Quantcast Camera flash in different areas of consecutive video frames? - digitalFAQ Forum
  #1  
08-04-2017, 09:05 AM
koberulz koberulz is offline
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When I run the attached sample through QTGMC, I get this:

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What's going on here? I'd expect the flash to occur on the whole screen at the same time.


Attached Files
File Type: avi CamFlash.avi (2.21 MB, 2 downloads)
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08-05-2017, 02:32 PM
sanlyn sanlyn is offline
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Quote:
Originally Posted by koberulz View Post
What's going on here? I'd expect the flash to occur on the whole screen at the same time.
Apparently the flash duration isn't sync'd with the camera's shutter. Does it matter? During play you can't see the difference.

That happens in the two fields of frame 3 of the sample. How about frame 4? The upper area of the top field in frame 4 is blacked out (white arrow):



How about frame 5? Both the top and bottom field of frame 5 have an orange blob (white arrow). Is this an effect of local lighting?

top field:


bottom field:


The color and exposure are atrocious. Another bad tape. I don't envy you.


Attached Images
File Type: jpg Frame 4 - top field blackout.jpg (83.9 KB, 9 downloads)
File Type: jpg frame 5 - top field orange blob.jpg (82.8 KB, 8 downloads)
File Type: jpg frame 5 - bottom field orange blob.jpg (76.8 KB, 8 downloads)
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  #3  
08-05-2017, 03:03 PM
koberulz koberulz is offline
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Quote:
Originally Posted by sanlyn View Post
Apparently the flash duration isn't sync'd with the camera's shutter. Does it matter? During play you can't see the difference.
If you don't think it matters, probably not. I just wasn't sure what it was, or whether it was indicative of some sort of issue.

The dark purple artifacts pop up around motion pretty much constantly in most of these tapes. They would've all been the exact same process - same team, same venue, same season - so consistent quality (or lack thereof) is to be expected.
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08-10-2017, 05:48 PM
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It's just camera flash sync. Any camera or video camera, not using the flash, will experience this.

The color of the flash varies due to temperature and reflections.

Based on that brief sample, I actually don't find the tape to be bad quality at all. Just some standard chroma noise, chroma shifting, chroma blooming.

This is expected behavior of a flash, and nothing to worry about. But, FYI, this is why flash photography is often forbidden at events and places. For example, you don't want your wedding video ruined by Aunt Mabel and her $100 POS camera. Or to get with the times, ruined by cell phones.

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