I understand that the best quality is 4:4:4 color space and 1:1 compression. The DVX100 produces a 4:1:1 color space and 5:1 compressed source file. Absent buying a new camera, can anything be added with a SDI deck or SDI card or any software options. I use FCP for NLE.
The best thing to do would be to consider a different camera, such as the SDX900, which provides 4:2:2 color and 3.3:1 compression.
Capturing DV data through SDI wouldn't change anything, as the DV data on tape is already compromised. Capturing through SDI can introduce some other effects, such as you could choose to implement some chroma smoothing or something like that during capture that may make the video look more pleasant to you, but you could also do that in post from the firewire data.
DV is 4:1:1/5:1. If you're using a DV camera, that's the best it can be (unless you believe in the ReelStream modification and want to modify your workflow around that, which is claiming 4:4:4 uncompressed).
