AVCHD quirks

I’ve had a few people come to me over the past months who are having problems importing AVCHD files into Final Cut Pro 7 and I did a simple test today to isolate the problem.  This test was done with a Canon Vixia HF S100, so I can’t say whether these results will apply to other cameras.

First, the problem:

Final Cut Pro won’t recognize certain types of AVCHD files under certain conditions.  A student will shoot with the Vixia and when she or he tries to import the footage using log and transfer in Final Cut Pro either nothing will happen (no files are added to the queue) or, if the “Private” folder was selected, the following message will appear:

“‘PRIVATE’ contains unsupported media or has an invalid directory structure.  Please choose a folder whose directory structure matches supported media.”

First, the solution:  Only use Class 6 SD cards on MXP recording quality with the Vixia HF S100.
Now, some details:
There are two potential problems I’ve identified:
1. Card speed.  The Vixia HF S100 works best with Class 6 cards.  Cards faster than Class 6 will not allow you to record with the two highest quality settings, MXP and FXP.  These settings are 1920×1080 resolution, while the lower-quality settings use the 1440×1080 standard.
2. Using SD cards with multiple types of cameras.  In this test I used the cards with a Canon DSLR and the Vixia without erasing the DSLR data.
I won’t bother detailing all the tests.  Here are the conclusions:
Class 6 cards:
If you use your SD card with a Canon DSLR camera, then attempt to use it to record on the Vixia in XP+ quality, it will be unreadable by Final Cut Pro.  It will even be unreadable if you erase the DCIM and MISC folders created by the Canon DSLR.  After using the SD card with a Canon DSLR, you have to re-format the card before using it to record on the Vixia in XP+ quality.
If you use your SD card in a Canon DSLR camera and then attempt to use it to record on the Vixia in MXP quality, it will work fine.
Class 10 cards:
If you record on the Vixia in XP+ quality, whether you’ve used the card previously with a DSLR or not, it will be unreadable by Final Cut Pro.
You cannot record in MXP quality on a Class 10 card, so unless you’re using another editing setup that you know will work with XP+ quality, use Class 6 SD cards.
Why does this happen?  I have a hunch that the problem has to do with the different resolution of the lower-quality recording formats.  XP+ and below record 1440×1080, whereas MXP and FXP record 1920×1080.  I could be wrong, but that’s the main difference between the higher and lower recording qualities.
The best way to avoid all these troubles with Final Cut Pro is to always use Class 6 cards in MXP quality.
EDIT (9/30/2013): I recently found out that Canon can do a firmware update on the HFS100 that makes it work with Class 10 cards.  Obviously, this is the ideal solution.  Unfortunately, you have to send it to Canon to have it updated (for free).  If you need to do this, contact Canon support.