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Issues with FCP7, Files in L&T changing frame rate from 60 to 29.97 in AVCHD

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Keith Massimino
Issues with FCP7, Files in L&T changing frame rate from 60 to 29.97 in AVCHD
on Feb 3, 2017 at 2:11:02 pm

Hey everyone

New to the forum. I've been working with FCP7 for a few years now. I recently noticed an issue with my L&T. Im shooting with a Sony NX5U, mainly sporting events. The source footage is 1080/60i AVCHD. For whatever reason when I L&T it changes the footage to 29.97FPS. Which is a big deal as the footage doesn't look nearly as smooth. Also the resolution size changes, it is shot in 1920x1080 and changes to 1440x1080. An ideas why this is happening and how to fix it?

Thanks
Keith


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Shane Ross
Re: Issues with FCP7, Files in L&T changing frame rate from 60 to 29.97 in AVCHD
on Feb 3, 2017 at 4:49:34 pm

[Keith Massimino] "The source footage is 1080/60i AVCHD. For whatever reason when I L&T it changes the footage to 29.97FPS. "

I know this is confusing, and I really wish that whoever makes these rules would not do this, but here goes. 1080i60 runs at 29.97fps. It's not 60fps. When you see the "i" in 1080i, that means INTERLACED. And interlaced footage is two fields per frame...so it still runs at 29.97fps. What the consortium has decided is that the number after the frame size is to stand for how many IMAGES per second. Interlaced has 60 independent images per second, except that there are two images per frame...an UPPER FIELD and a LOWER field. This is based on TV technology when it first came out when the gun pointing at the tube had to make two passes to get a full image on the screen.

So yes, sorry to say that you are shooting 29.97fps, not 60fps. It's only 60fps when you see something like 720p60 or 1080p60. "P" means PROGRESSIVE and that means one image per frame. So 1080p60 is 60fps, but running at 59.94.

[Keith Massimino] "Also the resolution size changes, it is shot in 1920x1080 and changes to 1440x1080."

When you shoot AVCHD HQ (9Mbps), that is 1440 x 1080/60i. This is also the case with the AVCHD LP (5Mbps) setting, that too is 1440 x 1080/60i. AVCHD FX (24Mbps) and AVCHD FH (17Mbps) are settings that shoot 1920 x 1080/60i.

(obtained from here: https://pro.sony.com/bbsc/assetDownloadController/nxcam_hxrnx5u_v2454.pdf?p...

This is an ANAMORPHIC format...meaning the image is squeezed to reduce the data rate to conserve space. But if you cut that in an NLE, it will unsqueeze it to 1920x1080...and if you output that full 1920x1080, it'll look right. HDV and DVCPRO HD and other formats offer anamorphic settings.

So, if you want full raster 1920x1080, you need to choose a setting that offers that. But at 1080 your frame rate maxes out at 29.97fps...for 60fps you need to shoot 720p.

Hope this helps.

Shane
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Read my blog, Little Frog in High Def


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Keith Massimino
Re: Issues with FCP7, Files in L&T changing frame rate from 60 to 29.97 in AVCHD
on Feb 3, 2017 at 8:26:33 pm

Thank you so much for the response. Believe it or not even after years working in productions I did not know this. Learn something new every day. So out of curiosity since im shooting fast paced sports would it be better to shoot in 720 60p to get the full clarity off 60fps? My camera will shoot that setting, but I always have had to set to 1080/60i.
You are correct btw with the Fh, Fx, HQ, and,LP settings. My nxcam is always set to HQ which would make sense for the resolution.


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Shane Ross
Re: Issues with FCP7, Files in L&T changing frame rate from 60 to 29.97 in AVCHD
on Feb 3, 2017 at 8:54:42 pm

Well, let me say that ESPN is 720p60 (as is ABC). They are pushing for the 1080p60 broadcast spec. But when airing, it airs...is streamed...as 1080i60 at 29.97.

Shoot some tests and you decide. If you are delivering to TV, or DVD on TV, shooting interlaced works. But if you intend for it to be seen on a computer screen...then shoot progressive. Computers don't do interlacing, only TVs do.

Shane
Little Frog Post
Read my blog, Little Frog in High Def


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