Removing Pulldown from Canon HV20 shot at 24P

Question

Hello,
I have been trying to understand this whole situation particularly with the Canon HV20 and the 1080p24 mode that the camera offers. It is my understanding that when this video is stored to HDV it is shot onto a 1080i60 timeline, thus when capturing the video capture the video at 1080i60.
Okay, that I can do without a problem. However now I want to remove the pulldown using Cinema Tools to get the video into the proper 1080p24 mode so that it can be edited on a 1080p24 timeline.
I have read two main posts regarding this:
http://discussions.apple.com/thread.jspa?messageID=4287943&#4287943
http://www.dvinfo.net/conf/showthread.php?t=89642&highlight=fcp
The user was kind enough to provide the following information:
p-p-i-i-p - aa
p-i-i-p-p - bb
i-p-p-p-i - bc
p-p-p-i-i - cd
However, I understand that this implies the sequencing of the Interlaced and Progressive frames.
With that said, I have no clue how this applies to the options available in Cinema tools. I have zero experience with Cinema Tools other than, "Hey, that looks interesting." just to fiddle around with it for a minute get bored and move on.
Thanks any help would be greatly appreciated and I am sure that there will be other HV20 owners soon popping up with the same question....
PowerMac G5 Quad / MacBook Pro 2.0GHz / PowerMac G4 Cube 1.8GHz   Mac OS X (10.4.9)   Final Cut Studio - Shake 4.1 - Adobe CS2

Answer 1

If someone can explain how this works or point to
someplace I can learn some more I would appreciate
it.
My apologies in advance for the long winded post.
I’ve seen this question several times but I haven’t yet seen a good answer for this. So I did a little digging and here’s what I can tell you. Any of you experts out there can correct me if need be.
First off, let’s look at how the HV20 actually stores the 24p frames in a 60i format. And let’s ignore the 23.98/29.97fps thing for a while. Remember that for 60i there are 60 interlaced fields every second, each containing half the video lines necessary to make up a complete frame of data. So in order to get a complete frame, it requires 2 fields. This means that 60i really only has 30 frames worth of video every second. Fairly basic stuff… I hope nothing new.
Now let’s break this down a little further, the most basic repeating pattern for this format is 4 progressive frames being fit into 10 interlaced fields (divide both 24 and 60 by 6, don’t ask me why, it’s just the way they did it because it fits.). These 4 progressive frames are referred to as A – B – C – D. What the HV20 (and other cameras) do is convert this to interlaced fields so that it fits inside the 60i data fields. This gives us something like Au – Al – Bu – Bl – Cu – Cl – Du – Dl. Where the “u” and “l” refer to the upper or lower field of video. To make a complete frame you have to reassemble an upper field with a lower field. Now it you’re keeping track, you’ll notice that this only adds up to 8 fields and 10 would be what is needed. So they duplicate 2 fields to get 10 in this fashion: Au – Al – Bu – Bl – Bl – Cu – Cl – Du - Du – Dl. Since it takes 2 sequential fields to make a frame, this sequence normally gets referred to as AA – BB – BC – CD – DD. It shouldn’t be that big of a leap now to see that this can also be referred to as p-p-i-i-p when looked at from a frame (two consecutive fields) perspective, ie: AA is considered progressive, BB is considered progressive, BC is considered interleaved, etc.
FCP uses the AA – BB – BC – CD – DD nomenclature to designate how the cadence of a clip starts.
p-p-i-i-p -> AA – BB – BC – CD – DD -> referred to as AA
p-i-i-p-p -> BB – BC – CD – DD – AA -> referred to as BB
i-i-p-p-p -> BC – CD – DD - AA – BB -> referred to as BC
i-p-p-p-i -> CD – DD - AA – BB – BC -> referred to as CD
p-p-p-i-i -> DD - AA – BB – BC – CD -> referred to as DD
As mentioned before, the easiest way to do this in Cinema Tools is to place the first of 3 p frames in the viewer and the set the cadence to DD.
Hope this helps.
Mark