In Camera Frame Rates

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pepper jack

I have a canon vixia hf r11 and in the menus of the camera there are frame rate settings of 24p 30p and the default (for the camera) 60i. So I've messed around changing the frame rates and I noticed regardless it seems to actually save the files as 60i, when I media info the video files on the computer they are 29.97 and interlaced.

I was wondering what exactly changing these frame rates actually does for this camera? And if there are differences which one would be the best to record in? Currently I've been using 24p or 30p and like I said they end up being 29.97 1080i regardless of what I choose in camera. Is it because this is a lower end camera that it can only really record to one format?
 
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It could be. Your consumer camera may just set themselves to output to your NTSC settings. Or for all I know, it could be some software setting after you've imported the footage to set it to NTSC.

Frame rates seem to be less and less important these days than it used to be. There seem to be two main camps. 1 says to shoot it at the frame rate that you're going to release it (24 for cinema) and another camp saying shoot it at the highest usable frame rate, preferably one that has a multiple of most of the output formats you're going to use.
 
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Sweetie said:
Frame rates seem to be less and less important these days than it used to be. There seem to be two main camps. 1 says to shoot it at the frame rate that you're going to release it (24 for cinema) and another camp saying shoot it at the highest usable frame rate, preferably one that has a multiple of most of the output formats you're going to use.
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I'm not sure why you would shoot it at the highest possible frame rate..? Makes no sense to me... I can tell you that on all the Red, Alexa, and F3 shoots I've been on, we've never decided to shoot at 50 frames, or 100 frames (PAL 25fps land) 'just because' - the only time we'd do that is if we wanted slow mo.

It's more work for your editor and can introduce audio syncing issues, at absolutely no gain at all in terms of image quality.

Also, AFAIK 23.976 is what you should be conforming your DCP packages to, rather than 24.

The issue here surrounding different frame rates could be a few things. It could be your import causing a change in the interpretation of the video. It could be that you're not selecting the correct thing in the menu (ie, maybe you need to select a confirm button to actually change the frame rate), or it could be that the computer is not reading the frame rate correctly - I've seen issues rather recently where we had Alexa's shooting 25fps, but the project timecode was set to 24fps somewhere in the menu. The project timecode is only saved as metadata, but the computer reads it and interprets the footage in 24fps, rather than the 25 the footage was actually shot in. Arri provided a timebase conversion software, which we had issues with and in the end we had to simply 'convert' the footage so the computer woudl see it as 25.
 
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This is from the specs on their website. This is why I'm confused.
Frame Rates: 60i, 24p Progressive (records at 60i), 30p Progressive (records at 60i)

What difference does it make setting it in the camera if it all ends up recording the same thing?

http://www.usa.canon.com/cusa/suppo...ders/vixia_hf_r11?selectedName=Specifications

Also I thought in general you are supposed to export in the settings that you record with?
 
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I don't know the exact details, but some cameras used to have a pseudo 24p recording mode that was wrapped in a 60i wrapper somehow. It was an attempt to fudge the 24fps that was quickly becoming the "must have" feature on your new cameras.

For example, the Canon HV20 had the phony 24p recorded in the 60i wrapper. It wasn't 'til the HV40 that the camera could actually record a true native 24p. (The HV40 actually lets you choose between the two types of 24p)

I'm sure there's some tech-head on here who can explain what it all really means. But yeah, I know what you're talking about.
 
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Okay, yeah I had it set to 24p in the camera for my last film but in my editor I exported and set the editor to interpret it as 29.97 because that is what it analyzed it as. Is that what I should be doing?

I was just reading up a bit on wikipedia. This is kind of different but this had happened to me before I realized that the footage was interlaced.
"60i to 24p conversions
Another method of achieving the 24p aesthetic is to capture 60i footage and convert it into 24p. Various techniques can be used to perform this conversion. A simple scheme would blend the fields together. This can result in motion artifacts where comb-like jagged artifacts appear in areas of high motion. De-interlacing can remove these artifacts, but certain methods will cause up to half the footage's vertical resolution to be lost. Adaptive de-interlacing schemes only de-interlace areas of high motion, hence preserving resolution in stationary areas. More advanced techniques can be used to mitigate problems such as aliasing from the temporal displacement between the 60i fields."

I was getting that comb like jagged effect until I eventually told the editor that the footage was interlaced. So now this brings me to the question that since I have no choice but to be in 60i, should I try and convert it? And if so what would be the best method to keep quality while avoiding that comb-like jagged effect. The more I'm finding out about this the more I'm getting confused..
 
