Maybe someone can explan.

DV25 compression 4:1:1

DV50 compression 4:2:2

HDCAM SR compression 4:4:4

What about NTSC betacam?

Many thanks

Allan

"What about NTSC betacam?"

Also 4:2:2.  Was there another question here?  These values aren't compression.  They are the sample rates applied to the various video components.

They are compressions. Because all of those formats are compressed.

As the values approach the 1:1 ratio they are better in terms of image quality.

Just a small reading

This explains about color-chroma subsampling

 actually you are both right. I think he meant 5:1 vs 15:1 etc as more traditional descriptions as opposed to color etc. But i wonder what the actual question from the post is?

Well, whatever the question is,

babyblue:

DV25 compression 4:1:1

is only true if you're working in NTSC.  In PAL it's 4:2:0 and DVCpro 25 is 4:1:1.  Since you don't say where you are the clarification may be necessary.

I really don't like those questions at which the OP disappears.

babyblue:

 

DV25 compression 4:1:1

DV50 compression 4:2:2

HDCAM SR compression 4:4:4

You are stating color sampling. This refers to the color accuracy not the actual compression ratio of a particular codec.

babyblue:

What about NTSC betacam?

Since Betacam is an analog format there is no compression per se. Compression as stated here is a digital concept. Basically, compression is the process in which information is discarded (usually but not always 'redundant' information) in order to reduce the size of a given data stream.

Betacam and other analog formats (like casette tapes, 8 track, VHS, etc) quality is measure dthrough analog parameters like bandwidth.