How to Convert MP3 to Minus One
With karaoke a popular pastime, songs in the Minus One format remain in high demand. Songs converted to Minus One can have any of the common audio file types, such as an MP3 or a WMA, but all have the vocal track removed. If you begin with an MP3 file, you have a variety of options for converting the file to the Minus One format.
1 Results and File Quality
To obtain a high quality end result no matter what process you use to convert, begin with a high quality MP3 file encoded in stereo. Because compressing an MP3 results in a small file, it sometimes does not retain enough audio information, or becomes distorted in some subtle way, making this type of MP3 file unsuitable for conversion -- you may end up with a distorted and perhaps even unusable Minus One file after you've undertaken the conversion process. When using an MP3, your best chance rests with using a large file derived from the original source media, not a copy or a low-quality file.
2 File Editing
When encoded in stereo, an MP3 file has two separate tracks: a left and a right channel. Therefore, when you listen to a music file encoded in stereo on a pair of headphones, the audio coming out of each side sounds different, as some instruments feature more heavily on the right or the left channels. Because vocals almost universally feature in the middle of both channels, you can edit out the vocal tracks by splitting the two channels apart and "inverting" one of the channels.
There are many free and professional audio editing programs that can assist you, such as the free, open-source program Audacity. After ensuring that you have the LAME MP3 codec installed, open your MP3 file in Audacity, click the down arrow beside the track's title, and then select "Split Stereo Track." Pick either of the two channels, and then select the entire length of the song. Go to the "Effect" menu, select "Invert," click on the arrow beside the track's title once again, and then select the "Mono" command for both tracks. Note that some echoes or distorted sound effects may remain.
Some programs are specifically designed to automate this process, and may provide even more options for your Minus One file needs, such as auto-tuning, editing, and the ability to change the key or time signature. Most of these programs are not free, but some are freeware, and a few of the paid programs provide free trial downloads. Some work as add-ons to existing programs, such as the free AnalogX Vocal Remover plugin for WinAmp, while others operate as independent programs, such as the free trial of Magic Vocal Remover (see Resources).