There are three basic elements to music:
In a song form you also have the element of: Lyrics.
When doing a remix, these are the four elements you are going to play with. If you change all four, then you have a completely different song, not a remix. Most commonly the melody and lyrics stay the same. Changes are made to the harmony and rhythm. Think of the last remix you heard (famous examples include “Knock on Wood”, “Red Red Wine” and “Lean On Me”Â – good chance it was the harmony and rhythm they changed.
For a parody, the opposite is true. A parody may change only the lyrics. The point being to sound kind of like the original, with new words.
For a jazz or big band arrangement it is largely the harmony and rhythm that will change. Melody will become swung instead of straight and harmonies will be more complex and “outside” (many times just adding 11th and 13th chords with a little swing can do the trick).
You can take any song and keep the lyrics while changing all other elements and most people will still recognize it as the original song (if they can understand the lyrics). A good example of this recently is the remix of “Somewhere Over the Rainbow”. The arrangement is not concerned with hitting the wide range of the original melody, only in alluding to it in a relaxed manner.
When approaching a remix, make a conscious decision about what elements you are going to change. Remixes are sometimes the result of an open jam, but more often the focused effort of a producer is involved. They may not think in such rigid terms as put here in “melody, harmony, rhythm, lyrics” – but the producer is effectively making the same decisions.
You can also use this as an approach to songwriting. Take a song you love, change all four elements and you have a totally new song. Remember, good composers borrow – great composers steal.
If using this approach to create new works and songs, always make sure your changes are drastic enough so there are no telltale signs of the original left that could lead to copyright infringement. If just changing a few elements of an existing published song, you can get a mechanical license to make it legal. Check with the song publisher on how to acquire a mechanical license – usually it’s through BMI, ASCAP or the Harry Fox Agency in New York.