Convert before or after CC?

[Luis Rolo]

Now that i solved my downconversion problems, i found some posts and articles explaining how HDV becomes 4:2:2 after down-conversion (to a 4:2:2 capable codec, of course...).
Here's a link explaining it: http://www.canopus.com/canopus/techn...pabilities.php
Now, if my final work is going to be SD DVD, will it be better do color correction in HDV and convert in the end, or should one convert before to take advantage of the improved color space?

Thanks.

L.R.

[Evan Donn]

I'd say do it before as the colorspace isn't really improved, you still have more pixels per channel in 4:2:0 HDV than you do in 4:2:2 SD. Each chroma channel has 720x540 pixels in HDV - so that could actually be downconverted to 4:4:4 SD, and going to a 4:2:2 SD format is actually discarding more than half of that total color information.

That aside, it's still better to do it before downconversion simply to reduce the number of compression passes - unless you are downconverting to an uncompressed format you'll introduce a third compression pass by doing it after the downcoversion.

[Luis Rolo]

Originally Posted by Evan Donn

I'd say do it before as the colorspace isn't really improved, you still have more pixels per channel in 4:2:0 HDV than you do in 4:2:2 SD. Each chroma channel has 720x540 pixels in HDV - so that could actually be downconverted to 4:4:4 SD, and going to a 4:2:2 SD format is actually discarding more than half of that total color information.

That aside, it's still better to do it before downconversion simply to reduce the number of compression passes - unless you are downconverting to an uncompressed format you'll introduce a third compression pass by doing it after the downcoversion.

Thanks, but i really need to go uncompressed SD or prores first. I don't have good experiences going directly to mpeg2.
So, if i go uncompressed SD it will be 4:4:4 ? Then definitely is better to CC after. Correct?


L.R.

[Evan Donn]

Originally Posted by Luis Rolo

Thanks, but i really need to go uncompressed SD or prores first. I don't have good experiences going directly to mpeg2.
So, if i go uncompressed SD it will be 4:4:4 ? Then definitely is better to CC after. Correct?

I'm not saying go from HDV straight to SD MPEG2. I'm just saying if you are capturing HDV you should probably do your color correction before you downconvert to uncompressed or whatever format you wish to master on. Even if you go to 4:4:4 SD you are discarding some of the color info from your original. The only exception I could think of is if you are going to a 10bit SD format - that may give you better results for your final color correction.