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If you've already shot the footage and you want it to be 24p, I wouldn't convert just to change the frame rate, unless you're also trying to perform some other function like converting it to a less compressed codec (like Prores 422) to reduce the strain on your cpu while editing. Even then I don't like the idea to change the framerate until you're exporting the footage.
 
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Sweetie said:
If you've already shot the footage and you want it to be 24p, I wouldn't convert just to change the frame rate, unless you're also trying to perform some other function like converting it to a less compressed codec (like Prores 422) to reduce the strain on your cpu while editing. Even then I don't like the idea to change the framerate until you're exporting the footage.
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No no that's not really what the problem is, I'm just trying to figure out what the point of it is? Just confusing and weird to me is all.
 
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Pepper, the camera generates a 60i signal from what it can extract every framerates offered by the firmware, using pulldown techniques (2:3 / 3:2). The point is that is quite reasonable for these cameras do not changing the capture engeneering and, instead of this, extract from the same signal all the rates needed.

So it just depends on firmware quality to make this process correctly. Some models do not make it right, and the users have to use another softwares in order to apply the pulldown and remove the extra and unwanted frames. I think it's not the case of Vixia HF series.
 
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See but that's just why I'm confused is if I set it to 24p and it ends up being 30 frames a second, what difference is it making? Is the outcome actually different? Is it almost like a simulated 24 fps played at 30?
 
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jax_rox said:
Also, AFAIK 23.976 is what you should be conforming your DCP packages to, rather than 24.
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23.976 is the frame rate used for HDTV not DCP. In theory you can put a 23.976 frame rate in a DCP but if I remember correctly that's only because it's part of the old Interop standard. You should really stick to 24fps for DCP content, although there is a good argument for using 25fps depending on your location and the resolution of the film.

I place myself firmly in the camp of believing that you should shoot at the frame rate you intend to edit and distribute at. I've seen too many foul ups with the audio being/going out of sync due to changes in frame rates.

G
 
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pepper jack said:
See but that's just why I'm confused is if I set it to 24p and it ends up being 30 frames a second, what difference is it making? Is the outcome actually different? Is it almost like a simulated 24 fps played at 30?
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No, it should not end with 30 frames if you set it to 24. The camera must output files with the correct frame rate that you chose in the firmware options. Maybe your NLE software is not interpreting the pulldown removal. I never saw any camera offering 24p mode and not delivering it as exactly 24p files (or 23,97).

Try analize the files on windows explorer and see if it shows the correct framerate there. If yes, so the problem is your NLE. If not, the problem is the camera firmware.
 
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See but that's just why I'm confused is if I set it to 24p and it ends up being 30 frames a second, what difference is it making? Is the outcome actually different? Is it almost like a simulated 24 fps played at 30?
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It's most likely your editing software. When your editor sets up your sequence, s/he has likely set to NTSC. Your footage should still be 60i. If you looked at the specs of the individual shots, you should see they are still 60i. If the majority of the footage is 60i, I suggest that you should edit at 60i (what the majority of the footage is) and output to the appropriate speeds/wrapper/codec depending on where you're showing.

So to sum up, unless there is something severely wrong with your camera, your footage should be in the format/frame rate that your camera was set to.
 
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The thing to look for is "conform to 24p" in after effects and shake and nuke and premeire and cinema tools (part of FCP Studio) It's in a 60i wrapper because that's all the DV standard can carry on the tape... how ever, it uses repetition of frames across the fields to keep the frame integrity. To display correctly, you'[ll have to figure out if it's a 3:2 pulldown or a 2:3:3:2 pulldown you're looking for to turn it back into the source 24p.
 
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It's not the editor because media info and windows explorer both say the raw footage is 29.97fps. The thing is though the camera specs specifically say even though you choose 24p it still records in 60i. The editor I use is Lightworks and it analyzes the same thing.

I don't know if lightworks has something like that knightly, I'll have to look into it a bit. I don't think it's the firmware of the camera because this seems that this is what the camera is supposed to be doing.

So to actually get it at 24p I have to somehow get rid of the 60i wrapper? So the 24p is hidden in there somewhere? I just have to get through the 60i somehow? I'll have to look how to do that in lightworks.
 
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So I got one more question now.. So when I am converting my footage from AVChd to something a little less strenuous on my computer, in the converter I am using (Prism video converter) there is an option to change the frame rate of the clips. In my converter should I change it to 24fps? Or is that just cutting out 6 frames every second?

I tried converting a clip to both different frame rates on the converter to compare it but I couldnt notice any difference. I figure it's probably not that big of a deal but am just trying to figure all this out so I can have a system setup for everything I do.
 
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