So how does recording for film work?
Well, the first problem with recording for film is making sure that critical points in the music match up with the film. This means that the conductor has a monitor with the film running so that he or she can make sure that the music lines up. In addition the musicians often play to a click track. This means the whilst recording they wear headphones with a click playing (like a metronome) so that they're exactly in time. This click will have been worked out so that the score lines up with the film exactly and (unlike most metronomes) the click will be planned to get faster or slower if a tempo change is needed!
So is there just a microphone at the front so it sounds like it would in concert?
NO! It's really important that the sound can be manipulated and controlled - It has to be mixed with dialogue and often background noise, and if for some reason the cellos play one note a tiny bit too loud, the producer needs to be able to turn them down. So, for that reason there are microphones all over the place - normally one per desk of string players and one each for wind instruments.
For the same reason of control in this session the horns and oboe (the only winds) were recorded in separate rooms (with glass walls so they can see the conductor! Click here to see the floor plan from the session and see how the orchestra were set out.
So does the composer conduct?
Well, sometimes yes, but in this case no. Instead Nitin Sawhney, the composer, was in the control room "the box" watching and listening to the session and talking to the conductor - Stephen Hussey - through his headphones to make sure they got exactly the right sound. For this session there were quite a few people watching and listening, including the director of the film, Mira Nair, the producer, two or three music assistants who were looking after the score and parts and writing down which 'takes' were to be used. This is all in addition to the 2 sound engineers.
What do the sound engineers do then?
They're the ones actually responsible for recording the sound and cueing up the click track and film to start in the right place. These days a lot of the recording process is done using computers, but they still have to be able to use mixing desks like this:
A lot of the work will actually be done after the session when the music is mixed to make sure the balance is correct and adding in other instruments (this particular film uses lots of Indian instruments, recorded a couple of months ago in India). The soundtrack will then be mixed again with any dialogue and sound effects mixed in with the music.