cl-wavelets

cl-wavelets
===========
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**cl-wavelets** is a library with a set of algorithms related to
various kinds of wavelet transform. Currently they all work with
arrays of type `(simple-array (signed-byte 32) (*))` (i.e. they are
1D). This makes this library suitable for audio processing and
compression. For more info visit the project page
[here](http://shamazmazum.github.io/cl-wavelets).

Currently supported algorithms:
* DWT
* Frequency analysis using PWT.
* Best-basis PWT.

Currently supported wavelets:
* Haar wavelet
* CDF (2,2) wavelet
* CDF (3,1) wavelet
* CDF (4,2) wavelet

### Usage

In examples:
~~~~
(wavelets:dwt (make-array 8
                          :element-type     '(signed-byte 32)
                          :initial-contents '(0 1 2 3 4 5 7 8))
              :wavelet        :cdf-2-2
              :boundary-style :mirror)
#(2 4 0 3 0 0 0 1)

(wavelets:dwt-inverse *
                      :wavelet        :cdf-2-2
                      :boundary-style :mirror)
#(0 1 2 3 4 5 7 8)
~~~~

Generally, there are two kinds of functions: with `!` at the end and without
`!`. Whose with `!` are in-place functions, in other words they modify their
first argument. Whose without `!` do not modify their first argument.

For more info, generate a documentation with **codex** like so:
`codex:document :cl-wavelets :skip-unsocumented t`.

### Examples package

You can load `cl-wavelets/examples` system which contains packages to
demonstrate some components of this library. For example, you can
build a spectrogram of an uncompressed WAV file making use of
`wavelets:frequency-domain` function. To build a spectrogram, try this:
~~~~
(wavelets-spectrogram:spectrogram "/path/to/audio.wav"
                                  "/path/to/spectrogram.jpg")
~~~~
This will produce `spectrogram.jpg` image with the spectrogram. Note,
that the time axis is the vertical one, with the time going
up-down. This is a spectrogram rotated by 90 degrees clockwise,
actually. Also, the quality of the spectrogram will be much worse
compared to the qualily of a spectrogram obtained via FFT. This is
because the filters used in the process are far from ideal.


alexandria

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cl-wavelets

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