Noisy/Grainy image

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BasharOfTheAges
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Post by BasharOfTheAges » Sat Jun 02, 2007 1:48 pm

Kitsuner wrote:
post-it wrote:if possible, get with Scintilla on this one 8-)
I certainly wouldn't mind getting with her. Image
Trap? :lol:
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Amo-Chan
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Post by Amo-Chan » Sun Jun 03, 2007 1:42 am

Zero1 wrote:This is quite an odd problem. Checking the upload, the quantizers used are fine; it's about what you want to aim for. There are three distinct problems. One is Gibbs effect, and one is blocking. Gibbs effect is caused by oversharpening, or a codec's inability to code fine edges either because there's not enough bitrate, or it's a limitation of the codec.

Unfortunately, XviD somewhat suffers this character flaw, but it shouldn't be that bad at Q2-3; so I would assume perhaps it was too sharp.

The other is haloing, or as post-it identified it, "1) notice the sudden-drop to White before the Black line appears." It's basically where the resize or sharpen algorithm increases contrast to give the effect of sharpness, and in doing so creates white outlines which not only look ugly, but don't compress particularly well.

Third is blocking. I noticed some very blocky areas that used Q2. This should not happen at Q2; all that happens at Q2 if it's a complicated part is that the filesize gets bigger, not the quality drops.

The only thing I can think of is that the original source isn't great, the shapening added to this problem, or that maybe (and now I'm grabbing at straws) Vegas didn't render to Huffyuv and rendered with something else (perhaps you meant to pick Huffyuv and you unknowningly selected another codec in the list like MJPEG?)

This is a strange problem. Try compressing it with XviD using the same settings but without any Vdub filters.
Ok, I'll try that. It wouldn't be a source problem if the source was a dvd though would it?

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Zero1
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Post by Zero1 » Sun Jun 03, 2007 2:25 am

Possibly, I've seen some pretty bad DVDs in my time:
Image

If you can, load your source into Virtualdub using mpeg2source alone and scrub through the timeline to find the parts you used in your AMV and see if they are blocky.

If they are then you may need to check out the orgs guides on filtering.

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Zero1
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Post by Zero1 » Sun Jun 03, 2007 2:26 am

And for the record, that isn't a bootleg, it's a high motion part on the Tenchi Muyo Ultimate Ed DVD set, where 13 eps or so were put on 2 discs...

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