i have a friend who has done a bit of film scoring and quite a lot of TV incidental stuff. he can regularly churn out "40 seconds of parisian street vibe with a techno undertone and hints of ethnic" or "farm fields with a threatening backdrop" in about 5 minutes.

needless to say, none of the tools he uses run natively on linux, and there's sadly nothing native for linux that he could use to do that job at that speed.