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Old April 14th, 2008, 07:51 PM   #1
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What is the difference between shooting 24p and 24pa?

Thanks to all who explain me the difference of shootting between 24p and 24pa? Is it noticeable?
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Old April 14th, 2008, 10:19 PM   #2
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It won't be noticeable to the average viewer if you simply play back the footage, but there is a significant enough difference in the two modes to greatly affect your post workflow.

First, let me specify that 24PA (Advanced pulldown) only exists in DV mode. There is no option in HDV mode.

24P mode uses a standard 2:3 pulldown to record the 24 progressively captured frames to DV NTSC. NTSC is always 30 frames per second (actually 29.97) so you need a way to fit those 24P frames into 30 every second. It is done with a 2:3 pulldown. This is the same method that has been used for film to video telecine transfers for years.
Since NTSC is an interlaced format the progressive frames can be split in half by every other scan line and you end up with NTSC frames that contain half of one progressive frame and half of another. Our eyes don't really see this. We are used it. Every 24P or film originated show broadcast on NTSC uses this method.
The 2:3 pulldown typically takes the first progressive frame and puts it into the first frame of NTSC using both fields. Simple enough.
The second progressive frame is likewise put into the second NTSC frame using both fields. However, on the third NTSC video frame one field is used for frame 2 of the progressive sequence, and the other field is used for frame 3. The pattern then repeats.
Google "2:3 pulldown" and you'll see some great articles with diagrams that explain it better than I can right now.

2:3 pulldown NTSC material is best for direct to broadcast or editing in NTSC 60i sequences.


24PA uses an advanced pulldown that avoids splitting progressive frames over fields. This pulldown is known as 2:3:3:2 pulldown.
It is designed for true 24P editing workflows. The concept is the same. 24 frames are being spread over 30, but the pattern is done is such a way to avoid interlace "ripping." Google 2:3:3:2 for a diagram of the pattern.

24PA is supported by most NLE systems and they can usually automatically remove the pulldown frames leaving you with a true 24fps file for editing in 24fps sequences (23.98.) This is the best workflow if your sequence does not require any 60i material to be mixed with 24P.


BTW, in HDV mode 2:3 pulldown is used in 60P. There is no interlacing and hence never any "ripping."
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Old April 14th, 2008, 11:48 PM   #3
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Thanks Tim

Thanks Tim, your always in the spot.
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