Slow-mo and sound

Green Hornet

Green Hornet

Veteran
If I shot slow mo or speed up. would the sound track to the correct playback speed?

In other words, if I were shooting a kung-fu movie to be played at 24p, and I wanted to speed things up by shooting 12 fps, the resulting clip would be twice as fast, but would the sound have to be dubbed? Would my actors sound like chipmunks?

How would this work?
 
Green Hornet said:
If I shot slow mo or speed up. would the sound track to the correct playback speed?

In other words, if I were shooting a kung-fu movie to be played at 24p, and I wanted to speed things up by shooting 12 fps, the resulting clip would be twice as fast, but would the sound have to be dubbed? Would my actors sound like chipmunks?

How would this work?
Click to expand...

I have no idea what the HVX200 i like handling sound at off sync speed. But I think as a general rule that you should dub the sound in post anyway. Yes your actors pitch would need to be adjusted in post. But think of all the other sounds that are going to be affected, such as hum, the traffic outside and airconditioners. So dub a clean soundFX track in post.

Johan
 
Well, we don't have it yet so I can't answer authoritatively, but -- you're asking two things there. If you shoot 12fps, then play back at 24fps, the action will be twice as fast. What would you expect to happen with the sound? You could extract the sound from the original file and play it at the original frame rate, but then it'll last twice as long as the action. Or, you could speed up the sound so it plays at the same rate as the action, but obviously it'd be playing twice as fast as normal, so yes: chipmunks.

Dubbing the audio is probably the only way to work with off-speed shooting.

EDIT: too slow, Johan beat me to it!
 
Without seeing the camera first I would assume your audio track will sound normal speed no matter what the frame rate when it comes to a VIDEO cameras method of recording. While audio and video are in sync they are still two unique files and I would think that the HVX makes 12 fps possible by simply repeating identical frames to come out to NTSC's 60i requirement thus audio should always be paired with a standard, across the board, NTSC signal.

In other words your audio should sound normal and if you want it to sound speed up you will need to do it in post.
 
Barry_Green said:
If you shoot 12fps, then play back at 24fps, the action will be twice as fast. You could extract the sound from the original file and play it at the original frame rate, but then it'll last twice as long as the action.
Click to expand...
If you're shooting 12fps, however, then you have to be in 720 mode as 1080 doesn't offer 12fps shooting. And if you're in 720 mode, it's only laying down the recorded frames to P2 - not a 60p stream. So I am not sure what you mean by "extract the sound from the original file," because the original file IS 12fps in 720 mode, correct?
 
But sound doesn't conform to fps -- sound is 48khz, regardless of what frame rate you shoot the video at. The sound file should be recorded separately anyway, as Op-Atom splits the video, the audio, the proxies, all the metadata, everything gets split up in its own files. So there should be a sound waveform that's recorded "live" at 48khz regardless of what frame rate you shoot at.
 
Barry_Green said:
But sound doesn't conform to fps -- sound is 48khz, regardless of what frame rate you shoot the video at. The sound file should be recorded separately anyway, as Op-Atom splits the video, the audio, the proxies, all the metadata, everything gets split up in its own files. So there should be a sound waveform that's recorded "live" at 48khz regardless of what frame rate you shoot at.
Click to expand...
Right, that's exactly what I was thinking. I got a little confused by the wording of an earlier post you had made, but this result is what I was expecting the camera to do.
 
In my mind, the only way to salvage the audio from that type of shoot would be to use audio software that can do audio stretching (shrinking) while maintaining pitch. Like Nuendo/Cubase, Logic, Live, or just an editor like Peak, CoolEdit 2000 (which is now Adobe Audition) , and I think Wavelab can too. Live 5 has a good algorithm for this effect, and is good for non-surround soundtrack work as well.

I'm sure there are other options out there as well... I would also suggest having the actors speak slowly though, so the words aren't all run together real fast...

-BitBuilder
 
Interesting, but I see on this link that it says:

"It is proper, but when photographing and playing back F/Rate differ, it cannot record Audio."

The page is somewhat loosely translated (or just reported by someone at a basic level of English), but that certainly reads to me that the camera does not record audio at all in variable framerate situations.
 
that would not be too good. It would be nice if it simply would record audio at normal speed.

so we can speculate on the HVX200A already: variable framerates with sound will be one feature :D
 
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