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i and p’s
I know the difference between Interlaced and Progressive. When I scroll through the camera setting to select the format that I am shooting why are the selections like 1080i 60i, 1080i 24p. When it reads 1080i I think that it is interlaced but then it shoots 24p which is progressive. So 1080i 24p is that interlaced or progressive shooting?
Why dosen’t is just say 1080 60i and 1080 24p? why put the P’s in front of the 720’s and the I’s before the 1080’s?
-Lars
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8 Replies
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[doka15] “So 1080i 24p is that interlaced or progressive shooting?… why put the P’s in front of the 720’s and the I’s before the 1080’s?”
The 720 HD format is always progressive.Hence the “p” It is never interlace.
The 1080 format is called a “progressive segmented frame” or “PsF”. This means the images are captured progressively but played back as interlace, so that they maintain usability with the legacy formats for standard def.
in 1080i 60, just as with the 24 frame capture in NTSC, there is a need to add additional content so the video will have the sufficient quantity to achieve the desired 60 fields per second that 1080 needs to smoothly playback at.
This capture as progressive and play back as interlace is indicative to all HDCAM content also. It is the way the format was designed.
gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Chicago, IL -
I see, so 720 progressive is the standard accross the board for all cameras and the same goes for 1080i. So if I were to shot a film that is going to be transfered to Film (which i’m not) would I shot 1080i 24p or 720p 24p
Would the results be some what the same just different size video?
-Lars
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Yes the results would be pretty much the same, but different size video. However, the data storage would be different. In 720p 24p, the camera stores only 24 frames per second. In 1080i 24p, the camera spreads the 24 frames over 30 frames, and stores 30 frames per second. There are 2 ways to spread the 24 frames over 30 frames, called 24pN and 24pA (normal and advanced). The Adam Wilt article gives a good explanation.
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[sumfun] ” In 720p 24p, the camera stores only 24 frames per second.”
at 720p24 the camera records 24 fps within the 60fps video stream. IF there is NO letter “N” in the frame rate the video is recorded as 720p60 with indication of the frame rate within the video file (like 24).
[sumfun] “In 1080i 24p, the camera spreads the 24 frames over 30 frames, and stores 30 frames per second.”
Technically in HD 1080 interlaced material is listed in fields. So that 24 frames is spread over 60 fields just like it is done in 24p NTSC video.The process of removing the frames is called a “reverse telecine”
HD is always 60 Fields OR 60 Frames for playback.
(HDCam @ 23.98 does not playback without special gear)[sumfun] “There are 2 ways to spread the 24 frames over 30 frames, called 24pN and 24pA (normal and advanced). The Adam Wilt article gives a good explanation.”
please read the article again,as adam does not explain it in that manner.
the PN modes on the HVX200 removes ALL redundant frames and only records the flagged frames to P2 cards
the PN modes do not record to Firestore via FW.The 24pA mode is only available in the interlaced captures (1080 and 480) and allows for a clean removal of the redundant frames (called pulldown) the cadence of the redundant frames in 24pA is 2:3:3:2 where every fifth frame appears to repeat.
gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Chicago, IL -
So if I were to shoot the HVX with intent to transfer to film I could shoot 24pA at 1080i and use reverse telecini to ge the true 24 framers per second or the 23.98
Is that my correct understanding?
-Lars
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Yes that understanding is correct.
The camera shoots progressive footage. It records it in an interlaced “wrapper”, since 1080 DVCPRO-HD is an interlaced codec. But the footage is progressive. It’s progressive footage being carried in an interlaced basket. Yes the NLE will recombine the fields to restore it to its original progressive nature.
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Cool, thanks Barry!
-Lars
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