DV Color correction

[fberger]

I am capturing analog PAL video through a Canopus ADVC-50 DV converter and noticed some slight loss in color saturation. Canopus tech support advised to capture at "150% RGB". What do they mean? Is there any way to tune the DV capture process? I am using XP and thought DV was going straight into an AVI file without possible correction. Can a PC application apply any "filter" to a DV stream?

Of course I can apply filters in tmpgenc, but I'd like to avoid that step if possible.

I tried using another DV codec than MS, but saw no difference at all. My guess is that a DV codec is used to re-encode the DV file in output from an NLE app, but not used to capture. Is this assumption correct?

[Jerry Jones]

That setting they're talking about is in your project "codec" settings in MediaStudio Pro (or whichever NLE you're using).

When you go into your compression settings where the Canopus codec is selected, you should see an option to 'expand RGB 150%.'

But you are correct.

When capturing from DV sources, the DV codec is not even involved.

The DV codec only becomes involved when one renders titles, transitions, layers, etc.

My understanding of the 'expand RGB 150%' was that it has to do with the 0 - 255 vs 16 - 235 RGB issue.

You might give it a try and see if it makes a difference.

I've expanded mine, but I'm not sure if I really notice a difference from before.

The whole luma clamping issue is complex and often confusing (to me at least).

Jerry Jones

http://www.jonesgroup.net

[fberger]

Jerrold,

I am using a Pyro card and don't have a Canopus codec on my system. The Canopus ADVC-50 is a hardware only solution that accepts analog input and outputs DV to my Pyro card. All DV encoding is done automatically. I suspect the 150% RGB should then take place in the Pyro card which is responsible for the "capture"?

I am capturing DV from DVD Workshop and don't see any option in there.

I don't know anything about the "0 - 255 vs 16 - 235 RGB issue" unfortunately, I am starting to realize that this is very complex... The ADVC-50 has a jumper that is labeled "0 IRE" and "7.5 IRE", I am not sure if that is related to this RGB setting. The manual provides no information what so ever on this jumper setting. A little disappointing.

Thank you for pointing me in the right direction, I'll do some more research on those RGB values now.

[Jerry Jones]

Since you're using the Pyro, you must also be using the Microsoft DV codec.

That means you should disregard what the Canopus rep said as he or she obviously misunderstood.

The 'expand RGB' feature is exclusively a feature of the Canopus DV codec.

To use the Canopus DV codec, one must usually have a Canopus DV board installed (with a few rare exceptions).

I would look into that jumper issue.

It sounds to me like you may be seeing the classic luma clamping issue that is associated with certain DV codecs.

As for the 0 and 7.5 IRE choice, here's a Web site page for you to read:

http://www.greatdv.com/video/smptebars2.htm

Good luck,

Jerry Jones

http://www.jonesgroup.net