NAME
tones - a sequential tone generator program
SYNOPSIS
tones [options] [waveform] T freq(s)|notes(s)|command_file(s)
DESCRIPTION
tones generates one or more tones of various types (waveforms) and
duration (T millisecs) of the specified frequencies or notes, or
mixtures of frequencies or notes. See tones -h for a list of possible
waveforms. The waveforms should include sine, cosine (90 degrees out of
phase to sine), square (50% mark/space ratio), sawtooth (a ramp
waveform), triangle and noise. Sine is the default. Besides the
inbuilt waveforms, waveforms can be loaded from suitable WAV files -
see below LOADABLE WAVEFORMS.
T is the default number of millisecs that each tone is to be played.
Frequencies (freq(s)) are specified in Hertz as integers. A frequency
of 0 causes T millisecs of silence to be played. Notes are specified as
the musical note letter with an optional ’#’ to sharpen the note, then
an octave number. Octaves run from C to C. Middle C is C3, the
immediately preceding note is B2! The first Octave is from C0 to C1.
Several frequencies/notes can be played at once, by specifying the
frequencies/notes required joined by a ’,’ character (but no spaces!).
e.g. 1000,1500,2000 specifies that the three frequencies are played
together, all at the same relative level. See AMPLITUDES sections below
for a discussion of how to set absolute amplitude levels or differing
relative amplitudes for notes played together or serially.
Each freq specification can optionally contain a duration, by appending
’:T’, where ’T’ is the duration in millisecs. This duration overrides
the default. Also the default duration can be changed by using a the
’:T’ format on it’s own - not appended to a freq spec.
e.g. 1200,600:1000 play the two freqs for 1 sec
e.g. c3,e3,g3 play the C major chord
e.g. :250 set the default tone duration to 250ms
Waveforms can be specified/altered at anytime. A single waveform name
specifies that waveform to be used for all channels. Alternatively a
comma (’,’) seperated list of waveforms can be given to specify or
alter the waveform to use for a given channel. Ommitting a waveform in
a list, means that the previous waveform is left unchanged.
e.g. square,,triangle specifies using square waves for chan 1, chan 2
is left unchanged, and triangular waves are used for channel 3.
The digital samples (either 8 or 16 bits) are played by default to the
Linux /dev/dsp device at a samplerate of 22050 samples per second, in
mono mode. (see CONFIGURATION FILES section below)
Fractional Hertz frequencies are not supported. Of course, only
frequencies less than half the samplerate (number of samples/sec) can
be accurately generated; but the program doesn’t check this.
Instead of playing the output to /dev/dsp the samples can be written to
a file as raw samples (-o file) or written in WAV format (-w wavfile).
These data files can then be played back quickly with a raw data or WAV
file player (e.g. wavplay) without the overhead of actually generating
the samples.
There are some special ’commands’ that can be specified, that may be
useful in input files.
N Set default tone duration to N millisecs
@N Set base amplitude level of tones when in absolute amplitude
mode
absolute
Set absolute amplitude mode (see below)
echo The rest of the line of the input file, or the rest of the
command line parameter (NB to use quotes where necessary) is
output to stdout.
relative
Set relative amplitude mode (see below)
reset|resync
All generator points are reset to the start of the waveform
buffers. This forces subsequant generation of multiple
frequencies/waveforms to be in phase.
Further, if the word is not one of the above, then tones checks to see
if a file of that name exists, and if it does then the file is assumed
to be a file of tones commands which are executed.
e.g. tones -v :100 tune1 tune2 will interpret and play the tones
commands in files tune1 and tune2. This file processing is recursive.
Files of commands can execute other files of commands etc. As usual,
- can be used to specify stdin.
RELATIVE AMPLITUDES
tones by default works in a ’relative’ amplitude mode, where the output
level and sample range are maximally maintained. This ensures the best
signal accuracy.
When specifying multiple frequencies/notes to be played together, then
the relative amplitudes can be specified in deciBells by appending
"@db" to the note.
e.g. 440,880@-12,1760@-30 specifies a mixture with 880Hz -12dB down,
and 1760Hz -30dB down relative to the level of 440Hz. The mixed signal
samples will span the full 16 or 8 bit range permitted for maximal
signal accuracy.
The dB levels indicate the relative power levels. -3dB being at a
relative power level of 0.5, -20dB being at a relative power level of
0.01 . However power levels are proportional to the square of the
signal amplitude. So a signal at -6dB (quarter power) will only have
its amplitude down by half. To reduce a signal amplitude by 1/10 then
specify -20dB, i.e. a power level down by a factor of a hundredth.
dB levels can be specified as decimal values.
ABSOLUTE AMPLITUDES
tones can work in an absolute amplitude mode, where signal power levels
are specified in deciBells (dB) relative to a 0dB level that indicates
a peak value of +32767/-32768 for 16 bit signed samples, and 255/0 for
8 bit unsigned values. Hence any signal at a positive dB level will be
clipped. Signals at a negative dB level will attentuated. If no level
is specified then 0dB is assumed.
e.g. 500@-20,750@-6,1000,-12 gives 500Hz at -20db (amplitude 0.1),
750Hz at -6db (amplitude 0.5), and 1000Hz at -12dB (amplitude 0.25).
The final mixed signal will have an amplitude of 0.1 + 0.5 + 0.25 =
0.85 or -1.4dB.
As can be seen, there is no "hands-free" in absolute mode. You have to
work out the dB levels yourself and ensure that the resultant mixed
signal does not go above 0dB and get clipped. Remember also that a sine
wave at -80dB down (amplitude 1/10000th) only has 6 digital levels and
is a pretty poor representation of a sine wave, not suitable for post
amplification and use!
