Really cool s/w accessory exposes possible VV problem

riredale wrote on 10/28/2002, 10:52 AM
I came across a new download called DVScope (www.videoforge.com) that can take either live video or an avi file and show both a vectorscope or waveform monitor display. The best part is that it is cheap ($40) and you can download a 20-day trial to see if you want to buy it.

Only problem is that when I run the VV3 colorbars through it, it shows the hue to be exactly spot-on, but the saturation is about 5-10% too hot. I tried using the colorbars provided with the DVScope download, and those match the boxes precisely. I then tried the colorbars that VV3 optionally puts at the beginning of a render--same problem; too hot.

This issue has nothing to do with the 16-235 luminance filter that VV3 offers, from what my tests show to me. I am assuming that the color saturation of the DV footage imported from my camcorder is not adversely affected by VV3, since it just passes the data through, so to me it implies that the SMPTE colorbar pattern stored in VV3 is too saturated.

Comments

GaryAshorn wrote on 10/28/2002, 11:21 AM
Have you run a true calibrated signal from say a Horita or other known source to see if the program itself is displaying the signal properly?

Gary Ashorn, PE
riredale wrote on 10/28/2002, 1:05 PM
No, and furthermore, in just the past few minutes I took an avi of the VV3 color bars, put it on the VV3 timeline, and made a still frame snapshot. I saved it to the bmp format, and imported that photo into this DVScope product. The end-points nailed the vectorscope boxes perfectly. But then, what does it mean to feed a vectorscope a bitmap? I guess it just shows that pixels of a certain color are properly translated by the software to the proper places on the vector display. That still doesn't answer why a colorbar video doesn't hit the vectorscope boxes correctly.

"Color" me confused.
SonyEPM wrote on 10/28/2002, 1:20 PM
The DV scope utility is using a different DV decoder (likely Microsoft's, definitely not SFDV) so that might account for some the difference.
Spot|DSE wrote on 10/28/2002, 9:04 PM
The scope is indeed using M$DV's codec for this, and that alone accounts for the shift. it's simply not accurate. Not to that point, anyway.
riredale wrote on 10/29/2002, 3:28 PM
Does this imply that if I were to tell VV3 to use the MS codec, the vectorscope dots would fall in the boxes squarely? Not that I would want to use the MS codec, mind you.
DGates wrote on 10/29/2002, 3:38 PM
Besides, 5-10% isn't that big of a deal.