm_frame frame;
|
||||
.SH "DESCRIPTION"
|
||||
Gsm is an implementation of the final draft GSM 06.10
|
||||
standard for full-rate speech transcoding.
|
||||
Test data for implementations of this particular document
|
||||
can be bought and used to verify an implementation.
|
||||
.PP
|
||||
The encoded test data uses a format different from what
|
||||
one would use to transmit frames with the least number
|
||||
of bits.
|
||||
Gsm_explode() and gsm_implode() convert between the
|
||||
internal, small, 33-byte format and the 76-word format
|
||||
used by the test data.
|
||||
.PP
|
||||
.SH "RETURN VALUE"
|
||||
gsm_explode() returns -1 if the passed frame is invalid, else 0.
|
||||
.SH BUGS
|
||||
Please direct bug reports to jutta@cs.tu-berlin.de and cabo@cs.tu-berlin.de.
|
||||
.SH "SEE ALSO"
|
||||
gsm(3)
|
||||
+183
@@ -0,0 +1,183 @@
|
||||
.\"
|
||||
.\" Copyright 1992-1995 by Jutta Degener and Carsten Bormann, Technische
|
||||
.\" Universitaet Berlin. See the accompanying file "COPYRIGHT" for
|
||||
.\" details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
|
||||
.\"
|
||||
.PU
|
||||
.TH GSM_OPTION 3
|
||||
.SH NAME
|
||||
gsm_option \(em customizing the GSM 06.10 implementation
|
||||
.SH SYNOPSIS
|
||||
#include "gsm.h"
|
||||
.PP
|
||||
int gsm_option(handle, option, valueP);
|
||||
.br
|
||||
gsm handle;
|
||||
.br
|
||||
int option;
|
||||
.br
|
||||
int * valueP;
|
||||
.SH "DESCRIPTION"
|
||||
The gsm library is an implementation of the final draft GSM 06.10
|
||||
standard for full-rate speech transcoding, a lossy
|
||||
speech compression algorithm.
|
||||
.PP
|
||||
The gsm_option() function can be used to set and query various
|
||||
options or flags that are not needed for regular GSM 06.10 encoding
|
||||
or decoding, but might be of interest in special cases.
|
||||
.PP
|
||||
The second argument to gsm_option specifies what parameter
|
||||
should be changed or queried.
|
||||
The third argument is either a null pointer, in which case
|
||||
the current value of that parameter is returned;
|
||||
or it is a pointer to an integer containing the value
|
||||
you want to set, in which case the previous value will
|
||||
be returned.
|
||||
.PP
|
||||
The following options are defined:
|
||||
.PP
|
||||
.I GSM_OPT_VERBOSE
|
||||
Verbosity level.
|
||||
.br
|
||||
.in+5
|
||||
This option is only supported if the library was compiled
|
||||
with debugging turned on, and may be used by developers of
|
||||
compression algorithms to aid debugging.
|
||||
.br
|
||||
The verbosity level can be changed at any time during encoding or decoding.
|
||||
.in-5
|
||||
.sp
|
||||
.PP
|
||||
.I GSM_OPT_FAST
|
||||
Faster compression algorithm.
|
||||
.br
|
||||
.in+5
|
||||
This implementation offers a not strictly standard-compliant, but
|
||||
faster compression algorithm that is compatible with the regular
|
||||
method and does not noticably degrade audio quality.
|
||||
.br
|
||||
The value passed to
|
||||
.br
|
||||
.nf
|
||||
gsm_option(handle, GSM_OPT_FAST, & value)
|
||||
.fi
|
||||
.br
|
||||
functions as a boolean flag; if it is zero, the regular algorithm
|
||||
will be used, if not, the faster version will be used.
|
||||
.br
|
||||
The availability of this option depends on the hardware used;
|
||||
if it is not available, gsm_option will return -1 on an attempt
|
||||
to set or query it.
|
||||
.br
|
||||
This option can be set any time during encoding or decoding.
|
||||
.in-5
|
||||
.ne 5
|
||||
.sp
|
||||
.PP
|
||||
.I GSM_OPT_LTP_CUT
|
||||
Enable, disable, or query the LTP cut-off optimization.
|
||||
.br
|
||||
.in+5
|
||||
During encoding, the search for the long-term correlation
|
||||
lag forms the bottleneck of the algorithm.
|
||||
The ltp-cut option enables an approximation that disregards most
|
||||
of the samples for purposes of finding that correlation,
|
||||
and hence speeds up the encoding at a noticable loss in quality.
