FIG. 3: Like other audio editors, Samplitude offers pitch correction.
The Art of Vocal Comping
Some vocalists are lucky enough and talented enough to be able to deliver a flawless performance of a song in a single run-through. Those of you in that category can skip this section; for the rest of us, the art of vocal comping (or compositing) comes into play. Comping involves recording several takes of the tune against the backing tracks, then selecting the strongest elements and combining them into a composite performance.
The lead vocal of a song is almost always its primary focal point, so it's very important to assemble the most in-tune, mistake-free performance you can. However, musical perfection must always be balanced against spontaneity and emotional delivery, both of which tend to get lost after too many takes. Having too much material to choose from can also slow the creative process to a crawl. So when you're preparing for a vocal-comping session, consider limiting yourself to a maximum of four source tracks. If the vocalist delivers more than four takes, choose the best four to work with and throw the rest away.
Next, line the tracks up in your DAW. Listen through the takes a verse at a time. Find the one you like the best and use it as your primary track, replacing elements with materials from other takes as necessary. The amount of detail you apply to the vocal edit is largely a matter of personal taste. Musical genre, skill level of the vocalist, and the producer's working style all factor into your decision-making process here. Some people like to choose whole sections of music, some work on the level of lines and phrases, some get to the level of words, and some people even edit syllables of words from different takes. How you work is up to you, but remember that pitch perfection can come at the expense of musical flow.
When the red light comes on, even the most advanced musicians make mistakes. This is especially true in improvised parts and solos. I feel that the most important thing to capture is the musician's energy in a spirited performance, so I don't let the occasional flub worry me too much. However, there are times when a beautiful solo is marred by a particularly egregious honker. If a note is a bit sharp or flat (within a semitone or so of the desired pitch), you can use pitch shifting to correct it (see Fig. 3). The problem is that significant pitch shifting disrupts the delicate attack transients that are so important to a sound's definition and also changes the formant relationship of the various overtones that define the instrument's timbre. Therefore, it's a good idea to try replacing a bum note with another note from elsewhere in the track. This treasure hunt does not always pay off - you need to find a replacement note with appropriate pitch, duration, and amplitude. Longer notes can be used to replace bad notes if you trim their duration carefully.
When you find a good substitute note, paste it into an empty track directly above the bad note. Zoom in to the beginning of the waveform and line up the attack portions of the notes as closely as possible. Drop the replacement note onto the old note's track and create crossfades before the attacks of the new note and the note that follows.