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= wav2vec
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== Introduction
wav2vec is a Python script and package for converting waveform files (WAV or AIFF) to vector graphics (SVG or PostScript). Use cases include using an audio waveform as an element in a graphic design or including a waveform in a document.
Note:: This project is completely unrelated to the https://arxiv.org/abs/1904.05862[wav2vec speech recognition model] (which was published after this tool).
== Features
sndhdr package (used by wav2vec to detect the file type) so if you are running Python 3.13 or later you will need to install the https://github.com/h2non/filetype.py[filetype] package.wave module (https://github.com/python/cpython/issues/60729)== Install
=== From PyPI with PIP
The easiest way to install wav2vec is to use pip to install from the Python Package Index:
Depending on your system, in order to install in the Python 3 path, you may have to use pip3 instead of pip.
=== From git repo
Alternatively, clone the git repository:
Now you can run wav2vec.py directly:
Or install the package with PIP:
== Usage
Once the package is installed using pip (see above), the command can be invoked as wav2vec. It takes an input file and outputs (SVG, by default) to stdout:
Run wav2vec -h to get a usage summary:
usage: wav2vec [-h] [--format {PostScript,SVG,CSV}] [--width WIDTH] [--height HEIGHT] [--stream BS] [--downtoss N] [--log {DEBUG,INFO,WARNING,ERROR,CRITICAL}] filename
Convert WAV and AIFF files to vector (SVG, PostScript, CSV) graphics.
positional arguments: filename The WAV file to read
optional arguments: -h, --help show this help message and exit --format {PostScript,SVG,CSV}, -f {PostScript,SVG,CSV} The output format, one of: SVG, CSV, PostScript. Default is SVG. --width WIDTH Maximum width of generated SVG (graphic will be scaled down to this size in px) --height HEIGHT Maximum height of generated SVG (graphic will be scaled down to this size in px). Note that this scales according to the highest possible amplitude (given the sample bit depth), not the highest amplitude that actually occurs in the data. --stream BS Stream the input file size in chunks (of BS number of frames at a time) and process/format each chunk separately. Useful for conserving memory when processing large files, but note that multi-channel paths will be split up into BS-sized chunks. By default BS=0, which causes the entire file to be read into memory before processing. --downtoss N Downsample by keeping only 1 out of every N samples. --log {DEBUG,INFO,WARNING,ERROR,CRITICAL} Set the logging level.
The output is sent to stdout.
=== Options ==== Output format
The --format flag sets the output format. wav2vec includes three formatters: SVG (default if no --format is given), PostScript, and CSV.
==== Scale output
Use the --width and --height options to scale the output so that its maximum bounds are equal to or less than the values following the flags. In SVG these values are pixels ("user units"); in PostScript the values are interpreted as pts (1/72 of an inch). By default (if the flags are not given), the width is set to 1000 and the height to 500.
==== Stream input file
By default, wav2vec reads the entire input file into memory and then streams the output to stdout as it process it. Passing the --stream flag will cause wav2vec to process the input file in chunks. This can be useful if the input file is very big and won't fit into available memory. The --stream flag requires one argument, the number of frames to read and process at a time (each frame includes one sample from each channel). A value of around 1024 seems to work well.
Note that using the --stream flag on files with multiple channels will result in non-continuous paths in the output (because channel data is interleaved in WAV/AIF files).
Note also that converting very large audio files to SVG may not be practical: most SVG editors will not handle paths with hundreds of thousands or millions of points well.
==== Downsampling
The --downtoss N flag will keep only 1 out of every N samples. This is a brutal form of downsampling which will clobber high frequency and add aliasing noise. It's best to instead downsample in your waveform recorder/editor before processing (or in your drawing program after processing).
=== API
You can also import wav2vec in order to convert wave files to the supported output formats in your own Python scripts. The package provides two main classes: WavDecoder and the abstract Formatter (and the concrete implementations: SVGFormatter, PSFormatter, and CSVFormatter). The documentation is currently contained in the source files; look at link:./wav2vec/main.py[main.py] for an example of usage.
The WavDecoder class wraps the standard library's wave and aifc modules and provides an easy way to read and decode WAV/AIFF files. Use it as a context manager to ensure close() is called. Use it as an iterator to process all frames:
wd = WavDecoder('filename') with wd as data: for frames in data: print(frames)
See link:./wav2vec/WavDecoder.py[wav2vec/WavDecoder.py].
The Formatter class is an abstract base class which defines the interface for all formatters which output WAV data in textual formats. Each concrete subclass of Formatter takes a WavDecoder object in its constructor which is what is responsible for reading/decoding data from a WAV or AIFF file.
The output() method will stream output to a file (stdout by default), but the entire output string can be captured using the __str__() method.
wd = WavDecoder("filename") svgformatter = SVGFormatter(wd) svgformatter.output() # outputs SVG to stdout svg_str = str(svgformatter) # get SVG as a string
See link:./wav2vec/formatter/[the formatter package].
=== Examples
==== SVG
Here's what the link:tests/valfiles/snd/test-16-stereo.wav[tests/valfiles/snd/test-16-stereo.wav] file looks like in Audacity:
image::./readme_imgs/audacity.png[]
We can convert it to an SVG and then open it in Inkscape:
image::./readme_imgs/inkscape.png[]
Then we can use Inkscape to non-destructively add filters and path effects and otherwise incorporate the waveform into a design:
image::./readme_imgs/output.png[]
==== PostScript
To convert to PostScript instead of SVG:
The above uses the Ghostscript ps2pdf tool to convert the resulting PostScript file to PDF and then opens it in the evince PDF reader (shown in the screenshot below). You could instead open test.ps directly in a PostScript viewer (or send it to a printer/plotter, or embed it in a LaTeX document, etc).
image::./readme_imgs/evince.png[]
==== CSV
wav2vec also comes with a CSV formatter, which is useful to get WAV data into a spreadsheet:
Note the --height 0 option which prevents wav2vec from scaling the raw PCM values.
== Hacking
=== Run tests
To run unit and validation tests (requires python3):
=== Write custom formatter
Creating a custom formatter is simply a matter of subclassing Formatter and overriding the five abstract methods it defines. Use the included SVGFormatter, PSFormatter, or CSVFormatter as a template (see link:./wav2vec/formatter/formatters.py[wav2vec/formatter/formatters.py]).
== Issues
Please feel free to use the Github issue tracker as a support forum for any questions, suggestions, bug reports, or feature requests. Thanks! https://github.com/cristoper/wav2vec/issues
== See also
http://www.audacityteam.org/[Audacity] is a good Free audio recorder and waveform editor.
https://inkscape.org/en/[Inkscape] is a Free SVG-based drawing program
https://www.ghostscript.com/[Ghostscript] is a Free PostScript interpreter which can distill to PDF.
https://github.com/afreiday/php-waveform-svg[php-waveform-svg] is a PHP script for converting mp3->wav->svg. (It looks simple, but I haven't tried it.)