VLC Media Player Solution
One of the first solutions involves using VLC media player. This is a free, portable multimedia player that supports different types of formats, including 5.1 AVCHD audio. You also need ffmpegX, which is a graphic user interface for Mac OS X. You can download a trial version of this program, but it costs $15 as of May 2011. It does mean purchasing another program, but this one is relatively inexpensive. It will also save you headaches when trying to import 5.1 audio.
1. Download these programs, and open both of them. Then follow the steps below:
2. Open up your MTS File in the VLC media player.
3. You need to export the audio. Set the A/52 setting, which is 512 kilobits per second, to a MPEG-TS file.
4. Now, import your MPEG-TS file into ffmpegX.
5. Next, only encode the audio stream. Change the settings for the audio stream to AC3, which is 5.1 audio set at 448 kilobits per second.
6. Finally, try importing the new 5.1 AC3 audio stream into Final Cut Pro.