Help a beginner! Slow motion basics using Canon 7D?

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Wed, 08/24/2011 - 19:54

#1

neverhood311

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Help a beginner! Slow motion basics using Canon 7D?

Hi everyone, I'm new to this forum and to Kdenlive. I'm hoping this is the right place to ask this question.

I recently upgraded my Canon Rebel XTi by buying a Canon EOS 7D. I'm primarily a still photographer which is why I don't know very much about video editing. However, I've recently developed an interest in cinematography and I really don't want to let the amazing video capabilities of my 7D go to waste.

I installed Kdenlive on my Ubuntu system yesterday and started playing around with it. As many of you know, the 7D can record 1080p @ 30fps/24fps and 720p @ 60fps. I like the look of 24fps so I'd like to record and export in 24fps.

So I want to do slow motion clips. I added a clip that was 60fps and tried to slow it down to 24fps (by using the Speed effect and setting the speed to 40%) but when I rendered the project to AVI and watched it, the video was kind of choppy and definitely slower than 24fps.

So basically what I want to know is: How do I start with 1080p or 720p .MOV files and end up with smooth 24fps video? What project settings do I need? What is a good file format to render to? Are there functions on my camera that I can set that will make this whole process easier? Do I need to worry about the difference between 60 and 59.94fps or 24 and 23.976fps?

Please help out a beginner

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Wed, 08/24/2011 - 22:06

#2

arthursucks

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Re: Help a beginner! Slow motion basics using Canon 7D?

It's not a perfect solution, but it works. If you open the clip in avidemux, you can change the frame rate and save the file losslessly into an avi container. It doesn't do anything for the audio, so I usually disable that.

Wed, 08/24/2011 - 23:05

#3

moorsey

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Re: Help a beginner! Slow motion basics using Canon 7D?

make sure you select "force progressive" when exporting, not doing this can cause choppy exports

Is the project setup as a 60fps profile? You are asked this when starting a new project. If it is not set up with a 60fps profile, then you may also not get the desired speed effects

Wed, 08/24/2011 - 23:11

#4

yellow

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Re: Help a beginner! Slow motion basics using Canon 7D?

moorsey, don't you mean force frame rate to 24P?

neverhood311, drop your 60P's into a 24P project and go into the properties of each clip and force frame rate, whilst in there you may also want to force luma too. ;-) Canon mov's are full range luma.

You may also need to generate proxies.

Thu, 08/25/2011 - 00:40

#5

neverhood311

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Re: Help a beginner! Slow motion basics using Canon 7D?

Yellow, if I understand you right, I need to set the project settings (resolution and framerate) to my desired output? For example, 1280x720 @ 23.98 fps, even though my video clips are 1280x720 @ 59.94fps? And then import all my clips and individually force them to be 23.98fps?

Oh, and what do you mean by 'you may need to generate proxies.'? I'm very new at Kdenlive and Video editing, so I'm not familiar with much of the terminology.

Another question: How do I render a 24p video? Most of the options I see are either 60 or 30 or they don't say anything at all.

Thu, 08/25/2011 - 06:46

#6

yellow

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Re: Help a beginner! Slow motion basics using Canon 7D?

For your purpose on this query for doing slowmo 24 from 60fps then yes choose the 720P 24P project, import your clips, cancel kdenlives helpful remark about fps of files does not match project settings, then go into clip properties, you may be able to select all 60P clips and force all of them, not sure how stable that is.

Proxies are probably going to be needed because your 7D files are tough to decode realtime but you certainly want to render with the source so we use lightweight proxies for preview.

You may find 60 from 24 not slow enough and need to use the speed effect after all.

As your project will be 24P you should see the necessary render profiles.

Thu, 08/25/2011 - 09:05

#7

moorsey

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Re: Help a beginner! Slow motion basics using Canon 7D?

apologies, I think I mis-understood how this would work, having not done it myself before. I assumed that if a clip was 60fps and the project was set to a 60fps profile, then the speed effect would work nicely and you wouldn't have to force framerate on any of the clips etc. So ignore me on that one neverhood, I'll have to give it a go at some point!

My comment on force progressive on the render dialog is also wrong, as your clips are already progressive. I have to set this option as my camcorder only records at 1080i and speed effects are screwed up otherwise!

Just to elaborate on proxy clips. These are, as yellow described, low resolution versions of your HD clips that your PC will be able to handle on the fly. Trying to stick your HD clips straight into the timeline will most likely bring your system to a halt when you are adding effects and playing the project through on the clip monitor. When you first start a new project, you can turn the proxy clips option on, then, all clips that are added afterwards and converted to proxy clips to be used in the project.

Thu, 08/25/2011 - 16:53

#8

neverhood311

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Re: Help a beginner! Slow motion basics using Canon 7D?

Hey Arthur, I don't think you suck. Your Avidemux workaround works great. And I imagine that I could copy the audio and run it through Audacity for some tweaking if I really wanted to keep it.

Moorsey and Yellow, thanks for the clarification on proxies. My laptop isn't cut out for realtime HD video editing. That should help quite a bit.

One problem I'm still running into is when I run my video through Avidemux then load it into Kdenlive (using project settings of 720p @ 23.98fps), then render it to an HDV format (720 30p 2-pass or something like that), the video will only be half as long as it should.
The original clip was 33 seconds. I slowed it down to 1:22.5 with Avidemux. I put it in Kdenlive and rendered it to the HDV format and it's sometimes 33 seconds and other times it's 1:06 (not 1:22.5). If it's 33 seconds, it plays in slow motion and stops just about halfway through. If it's 1:06, it plays at half speed, not 40% speed. Any ideas?

Thu, 08/25/2011 - 18:10

#9

yellow

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Re: Help a beginner! Slow motion basics using Canon 7D?

sigh. :-)

Your Avidemux route has really done nothing more than putting your 60P files directly into a 24P kdenlive project except waste you some time :-), you'll notice the file size and frame count is the same between the two files, all you've done is change the frame rate flag in the header of the file, so a player plays it at 24P, so say a 1 minute 60P file just plays out for 2.5 minutes at 24P, roughly. :-)

Why would you then encode it to HDV at 30P, your project is 23.98. :-) ?

Thu, 08/25/2011 - 19:35

#10

neverhood311

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Re: Help a beginner! Slow motion basics using Canon 7D?

When I click 'Render' and look through the available formats to save the video in, there is no option that explicitly says '24p' or '23.98p'. There are only formats that say 30p, 60p, or nothing at all. Is there a format that saves in 23.98fps?

Thu, 08/25/2011 - 20:07

#11

yellow

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Re: Help a beginner! Slow motion basics using Canon 7D?

The encode will be as per the project frame rate. :-)

Fri, 08/26/2011 - 16:40

#12

neverhood311

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Re: Help a beginner! Slow motion basics using Canon 7D?

I think I've got it pretty much figured out now. For some reason, the 'Speed' effect was giving me poor results; the final result was extremely jerky. I'll continue to play around with that effect, but for now the Avidemux workaround will do.

I've figured out how to use proxies finally, which is a tremendous help when previewing my project without having to render it.

And I'm saving my videos as .avi's with the Xvid codec (I think it's called Xvid. I'm away from my home computer right now otherwise I'd verify that.)

Now that I've got that kind of technical nitty-gritty stuff out of the way, I can get on to more substantial things like editing videos :)

Thanks so much for your help Arthur, Yellow and Moorsey.