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Old September 1st, 2008, 12:20 AM   #1
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EX3 - PAL or NTSC dilemma - advice please!

Hi all,

I am using the EX3 to get wildlife stock footage that I hope to sell internationally.
I live in a PAL country but I would like to make sure I will be able to sell to both NTSC and PAL countries.
What should be my best way to shoot? Interlace/progressive? If progressive - 1080/30p or 1080/25p ?
Is it possible to convert in post ?

Thanks!
Ofer Levy
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Old September 1st, 2008, 05:31 AM   #2
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25P or 30P

Hi
Do not record any interlaced format for nature documentaries. Always progressive. From what I have heard - 1080 p 25 is the standard in Europe for nature. But what is best to convert from and to - No idear.
I record in 720P 25 - then I am able to use the superslow on the EX3 and it works great.
But all I make, are downconverted to SD.
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Old September 1st, 2008, 06:13 AM   #3
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Originally Posted by Bo Skelmose View Post
Hi
Do not record any interlaced format for nature documentaries. Always progressive. From what I have heard - 1080 p 25 is the standard in Europe for nature. But what is best to convert from and to - No idear.
I record in 720P 25 - then I am able to use the superslow on the EX3 and it works great.
But all I make, are downconverted to SD.
Thanks for the comment Bo! That's a good start - no interlaced ! (-:
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Old September 1st, 2008, 07:09 AM   #4
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Decision between interlaced and progressive is based entirely on the final output and there is no standard. For filmout the best is 25p (if you are in Europe has some advantages with equipment compatibility) or 24p.

If you planning to downconvert to SD then both 720 50p/60p or 1080 50i/60i will do. More or less the have the same amount of information (1080i: double the pixels but half the lines versus 720p:half the pixels but double the lines). I will recommend the 720 50/60p because its best for fast moving subjects. Now since PAL is 50i and NTSC is 60i then is obvious that 50p is better for PAL and 60p is better for NTSC. Since you are living in Europe for equipment compatibility its best to shoot in 720 50p.

One more thing. Last year on IBC I have read that EBU contacted HDTV test with ordinary viewers and the result was that most viewers preferred the 720 50p over 1080 50i. The best would have been 1080 50/60p but at the moment only high high end cameras output so much information.
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Old September 1st, 2008, 12:02 PM   #5
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I have tested 720-50P for sports and it was great. The video I attached below is entirely on 720 50P except for one pair which was done in 25P. You will notice some stobing of some sort in that particular pair. I too recommend going for 720 50P over 1080 50i. Take note the video below was re encoded at 30P for vimeo. The actual 50P was really fluid, even for fast pannning.

Singapore Wushu Competition 2008 on Vimeo
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Old September 2nd, 2008, 02:23 AM   #6
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I'm also trying to figure out what to shoot in. I also mostly shoot wildlife so sometimes there is a lot of motion and sometimes there is little. When there is a lot of motion I don't think 1080/25p is working. So I have to go down to 720/50p but I really miss the image quality of 1080. When I look at the computer screen there is a big difference between 720 and 1080, at least to me. When I deliver to my stockvideo they want top quality, as they don't accept HDV. So my 720/50p footage is not very welcome unless there is unique content. As you can see I'm in PAL country so I have to stick to that. Since I mostly want to shoot in 1080/25p I find it problematic to change to 720/50p in the menus on the EX3, it takes a few seconds to do. Often what happens is that I shoot an animal which is not doing great movments in 25p but suddenly there is some intense action which will be spoiled by 25p but I don't have time to change to 50p. If I always shoot in 50p I have trouble getting the best use of the footage as described above.

Yesterday I found this from BBC. A few years old but there are some interesting points in there. http://www.bbc.co.uk/guidelines/dq/p...Bookv01_02.pdf

But still I don't really know what to shoot in.
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Old September 2nd, 2008, 04:57 AM   #7
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Originally Posted by Emmanuel Plakiotis View Post
Last year on IBC I have read that EBU contacted HDTV test with ordinary viewers and the result was that most viewers preferred the 720 50p over 1080 50i.
Not quite true - at the original level the interlace material (properly called 1080i/25 by the EBU) was considered superior, mainly due to the much higher horizontal resolution. What the EBU tests showed was that at high levels of compression the 720p/50 material stood up better. The slightly strange thing about those tests was that they didn't seem to consider 1080p/25, which is how the majority of material seems to be being originated!
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Old September 2nd, 2008, 06:08 AM   #8
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You can convert the footage ( PAL<> NTSC ) with Cineform

Last edited by Ray Bell; September 2nd, 2008 at 03:24 PM.
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Old September 2nd, 2008, 10:29 AM   #9
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Thanks for the input so far guys! It does look quite tricky.....
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Old September 2nd, 2008, 01:23 PM   #10
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Not quite true - at the original level the interlace material (properly called 1080i/25 by the EBU) was considered superior, mainly due to the much higher horizontal resolution. What the EBU tests showed was that at high levels of compression the 720p/50 material stood up better. The slightly strange thing about those tests was that they didn't seem to consider 1080p/25, which is how the majority of material seems to be being originated!
What I have read was an article in the IBC daily and although I cannot find it right now I'm pretty positive that I have not misquoted it.
The accurate way to name the format is 1080i/25 50Hz which translates at 25fps with 2 fields interlaced per frame thus 50Hz of perceived framerate (the screen blinks 50 times and not 25 as the fps speed suggests).
What they have found, is that in fast motion, blurring occurs within the fields of the same frame that decreases the perceived resolution of the image and the viewers preferred the 720p 50fps (although of half resolution). It is true that the test was conducted with Mpeg2 compressed images, exactly the way they would broadcast at an HDTV set and this factor did contribute as well.

