A simple harmonic synthesis and wavetable generation toy
npm install wavyd
npm install -g wavyd
dependencies
nodejs (tested with v0.10.n and 0.12.n)On ubuntu, installation of the audio package requires libasound2-dev: install using
sudu apt-get install libasound2-dev
On windows, the situation is a bit more complicated. The __speaker__ package used for audio output is built using
node-gyp, which requires both python and (to compile the binary extensions
to node) a MS Visual Studio C++ installation. Follow the instructions on the node-gyp github page before installing
wavyd.
Otherwise, all dependencies arte defined in package.json, except for node-canvas (for png support), which requires
an installation of Cairo. Check here for more information.
usage
$ wavyd
Arguments (with defaults):
--freq Audio frequency to play (440)
--type Wave type: hs (harmonic synthesis) || ew (etherwave) (hs)
--spec Specification for wave (depends on type, see below)
--dur Audio duration in seconds (3)
--silent Suppress audio preview of wave
--dump If given, write wavetable data to stdout (false)
--table Size (#samples) of wavetable to generate (1024)
--round If true, round samples in wavetable to integer values (false)
--scale Scale samples in wavetable by this value (1.0)
--plot If given, generate a graphic representation of waveform: ascii|png (false)
--pn For png plot, output filename (plot.png)
--pw For png plot, pixel width of image (640)
--ph For png plot, pixel height of image (360)
--pm For png plot, inner margin of image (4)
--preset If given, a path to a preset/template file
--help Show this help message (false)
Spec argument depends on the --type argument passed. For __hs__ (harmonic
synthesis) it should be a quoted list of weight:phase pairs w:p
separated by spaces and/or commas, e.g.
"1:0, 0.5:0, 0.25:0.2PI"
(Note that phases are in radians relative to the current partial, and
that you can use "PI" as a constant in these expressions)
For __ew__ (etherwave) it should be a quoted string with values for wf
(waveform offset) and br (brightness) as follows:
"wf:55, br:140"
Both wf and br values should be 0-255.
For information on the algorithm, see
Thierry Frankel's paper
on implementing the generator in native Arduino code.
To write output to a wave file, redirect stdout as follows
$ wavyd --preset ./MyCPPTemplate.js --silent > wavetable.cpp
Preset/template file
A preset/template file has the following form, which should be relatively self-explanatory:javascript
var template = [
"/*===========================================",
"Wavetable for Open.Theremin",
"Generated at {date} by wavyd",
"Type: {type}",
"Spec: {spec}",
"============================================*/",
"",
"#include ",
"",
"const int16_t wave_table[{table}] PROGMEM = {\\",
"*{value}{-,}",
"}"
];module.exports = {
opts: {
dump: true,
table: 1024,
round: true,
scale: 2048
},
template: template
};
``Note:
1. The file is a javascript source file, exporting via module.exports a template and a set of options
2. The options overwrite any additional or default options passed to wavyd
3. The template is an array of strings, that will be written to the output with values substituted
4. Any string in the template surrounded by curly braces {} will be substituted (with the braces) by the options field
with that name (e.g. the number of samples in the generated wavetable will be {table})
5. The special value {date} gives an ISO date string with the date and time of generation
6. Any line starting with '*' will be repeated once for every sample generated in the wavetable
7. In these lines, the only template values are {value} and {index}, the sample value and its index
in the wavetable respectively
8. Braces which include a dash followed by a literal value: the literal value will be emitted for all but
the last repetition of the line (to allow for commas between array values, for example, as above)