JsonWaveform is a class to generate waveform json files from audio files. You can combine it with http://waveformjs.org/ to create awesome waveforms in webpages. It also comes with a handy CLI you can use to generate waveform json files on the command line.

It is heavily influenced by https://github.com/benalavi/waveform

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 brew, etc...

Then:

$ gem install json-waveform

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

$ json-waveform song.wav

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

-s sets the samples of the waveform.
-A sets the max amplitude.
-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.

And to see (almost) this same info:

-h will print out a help screen with all this info.

$ json-waveform Motley\ Crüe/Kickstart\ my\ Heart.wav

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

JsonWaveform.generate("foo.wav", samples: 1000) # => [ 0, 0.1, 0.15, ... ]

ruby-audio

The gem version, not the old outdated library listed on RAA. ruby-audio is a wrapper for libsndfile. To install the necessary libs to build ruby-audio you can do sudo apt-get install libsndfile1-dev on Ubuntu or brew install libsndfile on OSX.

$ make

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