FCP Frame Rate / Slow Motion Help at DVinfo.net

Bob Richardson · April 23rd, 2010, 02:47 PM

Hi -

I've got a project where I'm trying to improve the look of some of my slow-motion footage.

First, some background:

A few months ago I did a promo for a client which involved a lot of footage from a soccer match. This promo is primarily to be published on the web (YouTube, Vimeo, etc.), and we decided on a frame rate of 30p.

The actual raw footage was shot in 60p (1280x720), with the intention that there would be a couple of slow-motion segments, so we could slow the footage down by half and have a really nice slo-mo.

Just one problem: At the time, I was editing in Final Cut Express. FCE is actually a very capable program, but you are limited to a very small set of sequence presets that Apple gives you. If you are particular about codecs and frame rates, you have to use FCP.

Here's the issue at hand:

When slowing down footage (by changing the playback speed of an individual clip), we only got half the frames that we expected. In other words, FCE appeared to first be converting the clip to 30p to conform with the timeline (tossing away every other frame), and THEN slowing it down again for our slo-mo reseulted in 15FPS.

Those problems aside, the client was happy and the project is done.

This week, I finally took the plunge and upgraded to Final Cut Studio / FCP7 (for a variety of reasons).

As a learning project, I decided to revisit this soccer promo. I made a copy of my original sequence and set the new sequence to be ProRes 422(HQ), 30p. Things looked a bit better in terms of resolution, but the slo-mo was having the same problem. (Strangely, unlike when creating a new sequence from scratch, you aren't allowed to change the frame rate of an existing one int he sequence settings dialog -- is that right?)

So for the next experiment, I created a blank sequence with a 60p frame rate, and then copied/pasted all my clips from the original sequence.

The clips didn't line up correctly on the new timeline, but that's something I can fix manually. But what's bugging me is that my slo-mo still has half as many frames in it as I would expect. What gives?

Do I need to pre-convert the clips I want to use as slow motion rather than changing the speed of the clip on the timeline?

Thanks in advance for any tips!

Erik Andersen · April 23rd, 2010, 10:38 PM

Yes, you should "pre-convert" the clips so they are already at 50% speed when you import them to Final Cut. If you have Cinema Tools, just open a 60p clip, hit Conform, and select 30p. Cinema Tools will instantaneously change the clip to 30p i.e. 50% slomo. Then edit in a 30p timeline.

Bob Richardson · April 23rd, 2010, 11:15 PM

Erik - Thank you for the reply. Yes, Cinema Tools is installed as part of the Final Cut Studio suite. I'll experiment tomorrow with pre-conversion and report back.

Bob Richardson · April 26th, 2010, 05:22 PM

Hi -

Well unfortunately Cinema Tools did not like my original clip. When I attempted to Conform it to a new frame rate, it generated an error that the clip had "temporal compression". I'm guessing this is because the clip is in the XDCAM-EX format (it's a native clip from a JVC GY-HM700 camera).

However, I was able to place the clip in its own 60p sequence.

So, I did an experiment in getting 1/4 speed slow motion:

I used ProRes 422(HQ) to ensure that there was no visible degradation of the clip through the process. On the 60p timeline, I slowed the clip to 25%, giving an effective frame rate of 15fps. I then exported this to a ProRes QuickTime file.

I dragged the resulting QuickTime file into the viewer, set in/out points, and then drug it into my original 30p sequence. It performed as I had hoped, with a perceivable change every 2 frames, still maintaining an effective frame rate of 15fps. This looks much better than the original results I was getting previously.

Erik Andersen · April 27th, 2010, 08:07 PM

I've never had that happen, but you may want to try transcoding to ProRes first (using Compressor or MPEG Streamclip), then taking that file into Cinema Tools and conforming. If it works it will be a much quicker workflow.

Shaun Roemich · April 27th, 2010, 11:58 PM

Yep, Cinema Tools wants INTRA frame compressed clips, not INTER frame (ie. MPEG derivatives and some others)

Robert Lane · April 28th, 2010, 09:01 AM

Bob,

Unfortunately the speed tools built into FCS don't work that well despite Apple's initial push of "Optical Flow" technology as being the end-all for speed ramping.

I did a review of the Kronos tool, part of the Furnace Core pack from The Foundry:

furnace core - the Foundry

You'll get far better results - as good as Twixtor - without the high cost and much, much faster renders of the effect than anything FCS can do for you.

