A search for this topic will result in countless discussions about the exact benefit of MPE during the export. While it's primary function is to enable real time playback of many types of footage with effects applied, some of us maintain that it does help with encoding, depending on your source footage, if you direct export from PrPro instead of going through AME. AME does not use MPE at all, for anything. However, many of us have noticed significantly quicker encodes using the direct export instead of running through AME (think on average, 25% quicker). And since the time difference appears only on footage types where MPE makes a difference, it has led some of us to believe that MPE does affect encoding through PrPro.
Though there have been countless posts on this topic on these fora, I've yet to see a definitive yea or nay from any Adobe tech folks as to whether or not MPE actually has any bearing on a direct export from Premiere, so officially I think it's still up in the air (or "No," since I think that's what the Adobe documentation says). I'm sure one of the Adobe techs will correct me if I'm wrong!
AME does not use MPE at all, for anything.
That is false. AME does not use hardware MPE for scaling, for example, but certain effects are handled by hardware MPE. Direct export does utilize hardware MPE in all capacities.
While the following post was made by Jeff Bellune, the information comes from an Adobe engineer: Not Getting the Quality You Expect From the Adobe Media Encoder?
Thanks, Colin--I tend to forget about the software side of MPE and refer only to hardware things...