Actually, while important, music (or, really, the audio track, including V/O, sound effects, etc.) is only a part of the production. The plant manager, lawyer, etc. are there for approval of the ENTIRE project, of which audio is an important, but sort of "journeyman" part. The project is done in a video editing suite, which has audio at one end. There are sometimes three off-line edits of components going on simultaneously, a major edit of the shell and music being recorded either in real time or of-line to click tracks.
Remember, these are internal communications documents, where message (and timing) is all important.
Commercial and internal film production, with simultaneous audio production is a hi bred communication category. And it's growing by leaps and bounds. Getting ever more demanding, too.
Contrast this with the scores that are done with more time, using sampling and other popular techniques and you have a completely different animal....generally, anything from film maker shorts to full length movies. Budgets vary widely. With business to business films, the score is, sadly, secondary, and generally, only 15-20% of the final production.
Another aspect of modern music production in today's market.
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