Remixing MP3s

From ITCH

david fettes wrote: > Hello, is it possible to do the following things? > 1.take an mp3 of a pop song with vocals and remove the > vocals?Then replace them with vocals sung by children. > 2.take an mp3 song and jazz it up by adding a modern > drumbeat, using eg drum samples rather than a real > drum? > If any of these is possible what programs could be > used? > Is it possible in audacity or other free software?

Hi David

It is possible but is not necessarily easy. The problem is that in an audio file format all the elements are mixed up and need to be un-mixed in order to remove individual sounds. That requires complex 'signal-processing'. You need to start with each instrument on it's own 'track' as recording studios do.

There are programs that have some success with stereo tracks by removing whatever appears in the centre on the stereo (left/right) image. Usually the solo is placed there by the recording engineers. You could play with some of those to see if you get usable results.

The fact that you start with MP3 rather than pure audio such as WAV complicates things further. MP3 messes with sound to remove stuff we can't usually hear. That could confuse any removal programs and as many sound editing programs don't work directly with MP3's you will need to convert to another format.

Any audio program that has basic mixing capabilities will allow you to add sounds. How well it 'sits' in the mix will depend on many things such as effects used.

Audacity will help you to some extent but you really need a full mixer program like Rosegarden. Audacity doesn't appear to have a solo/vocal removal effect.

I suggest that you really want to start with MIDI files. They don't store the sounds themselves but rather the musical events that happen (notes etc). When you play a midi file a synthesiser converts those events into sound. Most importantly each instrument is recorded separately on it's own track so they can be removed.

So I suggest that you find midi files of the songs you like. There are lots on the web. They will not be the originals that children are used to and will have a solo instrument instead of the singers voice. You then use a midi sequencer that also handles audio (most do now, rosegarden again) to remove the midi tracks you do not want. You then need to record the children singing and mix that into your composition and record it. You do much the same with with drums but using samples adds a view more twists.

You will need to honour copyright of the original material.

Be prepared to spend a lot of time but have a lot of fun too

Steve Lee

Good answer from Steve. I have had some success using a programme (not open source un fortunately) called Cool Edit Pro. I removed the vocals and added the solo on my Euphonium. You can also add additional tracks with sampled sounds if you want and it doesn't need a low latency sound card. The company that wrote cool edit pro was bought out by Adobe and they re-launched the programme as Adobe Audition. I don't know how this affects the copyrights to Cool Edit, but it is possible to obtain a time limited version i.e. it will only run for 30 days. I can let you have a copy if you want. I also have a library of around 10,000 songs in a midi format so I may have what you want if you decide to try it this way.

Nick Holme