Ut Codec/Virtualdub/VHS Capture Questions

[CountChocula]

Would it be ill-advised to capture VHS in BT.709 as opposed to BT.601? These two options seem to be compatible with my capture device (Hauppauge USB Live 2), but I understand 709 is intended for HD. Also, should I be using the Virtualdub "Set Custom Format" option to select YUY2/UYVY/YUYV prior to selecting the compression codec of my choice? Thanks for your input in advance!

[LMotlow]

VHS is SD BT601, unless you want color shifts by using something else. VHS is usually captured via VirtualDub as YUY2 with huffyuv lossless compression @720x480 NTSC (or 720x576 PAL).
http://www.digitalfaq.com/forum/video-capture/7427-capturing-virtualdub-settings.html and following posts.

[jagabo]

The difference between the two is how UT converts RGB to YUV (YUY2, UYVY, YUYV, etc.) and vice versa. If your video is YUV to start, and the codec decompresses to YUV there is no difference between the two, aside from the different fourcc code in the file. But if your video starts out as RGB the codec will convert it to YUV using the specified matrix (rec.601 or rec.709) before compression. If a later program requests RGB from the codec it will convert from YUV to RGB with the specified matrix. If you use the wrong version you will get the wrong colors.

SD video capture should be rec.601 and you should be capturing as YUY2 (or other YUV 4:2:2 subsampling) so you should use the rec.601 version for compression. That way, if a later program asks the codec for RGB it will be converted with the correct matrix. This reduces the possibility of getting the wrong colors.

[CountChocula]

Great, thanks jagabo and LMotlow! I'm sticking with 609 then. Now if I'm capturing with UT codec and selecting YUY2 4:2:2, there should be no conversion from RGB to YUV, correct? I've configured Vdub and Ut to capture YUV 4:2:2 so hopefully this conversion chain is as lossless as possible.

[jagabo]

if I'm capturing with UT codec and selecting YUY2 4:2:2, there should be no conversion from RGB to YUV, correct?

Yes, if your device is set to capture as YUY2. Capture devices usually have several options for capture format. In VirtualDub's capture module that's usually selected via Video -> Set Custom Format.

[LMotlow]

I guess the O.P. ignored the settings guide linked in post #2. Either that, or something didn't register. The guide clearly covers these issues more than once.

Whatever...

[jagabo]

Well, he did say

I've configured Vdub and Ut to capture YUV 4:2:2

I just wanted to be sure the capture driver was set to output YUY2 or other YUV 4:2:2 subsampling.

[CountChocula]

I'm familiar with the guide. Excuse you, Motlow.

[LMotlow]

Scusami, Count. The guide was written by an acquaintance of mine, so I'll let him know that a point or two might not be totally clear. Any complaints, let me or the author know.