I've noticed for the longest time that whenever I export/compress my movies with QT Pro using H.264, the result is a bit brighter than the original. I've tried compensating for this by adding a touch of density and contrast in the filter settings of QT but it's like flying blind. Is there a fix or some kind of way to correct for this?
Google for "Quicktime H.264 Gamma". There's a whole bunch of stuff out there about it.
But to save you time, here's a fix:
After you create the QuickTime/h.264 file, open it up in QuickTime and select "Show Movie Properties." Highlight the video track then click on the "Visual Settings" tab. Towards the bottom left you should see "Transparency" with a drop-down box next to it. Select "Blend" from the menu then move the "Transparency Level" slider to 100%. Right after that, choose "Straight Alpha" from the same drop-down and close the properties window. AND finally, "Save."
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!