I have used DVD Shrink as my first choice in re-authoring/compressing/encoding. I have always used the Analyzing before the Encoding when compression was needed. Is this really necessary (as it adds twice the time)? Is the analyzing actually used to aid the encoding or is it just checking the rip for any potential errors? What I'm asking, is the final result actually any different on the finished .iso from just encoding or using analyzing and encoding?

To get the most quality out of a compression job, I would continue to use it. It's that extra time that helps provide the high quality output that DVD Shrink is known for.

Here's a link that sorta explains it

http://www.doom9.org/mpg/dvdshrink31-finalsteps.htm

The initial analysis is necessary or DVD Shrink won't let you shrink the DVD at all.

The deep analysis isn't necessary, but it will help DVD Shrink to better allocate space to the parts of the video that are more complex, and the final result will be better.

I suggest you let DVD Shrink perform the deep analysis whenever it wants to, which is always except when the selected content will fit on a 4.7GB DVD without compression.

I've always wondered about just what the analyzing what actually doing. One thought was that is was doing something to aid the encoding and another thought was that is was just checking the disk for potential errors.

I have a friend who never uses it and me that always has used it. He disputes that his copies are any different than mine. It got me wondering if the result was really the same.

I've done side by side comparisons, and when I hit the 50-60% compression quality area, I can see the diff visually on my TV when I use Deep Analysis and Quality Enhancement and when I don't.

But everybodies eyes are different. Some may notice, others may not. I certainly do.

Deep Analysis definitely does improve the results. I think one of the functions of it is scene detection, which allows fine tuning of compression levels on a scene-by-scene basis. Every time a camera shot changes or lighting changes it's noticed, as well as a shift from a relatively still shot to a lot of movement.

You'll really notice the difference on a big screen, and usually with a movie that is compressed past 80-85%. It really depends on the movie. I would always use it for compression past 90%.

The good news is that Deep Analysis really benefits from CPU's with larger cache, and dual-core CPUs. My AMD X2 with 1MB x2 at 2.4mHz will run deep analysis at 600-800 FPS on most movies, and I've seen it run as high as 1000 FPS. So it's never more than a few minutes to complete the deep analysis. This assumes the files are on the HD, not on DVD.