Best way to convert mission from qgc json format to txt

Hi,

I need recommendation to convert mission file generated by QGC to previous format as txt. Goal is to simply edit waypoint in external software then reupload (or not) to flight controler.
Which lib to use to do that ? pymavlink ? standard python json ?

Thanks in advance

If you aren’t using any patterns the .plan json file format is pretty self explanatory. You can modify it directly. If you are using patterns best option is to round trip through the vehicle and save. This will turn a pattern into individual waypoints and then edit the json.