BackMasked is a sound reversing and processing web application.
To use BackMasked, run the application in a rails server. The homepage will show you a simple MP3 upload form. After uploading an MP3, you will be presented with two audio players: one for the unedited version of the audio and anther for the reversed (backmasked) version.
In order to use BackMasked, your server should have sox installed. If you are running BackMasked locally in a Ubuntu/Debian distribution, you can use the following command to install sox with mp3 support.
For more information on sox, click here.
sudo apt-get install sox libsox-fmt-mp3
The following commands can be used to reverse a song or clip
To reverse an entire song:
sox input.mp3 output.mp3 reverse
To reverse just a clip, you can use the trim command. The first param for trim is the starting point in seconds, the second param is an offset. So 0 10 is 10 seconds from the beginning of a file, 30 5 is 5 seconds starting from 30 seconds into the file.
sox input.mp3 output.mp3 trim 0 10 reverse