Any book recommendations on MPEG-2 (or similar) encoding?

I've seen several books on MPEG-2 and MPEG-4
encoding, but none of them seems to do much more
than repackage the standards (which I find really
quite readable),

What I'm looking for is a book that gives something
on the "secret sauce" needed to make a good encoder.

How does adaptive quantization work?
How do I get good vectors without too much computation?

Clearly, some of this stuff is company confidential, but even
still, I would think there would be a reasonable book by now.

I can always plough through a bunch of IEEE papers, but
it's difficult identifying the dead-ends.

Thanks

Pete