Sean Oneil
Forum Replies Created
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[JeremyG] “Sorry Sean, in the quick test, I was definitely not getting a 30p image from a 60p cross-convert.
It is in fact 1080i. “
Jeremy,
1080i is thirty frames per second. I don’t know why you think there are professional videos being made with only 1 field per frame. I’m shocked actually. What test did you do, and what makes you think it’s more than 30 frames per second?
Seriously, if there is a converter that processes one field in the manner you described, I’d like to know what it is. No place in the world would accept a tape with that on it.
What are you watching it on? Are you jogging through in a FCP sequence with the editing timebase set to 60? And you’re seeing 60 unique frames from 1080i footage!?! That’s ludicrous.
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Typo in my first paragraph (WHY CAN’T THE COW LET US EDIT OUR POSTS – we are editors!)
Meant to say there is no such thing as a 60 frame per second interlaced format. If there was it would be 120i.
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Please test all you like :). It’s really simple. His 720p source is 60 unique frames per second. 60p. He wants to convert it to an interlaced format, thus it will have to become 30 frames per second. All interlaced formats are 30 frames per second or less (PAL, film, etc.). There is no interlaced format, and if there was it would be called 120i.
A field is only half of a frame. There is always two or more of them for each frame of video. Always. No exceptions. Combine the two together and you get a complete image captured at the same moment in time. You can’t have just one field per frame, as you were suggesting. Sometimes you can have redundant frames or fields, like with 3:2 pulldown (some frames will have 3 fields, one of them is a dupe). But never just one.
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[JeremyG] “Hmm, I thought that each progressive frame became one field to create a true interlaced image (60p then becomes 60i with each p frame equaling one i field). If you threw out every other frame, you would end up with 1080p, not 1080i.”
Not at all. It throws out every other frame, making it 30p. Then it interlaces it to make it 60i. Otherwise, having 60 unique fields would be a disgusting mess of combing artifacts on any monitor. The only way to have 60 frames per second in an interlaced signal would be to convert it to 120i – which obviously doesn’t exist in real life.
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[chrispy] ”
Does anyone know of a good conversion tool/software to convert from 720p59.94 to 1080i29.97 and takes good care of the motion conversion from progression to interlaced.”There is no motion conversion. It just throws away every other frame, regardless if you do the conversion with a Teranex or Quicktime Pro.
This is pretty much the most basic conversion there is. Going from progressive to 30i interlace is monkey work for any software or hardware tool. Put your clips on a 1080i timeline and render. That’s all you need.
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Technically, what he heard is true. 1080->SD is mathematically less complicated. The scaling process just has to throw away one field, making it 540p square pixels – which calculates to 480p non-square. So the vertical scaling is very clean.
If the content is 4:3 (unusual for HD) then the horizontal scaling is even cleaner. It would be scaling 1440 to 720 – exactly 1/2 the resolution.
But as far as real world results you guys are correct. As long as it’s a high quality scaler like a Kona 3, a Teranex, or the downconverter on an SR deck, then 720p will look just as good. That said, when downconverting using a lousy scaler it is better to start with 1080. Perfect example is the Blackmagic cards’ software downconversion. Starting with 720 looks awful. Starting with 1080 looks less awful.
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[mortimer heathcliff] “i configured one for a mere $13,995”
Dude, are you crazy!?! Don’t spend that kind of money on a consumer desktop computer. That’s all it is. In 2008 you’ll be able to get one twice as good for half that price.
I’m going to guess you got an 8-core, 8 gigs of RAM, and the outdated yet incredibly expensive Nvidia Quadro card. Am I right?
I’ll start with the 8-core. It’s very poor value. Period. FCP doesn’t even take advantage of it. Intel just started selling their new Penryn chips – so your 14k machine is already about to have second-tier processors in it.
The RAM. I don’t believe >4GB is going to do anything useful for you. I guess you can have 100 large Photoshop documents open at the same time. That’s about all you’ll get from that.
The GPU. Serious ripoff. Actually all 3 GPU choices for the Mac Pro are lousy, but you picked the worst of all. Do your own research first as I don’t know the specifics, but my understanding is that you can use a lot of PC video cards for your secondary display. So in theory you could get a $250 PC Nvidia 7900GTX and you’ll have the similar Motion performance (on your 2nd display) that you would using the Quadro FX card. Both cards have the same GPU core. One costs 10 times more because it has features that the Mac won’t even take advantage of.
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Sycophant,
I GUARANTEE you that he isn’t going to read your post. His self-proclaimed A.D.D. wouldn’t allow it :).
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I absolutely do not like this if it’s true. What happens if you export from the viewer?
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Open them up in Photoshop and confirm the actual size. I’ll bet it really is 720×480.
The last few versions of QT have had this problem. It reports playback size as 640×480 (which is correct) but it says 640 for actual size as well (even though it’s really 720).