I'm helping with a small volunteer media team, and they have several .mpg videos that don't appear to have sound when played in QuickTime, iTunes, Real Player, etc, on the local Mac machine.

I was able to hear audio after transferring one of the movies to a Windows machine that had VLC media player on it. Through VLC I was able to discover that the audio stream is a52 / AC3 format.

We use Autodesk Cleaner in our normal workflow of converting the format of our videos to FLV, but for some reason it's unable to convert this particular batch of videos (well, the video converts fine, but with no audio).

Obviously, it seems that there's a codec issue here, but I'm not sure how to correct it. (I'm not extremely familiar with Macs, and/or Autodesk Cleaner).

I've seen the Perian codec pack, but I'm not sure that having the codecs on the system will enable Cleaner to convert these videos (particularly the audio stream, since the video converts fine).

Is there something obvious that I'm overlooking, or will we have to use something else for this particular batch of videos? If so, what?