|
||||
.br
|
||||
The value passed to
|
||||
.br
|
||||
.nf
|
||||
gsm_option(handle, GSM_OPT_LTP_CUT, & value)
|
||||
.fi
|
||||
.br
|
||||
turns the optimization on if nonzero, and off if zero.
|
||||
.br
|
||||
This option can be set any time during encoding
|
||||
or decoding; it will only affect the encoding pass, not
|
||||
the decoding.
|
||||
.sp
|
||||
.PP
|
||||
.I GSM_OPT_WAV49
|
||||
WAV-style byte ordering.
|
||||
.br
|
||||
.in+5
|
||||
A WAV file of type #49 contains GSM 06.10-encoded frames.
|
||||
Unfortunately, the framing and code ordering of the WAV version
|
||||
are incompatible with the native ones of this GSM 06.10 library.
|
||||
The GSM_OPT_WAV49 option turns on a different packing
|
||||
algorithm that produces alternating frames of 32 and 33 bytes
|
||||
(or makes it consume alternating frames of 33 and 32 bytes, note
|
||||
the opposite order of the two numbers) which, when concatenated,
|
||||
can be used in the body of a WAV #49 frame.
|
||||
It is up to the user program to write a WAV header, if any;
|
||||
neither the library itself nor the toast program produce
|
||||
complete WAV files.
|
||||
.br
|
||||
The value passed to
|
||||
.br
|
||||
.nf
|
||||
gsm_option(handle, GSM_OPT_WAV49, & value)
|
||||
.fi
|
||||
.br
|
||||
functions as a boolean flag; if it is zero, the library's native
|
||||
framing algorithm will be used, if nonzero, WAV-type packing is in effect.
|
||||
.br
|
||||
This option should be used before any frames are encoded.
|
||||
Whether or not it is supported at all depends on a
|
||||
compile-time switch, WAV49.
|
||||
Both option and compile time switch are new to the library
|
||||
as of patchlevel 9, and are considerably less tested than the
|
||||
well-worn rest of the it.
|
||||
.br
|
||||
Thanks to Jeff Chilton for the detective work and first free
|
||||
implementation of this version of the GSM 06.10 encoding.
|
||||
.sp
|
||||
.PP
|
||||
.I GSM_OPT_FRAME_CHAIN
|
||||
Query or set the chaining byte.
|
||||
.br
|
||||
.in+5
|
||||
Between the two frames of a WAV-style encoding, the GSM 06.10 library
|
||||
must keep track of one half-byte that is technically part of the first
|
||||
frame, but will be written as the first four bits of the second.
|
||||
This half-byte are the lowest four bits of the value returned by,
|
||||
and optionally set by,
|
||||
.br
|
||||
.nf
|
||||
gsm_option(handle, GSM_OPT_FRAME_CHAIN, & value)
|
||||
.fi
|
||||
.br
|
||||
This option can be queried and set at any time.
|
||||
.sp
|
||||
.PP
|
||||
.I GSM_OPT_FRAME_INDEX
|
||||
Query or set the current frame's index in a format's
|
||||
alternating list of frames.
|
||||
.br
|
||||
.in+5
|
||||
The WAV #49 framing uses two alternating types of frames.
|
||||
Which type the next GSM-coded frame belongs to can be queried, or,
|
||||
when decoding, announced, using
|
||||
.br
|
||||
.nf
|
||||
gsm_option(handle, GSM_OPT_FRAME_INDEX, & value)
|
||||
.fi
|
||||
.br
|
||||
For WAV-style framing, the value should be 0 or 1; the first frame
|
||||
of an encoding has an index of 0.
|
||||
At library initialization, the index is set to zero.
|
||||
.br
|
||||
The frame index can be queried and set at any time.
|
||||
Used in combination with the
|
||||
.IR GSM_OPT_FRAME_CHAIN ,
|
||||
option, it can be used to position on arbitrary GSM frames
|
||||
within a format like WAV #49 (not accounting for the lost
|
||||
internal GSM state).
|
||||
.in-5
|
||||
.SH "RETURN VALUE"
|
||||
gsm_option() returns -1 if an option is not supported, the
|
||||
previous value of the option otherwise.
|
||||
.SH BUGS
|
||||
Please direct bug reports to jutta@cs.tu-berlin.de and cabo@cs.tu-berlin.de.
