4:1:1 vs 4:2:0
 

Recently I came across a curious info regarding different compressions in XL2. It seems that XL2 NTSC uses 4:1:1 compression, while PAL version uses 4:2:0.

So, what does that mean for the visible picture quality and how different is it, really? Which is "better"?

Thanks

Dennis,

Both formats are storing the same amount of color data (1/4 the luma data). However, the store it in differents shapes, if you will. 4:1:1 in long, rectangular blocks, 1x4 pixels. 4:2:0 on square blocks, 2x2 pixels. The same amount of data, in a different configuration.

I don't think that one is necessarily better than the other. However, you must realize that they will result in different types of artifacts. Banding artifacts versus block artifacts.

Now, I have a theory about 4:1:1 being a better format for interlaced video, because for any motion where there will be interlace combing, 4:1:1 is accurate (as it can be) for each line. 4:2:0 encoding of interlace coding could end up being highly inaccurate.

For progressive video, 4:2:0 is likely better, as it distributes it's artifacts equally horizontally and vertically.

With that in mind, XL2 PAL 25p would seem to be a great format for eventual film transfer.

Josh