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Old December 25th, 2007, 03:05 PM   #1
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Slow motion in camera vs. post

Is there any quality difference doing slow motion in camera vs. shooting 720/60p and slowing in post?

Thanks!
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Old December 25th, 2007, 03:19 PM   #2
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I think that shooting slo-mo in camera will be quite a bit better.

This is because if you have the camera set at 24p and shoot at 60, the data is recorded at 2.5x the normal rate, so that it reconciles to 24p at 35Mbps.

When you shoot at 60p natively, the camera compresses 60 fps into 35Mbps.

Edit:
To clarify, regarding Adam's posting below, playing back material recorded at 60p at 24fps will essentially only use 35/2.5 or 14Mbps, whereas playing back material recorded at 24fps overcranked to 60 at 24fps will use 35Mbps.

This is fundamentally different from the way the HVX does it.

Last edited by Eric Pascarelli; December 25th, 2007 at 04:24 PM. Reason: clarification
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Old December 25th, 2007, 03:37 PM   #3
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If you record 60fps and then use a quality slow mo plugin you can get some astounding slow mo in post
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Old December 25th, 2007, 03:44 PM   #4
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Well, although my two EX1's have not arrived, I have had three HVX200's over the last two years. From what I understand, these cameras are very similar in how they handle slow motion. So...

There is no difference in the quality between shooting 60p over 60p and 60p over 24p (slow motion). The camera is shooting exactly the same framerate in both modes. The only difference is how the camera tags and therefore plays back the footage. shooting slow motion in camera makes it a little easier in post as when you import a slow motion file it plays back in slow motion when placed on a 24p timeline. I normally shot 60 over 24 when I knew it was for slow motion. But several times I shot 60p when I needed the option of slow motion, but I also needed the sound (60p over 24p does not record sound)

Unless...
The only thing that could make shooting slow motion better quality is if the camera uses the bandwith normally used for audio and used it for video, but I doubt this. I am pretty sure the HVX does not do this, but maybe I am missiing something with the EX1.

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Old December 25th, 2007, 03:50 PM   #5
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Thanks all! Phil, can you suggest a good slow mo plugin for Final Cut?
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Old December 25th, 2007, 05:02 PM   #6
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Thanks all! Phil, can you suggest a good slow mo plugin for Final Cut?
I'm not Phil BUT I can suggest a couple I use in FCP. Re Vision's Twixtor is really good. Boris makes Optical Flow which is pretty decent as well. I use both of them.
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Old December 27th, 2007, 11:25 AM   #7
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Thanks Gabe--very helpful. Twixtor looks like the ticket. Thanks Eric also for clarifying the difference here from the HVX--one of the only places it seems like the HVX has a leg up!
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Old December 27th, 2007, 11:30 AM   #8
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Gabe does Vision's Twixtor work with HD HQ?
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Old December 27th, 2007, 12:22 PM   #9
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About the only good thing for slo-mo in post is that you can play around with the fps rate pretty easily. I've not tried 'undoing' in-camera slo-mo - has anyone else?

I really like the smooth sine wave slow motion that I do on the timeline. I can start a clip at normal speed, smoothly slow it to 15% (say) and then gently bring it back up to normal speed again. Looks wonderful in the confetti sequence.

I feel shooting slo-mo in camera is a bit like filtering the lens at the scene. Difficult to undo.

tom.
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Old December 27th, 2007, 12:23 PM   #10
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I have used twixtor for a few ex1 things in HQ mode. Also go to www.philipbloom.co.uk and look at the short "Autumns done come" for a really lovely example of everything shot 60fps (apart from the shots with cigar. I forgot to shoot 60fps and it was all done with twixtor)
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Old December 27th, 2007, 12:31 PM   #11
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Rob,

Actually I think the EX1 has the leg up here.

As long as you know what the camera is doing with your footage, you have several compression options when shooting 60 frames.

You can set the camera at 24p and overcrank to 60. The camera records something like 87Mbps onto the card. If you play back at 60 (doing a post speed up), you get a form of super high quality (though I've never tested this to see if it's worth it). If you play back at 24 you get slomo at 35Mbps.

If you set the camera to 60p, the camera records at 35Mbps. If you play back at 60, you'll have 60p at 35Mbps. If you play back at 24p (post slow down) you get slowmo at 14Mbps.

Then there are other options - setting the camera for 25p or 30 and overcranking to 60. This should give more data rate options when playing back at 60 or 24 (all would require post speed changes). I haven't tried any of these. In fact I really should test all of this more extensively before saying much more about it!
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Old December 27th, 2007, 02:09 PM   #12
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Thanks Phil it is good to know Twixtor can handle HD HQ. I really enjoyed "Autumns done come".
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Old December 27th, 2007, 07:50 PM   #13
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Quote:
Originally Posted by Eric Pascarelli View Post
You can set the camera at 24p and overcrank to 60. The camera records something like 87Mbps onto the card. If you play back at 60 (doing a post speed up), you get a form of super high quality (though I've never tested this to see if it's worth it). If you play back at 24 you get slomo at 35Mbps.
Eric,
You put a very clear explanation about the compression/quality EX1 behaviors.
Unfortunately I don't get my EX1 yet, but if you make this post speed up to find out this form of super high quality, please post it. Ill be follow you.
Saludos!
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Old December 28th, 2007, 02:17 AM   #14
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Thanks Phil it is good to know Twixtor can handle HD HQ. I really enjoyed "Autumns done come".
twixtor is great but the biggest problem with it is the long render times and the lack of preview.
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Old December 28th, 2007, 03:40 AM   #15
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Happy New year to all.

Phil What does "Autumns done come" mean?
I really enjoyed your film.

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