April 23rd, 2010, 02:47 PM	#1
Bob Richardson Regular Crew Join Date: Mar 2009 Location: Portland, OR Posts: 178	FCP Frame Rate / Slow Motion Help Hi - I've got a project where I'm trying to improve the look of some of my slow-motion footage. First, some background: A few months ago I did a promo for a client which involved a lot of footage from a soccer match. This promo is primarily to be published on the web (YouTube, Vimeo, etc.), and we decided on a frame rate of 30p. The actual raw footage was shot in 60p (1280x720), with the intention that there would be a couple of slow-motion segments, so we could slow the footage down by half and have a really nice slo-mo. Just one problem: At the time, I was editing in Final Cut Express. FCE is actually a very capable program, but you are limited to a very small set of sequence presets that Apple gives you. If you are particular about codecs and frame rates, you have to use FCP. Here's the issue at hand: When slowing down footage (by changing the playback speed of an individual clip), we only got half the frames that we expected. In other words, FCE appeared to first be converting the clip to 30p to conform with the timeline (tossing away every other frame), and THEN slowing it down again for our slo-mo reseulted in 15FPS. Those problems aside, the client was happy and the project is done. This week, I finally took the plunge and upgraded to Final Cut Studio / FCP7 (for a variety of reasons). As a learning project, I decided to revisit this soccer promo. I made a copy of my original sequence and set the new sequence to be ProRes 422(HQ), 30p. Things looked a bit better in terms of resolution, but the slo-mo was having the same problem. (Strangely, unlike when creating a new sequence from scratch, you aren't allowed to change the frame rate of an existing one int he sequence settings dialog -- is that right?) So for the next experiment, I created a blank sequence with a 60p frame rate, and then copied/pasted all my clips from the original sequence. The clips didn't line up correctly on the new timeline, but that's something I can fix manually. But what's bugging me is that my slo-mo still has half as many frames in it as I would expect. What gives? Do I need to pre-convert the clips I want to use as slow motion rather than changing the speed of the clip on the timeline? Thanks in advance for any tips!

April 23rd, 2010, 10:38 PM	#2
Erik Andersen Major Player Join Date: Feb 2009 Location: Vancouver Canada Posts: 218	Yes, you should "pre-convert" the clips so they are already at 50% speed when you import them to Final Cut. If you have Cinema Tools, just open a 60p clip, hit Conform, and select 30p. Cinema Tools will instantaneously change the clip to 30p i.e. 50% slomo. Then edit in a 30p timeline. __________________ Canon 5D Mark II \|\| L-Series Lenses \|\| Steadicam Pilot \|\| Final Cut Studio www.lovestorymedia.com

April 27th, 2010, 08:07 PM	#5
Erik Andersen Major Player Join Date: Feb 2009 Location: Vancouver Canada Posts: 218	I've never had that happen, but you may want to try transcoding to ProRes first (using Compressor or MPEG Streamclip), then taking that file into Cinema Tools and conforming. If it works it will be a much quicker workflow. __________________ Canon 5D Mark II \|\| L-Series Lenses \|\| Steadicam Pilot \|\| Final Cut Studio www.lovestorymedia.com

April 27th, 2010, 11:58 PM	#6
Shaun Roemich Inner Circle Join Date: Sep 2002 Location: Vancouver, British Columbia (formerly Winnipeg, Manitoba) Canada Posts: 4,088	Yep, Cinema Tools wants INTRA frame compressed clips, not INTER frame (ie. MPEG derivatives and some others) __________________ Shaun C. Roemich Road Dog Media - Vancouver, BC - Videographer - Webcaster www.roaddogmedia.ca Blog: http://roaddogmedia.wordpress.com/

April 23rd, 2010, 11:15 PM	#3
Bob Richardson Regular Crew Join Date: Mar 2009 Location: Portland, OR Posts: 178	Erik - Thank you for the reply. Yes, Cinema Tools is installed as part of the Final Cut Studio suite. I'll experiment tomorrow with pre-conversion and report back.

April 26th, 2010, 05:22 PM	#4
Bob Richardson Regular Crew Join Date: Mar 2009 Location: Portland, OR Posts: 178	Hi - Well unfortunately Cinema Tools did not like my original clip. When I attempted to Conform it to a new frame rate, it generated an error that the clip had "temporal compression". I'm guessing this is because the clip is in the XDCAM-EX format (it's a native clip from a JVC GY-HM700 camera). However, I was able to place the clip in its own 60p sequence. So, I did an experiment in getting 1/4 speed slow motion: I used ProRes 422(HQ) to ensure that there was no visible degradation of the clip through the process. On the 60p timeline, I slowed the clip to 25%, giving an effective frame rate of 15fps. I then exported this to a ProRes QuickTime file. I dragged the resulting QuickTime file into the viewer, set in/out points, and then drug it into my original 30p sequence. It performed as I had hoped, with a perceivable change every 2 frames, still maintaining an effective frame rate of 15fps. This looks much better than the original results I was getting previously.

April 28th, 2010, 09:01 AM	#7
Robert Lane Go Go Godzilla Join Date: Nov 2004 Location: Scottsdale, AZ USA Posts: 2,823 Images: 15	Bob, Unfortunately the speed tools built into FCS don't work that well despite Apple's initial push of "Optical Flow" technology as being the end-all for speed ramping. I did a review of the Kronos tool, part of the Furnace Core pack from The Foundry: furnace core - the Foundry You'll get far better results - as good as Twixtor - without the high cost and much, much faster renders of the effect than anything FCS can do for you.