Shorter edits of compositions (commercial lengths) are tailored explicitly towards advertisements and commercials. They are shortened versions of the original song, specifically modified for use in commercials. They should contain the strongest musical element of your composition.
It is important to create a sound that is easy to follow and maintain a theme throughout. These commercial lengths are just as, if not more important than the main version.
They should be either 30 & 15 seconds in length, the timings of which must be accurate to the second.
The last downbeat or musical content should be no more than 1.5 sec from the end. Avoid finishing with long reverbs or delays. However, a slight natural fade beyond the duration could work.
ALL compositions MUST have ‘musical endings’ – do not use fade ins/outs. Ideally, endings should musically “resolve” and preferably finish on the root note. For example, if the arrangement finishes with a drum section, the ending could also be one final drum hit.
Editors will sometimes look at the soundwave of a song before listening to it, so try to have include noticeable dips in the arrangement. Enabling the editor to visually see where changes are, lets them easily skip to those points.