Subsurface media import problems

[Berthold Stoeger]

Dear Eric,

> So i can't achieve to modifiy the date and time value read by
>       sub-surface. Using "Attribute changer" (https://www.petges.lu/)
>       does not work. I can't figure where is hidden the value read by
>       subsurface.

The code responsible for reading out the metadata is found in core/
metadata.cpp. There are multiple ways that the timestamp is extracted, so it 
depends on your video file.

For MP4 and related files it will typically read out the media header (mdhd) 
atom, as defined in
https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/
QTFFChap2/qtff2.html#//apple_ref/doc/uid/TP40000939-CH204-SW34

However, some processing software writes "XMP" meta data blocks and these can 
be stored in different ways. Since these are added in post-processing, we are 
supposed to give priority to them. If you have a processed video where we fail 
to read out the correct date, you can send it to me and I'll try to see what I 
can do, time permitting.

Berthold