siggen.conf - the siggen configuration files
As from siggen version 2.3 onwards a versatile configuration file
scheme has been introduced. It allows parameters for the siggen
programs to be specified either across the board, or specifically for
Three possible configuration files can be used: a LOCAL config file
(usually in current directory), a HOME config file in user’s $HOME
directory and a GLOBAL config file.
All the programs are compiled with the names of the config files built
in. The filenames are set in the config.h header file and can be
changed. The LOCAL and GLOBAL config files are specified by the
LOCAL #define DEF_CONF_FILENAME ".siggen.conf"
GLOBAL #define DEF_GLOBAL_CONF_FILE "/etc/siggen.conf"
And can be set to any file name or to NULL to disable the file. The
HOME config filename is created using the $HOME environment variable
and the DEF_CONF_FILENAME together, i.e. using the above, the HOME
config file for a user whose home directory is at /home/jj, would be
The config files do not have to exist. If they exist and are readable
by the program they are used, otherwise they are simply ignored.
The config files are always searched for configuration values in the
order LOCAL, HOME, GLOBAL. This allows a scheme where the sysadmin sets
up default config values in the GLOBAL config file, but allows a user
to set some or all different values in their own HOME config file, and
to set yet more specific values when run from a particular directory.
If no configuration files exist, the programs themselves provide
builtin default values (see config.h etc), and most of these values can
be set by appropriate command line switches and flags.
A configuration value has a name and a value, and values for all
programs are set by simply entering a line in the appropriate config
file where the first word is the name, followed by arbitrary
spaces/tabs, followed by the value. The value is all the rest of that
line. e.g. to set the global default samplerate of 44100 samples per
sec, the following line would be entered in the GLOBAL config file:
Config value names are case insensitive.
A config value can be set for a specific program, by prefixing the
config value name with the program name and a ’:’. e.g. to specify a
samplerate of only 8000 samples per sec for the tones program enter
in the relevant config file. If both lines above were in the config
file, all programs except tones would use a samplerate of 44100, and
tones would use 8000.
You do not have to specify all configuration values in the config
files. If a particular value is missing, the programs will simply use
their builtin defaults (see config.h etc).
Configuration values set by command line switches or flags take
precedence over values in any of the config files.
Beware the programs do not have their ’name’ built-in, but use the name
they were invoked by. So if you change the name of a program,
remember to change the config file entries. However this does
means that by using links to a program, it can be made to pick
up a different set of configuration values, depending on the
name it is invoked by.
EXAMPLE CONFIGURATION FILE
A sample config file is provided in ".siggen.conf" in the distribution.
This may also be at /etc/siggen.conf . Any line whose first non-
whitespace character is a ’#’, is a comment line and is ignored.
WHAT CONFIGURATION VALUES ARE THERE?
Not all of the siggen programs use all the values described here. See
the relevant man page for which values are used by which programs.
In all programs except tones and fsynth, channels specifies the
number of output channels to use, i.e. 1 for Mono and 2 for
For tones, channels specifies the number of ’voices’ on which
tones can generate different waveforms before mixing them into
the one output channel.
For fsynth, channels specifies the numbers of seperately
configurable oscillators used to mix the single output channel.
The Digital to Analogue Converter (or PCM or DSP) device on
which to output the generated samples. This must be a real OSS
PCM device, otherwise the ioctls used will fail.
The number of Audio Buffer fragments to configure in the driver.
The interactive programs respond to changes made to parameters
from the keyboard immediately, but data will be buffered in the
driver in the buffer fragments. If the amount of data buffered
is too much then there will very noticable delays before the
output sound is altered. Against that, insufficient buffering
may mean that there is not enough data buffered for output to
cover the time when other processes are being run by the
scheduler. The programs set the buffer size to the nearest power
of 2 to give aprox. 100millisecs of sound. Hence if FRAGMENTS is
set to 3, there will be aprox. 0.3 secs worth of sound buffered
for output. On a lightly loaded fast machine this, or 2, should
be sufficient. To cover periods of heavy load or on a less
powerful machine use 4 or 5. But remember the interactive
programs will appear sluggish in responding to the keyboard.
The number of samples per second to use. If output is to the DAC
then the DAC device is set to output samples at this rate.
BEWARE: not all cards can support all samplerates. SoundBlasters
are fairly flexible in this respect. Other cheaper cards are
not. Indeed some cards can only handle a very restricted set of
related samplerates e.g. 11025, 22050, 44100 & 8000, 16000,
32000, 48000. When writing to DACFILE all programs will attempt
to set the samplerate given, but use the actual samplerate the
device used. Use the verbose command line flag to check actual
Some common samplerates used are:
is the samplerate used in the phone system with 8 bit samples,
and is adequate for voice range frequencies.
is the samplerate used in audio CDs
is the samplerate used in DAT systems, I think, and for much
is also used, but I forget where, minidisc?.
In general, the higher the samplerate the larger the memory and
processing requirement, but the higher the frequency range and
the more accurate the signals generated.
Number of bits per sample. Only two values are allowed
currently, 8 or 16.
8 bit samples are unsigned, with decimal value 128 being the
16 bit samples are signed little endian values, i.e. the least
significant byte comes before the most significant byte either
in a file, or in the byte stream to an output device.
If samplesize if left completely unspecified, then all programs
will attempt to do 16 bit samples to DACFILE, and if that isn’t
possible will do 8 bit samples. Or if writing to a file, 16 bit
samples will be written.
sets verbosity level.
0 is quiet
1 is be a bit verbose (equiv. to -v switch)
2 is be very verbose (equiv. to -vv switch)
if set to a non-zero value, then the VI cursor moving keys
"HJKL" are enabled.
Copyright 1995-2008 Jim Jackson
The software described by this manual is covered by the GNU General
Public License, Version 2, June 1991, issued by :
Free Software Foundation, Inc.,
675 Mass Ave,
Cambridge, MA 02139, USA
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