mixing frame rates

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Level 1

27 points

mixing frame rates

Hi all. I will be doing a 3 or 4 camera project soon. I have two Canon tapeless AVCHD cameras, a Vixia HFM43 and an HFG10. I'm going to borrow two more cameras but don't know what kind they are yet. I was thinking of shooting the HFM43 in Canon's FXP mode with a 30 frame rate, and the HFG10 also in FXP mode but with a true 24 fps progressive, a frame rate that the other Canon is not capable of. I wanted the better frame rate because I am sometimes going to crop and zoom in on parts of the video taken with that camera, and the higher quality video it takes seems to make this possible without making the video too grainy. I have since googled a bit on mixing frame rates like this in one project, and people generally warn against it. Is this true? Is it better to stick to one frame rate?

Posted on Feb 13, 2012 2:44 AM

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Answer 1

Best reply

Ian R. Brown

Level 7

21,072 points

Feb 13, 2012 3:30 AM in response to EddieT

Life will always be easier and quality higher if frame rates match.

Mixing them should only be done in dire emergency when there is no alternative.

If you put a 24p clip in a 30p sequence (or vice versa), it will have to be converted, which involves a very lengthy rendering process and the motion quality is never the same.

On the other hand, Conforming the video does not reduce any quality, but it slightly slows down or speeds up the video according to which way you are doing it.

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Answer 2

EddieT Author

Level 1

27 points

Feb 13, 2012 3:06 PM in response to Ian R. Brown

Thanks, Ian. Just out of curiosity, would this apply to mixing recording modes (for example Canon's FXP and MXP)?

Thanks again, Ian.

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Answer 3

Feb 13, 2012 3:19 PM in response to EddieT

I assume those are just shot at different data rates?

If that is so it should be fine mixing those together.

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Answer 4

EddieT Author

Level 1

27 points

Feb 13, 2012 3:45 PM in response to Ian R. Brown

Yes, I believe that is the only difference. Different data rates. Thanks Ian.

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Answer 5

Feb 14, 2012 1:03 AM in response to EddieT

I checked and it appears that is the case.

One of the settings will give you a longer shooting time but will have no effect on editing.

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Answer 6

EddieT Author

Level 1

27 points

Feb 14, 2012 5:28 PM in response to Ian R. Brown

At the risk of beating this horse to death . . .

Just borrowed a Sony HDR-CX120 (Japanese model). Went through the Japanese menus, and do not seem to see any frame rate setting, which leads me to think it is probably just 60i or something like that. I went over to FCPX page, and saw this

"Multicam editing with automatic sync and support for mixed formats, mixed frame rates, and up to 64 camera angles."

The "support for mixed formats" caught my eye. Now, maybe I'm reading too much into this, and I am more likely to believe the experts on this site, but it did give me pause.

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Answer 7

Feb 15, 2012 12:23 AM in response to EddieT

Support for something does not mean it is good, just that it can be done.

Converting framerates takes time and the results are never as smooth as "normal" footage.

If you have no choice you have to do it, but wherever possible it is best avoided.

However, as it is your film you are the final arbiter. Something that looks bad to me might be perfectly acceptable to you (and vice versa).

I do some things the "wrong" way and it suits me.

So the only way to find out what is OK for you is to do a dummy run, shoot a small amount of similar footage and edit it.

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Answer 8

EddieT Author

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27 points

Feb 15, 2012 3:05 AM in response to Ian R. Brown

Thanks, Ian. That really puts it into perspective for me. Good advice.

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Answer 9

EddieT Author

Level 1

27 points

Feb 17, 2012 7:16 PM in response to EddieT

OK, I think I may be losing my mind. I just did a test using three video cameras, recording at different combinations of recording modes and frame rates. The two frame rates I mixed were 60i and canon's pf30 progressive (with an asterisk that tells me it records at 60i, whatever that means). I had two canon cameras and an older sony that is capable of only 60i, the manual says. Imported it all into FCPX, and the inspector windows has everything listed at a frame rate of 29.97. Obviously, I'm missing something. Any direction is warmly welcome. Thanks in advance.

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Answer 10

Feb 18, 2012 1:07 AM in response to EddieT

Calm down, calm down . . . everything is OK.

Canon's 60i and 30p are both the same frame rate . . . 30fps. (Ignore the 29.97 as it is the daft American system and can be regarded as 30fps)

It's just that the 60i has 2 interlaced fields (don't worry about it!) per frame whereas 30p has 2 identical fields (equivalent to one field) per frame.

If you are interested you can read about interlaced and progressive frames in Wikipedia!

Suffice it to reiterate, they are both 30fps.

It would make sense in future to have all cameras set to the same although it shouldn't make any difference.

NOTE: Over the past few years a number of cameras have included a "60p" setting (note the "p").

This is 60fps and shouldn't be mixed with 60i or 30p

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Answer 11

EddieT Author

Level 1

27 points

Feb 18, 2012 4:53 AM in response to Ian R. Brown

OK, I've calmed myself. Well, that's interesting. So it turns out I was completely wrong about something, a daily occurrence for me so no need for alarm. Thanks, Ian.

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Answer 12

Feb 18, 2012 6:38 AM in response to EddieT

Don't worry, I too am frequently wrong!

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