|
||||
.SH "SEE ALSO"
|
||||
toast(1), gsm(3), gsm_explode(3), gsm_print(3)
|
||||
@@ -0,0 +1,52 @@
|
||||
.\"
|
||||
.\" Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
|
||||
.\" Universitaet Berlin. See the accompanying file "COPYRIGHT" for
|
||||
.\" details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
|
||||
.\"
|
||||
.PU
|
||||
.TH GSM_PRINT 3
|
||||
.SH NAME
|
||||
gsm_print \(em GSM\ 06.10 supplementary function for debugging
|
||||
.SH SYNOPSIS
|
||||
#include "gsm.h"
|
||||
#include <stdio.h>
|
||||
|
||||
int gsm_print(f, g, frame);
|
||||
.br
|
||||
FILE * f;
|
||||
.br
|
||||
gsm g;
|
||||
.br
|
||||
gsm_frame frame;
|
||||
.SH "DESCRIPTION"
|
||||
Gsm is an implementation of the final draft GSM 06.10
|
||||
standard for full-rate speech transcoding, a lossy
|
||||
speech compression algorithm.
|
||||
The compressed form involves 76 variables with different numbers
|
||||
of significant bits packed into 33 bytes.
|
||||
.PP
|
||||
If you are interested in investigating the details of this
|
||||
coding scheme, gsm_print() can be used to dump the contents
|
||||
of individual gsm_frames to a file pointer provided by
|
||||
the application.
|
||||
.PP
|
||||
.SH "RETURN VALUE"
|
||||
gsm_print() returns -1 if the frame is invalid, else 0.
|
||||
.SH EXAMPLE
|
||||
A single frame looks like this:
|
||||
.br
|
||||
.nf
|
||||
LARc: 29 32 20 11 08 05 06 07
|
||||
#1: Nc 0040 bc 0 Mc 1 xmaxc 60
|
||||
06 04 00 03 03 06 04 02 02 04 05 04 01
|
||||
#2: Nc 0045 bc 1 Mc 1 xmaxc 48
|
||||
03 07 01 03 04 04 07 01 03 02 04 05 03
|
||||
#3: Nc 0091 bc 1 Mc 1 xmaxc 46
|
||||
00 03 03 07 01 06 02 04 05 03 03 02 04
|
||||
#4: Nc 0120 bc 0 Mc 1 xmaxc 47
|
||||
07 03 06 00 03 03 06 05 00 03 02 07 04
|
||||
.nf
|
||||
.SH BUGS
|
||||
Please direct bug reports to jutta@cs.tu-berlin.de and cabo@cs.tu-berlin.de.
|
||||
.SH "SEE ALSO"
|
||||
gsm(3), gsm_explode(3)
|
||||
+156
@@ -0,0 +1,156 @@
|
||||
.\"
|
||||
.\" Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
|
||||
.\" Universitaet Berlin. See the accompanying file "COPYRIGHT" for
|
||||
.\" details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
|
||||
.\"
|
||||
.if n .ds mU u
|
||||
.if t .ds mU \(*m
|
||||
.\"
|
||||
.TH TOAST 1 local
|
||||
.SH NAME
|
||||
toast \(em GSM\ 06.10 lossy sound compression
|
||||
.SH SYNOPSIS
|
||||
.ll +8
|
||||
.B toast
|
||||
[
|
||||
.B \-cdfpvhualsFC
|
||||
] [
|
||||
.I "filename...\&"
|
||||
]
|
||||
.LP
|
||||
.B untoast
|
||||
[
|
||||
.B \-cfpvhuaslF
|
||||
] [
|
||||
.I "filename...\&"
|
||||
]
|
||||
.LP
|
||||
.B tcat
|
||||
[
|
||||
.B \-vhuaslF
|
||||
] [
|
||||
.I "filename...\&"
|
||||
]
|
||||
.ll -8
|
||||
.SH DESCRIPTION
|
||||
Toast compresses the sound files given on its command line.
|
||||
Each file is replaced by a file with the extension
|
||||
.I \&.gsm .
|
||||
If no files are specified, the compression is applied to the
|
||||
standard input, and its result is written to standard output.
|
||||
.PP
|
||||
Toasted files can be restored to something not quite unlike
|
||||
their original form by running toast
|
||||
.I "\-d"
|
||||
, or
|
||||
.I untoast
|
||||
, on the \&.gsm-files or standard input.