In absolute mode the base ’zero’ level can be altered at any time by
use of the @dB command. All subsequent dB levels specified will have
this base level added to them.
e.g. @-20 1000,1200@+6,1400@-6 is the same as 1000Hz at -20dB, 1200Hz
at -14dB and 1400Hz at -26dB.
LOADABLE WAVEFORMS
Given that the generation method used by tones to generate a waveform
of FHz is simply to sequentially select every Fth sample from a buffer
containing S samples of one complete waveform at a frequency of 1Hz
(treating the buffer as circular, the beginning conceptually joined to
the end), where S is the number of samples per second, it is possible
to load a customised waveform from a WAV file containing the S samples
of a 1Hz waveform. See the -load WavFile and -lw N options below. The
name of the waveform is taken as the basename of the WavFile, i.e. with
any trailing ’.suffix’ and leading path removed. Each loaded waveform
should hence have this name unique, and different from the inbuilt
waveform names.
The samples in WavFile should be 16 bit, mono, of the same number of
samples as tones’ playing samplerate, e.g. if tones is playing at 32000
samples per sec then the WavFile should contain 32000 16 bit samples.
16 bit samples are needed, because tones works internally with 16 bit
samples, even if it is feeding 8 bit samples to the sound card or
output file. Ideally the samples should span one complete wavelength,
i.e. represent 1 second of a 1Hz signal. However this can be varied if
used with some intelligence. If, say, 1 seconds worth of 5Hz of the
waveform is used, then the output frequency will be 5 times higher than
specified. If you have a mixture of 3Hz and 5Hz samples, then the
frequencies generated will be a mixture of 3 and 5 times the frequency
specified. I hope that is all understandable!
See the tones.eg directory for some examples of loadable modules and
how tones itself can be used to generate the loadable waveforms.
OPTIONS
-8 | -b 8
set 8 bit unsigned data samples
-16 | -b 16
set 16 bit signed little-endian data samples.
-abs|-absolute
set absolute amplitude mode
-a when used in conjunction with the -o option, data is appended to
the file.
-C file
use "file" as the local configuration file (see below).
-c CHANNELS
set the maximum number of channels (concurrent played
frequencies) to CHANNELS. The default number is 4. There is some
virtue in keeping the number of channels to a minimum.
-f when used in conjunction with the -o or -w options, any existing
file is silently overwritten.
-h display usage and help info
-i file
read frequencies/waveforms to generate from file ’file’. Reads
from standard input if filename is ’-’. Any command line
specifications are actioned before the input file is read.
-l play the tone sequence repetitively. Forced off if writing
samples to a file with the -o or -w options.
-loop N
play the tone sequence N times.
-o file
write out samples to a raw data file. You will have to remember
the data format, e.g. samplerate and 8/16 bit.
-rel|-relative
set relative amplitude mode
-s samplerate
set the number of samples per second to samplerate. For many
simple uses a samplerate of 8000 is sufficient, making any saved
data files smaller.
-w wavfile
write samples out in WAV format to wavfile. The WAV header
contains details of whether the data is 8 or 16 bits and the
sampling rate. You cannot use the append (-a) option with WAV
files.
-v be verbose
-lw N Specify the number of loadable waveforms allowed, the default is
4
-load WavFile
Load the waveform from the WavFile.
EXAMPLES
tones 50 1000 700,1200 800,1100,1300
generates 3 50 millisecs sine tones, the first consisting of
only 1000Hz, the second of 700Hz and 1200Hz and the third of
800Hz, 1100Hz and 1300Hz
tones -loop square 200 700 900 400 500
generates a sequence of 4 200 millisecs square wave tones which
is repeated until the program is interupted.
tones -w seq.wav 70 1016 1200 1080 1150 1016
generates a sequence of 5 70 millisecs sine tones, and instead
of playing them the samples are stored in WAV format in seq.wav
which can be played by any WAV file player.
tones -w trap.wav :1000 triangle absolute 1@6
Generates a WAV file trap.wav consisting of a trapezoid waveform
where the rise and fall slopes take up half the wavelength. A
sawtooth is generated with a maximum that has twice the
amplitude of the maximum sample sizes allowed, hence it is
clipped flat for half the waveform period making a trapezoid
shape.
tones -load trap.wav :1000 triangle 1000 trap 500 triangletrap 1000500
Will load the trapezoid waveform generated above as a new
waveform called trap and then plays 1 seconds each of first a
1000Hz triangle wave, then a 500Hz trap waveform and finally
both waveforms played together.
See also the tones.eg directory in the siggen distribution.
CONFIGURATION FILES
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 siggen suite of programs are compiled with the names of the
config files built in. By default the configuration files are:
./.siggen.conf
is the LOCAL config file.
$HOME/.siggen.conf
is the HOME config file.
/etc/siggen.conf
is the GLOBAL config file.
tones -h
will indicate which config files will be searched for.
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 program provides builtin default
values, and most of these values can be set by appropriate command line
switches and flags.
See siggen.conf(5) for details of the configuration files.
tones looks for configuration values CHANNELS, DACFILE, SAMPLERATE,
SAMPLESIZE, VERBOSE, LOADABLE_WAVEFORMS.
CHANNELS
sets the number of channels, see ’-c’ option.
DACFILE
allows the name of the DAC/DSP/PCM device to be changed from
/dev/dsp
LOADABLE_WAVEFORMS
specifies the allowable number of loadable waveforms
SAMPLERATE
sets the number of samples/sec for the DAC device
SAMPLESIZE
sets whether 8 or 16 bit samples to be generated
VERBOSE
sets whether or not to run in verbose mode.
SEE ALSO
siggen.conf(5), signalgen(1), swgen(1)
BUGS
COPYING
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
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be included in
translation instead of in the original English.
AUTHOR
Jim Jackson
Email: jj@franjam.org.uk