The reason why they did not test the 1080p/25 25Hz is that is not a broadcast format but only a format suitable for filmout or distribution/conversion. If I remember well from my college years you need at least 32Hz for persistence of vision to occur, so broadcasting 1080p/25 25Hz would result in strobbing.

This is not happening in film projection, because the shutter cuts the light before and after each frame resulting in 24fps 48Hz, essentially "interlacing" one black frame with a normal film frame (the screen blinks 48 times and not 24 as the fps speed suggests). In newer projectors the shutter intercuts and within the frame resulting in 24fps 72Hz for even better illusion of motion.

I know that the notion of film projection labeled as interlaced sounds heretic but that's how it is.
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Old September 2nd, 2008, 01:59 PM   #11
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I shoot all my stock footage at 1080 25P. Channels such as Discovery, the BBC and many others now insist on 1080 material. If you shoot 720 then you are stuck with 720, but if you shoot 1080 you can always down res. I shoot at 25P as conversion to SD PAL is easy. For international sales a 4% slow down gives 24P and is easy to do. There are also plenty of good software options that will do decent frame rate conversion with motion estimation or compensation that gives a perfectly useable result when converting to 30P. Remember that if you shoot at 25P you should use a 1/50th shutter to avoid softening due to motion blur.

Converting Interlaced material to different frame rates is far harder than converting progressive.

I've seen the EBU demo and David is correct. Uncompressed 1080i at 25fps was superior to uncompressed 720P50, however with the mpeg encoded material (around 8mbps) the 1080i material had artifacts that reduced the spacial resolution to the point where it looked softer than the 720P.
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Old September 2nd, 2008, 02:51 PM   #12
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Originally Posted by Alister Chapman View Post
Uncompressed 1080i at 25fps was superior to uncompressed 720P50
As an aside, are there any naturally interlaced display devices in the HD world? I thought interlace was a hack for CRTs, and comes at the cost of 25% lower resolution when deinterlaced for progressive delays such as LCD and Plasma...
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Old September 2nd, 2008, 05:30 PM   #13
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Quote:
Originally Posted by Emmanuel Plakiotis View Post
The reason why they did not test the 1080p/25 25Hz is that is not a broadcast format but only a format suitable for filmout or distribution/conversion. If I remember well from my college years you need at least 32Hz for persistence of vision to occur, so broadcasting 1080p/25 25Hz would result in strobbing.
I saw the EBU presentation at IBC a couple of years ago, and it was as Alister says. They first showed the material at high bitrates and both were pretty good, but on subsequent tests (at lower and lower bitrates), the 1080i material showed worse artifacting. The question about 1080p/25 was put at the presentation, but never really answered. I got the impression they'd done tests of a 720p/50 v 1080i/25 comparison, and "what about 25p" only got asked about later.

It's true that 1080p/25 isn't transmitted as such, but probably the majority of material is originated as 1080p/25, and transmitted as 1080psf/25. ("Progressive, segmented field".) The line order is rearranged from 1,2,3,4,5..... to be 1,3,5.... then 2,4,6.... for transmission to make it compatible with 1080i transmissions. Since all that happens is simple reordering, no processing, a suitable display can fairly easily resurrect the original true progressive nature with no loss. Whether 1080psf/25 compresses better than 1080i/25 was the unanswered question at the presentation.

You need more than 32 Hz to avoid flicker (about 48Hz, or more), but less for a reasonable effect of motion, about 15Hz. Hence the silent film speed of 16fps, and a three blade shutter to flash each frame on the screen three times, so a flicker rate of 48Hz. Sound films running at 24fps was nothing to do with vision - they needed to increase the linear speed of the film to keep the optical soundtrack reasonable, hence 24fps, a two blade shutter, and still 48Hz flicker. (Which is also why AC mains distribution is at 50 or 60Hz - just high enough to not see lights flickering!)

I disagree that film projection can be considered interlace - with cinema projection the COMPLETE frame is flashed twice onto the screen. With a telecined film (psf transmission) half the frame is displayed in the first 1/50s (the odd lines), the other half the next 1/50s (the even lines), then onto the next frame.

As far as this thread goes, the question is whether "film look" or smooth motion is needed. If film look, then 1080p/25 should be the obvious choice. Transmission in 50Hz countries is easy, including downconversion to PAL, and for 60Hz countries it can be slowed down 4% to 24fps, 3:2 pulldown added and broadcast 1080psf/24.
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Old September 2nd, 2008, 09:48 PM   #14
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WOW ! What a great input guys!! Thank you so much ! I spend a fortune to get the best equipment, spend months and months getting the footage so not getting it right in the first place would be heart breaking.

I am planning to do all my photography using the Flash XDR (whenever its available...) so I hope to get my footage in 50Mbs or better 100Mbs I wonder if this should effect my decision re progressive/interlaced etc ?
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Old September 3rd, 2008, 01:06 AM   #15
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Originally Posted by Alister Chapman View Post
I shoot all my stock footage at 1080 25P. Channels such as Discovery, the BBC and many others now insist on 1080 material. If you shoot 720 then you are stuck with 720, but if you shoot 1080 you can always down res. I shoot at 25P as conversion to SD PAL is easy. For international sales a 4% slow down gives 24P and is easy to do.
Alister, how do you deal with fast movements? When I use it in 25p it doesn't look good, even if I use 1/50th shutter.

I want 1080/50p ;-)
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