How to look for MPEG decoding quality?

I'm not exactly shure in which forum to post this, so bare with me:


In a hopefully not too distant future, we will se completely digital transferring of the DVD image to the display. But, as we all know(?) "digital" doesn't always mean "perfect". If I'm not mistaking, there would generally be 3 main things to consider in the transferring of the DVD image, even if the signal path is fully digital:

1: MPEG decoding

2: De-interlacing

3: Scaling


Correct?


So, to fully understand the quality of the signal path, we must look at the quality of these three bits. I'm pretty confident in evaluating the de-interlacing, this has been covered hundreds of times. And scaling artifacts isn't that hard to understand either, although I guess it could sometimes be hard to tell whether artifacts is brought in by poor de-interlacing or poor scaling. If anyone has a "scaling artifacts for dummies"-like test, i.e. "chapter 247 of Star wars episode 14, look for xxxx", I would be very pleased.


But on to my main concern: MPEG decoding. Does anyone have a simple, yet pretty reliable way of testing the player's ability to decode the MPEG stream? Or any other source of picture degration that isn't due to de-interlacing/scaling? Something specific to look for? Any help will be appreciated.