hhhmm
First, I would like to apologize to michaelyoung and others for coming off as an a## in my first post.
I started working with digital video back when most of our work was shot on BetaSP. I used a Media100 Vincent 601 card. Back then we had 3:1 compression was about the best. And yes we needed alot of fast drives to run things at that high of a data rate. Nowadays a RAID on FW400 could handle that system for projects that aren't too graphic intensive. I used that setup with a B&W G3 for awhile.
When I referred to SDI, and uncompressed cards, I meant that you get what ever format you send to the computer, into the computer, is mostly unaffected. I always referred to CODECS myself, as compress/decompress. I never consider 1:1 codecs that are used with uncompressed boards, as compression, because they barely affect the data in comparison to the analog to digital converstors and 3:1 compression rates of my old media100.
If I send DV25 which is 4:1:1 sampling rate and a 5:1 compression ratio rfrom a deck over SDI to an Uncompressed SDI card. I am going to end up with DV25,4:1:1,5:1, in the cpu, barely affected by the "codec"
If I have a similar set up with DV50 or DigiBeta, that is what I am going to get in the cpu. From the deck to the uncompressed card, over SDI, the "codec" encodes the video in a format the the card can use. This encoding process has very little effect on the video, 1:1, and it is not compressing it in the same sense as the media100 card.
This is why I don't consider 1:1 codecs as compression.
maybe I am am technically wrong, but most people would be hard pressed to tell the difference in the footage.
peace