MPF segment is not writable?

[miric]

Hi there.

I've been passively struggling to create MPO files on my own for the last year and still don't have success.
I'm curious why it is stated that MPF segment is not writable, it might be only extracted (MPImage2 for instance) or entirely deleted. In that case how do iPhones create JPEGs with HDR Gain Maps written to MPImage2 if it is not writable?

[Phil Harvey]

It is not writable by ExifTool.  I doubt any other utility can write it either, but obviously manufacturer's software can create this.

There isn't much call for writing this.  And the specification was poorly designed, so adding this feature would be a pain in the ass.

- Phil