Waveformjson is based on waveform and functions the same. The only difference is that it generates json instead of png files.
Waveformjson depends on
ruby-audio, which in turn depends on libsndfile.
Build libsndfile from (http://www.mega-nerd.com/libsndfile/), install it via
sudo apt-get install libsndfile1-dev),
libsndfile in macports, etc...
$ gem install waveformjson
or add following to Gemfile:
$ waveformjson song.wav waveform.json
There are some nifty options you can supply to switch things up:
-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. -W sets the width (in pixels) of the waveform.
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. -o will output your waveform data to the console.
Usage in code
The CLI is really just a thin wrapper around the Waveformjson 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.
The gem version, not the old outdated library listed on RAA.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
sudo apt-get install libsndfile1-dev.
Converting MP3 to WAV
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"
Sample sound file used in tests is in the Public Domain from soundbible.com: http://soundbible.com/1598-Electronic-Chime.html.
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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