|
||||
.PP
|
||||
The program
|
||||
.I tcat
|
||||
(the same as running
|
||||
.I "untoast \-c"
|
||||
) uncompresses its input on standard output,
|
||||
but leaves the compressed .gsm\-files alone.
|
||||
.PP
|
||||
When files are compressed or uncompressed into other files,
|
||||
the ownership (if run by root), modes, accessed and modified times
|
||||
are maintained between both versions.
|
||||
.SH OPTIONS
|
||||
.TP
|
||||
.B \-c
|
||||
(cat)
|
||||
Write to the standard output; no files are changed.
|
||||
.TP
|
||||
.B \-d
|
||||
(decode)
|
||||
Decode, rather than encode, the files.
|
||||
.TP
|
||||
.B \-f
|
||||
(force)
|
||||
Force replacement of output files if they exist.
|
||||
If \-f is omitted and toast (or untoast) is run interactively from
|
||||
a terminal, the user is prompted as to whether the file should be replaced.
|
||||
.TP
|
||||
.B \-p
|
||||
(precious)
|
||||
Do not delete the source files.
|
||||
Source files are implicitly left alone whenever \-c is
|
||||
specified or tcat is run.
|
||||
.TP
|
||||
.B \-C
|
||||
(LTP cut-off)
|
||||
Ignore most sample values when calculating the GSM long-term
|
||||
correlation lag during encoding.
|
||||
(The multiplications that do this are a bottleneck
|
||||
of the algorithm.)
|
||||
The resulting encoding process will not produce
|
||||
exactly the same results as GSM 06.10 would,
|
||||
but remains close enough to be compatible.
|
||||
.br
|
||||
The
|
||||
.B \-C
|
||||
option applies only to the encoder and is silently
|
||||
ignored by the decoder.
|
||||
.TP
|
||||
.B \-F
|
||||
(fast)
|
||||
On systems with a floating point processor, but without
|
||||
a multiplication instruction, \-F sacrifices standard conformance to
|
||||
performance and nearly doubles the speed of the algorithm.
|
||||
.br
|
||||
The resulting encoding and decoding process will not produce
|
||||
exactly the same results as GSM 06.10 would, but remains close
|
||||
enough to be compatible.
|
||||
.br
|
||||
The default is standard-conforming operation.
|
||||
.TP
|
||||
.B \-v
|
||||
(version)\
|
||||
outputs the version of toast (or untoast or tcat) to stdout and exits.
|
||||
.TP
|
||||
.B \-h
|
||||
(help)\
|
||||
prints a short overview of the options.
|
||||
.PP
|
||||
Toast, untoast and tcat try to guess the appropriate audio data
|
||||
format from the file suffix.
|
||||
Command line options can also specify a format to be used for
|
||||
all files.
|
||||
.br
|
||||
The following formats are supported:
|
||||
.TP
|
||||
.B "\-u"
|
||||
(\(*mU-law)
|
||||
8 kHz, 8 bit \(*mU-law encoding (file suffix .u)
|
||||
.TP
|
||||
.B "\-a"
|
||||
(A-law)
|
||||
8 kHz, 8 bit A-law encoding (file suffix .A)
|
||||
.TP
|
||||
.B "\-s"
|
||||
(Sun audio)
|
||||
8 kHz, 8 bit \(*mU-law encoding with audio header (file suffix .au)
|
||||
.TP
|
||||
.B "-l"
|
||||
(linear)
|
||||
8 kHz, 16 bit signed linear encoding in host byte order
|
||||
with 13 significant bits (file suffix .l)
|
||||
.PP
|
||||
In absence of options or suffixes to specify a format,
|
||||
\(*mU-law encoding as forced by \-u is assumed.
|
||||
.PP
|
||||
.SH PECULIARITIES
|
||||
A four bit magic number is prefixed to each 32 1/2-byte GSM frame,
|
||||
mainly because 32 1/2-bytes are rather clumsy to handle.
|
||||
.SH WARNING
|
||||
The compression algorithm used is a lossy compression algorithm
|
||||
devised especially for speech; on no account should it be used
|
||||
for text, pictures or any other non-speech-data you consider
|
||||
valuable.
|
||||
.SH BUGS
|
||||
Please direct bug reports to jutta@cs.tu-berlin.de.
|
||||
.SH "SEE ALSO"
|
||||
gsm(3)
|
||||
.\"
|
||||
.\" Toast is dedicated to Bill Sienkiewicz, author of "Stray Toasters".
|
||||
Reference in new issue
Block a user