Question about 4K codec Sony A6300

[spotmeter]

I have my camera set to 4K for movie mode, XAVC S, 100M.

When I inserted the memory card into my computer card reader, the files were all MPEG 4.

I am confused about what has happened.

Why would the files be recorded as MPEG 4 when I specified XAVC s in the menu?

 

[ftbt]

I have a A7Rii and the first time I tried to record 4K, the camera refused to do so, claiming that my card wasn't up to 4K specs (even though it was). After some research, it seems that Sony cameras are very fussy about which cards it will record 4K to.

 

[mbroomfield]

I dont know much about video, but this is from the help guide ...
http://helpguide.sony.net/ilc/1540/v1/en/index.html
http://helpguide.sony.net/ilc/1540/v1/en/contents/TP0000824623.html

Movie recording formats

The following movie recording formats are available with this camera.
What is XAVC S?
Records high-definition movies such as 4K by converting them to MP4 movies using the MPEG-4 AVC/H.264 codec. MPEG-4 AVC/H.264 is capable of compressing images at higher efficiency. You can record high-quality images while reducing the amount of data.
XAVC S/AVCHD recording format
XAVC S 4K:
Bit-rate: Approx. 100 Mbps or approx. 60 Mbps
Records movies in 4K resolution (3840×2160).
XAVC S HD:
Bit-rate: Approx. 100 Mbps, Approx. 60 Mbps, or Approx. 50 Mbps
Records a more vivid movie compared to AVCHD with increased amounts of information.
Movies will be recorded at a bit-rate of approximately 16 Mbps or 12 Mbps during High Frame Rate shooting.
AVCHD:
Bit-rate: Approx. 28 Mbps (Maximum), Approx. 24 Mbps (Maximum) or Approx. 17 Mbps (Average)
The AVCHD format has a high degree of compatibility with storage devices other than computers.
Bit rate is the amount of the data processed within a given length of time.