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Old May 5th, 2008, 07:31 PM   #61
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In terms of frame rate for smooth motion 60i is closer to 60p. The camera is taking 60 pictures a second but only sending out odd or even scan lines for each of these pictures. In an interlaced world the CRT phosphors and our brains filled in the detail to emulate 60 frames a second. For me the frame rate is more important. I want smooth motion. Modern electronics should be able to emulate this interlace effect through interpolation and display a true progressive, smooth image. 24p and 30p cannot generate this smoothness there just aren't enough frames.

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Old May 5th, 2008, 07:49 PM   #62
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The way you describe things, I assume that 30P is normally sent to the TV as 30PsF, not true 30P.
Thanks Dave for clearing up some of my absent-minded rantings. Yes, when I am talking about 30P, I am referring to 30P delivered via 60i stream. Due to the extreme shortsightedness of the BDA and the obvious irrelevance of HD-DVD (now), we are left with 1080/30P being flagged and delivered as 1080/60i. Also, I don't know of any consumer encoder that will allow us to encode 30P as truly 1080/30P (even though it must be flagged as 1080/60i per BDA spec). It can be done, however, as many HD music DVD's are now being encoded as 1080/30P even if they have to be flagged as 60i.

As I mentioned earlier in this thread, I find it interesting that ATSC includes 1080/30P as a valid broadcast format. Now that I think about it again, though, I don't think any of the progressive displays in use today would have any problems at all correctly displaying 1080/30P as 1080/60P (by frame doubling) because it would be a progressive broadcast signal not requiring any de-interlacing. The set would simply receive a full frame and then flash it twice to hit its 60Hz refresh rate.
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Old May 5th, 2008, 07:57 PM   #63
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Ron, that's not how interlaced fields are de-interlaced by progressive sets. The set buffers field A while waiting for field B comprising frame 1. The video processor then combines fields A+B and processes the resultant frame 1 and tries to mitigate the damage through various de-interlacing algorithms. This yields 30fps, NOT 60fps. The video processor then flashes frame 1 twice to hit 60Hz refresh rate of today's progressive sets. No where does the video processing chipset attempt to interpolate the even scan lines missing from field A, nor the odd scan lines missing from field B. It combines these two fields and may interpolate or apply motion adaptive technology in order to eradicate the inherent interlaced artifacts present from interlaced capture during acquisition.

Assuming correct video processing of 1080/30P, the only difference between 30P and 60i is the fact that the entire frame was captured at the same moment in time, thus eliminating the interlaced problems associated with 60i. Both formats yield exactly 30 frames per second on a progressive display.
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Old May 5th, 2008, 10:56 PM   #64
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As I mentioned earlier in this thread, I find it interesting that ATSC includes 1080/30P as a valid broadcast format. Now that I think about it again, though, I don't think any of the progressive displays in use today would have any problems at all correctly displaying 1080/30P as 1080/60P (by frame doubling) because it would be a progressive broadcast signal not requiring any de-interlacing. The set would simply receive a full frame and then flash it twice to hit its 60Hz refresh rate.
I think I'm still a little confused. So, if the ATSC standard includes true 1080/30P, does that mean that most TV's can understand and display true 30P (as opposed to 30P in 60i)? If so, then one would just need to re-encode one's camcorders 30PsF output as true 30P - is it not true that some encoders, like x264, can do that? But then I guess the only way to deliver it to the TV would be via a PC since blue-ray players will apparently re-convert it back to 30PsF..??..

What a mess. At first I was happy that Blu-ray won the format war because of the larger disk capacity, but now I think it might have been better the other way.
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Old May 5th, 2008, 11:01 PM   #65
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Aaron I understand what you are saying which is why I still prefer the interlace display. 60i is a lot smoother than 30p it effectively has twice the frame rate on an interlace display. I was just hoping that one day the electronics will be able to emulate what one actually sees from an interlace display on a progressive display. Yes interpolate the missing lines. I still prefer the image from my JVC iART CRT to the image on my Panasonic Plasma. There is more detail in the Panasonic but the motion is nowhere near as smooth as on the CRT and the upscaling of SD from cable is awful. This is not just the Panasonic its true of every set I have looked at so far. In choosing the Panasonic it was the best of the 16x9 sets I was prepared to pay for and it is not as good as the Sony HiScan CRT!!!! I would like the smoothness of interlace and high definition. Just hope that sometime soon the technology will give me what I want. Clearly I am more disturbed by motion artifacts than I am about interlace artifacts!!!!

