AVCHD file batch adjustment question

[LSBREWER]

I have shot several hours of HDV using the Sony HVR-s270 camcorder. The video exists on both DV cassettes and compact flash cards. The compact flash card files are AVCHD with a .m2t file extention.

After reviewing the video, I've concluded that overall, I shot about a half stop under exposed. While the video is fine, using my Vegas Pro 9e adjustments "contrast and brightness", I've concluded it could look a lot better.

What's a good batch color corrector that could make these subtle adjustments and write over the old file so the files keep the original file name?

Thanks in advance for your help.

Larry Brewer