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March 23rd, 2008, 04:07 PM
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#1 |
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Regular Crew
Join Date: Aug 2005
Location: Torres Strait - Australia
Posts: 76
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image not smooth
hi,
I'm trying to video a 2' high document by panning from top to bottom. I have done several takes but, when played back on Mac Book Pro the image appears juttery & distracting i.e. not a smooth. I'm using almost full wide (A1P) to reduce exaggeration of camera movement but still it does not look smooth. Is this due to the nature of interlacing & is there a technique to remedy this "jumpy" appearance ? Would a V1P be better for vertical pans of printing ? thanks for any hints. cheers |
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March 24th, 2008, 07:30 AM
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#2 |
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Regular Crew
Join Date: Dec 2005
Location: Austin, TX
Posts: 148
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The smoothest solution is to take a still picture and pan in your NLE. This is known as the "Ken Burns" look.
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March 24th, 2008, 03:01 PM
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#3 |
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Regular Crew
Join Date: Aug 2005
Location: Torres Strait - Australia
Posts: 76
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Many thanks Konrad,
I googled this technique & found some software to do exactly what I'm after. I had heard of the Ken Burns effect but always believed it to be a big boys ($$$$) kind of thing.. cheers |
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March 25th, 2008, 01:17 AM
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#4 | |
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Regular Crew
Join Date: Mar 2008
Location: Los Angeles, CA
Posts: 45
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Quote:
Interlacing actually smooths the judder. If you're seeing this artifact on a computer monitor my guess is that it has to do with your NLE displaying only one field of video. Low-res capture modes may discard one field to protect storage space. It could also have to do with the fact that computer monitors are most commonly non-interlaced. Displaying interlaced video on such displays produces temporal artifacts. If you're seeing this on a CRT video monitor then my guess is that your camera tilt just hit that "wrong" speed at which you see strobing. Finally, you could have reversed field interweaving in the offending clip. This mistake is very easy to do in FCP. Regarding the "Ken Burns" technique, this used to be done with motion control cameras which are computer controlled rigs. You program a move by setting keyframes and repeat it as many times as you wish. Over the last 4-5 years most of that work is done digitally although traditional moco rigs are still faster (no scanning, no rendering). You can do this effect in almost every NLE or effects software like Combustion, Shake or After Effects. There are also plugins for this like Motion Picture Plugin. And the final word about interlacing -- if your project is standard def or HD using one of the interlaced standards, use interlacing in your rendered picture moves. It will make a much smoother effect. |
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March 26th, 2008, 05:50 AM
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#5 |
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Regular Crew
Join Date: Aug 2005
Location: Torres Strait - Australia
Posts: 76
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Image not smooth
Hi Igor,
Many thanks for your help & advise. I am an old dog who is trying to learn new tricks. I had never even heard of reversed interweaving & I will google everything about it. Hell, I didn't even think that what I referred to as a "vertical pan" is actually a tilt. cheers |
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March 29th, 2008, 01:18 PM
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#6 |
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Regular Crew
Join Date: Mar 2008
Location: Los Angeles, CA
Posts: 45
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Hubert,
Interweaving is sometimes erroneously described as "field dominance." Just to clarify, field dominance determines if the cuts take place on field one or field two. Typically it's field one so the visual cut happens at the same time as the frame TC count change. Field dominance has no bearing on picture smoothness. Now, interweaving is an entirely different thing. Let's say you're capturing interlaced video into an NLE. You freeze a captured frame and observe the field structure. There are two fields. Two snippets of time in that one frame. The NLE and the capture hardware must agree at all times which of those two fields is the first one which one is the second. Any discrepancy will create artifacts. So if we say that "A, B, C, D" are the frames and "12" are the fields corresponding to those frames: A12 B12 C12 D12... is on the tape A12 B12 C12 D12... is captured by the hardware A12 B12 C12 D12... is manipulated by the NLE A12 B12 C12 D12... is recorded back to tape There are no artifacts with the above example. A12 B12 C12 D12... is on the tape A12 B12 C12 D12... is captured by the hardware A21 B21 C21 D21... is manipulated by the NLE A21 B21 C21 D21... is recorded back to tape As you can see the NLE swaps the fields (changes interweaving) resulting in stuttering playback. The artifact may not be very visible on computer monitors which are progressive but will be very apparent on any CRT. This field swap can also happen when you transfer Quicktime or other files between workstations. Improperly selected field order will result in the exact same artifact. The worst thing that can happen is when you have a composite in which some layers have reversed field interweaving. This situation is nearly impossible to repair unless you can go back and recomp the shot. |
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March 29th, 2008, 03:09 PM
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#7 |
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Regular Crew
Join Date: Aug 2005
Location: Torres Strait - Australia
Posts: 76
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Hi Igor,
Thank you for the info. I'm gradually starting to come to get some sort of comprehension with the varied terminology. When I looked up interweaving I drew blanks. I then called Apple support & the guy told me he'd never heard of interweaving but when I described the symptom he referred to field dominance. Well, as confused as this old dog is I'm confident I'll still learn at least one more trick. thanks again cheers |
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