Flashes from cameras causing problems in HDV?
I shot some video with my HC1 of some models getting their photos taken and after each flash there were several frames that had very bad blocky artifacts.
I have shot similar footage with an FX1 and never have seen such problems. Anyone have similar problems? |
Thanks for posting this, Greg. My first reaction is that it's perhaps due to an MPEG encoding problem, but strange that it would happen with one HDV camcorder and not the other. I think you've just created the basis for a very interesting side-by-side test!
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CMOS devices(HC1)use rolling shutter charge/readout architectures. A flash causes local strong frame content change which fools the MPEG encoding.
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Quite common actually?
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Also seen this on Leno with strobing lights. Same effect. |
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This has nothing to do with decrompressors. Like previously stated, it is indeed the rolling shutter effect. You can see similar artifacts with fireworks. Unfortunately, this is a problem with the CMOS sensor and HDV. So no other HDV camcorder will produce this problem; only the HC1. I have been asking DSE if the A1U reproduced such problems and he was not able to answer. I guess we need to wait and see. I predict that you will get similar problems as it uses the same chip.
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I filmed the Butthole Surfers in 2002 and the strobe lights were incredibly hard to compress to MPEG2 without blocks. I can't even begin to imagine a realtime encoder doing any better.
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[QUOTE=Greg Jacobson]I shot some video with my HC1 of some models getting their photos taken and after each flash there were several frames that had very bad blocky artifacts.
Alexander, several frames are contaminated. Could you explain, if the (long GOP) MPEG2 codec is not involved, how a rolling shutter could affect "several frames" while an electronic flash lights up during only less than a few % of a frametime |
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