Hi Chris / list,
At http://www.umatic.nl/pdp_picts.html you can see what a such a horizontal line looks like. Sometimes you can get similar results when you change the field dominance when you edit / compress video. See quote below from a mail i got from Miguel Carvalhais.
<quote> usually it comes from swapping the field order in videos, so if your video standard/codec uses lower field before upper field and you compress the video the other way around (upper first) then that means that by reversing the fields you get a bit of a flickering in the image as within each frame you're seeing reversed fields..
in a simpler explanation: when you have a sequence of frames 1 - 2 - 3
- 4 - 5 - etc you have a sequence of fields within each frame:
1L - 1U - 2L - 2U - 3L - 3U - 4L - 4U - etc... each field containing
half of a frame... if you number this correct order of fields then you
get:
F1 - F2 - F3 - F4 - F5 - F6 - F7 - F8 - etc
when they get swapped, this happens:
F2 - F1 - F4 - F3 - F6 - F5 - F8 - F7 - etc
so whenever we advance in time, we also skip backwards within each
frame...
this effect is not too visible if there's not much motion but in takes
with more movement it can become rather obvious...
</quote>
I don't know how pd handles the field dominance of the video-input, but maybe it could help if you could manually change the field dominance from: not set, to upper and lower.
Just a thought, don't know if it's possible and if it would fix the problem.
Ciao,
Sara
chris clepper wrote:
On Dec 1, 2004, at 2:52 AM, sara kolster wrote:
Hi Chris, Jamie a.o.
The horizontal lines don't really look like interlacing, it's really a field-swapping thing. The more you move the camera the more you see those horizontal lines going down your screen. You have 1 or 2 lines on the screen that seems to break the image in half and it seems the video cannot keep up with the speed in which it's moving.
I haven't seen anything like that since the old Nato/OS9 days!
Can you post a picture of this if possible? The OSX Grab application might be able to get the frame, but SnapzPro has a movie recording capability that's probably easier. They have a demo version that works for a month or so.
http://www.ambrosiasw.com/utilities/snapzprox/
This is also a pretty good way to record the output of GEM windows, especially on dual CPU machines.
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Hi sara,
On Dec 3, 2004, at 4:05 AM, sara kolster wrote:
At http://www.umatic.nl/pdp_picts.html you can see what a such a horizontal line looks like. Sometimes you can get similar results when you change the field dominance when you edit / compress video. See quote below from a mail i got from Miguel Carvalhais.
...these don't really look like field problems, but rather frame tearing, which comes from unsynchronized grabbing of the video and it's display: in other words, pdp is displaying frames that haven't completely been captured...
...can't work on it atm...
jamie
Hi James,
...these don't really look like field problems, but rather frame tearing, which comes from unsynchronized grabbing of the video and it's display: in other words, pdp is displaying frames that haven't completely been captured...
I just made a video, where one clip caused the same error when captured and exported. I solved the problem by exporting the video with the same field dominance as the original captured 'source-material' - thanks to the advice from Miguel. [see last email]
This is why i thought it was a field dominance problem; but if you think it's something else and you can fix it, i'll be happy too ;) Does it have something to do with the way pdp displays the movie in milliseconds while it actually exist in frames?
...can't work on it atm...
I really hope you have some time in the near future..
jamie
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-
james tittle -
sara kolster