Why are there occasional black flashes in my exported video?

Apple Final Cut Pro Legacy

Why are there occasional black flashes in my exported video?

Posted by Noam Osband on February 13, 2015 at 4:02 pm

I exported a video from FCP 7. There are no gaps in the timeline. But in the exported video, occasionally there is a quick black frame between cuts, as if there was a frame or two open. Again, I’ve checked the timeline and that is definitely not the case. Any thoughts?

Shane Ross replied 11 years, 6 months ago 3 Members · 14 Replies
14 Replies

Noam Osband
February 13, 2015 at 4:05 pm

I should say I wonder if it’s related to the fact some of the footage was shot in 24 fps but when I look at the info of the clip in the browser, it says it is 29 fps. I dont know why/how that happened. I never changed it and I dont think Log and Transfer changes it. So frustrating.
Shane Ross
February 13, 2015 at 5:11 pm

What was this shot with? Some cameras shoot a 24p that’s still 29.97, but with the 24p “look.” So it may appear to be 24fps, but really run at 29.97.

And since you mention LOG and TRANSFER that all the footage was converted to ProRes.

Is your sequence settings 29.97? Does it match the footage exactly? Meaning when you added a clip, did you need to render?

Shane
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Noam Osband
February 13, 2015 at 5:13 pm

Yeah, I dont get it. I shot in 24p. For sure. But the video does look 24fps even if the file is 30fps. When I exported as 30fps, the problem disappeared. Hmmm…..
Shane Ross
February 13, 2015 at 5:15 pm

Then you shot a 24p format that runs at 30fps. And when you export from FCP, you should always export a self contained QT file, and do whatever compressing in Compressor. You might even be able to do a REVERSE TELECINE and get it to 24fps and look fine.

Shane
Little Frog Post
Read my blog, Little Frog in High Def
Noam Osband
February 13, 2015 at 5:17 pm

I’m not sure that means, a 24fps that runs at 30fps. Can you link me to an article or something with more info to explain it?

thanks as always!
Shane Ross
February 13, 2015 at 5:21 pm

The short explaination is that it’s like when we take film, shot at 24pfs, and transfer it to video tape, that runs at 29.97. PULLDOWN is added…frames are spread out amongst the fields of the interlaced 29.97 so that 6 extra frames (from 24 to 30) are added, and smoothly. And many early video cameras, and some current ones, still do this…have the 24fps LOOK, but really run at 29.97.

https://en.wikipedia.org/wiki/Telecine#2:3_pulldown

Shane
Little Frog Post
Read my blog, Little Frog in High Def
David Roth weiss
February 13, 2015 at 5:36 pm

Noam, you never answered Shane’s question. What cam was used to shoot the material in questionl?

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.
Noam Osband
February 13, 2015 at 5:37 pm

It was a Canon XA-10
Shane Ross
February 13, 2015 at 5:42 pm

You must have shot in PF24 mode, and not native 24.

Shane
Little Frog Post
Read my blog, Little Frog in High Def
David Roth weiss
February 13, 2015 at 5:46 pm

Your canera shoots two versions of 24 fps video – the PF24 generates 60i files encoded in order to be able to apply a pulldown removal; 24p generated true progressive output at 23.978 framerate without pulldown.

Sounds as if you shot at PF24.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions

David is a Creative COW contributing editor and a forum host of the Apple Final Cut Pro forum.

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