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Converting 60i to 24p: Twixtor or FCP X's process?

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Noam Osband
Converting 60i to 24p: Twixtor or FCP X's process?
on May 20, 2015 at 11:58:27 pm

I'm making a film that is 24p. I have a lot of footage that I thought was being shot in 24p but was really being shot in 60i. I know I can create a 24p timeline, drag it to the timeline, and FCP X automatically adapts the footage. That said, a buddy of mine was recently raving about Twixtor, saying it's a great program precisely for turning interlaced footage progressive without sacrificing too much.

Anyone have thoughts on using Twixtor as opposed to just doing it all within FCP X?


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Doug Metz
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 21, 2015 at 5:51:39 pm

Based on your question, I'm thinking you've got 24p over 60i, so there would be zero benefit to using Twixtor. You might consider doing a batch reverse-telecine to conform, though.

How you process the footage will depend on the cadence. Is it really 60fps, or is it 24p over 60i, or 29.97 i/p over 60?

Open one of the source clips in QT7 and step through frame by frame. Look for duplicate frames and a mix of progressive and interlaced - this will give you a good idea what you're actually dealing with.

Doug Metz

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Noam Osband
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 21, 2015 at 7:26:49 pm

It's footage from the Canon XA-10 shot in the PF24 setting which means it's captured in 60i. When FCP converts it, the resultantly Pro Res file is 29.97. Some of my footage has people at work planting trees which was my logic in going with that route.

That said, what process might you suggest?


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Doug Metz
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 21, 2015 at 11:34:57 pm

Canon PF24 is 24p over 60i. When you import, FCPX will translate that to 29.97i... but the footage is actually 24p with pulldown added. So, now that you've imported, time to get rid of the pulldown.

There are a couple of ways to do this, and your image quality doesn't suffer for it, as we're just interpreting the interlaced frames back to progressive.

If you've already got a 24p timeline / project (double-check this in the inspector), FCPX will recognize the pulldown and remove it for you. No need for further action. Playback may look a little janky until / unless you render, but probably not, and your output will be fine regardless.

If you start with an empty timeline / project, FCPX will want to change your framerate to 29.97i (if your first clip is one of your Canon PF24 files). You can override this by putting a gap clip in the empty timeline and specifying 1080p @ 23.98. Leave the gap clip there until you've added at least one of your Canon clips - this way the framerate change will stick.

Doug Metz

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Noam Osband
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 22, 2015 at 12:07:20 am

Oh, this is better than I hoped.

So....I can safely just create 29.97 fps timelines and let FCP X do the rest for me? imagine I'll get tons of render files I'll want to periodically clear out while editing (and then let the computer re-render) for things I try out but don't use. Given the fact it's actually 24p with pulldown, this also means it'll be OK to use proxy files, later convert them to optimized files when the project is complete, and not have to worry about weird timeline things happening?

(Most importantly, thanks Doug!)


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Doug Metz
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 22, 2015 at 1:46:27 pm

Sort of... since you shot PF24, I think you should edit in a 24p timeline - though I'm not sure how this will affect proxies. If you edit at 29.97, every 5th frame of these clips will be a duplicate which will manifest itself as a slight stutter (even on output).

Do a quick test with one timeline at 24p and another at 29.97... I think you'll prefer the former.

I'm running a nMP with an Areca 8050t2, so I use original media and leave rendering turned off. Your mileage may vary. ;^)

Doug Metz

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Noam Osband
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 27, 2015 at 3:18:14 pm

Doug, so the 29.97 footage is definitely less choppy at times when I play it. What's also weird is that whether putting it in a 29.97 or 23.98 timeline, FCP X imports it. I wonder if it deals with this? http://www.provideocoalition.com/psf8217s_missing_workflow_em_part_1_benign...

I'm going to be home soon and want to check the field dominance of these clips as discussed here: http://www.provideocoalition.com/psfs_missing_workflow_part_10_fcp_x

It's so frustrating I just didn't shoot in 24P to begin with. Lesson learned.

I just hope I can do this all internally in X as opposed to needing to mess with the clips outside of FCP.

Thanks for the help!


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Noam Osband
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 27, 2015 at 5:56:17 pm

Doug, so I checked out the files and, indeed, they were not progressive. I changed all the movie files to progressive and I put some on a 23.98 FPS timeline and some on a 29.98 timeline. The 29.98 seems smoother to me. Right?

Here are two different examples. I exported files and uploaded them here. Thoughts? I'd love for the 24fps to look smoother if possible.

23.98 dancing footage: 8870_23.98dancing.mov.zip
29.97 dancing footage: 8869_23.98dancing.mov.zip

23.98 street footage: 8868_23.98test.mov.zip
29.97 street footage: 8867_29.97test.mov.zip


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Howard Duy Vu
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 28, 2015 at 7:14:16 pm

There are two ways to deal with this:

1) Bring it into Cinema Tools and do a reverse telecine on all the footage. You can do a batch of them, and it will strip out the pulldown and get you to 23.976.

2) FCPX will do this automatically when you cut it into a 23.976 timeline, but it seems to be finicky about how you've initially interpreted the footage. Click on your original clip in the browser, and in the inspector, go over to the "info" tab, and on the bottom left of the inspector, set the drop-down box to "settings". I had to tell it to interpret the field dominance as "Upper" for it to be properly cut into a 23.976 timeline and have it remove pulldown. This seems to be contrary to the article that you linked, where it says it should be flagged as progressive (that's actually technically correct, it's progressive with pulldown. It is NOT normal interlaced footage.)

When dealing with such footage, it's almost never a good idea to cut it in a 29.97 timeline, even though it might look "ok." The problem is that you will often cut in a clip not on a correct frame and mess-up the pulldown cadence. Then it will be a real pain when it comes time to make a proper master.



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Noam Osband
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 28, 2015 at 7:21:39 pm

Guys, this post has been a life saver. Thanks so much for the help.

Question: is there any practical difference between going through Cinema Tools or changing the dominance as you suggest in FCP X? Will one look better than the other?


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Doug Metz
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 29, 2015 at 4:23:39 pm
Last Edited By Doug Metz on May 29, 2015 at 4:26:43 pm

In order for Cinema Tools to work with it, you'll need to re-wrap the files first - I haven't tried it with AVCHD.mov files though, so I think you'd need to go all ProRes in order to batch them. Conversely, bringing the footage into FCPX directly will also re-wrap the files, but with a little care will correctly interpret the clips.

I also agree with Howard... you don't want to cut in a 29.97 timeline unless you're sure you only want to deliver that framerate. Cadence will bite you otherwise.

Quality-wise, I think they're equal.

Happy hunting!

Doug Metz

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Noam Osband
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on May 29, 2015 at 4:25:40 pm

Cool. I want a 23.98 timeline anyways so that's good.

Last question: given this weirdness, should I import everything as a proxy and edit that way rather than native? I just assume Pro Res Proxy in editing will look like Pro Res optimized when I export whereas perhaps there will be weird differences if I make a complete 80 minute H264 timeline and then convert it all to optimized Pro Res at the end?


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Noam Osband
Re: Converting 60i to 24p: Twixtor or FCP X's process?
on Jun 3, 2015 at 7:09:09 pm

One other question: when picking the option howard suggested, choosing uppter dominance as the field, should I also click on and choose "deinterlace"?


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