Waveform is a class to generate waveform images from audio files. You can combine it with jPlayer to make a soundcloud.com style MP3 player. It also comes with a handy CLI you can use to generate waveform images on the command line.

Waveform depends on ruby-audio, which in turn depends on libsndfile.

Build libsndfile from (http://www.mega-nerd.com/libsndfile/), install it via apt (sudo apt-get install libsndfile1-dev), libsndfile in macports, etc...

Then:

$ sudo gem install waveform

Image creation depends on chunky_png, which has a faster native library called oily_png which will be used if available.

$ sudo gem install oily_png

NOTE: If ruby-audio fails to compile and you have libsndfile available, it may be because of this: http://stackoverflow.com/questions/19919640/ruby-audio-1-6-1-install-error-with-installed-libsndfile-1-0-25

$ waveform song.wav waveform.png

There are some nifty options you can supply to switch things up:

-W sets the width (in pixels) of the waveform image.
-H sets the height (in pixels).
-c sets the color used to draw the waveform (in hex, can also use
    'transparent').
-b sets the background color to draw the waveform on (in hex, and can use
    'transparent' as well).
-m sets the method used to sample the source audio file, it can either be
    'peak' or 'rms'. 'peak' is probably what you want because it looks
    cooler, but 'rms' is closer to what you actually hear.

There are also some less-nifty options:

-q will generate your waveform without printing out a bunch of stuff.
-h will print out a help screen with all this info.
-F will automatically overwrite destination file.

Generating a small waveform "cut out" of a white background is pretty useful, then you can overlay it on a web-gradient on the website for your new startup and it will look really cool. To make it you could use:

$ waveform -W900 -H140 -ctransparent -b#ffffff Motley\ Crüe/Kickstart\ my\ Heart.wav sweet_waveforms/Kickstart\ my\ Heart.png

The CLI is really just a thin wrapper around the Waveform class, which you can also use in your programs for reasons I haven't thought of. The Waveform class takes pretty much the same options as the CLI when generating waveforms.

ruby-audio

The gem version, not the old outdated library listed on RAA. ruby-audio is a wrapper for libsndfile, on my Ubuntu 10.04LTS VM I installed the necessary libs to build ruby-audio via: sudo apt-get install libsndfile1-dev.

chunky_png

chunky_png is a pure ruby (!) PNG manipulation library. Caveat to this requirement is that if you also install oily_png you will get better performance as it uses some C code, and C code is fast.

Waveform used to (very thinly) wrap ffmpeg to convert MP3 (and whatever other format) to WAV audio before processing the WAV and generating the waveform image. It seemed a bit presumptious for Waveform to handle that, especially since you might want to use your own conversion options (i.e. downsampling the bitrate to generate waveforms faster, etc...).

If you happen to be using ffmpeg, you can easily convert MP3 to WAV via:

ffmpeg -i "/path/to/source/file.mp3" -f wav "/path/to/output/file.wav"

$ rake

If you get an error about not being able to find ruby-audio gem (and you have ruby-audio gem) you might need to let rake know how to load your gems -- if you're using rubygems:

$ export RUBYOPT="rubygems"
$ rake

Sample sound file used in tests is in the Public Domain from soundbible.com: http://soundbible.com/1598-Electronic-Chime.html.

• Update for ruby 3.2 (replace File.exists? w/ File.exist?)

• Added more helpful deprecation notice for non-WAV audio files

• Fixed RMS calculation (was calculating RMSD instead of RMS before) -- thanks, cviedmai

• No more wrapping ffmpeg to automatically convert mp3 to wav
• Fixed support for mono audio sources (4-channel, surround, etc. should also work)
• Change to gemspec & added seperate version file so that bundler won't try to load ruby-audio (thanks, amiel)
• Changed Waveform-class API as there's no longer a need to instantiate a waveform

http://pscode.org/javadoc/src-html/org/pscode/ui/audiotrace/AudioPlotPanel.html#line.996 http://github.com/pangdudu/rude/blob/master/lib/waveform_narray_testing.rb http://stackoverflow.com/questions/1931952/asp-net-create-waveform-image-from-mp3 http://codeidol.com/java/swing/Audio/Build-an-Audio-Waveform-Display

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