Syncing audio recording with slow motion video

S

Sneakle

Well-known member
Not sure which section to post this, here or post editing, but,
I have a fight scene to shoot where I want to shoot some takes maybe 48 or 60 fps; so obviously no sound coming into my HPX170 at that rate, but I will have to make the fight sounds including a guy falling in the water, big splash. I know i can do all that in post with foley but wondering if it is recommended to take the live sound anyway, double system, and maybe slow it down in post? But I guess if I slow it down the pitch comes down too.
 
I think you need to talk to your post sound guy/ designer etc. You are talking about less that 1/2 speed and that has a lot of impact on the sound. Time stretch is not going to sound very nice at that amount of stretch and all the "impact" is going to get very diluted because of the stretch, no mater how you do it.

Despite that I would probably go with Uncle Bob on this. BUT it's important to know what you want to end up with BEFORE you shoot.

Anything that slow is going to be very stylized. You probably do want the sound slowed and you probably also want the pitch lowered. People expect the two to go together and unless your doing a comedy...

I would take a look at Ragging Bull, though that may be your inspiration? It was one of the first heavy style slomo sound designs for a fight (that I know of anyway). It's the film one goes back to to see how well it can work.

If I were the designer I would probably want the vocals recorded live at 96K/24 bit. This is one case where I would record at the higher sample rate because the slow down will be MUCH smoother. If you shoot at 48K when you slow down to match your going to be at 24K at most and that is going to sound "grainy". The hits you are going to have to "design" so they sound right and still have impact. Body falls etc. you will probably have to sweeten a bit but the production might work?
 
Noiz2 said:
I think you need to talk to your post sound guy/ designer etc. You are talking about less that 1/2 speed and that has a lot of impact on the sound. Time stretch is not going to sound very nice at that amount of stretch and all the "impact" is going to get very diluted because of the stretch, no mater how you do it.

Despite that I would probably go with Uncle Bob on this. BUT it's important to know what you want to end up with BEFORE you shoot.

Anything that slow is going to be very stylized. You probably do want the sound slowed and you probably also want the pitch lowered. People expect the two to go together and unless your doing a comedy...

I would take a look at Ragging Bull, though that may be your inspiration? It was one of the first heavy style slomo sound designs for a fight (that I know of anyway). It's the film one goes back to to see how well it can work.

If I were the designer I would probably want the vocals recorded live at 96K/24 bit. This is one case where I would record at the higher sample rate because the slow down will be MUCH smoother. If you shoot at 48K when you slow down to match your going to be at 24K at most and that is going to sound "grainy". The hits you are going to have to "design" so they sound right and still have impact. Body falls etc. you will probably have to sweeten a bit but the production might work?
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Raging bull came to mind for me also when I was considering this. Recording at 96k is indeed good advice. I think I should run some tests in advance of that shoot in 2 weeks.
 
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