Bugs item #3191771, was opened at 2011-02-25 01:32 Message generated for change (Comment added) made by zmoelnig You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=507079&aid=3191771...
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Pixes (pix_ objects) Group: osx Status: Open Resolution: None Priority: 6 Private: No Submitted By: Matteo Sisti Sette (sistisette) Assigned to: Nobody/Anonymous (nobody) Summary: pix_movement treats a duplicate frame as black in Mac OS
Initial Comment: Consider:
[pix_video] | [pix_movement]
Expected behavior: When pix_video produces a duplicate frame (i.e. doesn't grab a new frame), one may expect any of these two: A - (best) pix_movement won't generate a new image B - (acceptable) pix_movement will generate a black image since it's comparing two identical frames (actually the same frame)
Observed behavior in Linux: - I'm almost sure it's A
Observed behavior in Mac OS: - pix_movement treats the duplicate frame as if it was a black frame; so it will compare the current frame with a completely black frame, outputting an image with a lot of "false movement".
Not sure about Windows, I seem to remember it works fine just like in Linux; or it may be behavior B; surely not like Mac OS.
This has been known for a long time but I couldn't find it in the bug tracker and it is not fixed, so I thought I would report it.
Note that it is not just a matter of failing to detect that the new frame hasn't been grabbed. That would explain behavior B described above, flickering to black. What's happening is much wronger: duplicate frames are treated as black frames which causes the output to flicker to almost-white.
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Comment By: IOhannes m zmölnig (zmoelnig)
Date: 2011-07-21 18:25
Message: ack.
the problem seems to be only the YUV handling, so a quick fix is to switch the colorspace e.g. by using [pix_grey] just before [pix_movement]
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Comment By: Matteo Sisti Sette (sistisette) Date: 2011-04-05 13:51
Message: I'm raising priority as this renders pix_movement almost useless in Mac OS, and it is a pretty basic object. Hope this is ok
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You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=507079&aid=3191771...