The film music recording engineer cum composer like ARR is a rare breed. They are also known as music scoring mixers, music mixers, film mixers, scoring engineers or mixing engineers. Their purpose is to uniformly capture the sound of an orchestra or music so that when we go to the movies we can hear the blazing brass on Star Wars or to hear electric guitar as James Bond walks the screen. To do this they must deploy microphones throughout the orchestra which are fed into a mixing desk and then to a tape machine. Film music recording engineers differ from a "standard" orchestral engineer in that they must record and mix the music with sound effects and dialogue in mind. They must be aware of the audio and visual content of a picture for whose score they are recording. This is why some engineers like AR Rahman, those whose style I like the one of the most, mix with a wide stereo image -- that is, instruments are placed further to the left and right speakers than to the center.
Film music engineers are used to long working days, in the order or 12-15 hours a day, for a few weeks at a time: they must deliver the mixed down tapes on time or the film will be behind schedule and budget. As a result of this, highly esteemed and sought-after engineers are paid a considerable amount of money.
Film music recording engineers can cover everything to do with the music in a film: from looking at scores and talking with clients to setting up the studio and checking the "pipe-line" from orchestra to tape.
It is not uncommon, however, for more than just one person involved in the recording of film music. We often only see the "head" or "main" recording engineer get the credit but he (or she) will usually have assistants, or scoring crew, who set-up microphones in positions decided by the engineer, who will operate tape machines, cut tapes (analog), route cables and make recommendations on how to tackle problems, etc. It is often a team affair being captained from the control room. At other time sit is under the directions of the main composer.AR Rahman is an engineer who has recorded most of his assignments this way.
After the many takes of cues from a film are recorded the recording engineer cum composer must then "mix" the music. (As mentioned earlier this is sometimes done by a different person.) The producer is often present, as is the composer, who I guess have the final say over the mix but most times the engineer is left pretty much to their own devices. The mix of the music is greatly determined by the style of recording. If close-miking techniques were used (placing microphones closely to intruments or groups of instruments) then many more degrees of freedom are available to the mixer. Intruments can be panned (or placed) in their respective positions in the stereo field, as if one was standing on the conductor's podium. For example: double basses can be panned hard right, French horns left, flutes and clarinets center. Close-miking achieves a much more punchy sound, especially in the basses and some percussion but as a side effect it requires extensive artificial reverberation (Reverb is the sound you get when you clap your hands in a recording studio and the sound reflects, or comes back, a fraction of a second after). I think two seconds is around the norm for reverb. Close-miked recordings without added reverb would sometimes sound too "clean".
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but they make good money.
It should be evident, by listening to ARR's film music, that there is only a select group of excellent recording engineers out there. Many of them have been in the business for 20 or 30 years and have tens of scores under their belts. It is an occupation that requires skill, patience and dedication, and although many of them think their job is "simple" , it's not.