For the new AX1 a variation on XAVC has been developed called XAVC / S. This format differs from XAVC in that it uses Long GOP compression. There are a few issues when it comes to viewing, loading and editing XAVC and XAVC / S files in your non-linear editing software. Sony provides a copy of Sony Vegas with the AX1, which I presume nicely handles the camera's files. However, Mac users are out of luck in terms of a solution from Sony, since Vegas is a Windows only program. To compress AX1 4K XAVC S MP4 to FCP X, we need conversion.
I shot 1 min film with AX1. Be aware though that the camera's files, which are in an MP4 wrapper, will increase in size by a factor of about 3X when converted in 24P to ProRes, and up to 9X for 60P. Luckily, Aunsoft iMedia Converter for Mac convert 4K MP4 to ProRes as original quality and video size. The footage was shot at 60P, but I downconverted to 24P with Aunsoft (typically, 23.976 frames/s when using equipment based on NTSC frame rates), because neither Premiere Pro nor FCP-X could smoothly handle 4K 60P files on my MacBook Pro Retina. In future I'll be shooting exclusively in 24P (except for slo-mo). But now the Aunsoft is the only converter that allows me freely set frame rate as 23.976, 24, 29.97, 30, 50, 59.94, or 60.
Here is my experiences with this 4K Ultra HD Converter to convert 4K XAVC S to Final Cut Pro 7.
Step 1: Import 4k clips
Click "add video" or "add folder" to load 4K MXF XAVC.
Step 2: Choose ProRes 422 as output formats
Step 3: Set frame rate as 23.96
Here you can easily set frame rate as 23.96 to downconvert 60P 4K file to 24P ProRes.
Step 4: Conversion
The Sony AX1 4K to FCP X Compressor is intuitive. Conversion time is also affected by the power of your CPU and the memory.