If you are not against the .tlm sidecar idea in GDAL/OpenJPEG, that's good enough for me for now, and it might allow further discussions with ESA.
Well, you should tell them I'm actively *against* the sidecar idea to motivate them doing the proper thing, otherwise they'll have little incentive to move :-)
I just said it can be technically done (what can't ?), not that I'm a big fan of it. That would be purely a openjpeg change.
Actually, if you only target GDAL, you could do something that requires no change neither in GDAL or openjpeg, which would be a variation of rewriting a new .jp2 file with the TLM marker without actually rewriting them. GDAL has a rather little-known /vsisparse/ virtual file system (Cf https://gdal.org/en/stable/user/virtual_file_systems.html#vsisparse-sparse-files) where you can point at a XML file that concatenates portions of various files into a virtual file. So you would have a XML file that would point to the beginning of the .jp2 file, then an auxiliary file with the TLM marker, and then the rest of the .jp2 file, and then you open /vsisparse/my_patched_jp2.xml . I believe that should work because there are no absolute offsets in JP2 files.
-- http://www.spatialys.com My software is free, but my time generally not. Butcher of all kinds of standards, open or closed formats. At the end, this is just about bytes. _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/gdal-dev
