How do the studios do their DVD's

[Ervin Farkas]

We call that FRAME DOUBLING, not deinterlacing.

You can either simply play the same frame twice or you can CREATE new intermediary frames with software such as Twixtor.

Deinterlacing does NOT produce 60P from 60i no matter what you call it, period.

Let's not confuse the OP and others please.

[Eric Olson]

Originally Posted by Ervin Farkas

You can either simply play the same frame twice or you can CREATE new intermediary frames with software such as Twixtor.

Correct 60i to 60p conversion does not play the same frame twice nor does it use motion interpolation to create new intermediary frames. The process only converts the 60 distinct fields already present in 60i footage into 60 distinct frames per second. Clearly

1080i60 -> deinterlace->1080p30->scale->480p30->filter->DVD

is faster. However, what I suggested earlier has the potential of resulting in a higher quality DVD. If the source is very sharp or has fine grained noise, the difference between the two methods will be more pronounced.

[Andrew Smith]

On the other hand, view the need to go to dual-layer as a good thing. It will stop a lot of mom+pop people in their tracks when they try to copy it on to a regular DVD. This may well translate to additional sales for you.

Andrew

[Robert Turchick]

I worked for a large company (converting and archiving home movies) that spit out thousands of burned DVD's a day and had a very similar question to the OP's for the engineers responsible for stuffing the data onto the discs.

Two things everyone should know...

First...Dual layer burned discs are incredibly unreliable. The company stopped offering them as a result of so many returns that played perfectly on our players but wouldnt play for the end customers.

Second, which has already been addressed, the major studios have either very expensive or proprietary software for encoding. There's a lot more calculations happening specific to content and how it changes frame to frame. Think microscope vs wide angle lens.

The company I worked for had a team of software engineers develop their own encoding software as a result of not offering dual layer discs. They could fit 170min of material on a single layer disc and it looked better than what I could get out of the highest quality settings in compressor or adobe media converter. I call it voodoo, our lead software engineer (from MIT) thought it was pretty simple!
Of course the end cost of "brewing" their own software was probably well into the five figures counting the manpower and hours spent but the quality and compatibility they now offer their customers rivals the big studios.

Lower Bitrates have two advantages...better compatibility with older players and the ability to stuff larger amounts of data on the same disc.
Our "bundled" encoding software is not designed to optimally work at those lower bit rates. It's designed to work reasonably well across a wide range of bit rates.