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Old May 5th, 2008, 11:57 PM   #66
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yeah Dave, you've got it right. Yes, those of us without a broadcast station at our fingertips, LOL!, must distribute HD video via BD. And that means 30P in 60i.

And Ron, I agree 100%. Interlaced video displayed on an interlaced set is great because you're talking the native language of the display. When you try to de-interlace for progressive displays, you're manipulating the original interlace stream in a manner in which it was not originally intended to be manipulated. So now you have to create a bunch of voodoo magic to try to make it all work with modern displays. My whole point in this thread is simply to say drop interlacing because we're not using interlaced displays any longer. They're dead. Let's move on to the native language of the displays we're using today, and of course that's progressive.

As the MIT expert pointed out in his little blurb I linked to in the HV20/30 forum, there is not one single advantage to using 1080/60i over 1080/30P when the target display is progressive. And actually, there is LESS of an advantage because motion between the two fields makes it more difficult for the compression algorithm vis-a-vis a progressively acquired frame.
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Old May 6th, 2008, 07:27 AM   #67
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I agree to move to progressive but in that case it should be 60p to match the display completely and get nice smooth motion. Maybe JVC / Panasonic were correct in going with 1280x720P60. Do the displays correctly up scale this to 1920x1080P60 its a 1.5 multiple?
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Old May 6th, 2008, 09:50 AM   #68
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Again, agree 100% Ron. That's the best we've got for progressive displays and motion fluidity. But, anyone who's happy with 1080/60i on progressive displays and motion potrayal would also be happy with 1080/30P as long as the display chain properly processed 30P - either properly de-interlacing and frame doubling if delivered via 60i, or simply frame doubling if delivered via ATSC broadcast. And yes, your 1080P sets will scale 720P to 1080P. Of course, you're not getting a true 1920x1080 source frame. But the scaling technology today is pretty good. And there is plenty of competition among chipset manufacturers to insure technology continues to improve in both de-interlacing and scaling.

I understand you're not happy with 60i on a progressive set, so the above 60i vs. 30P doesn't apply to you.
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Old May 6th, 2008, 10:49 AM   #69
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Last week I shot some footage with my HF10 in 60i, 30p and 24p mode. here is a comparison that should give you an idea how the frame rates compare:

60i:
http://www.vimeo.com/960647

30p:
http://www.vimeo.com/960652

24p:
http://www.vimeo.com/960659

The clips are very short, so better loop them.
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Old May 6th, 2008, 12:56 PM   #70
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Originally Posted by Aaron Courtney View Post
yeah Dave, you've got it right. Yes, those of us without a broadcast station at our fingertips, LOL!, must distribute HD video via BD. And that means 30P in 60i.
Due to the large number of existing TV's that don't handle 30P in 60i properly, it sounds like maybe there's a market for a small box that can detect 30P in 60i, deinterlace it correctly (basically just weave), frame double and output the resulting 60P to the TV. Does any such device exist?
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Old May 6th, 2008, 07:06 PM   #71
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Originally Posted by Stefan Immler View Post
Last week I shot some footage with my HF10 in 60i, 30p and 24p mode. here is a comparison that should give you an idea how the frame rates compare:

60i:
http://www.vimeo.com/960647

30p:
http://www.vimeo.com/960652

24p:
http://www.vimeo.com/960659

The clips are very short, so better loop them.
60i thank you. :)
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Old May 6th, 2008, 11:02 PM   #72
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Originally Posted by Dave Rosky View Post
Does any such device exist?
According to that link I provided to HQV's website, the Reon chipset is being used in AVR's and displays, not just BD players. I have not yet received a response to my email inquiry, so I'll send it off again. Basically, I asked them if merely including that chipset in one of the video playback components (BD player, AVR, and display) guarantees proper 30P de-interlacing regardless of the implementation. I'll also send off the same question to Anchor Bay since they will soon be releasing a new HD de-interlacing chipset.

