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.

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...

18th July 2003, 08:15	#1 \| Link
FredThompson Registered User Join Date: Feb 2002 Location: Charlotte, NC USA Posts: 1,988	NTSC DV and ConvertToYUY2() 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? __________________ Reclusive fart. Collecting Military, Trains, Cooking, Woodworking, Fighting Illini, Auburn Tigers

18th July 2003, 09:25	#2 \| Link
sh0dan Retired AviSynth Dev ;) Join Date: Nov 2001 Location: Dark Side of the Moon Posts: 3,480	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. __________________ Regards, sh0dan // VoxPod

18th July 2003, 15:36	#3 \| Link
FredThompson Registered User Join Date: Feb 2002 Location: Charlotte, NC USA Posts: 1,988	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. __________________ Reclusive fart. Collecting Military, Trains, Cooking, Woodworking, Fighting Illini, Auburn Tigers

18th July 2003, 15:59	#4 \| Link
sh0dan Retired AviSynth Dev ;) Join Date: Nov 2001 Location: Dark Side of the Moon Posts: 3,480	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). __________________ Regards, sh0dan // VoxPod

18th July 2003, 18:52	#5 \| Link
FredThompson Registered User Join Date: Feb 2002 Location: Charlotte, NC USA Posts: 1,988	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. __________________ Reclusive fart. Collecting Military, Trains, Cooking, Woodworking, Fighting Illini, Auburn Tigers

26th July 2003, 16:44	#6 \| Link
Stereodude Registered User Join Date: Dec 2002 Location: Region 0 Posts: 1,481	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... Last edited by Stereodude; 26th July 2003 at 16:50.