MTS / AVCHD / AC3 files with High Sierra: the beginning of a solution? (But I still need some help...)

Hi all,

I recently "upgraded" my iMac (end 2009) to High Sierra and I purchased Adobe Premiere Elements 18 to create some very basic holiday movies. Like many users, I had no sound while importing the AVCHD (MTS) files from my Sony-HDR11 camcorder. Through the discussion groups, I discovered that MacOS High Sierra can't read the AC3 audio files which are embedded in my videos!!!

After numerous tries, I may have the beginning of a solution.

I have to convert (and downgrade) my 5.1 AC3 soundtrack into a mp3 or m4v via VLC player.

Then, I can remix each video with its corresponding soundtrack via Premiere Elements.

This is very complicated but at least it works. Why did Apple decide to block the AC3 format????

My user experience with Mac OS High Sierra to simply merge some films I made with a standard Sony camcorder is absolutely awful! Let's continue...

The problem I now have is that I need to merge 268 MTS files, which means 268 mp3 to extract and to manually synchronise. I didn't find how to batch convert all those files into mp3 or m4v. I feel quite lazy and I don't want to spend the coming weeks to manually convert each file.

Question: would anyone have a solution to batch convert a large number of video files into mp3 or m4v thanks to VLC or any other program?

Question 2: even better, does anyone know where I can download an AC3 codec?

Thanks for your support!