It will be interesting reading the responses from these manufacturers.
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Old May 6th, 2008, 11:14 PM   #73
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Originally Posted by Stefan Immler View Post
Last week I shot some footage with my HF10 in 60i, 30p and 24p mode. here is a comparison that should give you an idea how the frame rates compare:
There are too many unknowns in this comparison. First, did you IVTC the 24PF in order to remove pulldown and edit on a 24P timeline and author a true 24P file? Second, what was your de-interlacer set at in your NLE for the 30P? (anything other than weave is wrong) Third, exactly how did you encode a 30P file out of your NLE? (I know of no other way than to deliver it via 1080/60I, in which case either Vimeo's de-interlacer in the software player or your progressive display must weave and frame double - highly doubt either is capable of doing that). For that matter, exactly what is the frame rate used in Vimeo. I thought it was 15 fps?
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Old May 6th, 2008, 11:23 PM   #74
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Aaron, I mean no disrespect but you haven't provided any sources to back up your assertion that fixed pixel displays produce 30fps output from 60i input streams. I can't prove you incorrect either, but intuitively what you said doesn't seem to add up. How can the following points be explained?

- If displays process 60i as you describe, then half of the motion resolution would just be thrown away for video content that was actually recorded in 60i. I don't know about anyone else, but when I replaced my CRT display with a fixed pixel display, I did not notice any loss of motion smoothness. I would think that a reduction by half would be noticeable.

- The latest camcorders continue to record in 60i as their default mode, even if capable of 30p recording. Canon does not market 30p as being equivalent or better than 60i when played back on a "good" display. We know that recording in 30p eliminates deinterlacing artifacts, so why would anyone want to record in 60i unless it provided some benefit in terms of motion resolution? You could argue that this is because there are so many displays that don't handle 30p 2:2 properly, but still I would think that if ANY displays existed on which 30p was flat out better than 60i, then Canon would market that fact.

- Our buddy Ken Ross is an experienced video enthusiast who has tested both raw 30p and 60i video footage on a Kuro, which is one of the best displays available. He has clearly said that 60i video looks smoother to him.

- The article below notes that some crummy displays simply interpolate each individual field to form a full frame. This results in poor spatial resolution, but the full motion resolution of the 60i input stream is preserved. If crummy displays can retain full motion resolution, I find it hard to believe that good displays would not do likewise. I have not seen any articles that say motion resolution has to be sacrificed to get full spatial resolution.
http://www.hometheatermag.com/hookmeup/1107hook2/

- This is pure speculation on my part, but if a good display can properly deinterlace field pairs within a frame, wouldn't it be possible to likewise deinterlace fields from adjacent frames?
For example:
Input frame 1 field A + input frame 1 field B = Output frame 1
Input frame 1 field B + input frame 2 field A = Output frame 2
Input frame 2 field A + input frame 2 field B = Output frame 3
Input frame 2 field B + input frame 3 field A = Output frame 4
...
This approach would in theory yield 60 unique output frames per sec on the display. It doesn't seem fundamentally different or more difficult than only deinterlacing intra-frame field pairs, other than requiring more processing power because more deinterlacing is being done.
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Old May 7th, 2008, 01:56 AM   #75
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- The article below notes that some crummy displays simply interpolate each individual field to form a full frame. This results in poor spatial resolution, but the full motion resolution of the 60i input stream is preserved. If crummy displays can retain full motion resolution, I find it hard to believe that good displays would not do likewise. I have not seen any articles that say motion resolution has to be sacrificed to get full spatial resolution.
http://www.hometheatermag.com/hookmeup/1107hook2/
Bob, It's really a shame that it's so hard to find definitive information about this, I also find it frustrating, but from the article you reference:

"The TV then has to combine these two fields into one frame to display on the screen. Done correctly, you'll see white and black alternating lines. Done incorrectly, you'll see a flashing box that flashes between solid black and solid white."

This is inconclusive because the first sentence seems to be saying what Aaron and I have been saying - that the two fields are combined into one single frame, but the second sentence seems to indicate that some TV's line-double each field and display them as individual frames. He is saying both things at the same time.

Here is another article that I referenced earlier in the thread that seems to indicate that many if not most TV's de-interlace the two fields into a single frame and then just display the same frame twice (2:2):

http://hometheater.about.com/od/tele...80ivs1080p.htm

To deinterlace a 60i frame into two true 60P frames would require a deinterlacer that could do motion interpolation. This is complex and requires buffering many frames, it is essentially what an MPEG encoder does. This would be the only high quality way to generate 60 *full resolution* progressive frames where there were only 30 originally, I just don't know if any TV's actually do this, but maybe some do.
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