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View Full Version : NTSC DV and ConvertToYUY2()


FredThompson
18th July 2003, 08:15
This simple script:

AVISource("source.avi")
ConvertToYUY2()

when used with NTSC DV and VirtualDub appears to make the darks darker and whites whiter and larger. I'm working with a camcorder source where no filters were used and blue and green stage lights were hitting the camera.

Darks getting darker doesn't bother me too much but I would prefer that to be something I control.

The real problem is the overly saturated white areas are becoming enlarged. Faces, hands, dark details on otherwise white objects are all becoming less distinct. They're horrible in the original because they're white blobs with dark spots where eyes should be, etc. After conversion, those dark areas are smaller or non-existant.

Is there a technique for converting the colorspace which will help prevent this?

sh0dan
18th July 2003, 09:25
Probably related to your DV codec, which makes an incorrect YUV->RGB conversion. Which codec are you using?

Furthermore have a look at this thread (http://forum.doom9.org/showthread.php?s=&threadid=33526).

FredThompson
18th July 2003, 15:36
MainConcept 2.31

This is a common problem. Have seen it with Panasonic and Canopus as well.

I know all about that thread. Can't possibly agree with the conclusion that the Panasonic is more accurate as there's no metric on which to base that statement.

sh0dan
18th July 2003, 15:59
You could try using Colotyuv(levels="pc->tv"), but I don't think it will restore the black/white areas properly - at least if it delivers the material as RGB. It will help, if the codec delivers material as YUY2 (or even YV12, if any of them do).

FredThompson
18th July 2003, 18:52
See this thread: http://forum.doom9.org/showthread.php?s=&threadid=57112

MainConcept's 2.3.1 version has these decoder options:

RGB 16...235
Change Fields Order (dangerous, IMHO)
Preview Quality
Clamb (sic) YUV to ITU601r
YUY2 disable
UYVY disable

The encoder has these:

RGB 16..235
Change Fields Order
Fastest
Clamb YUV to ITU601r
16:9

The more I think about this, the more I realize some proper testing is needed. There's more in the thread I just referenced. If you have any ideas for the testing procedure, please let me know.

Stereodude
26th July 2003, 16:44
No to hijack, but where do you get a DV codec from? I work with DV a lot and I'm sick of using the DirectShowSource tricks.

Edit: nevermind...