confused after barry's dvx book - slow motion

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Peter_Gaudry

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Just bought Barry's DVX book, and love it, but with one confusion:

Currently shooting a movie, all in 24pa, removing the pulldown in FCP for pure 24p goodness. Have slowed down a few scenes thus far, and received the lovely 'strobing' of slowmotion in FCP.

In Barry's book, he said to overcrank the camera, set it to 30p, then put it in a 24p timeline and slow down by 80%.

I'm not at my computer so can't try it right now - but is this saying I can effectively mix 30p and 24pa footage all on a 24pa timeline?

I can expand more, but can anyone help me out here? If possible, I'd like to keep the entire movie in 24pa.
 
Re: confused after barry's dvx book - slow motion

yes. it will require re rendering the 30p segment, but it will use all original progressive whole frames.  1 second of 30p = 1.25 seconds on a 24p timeline.
 
Re: confused after barry's dvx book - slow motion

good ****! That's the answer I was looking for. My only two follow-up questions:

1. What if I shot 60i and tried pulling the same stunt? Still whole frames?

2. I presume there will not be any degradation in the 30p>24p conversion because they're all using whole frames?

Thanks! ;)
 
Re: confused after barry's dvx book - slow motion

To create slow motion with film you shoot at a higher frame rate. If you shot at 72fps and then projected back at 24fps (normal movie speed) then the action will take 3 times as long (slow motion)
Same principle applies to video. If you can shoot at a faster frame rate then it's easier and better looking when put in a 24fps sequence. The 30 frames shot at 30p (1 second) now take 1 second 6 frames in 24fps sequence. If you just take 24fps in any editing program and time stetch it such that you have 2x slow motion all you're doing is duplicating frames. It may blend fields together but there are now new images so it will be slow but may appear a bit steppy or processed compared to having more original frames to begin with,
 
Re: confused after barry's dvx book - slow motion

60i doesnt have whole frames to begin with. it has feilds.. every "frame" is made up of 2 feilds. each feild is taken 1/60th of a sec apart and only includes the information for every other line in the image. then its played back alternating the feild order: odd, even, odd, even ect. at 60 feilds per sec it plays back so fast that you dont notice it only has 1/2 the lines displayed at any given moment.   in oder to use 60i in a progressive environment you would deinterlace it ..which means your taking all 60 feilds and converting them to 60 full frames. so you interpolating the image data missing on the missing lines for each frame.. the software/hardware guesses as to what color and luma and chroma info should fill in the gaps based on the given info of the existing pixels around it on the lines that are actually there. once its all done beind deinterlaced,  essentially you have 1/2 or more resolution pending how good your deinterlacer is and what sort of results it gives given the motion and complexity of  the image and all.
but then you could take the 60 interpolated full frames and put them on a 24p timeline and from one second, you would get  well 60/24     which is 2.5 secs of playback time
so 1 sec 60i = 2.5 secs 24p at 1/2 or better resolution.
 
Re: confused after barry's dvx book - slow motion

You're using FCP, which complicates matters some; FCP apparently doesn't allow different frame rates on the same timeline. Vegas does, and that's what I used, so perhaps I assumed an easier workflow than you're encountering.

However, in Vegas, yes you shoot 60i, slow it down to 40% speed, and get super-smooth super-slow-mo (watch on the DVD for an example). If FCP can't do the multiple-frame-rate-in-same-timeline thing, then perhaps you can do as Neil said, and export the 60i fields as individual frames.

Any FCP expert want to give us a tutorial on how to do this?
 
Re: confused after barry's dvx book - slow motion

..doh! :o didnt know fcp couldt do that. ..thats actually a big suprise to me. whats up with that?
 
Re: confused after barry's dvx book - slow motion

damn, that is very sour news. Yes please to any FCP expert with a tutorial. Otherwise what are now my options? Twixtor at 600 bucks? Ech.... :(
 
Re: confused after barry's dvx book - slow motion

I just did a quick test to confirm my suspicions - It appears you can do exactly what Barry is suggesting. The only caveat is that if you are adding a 60i clip to a 24p timeline, you will have to render that portion in order to see the result. Give it a go and see if it isn't pretty smooth. It worked fine for me just now.

Cheers
 
Re: confused after barry's dvx book - slow motion

Thank you sincerely. I'll give it a go too when I get home - that's great news. :D
 
Re: confused after barry's dvx book - slow motion

You can mix different fps clips in FCP but it will convert it to keep the same time just as most effects packages do.
So if you place a 1 second 60 fps clip in a 24fps timeline it will still be 1 second long (frames will be dropped or blended)
In a slow motion case you'd want to take a clip and mark it as being 24fps even if it were shot at 30 or 60fps. This would provide one frame of original to frame in sequence and do the natural slow motion. After Effects and other packages allow you to tell the program how to consider the footage but I don't think FCP allows it.
 
Re: confused after barry's dvx book - slow motion

What you're describing is how Vegas works as well (regarding it playing back at the same time duration, and dropping/synthesizing frames to fit the playback rate).

So, the question becomes: can FCP allow you to play back at a slower frame rate, and give you frame-for-frame accuracy? i.e., if you put a 30p clip on a 24p timeline, and tell the clip to play back at 80% speed, does it give you the pure raw frames, at a 1-for-1 ratio? If so, that would be exactly what you need for overcranking slow-mo.
 
Re: confused after barry's dvx book - slow motion

I see the issue more clearly now - we're looking to get slow-mo exactly the way I get it if I shoot at a higher frame rate on 16mm film and then run it through a projector at 24fps.

It might be possible by doing multiple timelines w/ different frame rates and some funky exporting.

I'm interested to see how this pans out. I'll do a bit more experimenting and post my results.

Cheers
 
Re: confused after barry's dvx book - slow motion

At 80% it doesn't give all pure frames. Default is frame blending on but with it off it ends up skipping frame 5,10, etc and doubling the frame that comes after. I suspect it's a rounding error internally or needs a slightly different setting other than 80%
 
Re: confused after barry's dvx book - slow motion

I have played around with DVX slo mo in FCP (24p timeline,60i clip) with decent results, strobing is less noticable when subject is moving towards or away from camera, the subject is a vehicle. My problem is outputing through firewire, I can preview in the canvas after rendering but I can't seem to output to my deck. Help, no doubt my settings are wrong some where but where?
 
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