Welcome to our community

Be a part of something great, join today!

Log in
  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Sync slo-mo, possible?

D

Dorian Weber

Well-known member
Joined
Aug 28, 2007
Messages
182
Reaction score
1
Points
18
Location
Jpn
Don't use much Audio, therefore ask advice for you Audio Guys:
I want to shoot a drummer in slow mo-Epic and 96 fps is enough. But what about the audio?
I could record the audio with my Zoom H4n, no problem about that... but is there any way to sync it?
Any way in either Audition or Sound Track Pro to slow it down.....?
I guess, I will have 3 drum beats in audio when he hit the drum once in video.......
Would appreciate any advice!
 
Im pretty sure ive seen an App somewhere where you can upload an Mp3 of your song onto your phone....then dial in the Fps you want to record in and the app slows down or speeds up the playback depending on the delay and base frame rate.
that should help to sync later on in post when you're editing according to your playback frame rate.
is that what you are after ?
 
The relationship between frame rate and audio Hz is irrelevant.

As you are shooting varispeed you will need to record the audio separately. Record at 24bit 48KHZ.
Sync up the audio in the editing programme. Edit the footage to fit.

If you want the audio to be in sync with the slow footage completely, there are two factors to consider: time and pitch.
Simply slow the audio down in Soundforge by extending the duration x 3.84 (assuming that you are in PAL land, so 96/25)
Change the pitch in soundforge by dropping it down 2 octaves.

If you don't have Soundforge, use Audition.
 
Paul, great thank you. Have not shot it yet, but was wondering if possible.... so I can go ahead to plan it. Might get back to you if I need more advice. I am in NTSC territory (Japan)
 
I think what the OP is asking, is how to film the drummer in slow-mo while in sync with the audio track at normal speed.
If the project fame rate is 24fps, and you are recording the drummer at 96fps, then the drummer will need to play at 4x normal speed in order to sync with the audio when played back.

You should first try practicing with the drummer filming at 48fps with the audio playing at 2x normal speed to see how that works out for everyone, the 72fps at 3x normal speed. Unless it is a very slow song, it will be quite a challenge for the drummer to play at 4x speed.
 
actually, it is not a song... just drums..... japanese drums, they are played by a group
 
So like Taiko drums?
Yes, get them to mime or play along with a speeded up track. If you're going to shoot at 96fps then your audio track duration should be reduced by a factor of 3.203 (96/29.976). So a track originally 60 seconds long should only last 18.7 seconds. Most drummers will find this very difficult. If it's anything like the traditional Japanese Taiko drumming that I've seen it's next to impossible for anything longer than a burst.
 
Paul, yes... it is exciting to watch those guys..... actually, during a performance, I took slo-mo shots in 96fps, but MOS (did not even have a mike nor recorder with me).
So the shots are kind of dull, therefore I was thinking, it would be nice to add the audio to it. I could shoot an other performance, but can not tell them to change their speed since that will be a live performance.
 
If it was me I'd go back and setup an audio recorder in the best place in the hall to grab the entire performance. And then while that is happening, shoot lots of new stuff at a variety of different speeds and angles and distances, and then cut it all together into a 3 minute 'song' to one of the best tracks on the tape.
 
Before we had affordable high-frame rate cameras, the usual slowmo scenarios were 30p to 24p and 60p to 24p.

In my experience, even 60 to 24 is very very difficult to synch to, unless it's a really slow ballad. You're just not going to have much luck synching at 3-4 times the speed.

It's easy to see for yourself - even Audacity (free) can slow down or speed up audio and keep the pitch the same. 60-to-24 is about 250% faster - at that speed you can barely recognize many songs, much less synch to them.

Like many things posted around here, the appropriate answer is "test test test" and you'll know all the vairables unique to your situation.
 
Ok, so everyone seems to be answering three different topics here - so lets look at the different kind of scenarios:

Scenario ONE: Footage shot off speed, MOS - creating a synch music/effect track in post. In this case Japanese Drums.

In this case, either you get the matching music, and slow it down to match the actual footage so you are listening to slow mo music, or you simply edit the footage so that individual drum hits. Both of these examples are more typically used in nature documentaries. Half the experience is sound, and most of the time the sound in a nature documentary, especially when it comes to gorgeous slow mo shots, are entirely sound design plus music.


Scenario TWO: Footage shot off speed, with live audio recording.
In this case your recorded live audio is destined to match the slow mo footage. Probably the most common example of this would be if you want to shoot slow mo of actuality, and play back in real speed and ramp down to slow mo in post, keeping the audio so that the effect of the ramp means the audio slows down with the ramp.

Aside from visual concerns here, which are making sure your shutter speed is going to work on the post effected ramp from realtime to slow mo, you also want to ensure you are recording at an appropriately high sample rate to avoid audio artifacting when you sync the audio to the slow mo footage. a 96Khz sample rate is good for shooting 48 fps on a 24fps project, a 192khz sample rate is good for shooting 96fps on a 24fps project etc.


Scenario THREE; Footage shot off speed, to match pre recorded realtime sound.
This is the case where you want the slow mo look while audio plays back in realtime - most common usage of this is in music videos.

With a slowish song you can shoot at to 60fps and get the singer to sing the song 2.5 times faster than normal on a 24fps timeline, generally syncing to a pre recorded version of the song playing back at 2.5 normal speed. I've done this in this music video here, definitely wouldn't want to try and do faster than 60fps given how fast the singer had to sing in reality:

http://www.youtube.com/watch?v=6WWHxTbycKQ
 
looks like, I would be into a lot of testing. Anyway, I have already some MOS slow-mo clips and the sound I can record an other time and will see, if I can somehow match the beatings
 
I have had excellent results keeping the music real time with slo mo visuals. Our brains are very good at filling in the blanks. Like you mentioned before, you will hear beats with no hit, but it doesn't matter, especially if there are multiple drummers and you are focusing just on one. The viewer will assume the other drummers are filling. You do need to make sure the visual hit corresponds to a sound.

Most music is 4/4 so shooting at 96 frames would work well slowing to 24. For 3/3 time 72 frames work well. If the drummers are only playing quarter notes and are perfectly in time it would always work perfectly, of course that would be beyond boring, so in real life it will be much more complex. I typically would slide the footage around until I found one that works and only use a few seconds at a time then cut to another angle. If there are a lot of syncopated beats it can be a little more challenging as well.

Slowing down the music can look pretty awesome as well if the beat is insanely complex. For this I probably would not go all the way to 96 but keep it 2X or 3X.

Let us know how it works.
 
Cliff Hokanson said:
So if my iphone can do slowmo with audio why cant a RED do it?
Click to expand...

You can do this with Red, or any other camera. It really has nothing to do with the camera, or audio recording device. It has everything to do with the tools and techniques you use to manipulate the media captured.
 
Last edited:
Dorian, we did something similar in this music video, except drummer/performers were shot at 48fps (not 96), 24fps, and 12fps:


Basically, we made three versions of the track:

1) NORMAL
2) SPED UP TWICE (for 48fps)
3) SLOWED DOWN BY 1/2 (for 12fps)

We then had band perform each setup in all 3 time signatures.

By playing the song TWICE AS FAST in 48fps, band's performance was still IN TIME when played agains NORMAL playback of song, except their performances were silky smooth slowmo.

Same for when they played TWICE AS SLOW in 12fps, when played back against normal track, their performance had a great frenetic, sped up energy.

My DP came up with this idea, and it was genius.

Hope this helps!

best

PS - video shot on RED ONE MX w/ B-Speeds, case anyone's curious...
 
You must log in or register to reply here.
Back
Top