Copied from a forum, can’t remember which one:
If your MPEG file contains AC3 (Dolby Digital) audio then Mitch411 said:
If you’ve got Encore CS3 installed , copy the file ad2ac3dec.dll from
the Encore CS3 directory and paste it into the PPro CS3 root directory
. Once you restart CS3, you’ll be able to import the file with the
audio. This means if you’ve already have a project with the files
imported, you’ll need to remove the files from the project and
then re-import them, or just start over with a new project.
Eddie, you’re right. PPro doesn’t import files with an AC3
extension, but it did import ac3 audio embedded in mpeg files
from DVD camcorders. The ad2mcac3dec.dll that was included in
2.0 allowed those ac3 files to import as stereo (but not 5.1).
It looks like that functionality was removed or broken in
Premiere Pro CS3, but the functionality still exists in Encore CS3.
You can copy the file over from Enc to PPro and get the
functionality back. You may end up breaking something else, but
it does work to allow the AC3 audio stream in the mpeg file to import.