Soundtracks have a couple of advantages over live bands. One is, rehearsal time, another is, you know what the track will sound like during and after recording.
Disadvantage is, you have to live with the arrangement and key pitch.
Soundtracks are recorded using a multi-track recorder, usually digital, and digitally mastered. Instruments are usually recorded on individual tracks, sometimes by a band or orchastra, and sometimes by only one person. Overdubs are common, before the final mix.
ProTools is is one of the best way to record sound in today’s Hi Tech world. I have 32 digital tracks, many times the quality of tape, with hundreds of ways to edit and mix.
I usually start out with a dub or dummy (temporary) track, someone gives me. Then I find the tempo and setup a rhythm track. If I use drums, they are built on 4 or more separate tracks. Next, I will follow the dummy track and drums, and record a piano or guitar track, recording both MIDI and ‘sound’ track. MIDI lets me correct a few notes and duplicate sections that repeat. Then mixing all of the recorded tracks, I usually build a bass track. Adding more tracks, Elect Pianos, Guitars, Horns and Woodwinds, etc, I finish the ‘Rhythm’ Track. Then, I usually build an ‘Intro’ and ‘Ending’ section. Sometimes, there’s a place for a lead, maybe Strat Guitar, or Soprano Sax, Flute, Harmonica, or something. For most instruments, I use the Korg Triton Studio.The Korg Triton was used on many movie soundtracks, and offers hundreds of great sounding instruments. With ProTools and a good sampler, like the Korg Triton Studio, Soundtracks are only limited by our ability, imagination, and what we feel. Click, to listen to some of my Sound Tracks (clips).
I also have many purchased sound tracks available, and with ProTools, the ability to raise or lower the key pitch.
Bill