I've answered it by myself....
What I wanted to do is that ;
After testing it was impossible with Symax360 Video Converter and (for now) thru GIMP (even i'm sure that i just need the right expression in mathmap...)...
We need 2 things ;
- an equirectangular picture with a ratio 2:1 ratio with at maximum 6000 x 3000 pixels
- the Exif XMP data “ProjectionType=equirectangular”
How to proceed ?
Pictures from AMK100S can be processed by Symax360 Video Converter but to use a picture from a video you have to process it first also with Symax360 Video Converter. Then you can use Exiftool to inject the data “ProjectionType=equirectangular”
In french a systhesis on how to manipulate AMK100s data :