I've seen a few people adding new soundtracks to old films over the years. It's an interesting idea but I reckon it's really hard to get right. Some highlights/lowlights from my experience:
- aPAtT performed a live soundtrack to the 1922 silent classic Nosferatu. You can download it here. Their soundtrack is great, partly cos they've got a wide selection of sounds they can do (from melodic to abstract, etc) and cos the music changes well with the scene-changes and atmosphere-changes. There's a brilliant bit near the end where two different sorts of "travelling" music overlap each other, while the film shows us two different journeys happening in parallel. And the scary climax of the film has a really great accompaniment, really worth seeing.
- A few years ago I saw [Faust](http://en.wikipedia.org/wiki/Faust_(band%29) soundtracking Nosferatu (i.e. the same film as aPAtT), which was less good, to be honest - they seemed to be enjoying themselves too much making music, and didn't make enough of an attempt to attach to the contours of the film.
- I think the worst attempt I saw was someone soundtracking The Big Lebowski. The reason it's so bad is that The Big Lebowski is such a verbal film, it's all about what people are saying, but the new soundtrack only included the occasional snippet of what people were saying. So we watch lots of people with their mouths moving, wonder what they're saying, and what the music's got to do with it.
- Over Christmas BBC4 showed the original [King Kong](http://en.wikipedia.org/wiki/King_Kong_(1933_film%29), with Rob Da Bank soundtracking it with various records. This was sometimes pointless but sometimes great. Often the soundtrack was oblivious to scene-changes or mood-changes: for example some chill music despite a scene that started chill and got exciting. Near the end there were some great choices: "It had to be you" came in as KK re-discovered Fay Wray. And despite KK being a non-silent film, the voices aren't so important, almost everything's there in the action.
- I saw RLF soundtrack some Godzilla stuff. This was pretty good (my favourite memory is the zappy sounds which happened when jets of flame came out of monsters' mouths). One thing which is a bit of a cheat is that it was a kind of edited-Godzilla-highlights (I think) rather than a full film, so he didn't need to make sure we were following the plot or anything. It meant it wasn't dull though!
- Oh and I also have a DVD of Wizards of the Lost Kingdom with 3 alternative soundtracks by Billy Ruffian crew. There's some great moments in there, though it's a while since I watched that - but again, Wizards is one of those films where you don't really need the voices since the action and the bizarre interjections from stock footage are all you need to know.
There's quite a variety of approaches - for example, should the soundtrack faithfully support the film (which I think is what aPAtT's does), or should it be ironical and playful, suggesting reinterpretations (which Rob da Bank did here and there)?
I do think there are some "rules" which you can generally derive about this business. As usual rules are good for breaking, but here are some suggestions:
- The soundtrack must fit to the broad contours of the film, reacting to things like dramatic changes in mood. Often you can deliberately contradict the intentions of the film, fine, but if there's no association in the contours then you get an icky sort of audio-visual dissocation: my ears aren't watching the same film as my eyes are.
- It's handy to mimic physical events in the soundtrack. All of the above do this: jets of fire cause zappy sounds, bell-like sounds happen when someone in the film hits a gong or a bell, gunshots ring out. It's pretty easy to do, and reduces the dissociation I mentioned above, but it's not compulsory, and it can be gimmicky if overused.
- People can't watch a full-length film without a plot (which is what happened with The Big Lebowski re-do). If you can't mix crucial bits of voice into the new soundtrack (e.g. cos of pollution from the old one) then perhaps you could give us some selected subtitles? Thanks.
- The standard stuff about how to score a film still applies - e.g. themes that can return later on, pushing and pulling the musical density. I think aPAtT's soundtrack does this nicely, one of the reasons it's a good un.