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Frame Rate conversion - best practice?

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Christopher Travis
Frame Rate conversion - best practice?
on May 15, 2012 at 5:15:12 pm

Hello,

We have about 30 hours of footage shot at 23.98FPS which we need to cut into about 3 minutes of content for broadcast at 25FPS.

Since we are only going to end up using a tiny fraction of the footage, it makes no sense to conform all of the footage before editing. and since each finished clip must be an exact duration (5s, 10s, or 15s precisely) I don't like the sound of conforming the finished edits because they will end up being under time.

My idea is to edit at 23.98 and then, after final client sign off, conform only the clips that were used in the edits and rebuild the edits at 25FPS. There would naturally be tiny differences in the edit points but doing it this way, I figure it'll be at my discretion how to make adjustments so this will be least noticeable.

Problem is, this will probably add about a day to the schedule. Has anyone got a better idea?


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Shane Ross
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 5:30:07 pm

Cut at 30fps. Export the final. Convert the final to 25fps

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


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Christopher Travis
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 5:36:07 pm

Cut at 30fps? Do you mean convert the 23.98 to 30 before cutting? and then won't the duration change once i convert that to 25?


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Shane Ross
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 5:42:44 pm

GAH...pardon me. Yeah, cut at 23.98, then convert to 25fps. If you want to do it the easy and very fast way, you use Cinema Tools and CONFORM 24 to 25. This will slightly speed up the footage, and the audio will have a slight pitch shift. You can fix the pitch shift in Soundtrack Pro. But if the timing needs to match exactly...well...then it can get complicated. Best to convert at a post place with a Terranex. Barring that, you can use Compressor and know that one frame a second will be repeated...causing a slight stutter. Personally, I'd conform.

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


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Christopher Travis
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 5:49:16 pm

Yeah this is what I thought. These are really simple edits, just a handful of shots in each one. What do you think of my idea of conforming only the shots we've used after the final sign off and then rebuilding the edits?

It's a bit tedious but as far as I can tell this gives us nice smooth conversion, with no stutters and control over where we adjust for changes in timing. This also means we're only speeding up our picture, we can keep our music, SFX and VO at their original speed.


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Shane Ross
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 6:15:26 pm

Why not conform before and work in a 25fps project from the start? Duplicate all the clips (as conform will change the files you select, and you cannot go back)...Batch Conform them. Edit with them using a 25fps sequence.

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


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Christopher Travis
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 6:39:32 pm

I don't want to conform it all before editing because there's so much of it (20-30hrs of Prores 444) we simply don't have the space to duplicate it. We're producing no more than 3-4 minutes of edited content, it seems insane to duplicate all that media for that.


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Shane Ross
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 7:19:42 pm

Well, if you edit at 23.98....then conform only the clips you use...they will be 25fps and the sequence will be 23.98...so they won't fit back in. And copying/pasting content from a sequence at one frame rate to another causes gaps between nearly every cut...so that needs to be fixed.

So either cut at 23.98 and conform the final output to 25fps (pitch shifting audio)...pull your selects before you cut and conform a small few...or conform everything.

PRORES 4444? Really? That is WAY overkill for broadcast All you are doing is wasting space. ProRes 422 would be the way to go. 4444 is for film outs, 4K files...10-bit RED or ALEXA codecs. Very high end stuff that is beyond broadcast. Or, for graphics that you need an alpha channel for.

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


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Nick Price
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 7:50:13 pm

Hi Travis,
or cut in 23.98 and then get a blackmagic up/own cross converter for around £300. Hardware is always preferable to software.

http://www.creativevideo.co.uk/index.php?t=product/blackmagic_up_down_cross.

For what it will cost you in wages a day, you can get this great little gizmo that will convert your playout. Could do it while playing out to tape, or possible just ingest it back into the edit?

nick


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Christopher Travis
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 9:57:19 pm

Hmmm,

This could be something to look into. I know that more and more of this commercial/cinema stuff is coming through this place so a solution like this might be worthwhile.

Thinking about it now though, I should probably check with the guys at the online facility to see if they have something like this they could do on playout at their end.

Thanks, I'll look into this.


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Christopher Travis
Re: Frame Rate conversion - best practice?
on May 15, 2012 at 7:51:43 pm

It's Alexa footage. Its footage from a commercial shoot that arrived on LTO tapes from the other side of the Atlantic. We need to make 16 sponsorship idents (some 5s, some 10s and some 15s) from footage not used in the commercials. The footage had been pulled off the tapes when I sat down yesterday, all 8 TB of it. Since the amount of footage is so huge, but the actual amount of deliverable content is so small, I didn't see the point in duplicating and/or transcoding to a lighter codec or new frame rate. Besides there is no space for it.

My plan is to cut at 23.98 in a 23.98 timeline to the exact duration required.

