Not Getting the Quality You Expect From the Adobe Media Encoder?

Question

If your Premiere Pro CS5 project is set up to use Mercury Playback Engine GPU Acceleration (affectionately known as Hardware MPE), then there is some important information you need to know about the AME.
During a Direct Export from Pr, Hardware MPE automatically uses the same scaling and deinterlacing algorithms that are invoked by selecting Use Maximum Render Quality in either the Sequence Settings or the Export Settings.  However, if you queue the exported sequence in the AME, there is some un-accelerated scaling that occurs after Pr hands off the sequence to the AME.  That un-accelerated scaling is affected by the Use Maximum Render Quality option.
So although a Direct Export from a Pr project that is using Hardware MPE will produce the quality results you expect without having MRQ selected, that's not necessarily true for a queued export from the AME.
Bottom line: even with Hardware MPE in use, it may be necessary to select Use Maximum Render Quality in the Export Settings dialog to get the best quality results when the export is queued in the AME.  Unfortunately, this will also greatly increase the time required for the export.
-Jeff

Answer 1

I'm seeing my final color corrections not taking effect if I export via AME, but if I Export within Premiere instead of queueing it out to AME, the color is saturated and as expected.  For this export I'm using H.264, basically a VimeoHD setup.
Of course, the export of a 4-minute 1080p piece thru Premiere is ~35 minutes compared to 13 minutes via AME, plus I have to walk away from editing while it consumes Premiere.
Any ideas what is causing this visual discrepancy?