HD250 HD SDI output signal - 720p60 or 1080i for 24p conversion? at DVinfo.net

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Old August 18th, 2009, 11:02 PM   #1
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HD250 HD SDI output signal - 720p60 or 1080i for 24p conversion?

Which output signal from the HD250's HD SDI would give you the cleanest 24p pulldown?

I'm assuming the 720p60 would because of the full progressive frames to choose from and it being the CCDs' native resolution. Am I wrong? Does it even matter? Is pulldown from a 60p signal even possible?

Thanks.
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Old August 19th, 2009, 02:17 AM   #2
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Yes you are correct. 24p 2:3 pulldown is cleaner in 720p then 1080i because there are no frames split across fields. If the camera was capable of 2:3:3:2 pulldown in HD then it wouldn't matter either way, but unfortunately 2:3:3:2 pulldown is only available in NTSC-DV24P mode.
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Old August 19th, 2009, 02:33 PM   #3
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Thanks, Tim.

So, this has always confused me, or irritated me in this case. Why is the HD SDI setup to only stream 60p (0r 60i through the up convert)? HD SDI isn't limited as an output signal to those formats and the camera is supposed to do true progressive 24p recording, at least to tape via the HDV compression.

So, is the 24p actually pulled off by the HDV encoder with a pulldown? If not then why didn't they implement a 24p output for the HD SDI?
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Old August 19th, 2009, 04:42 PM   #4
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The output needs to be compliant to HD standards, and the only standards supported as input by ALL HD displays (in North America) is 1080i60 and 720p60. There are variants of course (PsF for example) on professional monitors and in the digital realm of post-production you can work in true 24p, but you would be hard-pressed to find a monitor that can sync at 24Hz.

As an added note: When outputting 720p24 to the HD-SDI (in 2:3 pulldown @ 720p60) "varicam flags" will be added to the 24 frames that actually matter. Most capture cards and/or NLEs will use these flagged frames only and disregard the pulldown frames.
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