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Black Magic 720p SD Downconvert – 2:3 pulldown = stuttery – REPOST
Sorry for the repost, but I got absolutely no answers on the Blackmagic forum.
I’ve talked to Black Magic about this, and although their explanation made plenty of sense I just wanted to post this out there and make sure I’m not getting it wrong…
I’m looking at footage that is 720p DVCPRO HD @ 23.98fps and I’m downconverting it to SD with Blackmagic’s Software Downconvert feature (located in the System Preferences) and it looks like the 2:3 pulldown that’s getting put on it (I’m downconverting to NTSC, obviously) is kinda off. The motion is stuttery and is general not very fluid. It’s not a HUGE in your face kind of badness, but it is BAD. The motion looks bad, particularly on pans and tilts.
As a comparison, I looked at the same footage at 1080i60 @ 23.98 downconverted to SD and it looked great. The motion was totally fluid and there was no stutter.
I called BM support and the BM people told me that YES their 720p60 downconversion is not as good as their 1080i60 downconversion and the reason for this is that they’re converting twice… once from 720p23.98 to 720p59.94 and then once again to SD. Somewhere in this double conversion the motion gets kinda wonked.
Soooo, I just wanted to confirm that YES, this is the case, that getting a good 720p23.98 – SD downconvert requires a deck or some software downconvert. If this IS the case, I’d like to petition BM to fix this issue. I know that 720p23.98 is, in itself, not a viable finishing format (all 720p is 59.94 apparently), BUT getting a good downconvert from 720p23.98 would be very helpful, and it kinda sucks that BM hasn’t figured this out, yet. Clients tend not to have the ability to evaluate rough cuts in HD so the only way to get them anything from a 720p23.98 timeline is through the software downconvert feature. Not having good quality motion (not to mention super jaggedy edges on letterbox downconversion) kinda makes having a downconversion kinda pointless, no?
Better downconversion, please, BM! Your 1080 downconversion rocks! Why is 720 so hard?
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6 Replies
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I was trying to do 720P 60 to center cut 4:3 SD NTSC and it wouldn’t work through my multibridge.
But I did get it to work.
I converted it using mpeg streamclip.
You might try it out, its free and amazingly powerful and high quality.
A very robust tool I couldn’t live without.
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I don’t really understand why you seem to think it’s Blackmagic Design’s responsibility to support a format that doesn’t actually exist, at least not in the video world. There is no such thing as a 720p/24 video format, period. It only exists in a computer.
I would suggest that you try using Compressor’s Advanced Format Conversions. If you have a reasonably fast Mac, it works pretty quickly – about 2.5 times running time – and does a very clean job, without having to go through the 24->60->24 thing.
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[Mike Most] “There is no such thing as a 720p/24 video format, period. It only exists in a computer.”
well to be fair it exists in JVC & Panasonic’s world.
Canon’s as well soon.
But I’d give BlackMagic a break as well. They make great products.
Your more likely to get a quick response if you email their support directly.
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[Borjis] “[Mike Most] “There is no such thing as a 720p/24 video format, period. It only exists in a computer.” well to be fair it exists in JVC & Panasonic’s world.”
Actually no.
Mike is correct. The SMPTE spec is 720p60 even though apps like FCP support the 23.98 timebase for editing it does require that to maintain a proper video stream some external device needs (capture card or panasonic deck) to add the pulldown back into the format to make sure that the video stream has 60 frames.I do not have any issue with outputting 720p24 from my Kona card to 720p60
gary adcock
Studio37
HD & Film Consultation
Post and Production WorkflowsMy DVD’s are available @
https://www.rastervector.com/dvd/dvd.html -
[sammyg] “Soooo, I just wanted to confirm that YES, this is the case, that getting a good 720p23.98 – SD downconvert requires a deck or some software downconvert.”
NOT in SOFTWARE,
when this is done in Hardware there is not an issue, next time get a kona card.gary adcock
Studio37
HD & Film Consultation
Post and Production WorkflowsMy DVD’s are available @
https://www.rastervector.com/dvd/dvd.html -
Can anyone just confirm that they’re seeing the same thing? Stuttery 720p60 SD conversion with Blackmagic Cards.
I guess Kona has better 720p60 support, but this is one of the ONLY problems I’ve ever had w/ BM’s cards. Looks like we’re going to do 1080i anyway, which is the better format so I’m not bumming it.
Sam
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