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Patterns over Video Capture
This is regarding an old issue with checkerboard patterns on MJPEG captured video I am trying to resolve for months.
When I capture MJPEG at 704 x 480 I get a checkerboard effect that looks like:
http://members.nbci.com/worldwinner1...eckerboard.jpg (download the image and then view it)
I sent my Matrox G200 for RMA and received a new one, but the prolem remained. The Matrox tech convinced me that it is the power grid noise what I see as a checkerboard pattern on the recording, so I went on and tested the card on 5 different power supplies, on 2 diffirent computers in 4 different city locations. The checkerboard effect was always visible. I found other people, who noticed the same effect on their capture:
http://forums.murc.ws/ubb/Forum2/HTML/003804.html http://forums.murc.ws/ubb/Forum2/HTML/004137.html http://forum.matrox.com/mgaforum/For...ML/002516.html
and feel that the problem is more common as it seems but people simply do not notice it, because they do not capture at 704x480 or pattern is blurred by the de-interlace and the MJPEG decoder.
So, for that reason I created a simple test at http://members.nbci.com/_XMCM/worldw...deo/index.html
The steps you should follow are: set the screen resolution to 800 x 600, 16 bit, enable TV out, in Display properties/Settings/Advanced/TV output, set Brightness to 150, Contrast to 200, Saturation 120, antiflicker to 0. Then create a loop by connecting the BOB Video Out with Video In.
Bring up the PC-VCR, set it to record MJPEG at 704x480. Open the test page in the browser and record 3-4 minutes with PC-VCR.
Then, try to play it with Windows Media Player or PC-VCR. Sometimes, when played, the image is so blurred by the video driver that the pattern is "dissolved", but in fact if you look carefully, it appears as a "boiling" noise, like from an old VHS tape. If you do not see the pattern, open the capture in VirtualDub (http://www.geocities.com/virtualdub/v1_4c/VirtualDub-1_4c.zip ). There it is clearly visible: http://members.nbci.com/worldwinner1/video/prfile.gif
you can clearly see the pattern over the red, yellow and the green circles.
Please, run that test and tell me the what are the results.
Here's the original thread
http://forum.matrox.com/mgaforum/For...ML/002849.html
When I capture MJPEG at 704 x 480 I get a checkerboard effect that looks like:
http://members.nbci.com/worldwinner1...eckerboard.jpg (download the image and then view it)
I sent my Matrox G200 for RMA and received a new one, but the prolem remained. The Matrox tech convinced me that it is the power grid noise what I see as a checkerboard pattern on the recording, so I went on and tested the card on 5 different power supplies, on 2 diffirent computers in 4 different city locations. The checkerboard effect was always visible. I found other people, who noticed the same effect on their capture:
http://forums.murc.ws/ubb/Forum2/HTML/003804.html http://forums.murc.ws/ubb/Forum2/HTML/004137.html http://forum.matrox.com/mgaforum/For...ML/002516.html
and feel that the problem is more common as it seems but people simply do not notice it, because they do not capture at 704x480 or pattern is blurred by the de-interlace and the MJPEG decoder.
So, for that reason I created a simple test at http://members.nbci.com/_XMCM/worldw...deo/index.html
The steps you should follow are: set the screen resolution to 800 x 600, 16 bit, enable TV out, in Display properties/Settings/Advanced/TV output, set Brightness to 150, Contrast to 200, Saturation 120, antiflicker to 0. Then create a loop by connecting the BOB Video Out with Video In.
Bring up the PC-VCR, set it to record MJPEG at 704x480. Open the test page in the browser and record 3-4 minutes with PC-VCR.
Then, try to play it with Windows Media Player or PC-VCR. Sometimes, when played, the image is so blurred by the video driver that the pattern is "dissolved", but in fact if you look carefully, it appears as a "boiling" noise, like from an old VHS tape. If you do not see the pattern, open the capture in VirtualDub (http://www.geocities.com/virtualdub/v1_4c/VirtualDub-1_4c.zip ). There it is clearly visible: http://members.nbci.com/worldwinner1/video/prfile.gif
you can clearly see the pattern over the red, yellow and the green circles.
Please, run that test and tell me the what are the results.
Here's the original thread
http://forum.matrox.com/mgaforum/For...ML/002849.html
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