Then after final sign off, duplicate all the clips used in the final timelines. Conform those to 25FPS and rebuild the edits on a new 25FPS timeline. Doing it this way I:

*Only dupe the footage I need
*Only speed up the picture, leaving my seperate atmos, music and VO untouched and un-pitch adjusted.
*Get more control over my final duration.


This is tedious but the edits are very simple, with only a handful of shots in each clip so it's manageable.

I was wondering if there might be a simpler way that would give as clean a result but it seems that my only other options are:

*Conform all footage first - Not an option, there is too much
*Conform final clip - Not so great since we have exact durations to meet.


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John Heagy
Re: Frame Rate conversion - best practice?
on May 16, 2012 at 3:02:15 am

[Christopher Travis] "My plan is to cut at 23.98 in a 23.98 timeline to the exact duration required.

Then after final sign off, duplicate all the clips used in the final timelines. Conform those to 25FPS and rebuild the edits on a new 25FPS timeline."


Like Shane said... the sped up shoots will be too short. You'll have to extend the conformed shots.

Why not just edit the 23.98 4% longer so when you conform to 25 the time will be correct.

John


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Dave LaRonde
Re: Frame Rate conversion - best practice?
on May 17, 2012 at 3:18:38 pm

[Christopher Travis] "My plan is to cut at 23.98 in a 23.98 timeline to the exact duration required.

Then after final sign off, duplicate all the clips used in the final timelines. Conform those to 25FPS and rebuild the edits on a new 25FPS timeline. Doing it this way I:

*Only dupe the footage I need
*Only speed up the picture, leaving my seperate atmos, music and VO untouched and un-pitch adjusted.
*Get more control over my final duration."


OR...

Export the completed. 23.976 edits, and do a frame rate CONVERSION: no conforming. No time Worries.

It can be done in hardware at production house (best image quality , but pricey) or using frame rate conversion software like Re:Vision's Twixtor Pro (almost as good image quality, cheaper, and there's a tryout version).

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Petter Brox
Re: Frame Rate conversion - best practice?
on May 17, 2012 at 12:19:15 pm

Try this:

1) Cut your original footage as 23.98.
2) Export video without audio as a self-contained QuickTime movie using "Current Settings".
3) Conform to 25fps in Cinema Tools.
4) Open in Compressor and convert to a clip maintaining the original settings (in 25fps), but with "Duration" set to the exact duration of the original clip in 23.98.
5) Import clip to a 25fps sequence in FCP.
6) Copy and paste the sound from your 23.98 to your 25fps sequence. Or export and re-import it if you have created a new project.

Be aware to create PAL projects the "right way" if you're switching from NTSC: Close all projects, shut down FCP, re-open it, set your PAL-settings and create a new sequence.

This procedure has worked for me on movies up to 20 minutes. Good luck!

Petter Brox
Spain


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Christopher Travis
Re: Frame Rate conversion - best practice?
on May 17, 2012 at 12:35:17 pm

Hi John,

I just tried this and it did retain the exact duration, however when going through it frame-by-frame I see that it is repeating frames to do this.

I exported the 15s clip from my 23.98 Timeline
Conformed to 25fps in Cinema Tools
Took it into Compressor and in "Frame Controls" set "Set Duration" to 00:00:15:00 and exported from Compressor

Did I miss a step? Would it make a difference if I changed the "Rate Conversion" setting to something like "Best"?

thanks,
Chris


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Petter Brox
Re: Frame Rate conversion - best practice?
on May 17, 2012 at 1:37:05 pm

Christopher,

I've been looking at the last thing I made using this method and no frames are repeated, so yes, you should probably use the "Best" option ("Max" in my Spanish version of Compressor) in the "Rate Conversion" pop-up menu.

Give it a try...

Petter Brox
Spain


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Christopher Travis
Re: Frame Rate conversion - best practice?
on May 17, 2012 at 1:46:24 pm

ok, I just tried this and now I'm getting lots of warping around moving elements. If it's not too much trouble, could you post ALL of your settings for one of your successful conversions?


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Petter Brox
Re: Frame Rate conversion - best practice?
on May 17, 2012 at 4:30:01 pm

Oops, you're right, I've made some tests and there are some strange things happening. In my case it's quite subtle, in fact I've never noticed it, but I suppose it depends on the characteristics of your footage.


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John Heagy
Re: Frame Rate conversion - best practice?
on May 17, 2012 at 2:42:10 pm

[Christopher Travis] "I exported the 15s clip from my 23.98 Timeline
Conformed to 25fps in Cinema Tools
Took it into Compressor and in "Frame Controls" set "Set Duration" to 00:00:15:00 and exported from Compressor"


You did an extra step. If you created a 23.98 seg 4% longer and then conformed to 25fps you are done. No need to do anything in Compressor.

In the case of your 23.98 15sec seq you would need to make it 15:15 long. Conform 23.98 15:15 to 25 and you'll get 15:00


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