Hey guys,
I'm trying to submit a video to a distribution company and this is what they told me:
"Please follow the instructions on our spec guide to repair 4:1 cadence. To avoid a resubmission fee it is best to assume your video has 4:1 cadence and repair it as a safety precaution."
Honestly, I have no idea what cadence is- and there is no information on what 4:1 cadence is on the internet.
Can anybody help?
Thanks a lot!
Nothing on the internet? This was the first hit on Google:
http://forums.creativecow.net/thread/8/1119598
There are some suggestions in there...
Nick,
I did read that thread already and I didn't understand any of it - that's why I came here. The problem is: I don't even know what they're asking me. How can I check what cadence my file is? If it's already 4:1 then I guess I have nothing to worry about. If it isn't - then I need to understand what "cadence" means so that I can make sense of what the replies on the other post are talking about. Do I need extra plug-ins or software to change the cadence? How do I set the cadence of the file? Etc...
I work in PAL which is always 25fps and honestly don't know much about it, other than it has to do with changing the frame rate of your source footage to something else. In this case, you appear to have a repeating pattern of frames where 4 are original and the 5th is a duplicate of the 4th.
According to your first post, the distributor sent you a spec sheet -what does that tell you?
The link in my initial reply also has a comment that suggests re-exporting from QuickTime Player at 23.976 fps, which sounds pretty straightforward. Note that you will need to use QT Player 7 as QT Player X can't do this.
Play your footage one frame at a time. Use the arrow key. Step through and see, do you see movement on frame 1, 2, 3, 4...and then frame 4 repeats? And then 5, 6, 7, 8...8? Or 1, 2, 3, 3...4, 5, 6, 6? Are you seeing repeated frames?
This is 4:1 cadence. It happens when you put 23.98 (24fps) footage into a 29.97 (30fps) timeline. There are 6 frames missing, and FCP has to make them up somehow. So it does it the fast cheap way...repeat every 4th frame. Unfortunately, that isn't the best way to do this...not by a long shot. The project will then look stuttery.
The best way is 3:2...and this goes into video FIELDS. Go to the WikiPedia and look up 3:2 cadence...and how the frames are spread out evenly between fields.
What they are saying is that your project needs to fix the repeated frame...it needs to be output with proper 3:2 pulldown. And this will take a bit of doing, and a bit of technical knowhow. Obviously this is a bit over your head, so you will need to hire someone or a company that knows about this to fix it. And it won't be a quick and easy fix...it might take a day or so.
Hey Shane,
Thanks so much for the simple explanation (as always!). It really helped me crear up some confusion in my head. In addition to that, I called the distribution company and asked them for that spec guide and in that spec guide I found the following explanation which I think other people might find useful:
Below are instructions on how to fix 4:1 Cadence:
1. In FCP, select your sequence then choose FILE > SEND TO > COMPRESSOR. Or you can export your sequence to a video or reference video then open that in Compressor.
2. In Compressor, select your video then right click and choose NEW TARGET WITH SETTING > APPLE > FORMATS > QUICKTIME > APPLE PRORES 422 (HQ).
3. Click on that newly created compression setting to open it in the Inspector window. Click the Encoder tab. Click the Video: (Settings...) button. Make the frame rate 29.97. Check the interlaced box.
4. Click the Frame Controls tab. Set Frame Controls to On. Set Output Fields to Bottom first if SD(720x486) , Upper first if SD(720x480) or HD. Leave Deinterlace on Fast. Leave Adaptive Details checked. Leave Rate Conversion set to Fast. Leave the Set Duration to: on 100% and make sure it’s radio button is selected and NOT the “so source frames play at 29.97 fps” button.
5. Make changes to the Filters or Geometry sections as needed. If you’re outputting SD letterbox, set the Padding to Preserve Source Aspect Ratio. Those settings listed above are the ones critical to getting the proper 3:2 pulldown added.
6. Submit the compression, then bring the resulting video back into Final Cut Pro. Place it in a 29.97 timeline and make sure you watch it on an NTSC monitor to verify that it looks good. If you step through it frame-by-frame you should see the familiar pattern of 2 split/interlaced frames followed by 3 whole frames.
Doesn't sound too hard. I'll give it a try and let you know if I have any problems with it.
Thanks!
That will work if your sequence is 23.98, and consists of 23.98 material. But if the sequence is 29.97, and all the footage in it is 23.98, that won't fix it.
BUt, as I said, if this is 23.98 sequence converting to 29.97...that's the right workflow.
4:1 cadence repair?
