[gdal-dev] NITF TRE parsing - possible extensions for MIE4NITF

[Even Rouault]

Le dimanche 28 août 2016 13:25:07, Brad Hards a écrit :
> MIE4NITF 1.1 can be downloaded from
> https://nsgreg.nga.mil/NSGDOC/files/doc/Document/MIE4NITF%20v%201_1.zip
> (see https://nsgreg.nga.mil/doc/view?i=4205 for info).

Note for others: direct download link doesn't work, unless you add "Host: 
nsgreg.nga.mil" and "Referer: https://nsgreg.nga.mil/doc/view?i=4205" headers.

> 
> > Is the UINT naming somewhat standardized ? Otherwise perhaps uint_be to
> > reflect
> > that it is binary encoded with big endianness (contrary to integer)
> 
> I can live with either.
> 
> The spec says:
> 5.9.2 MIE4NITF defined data types
> MIE4NITF defines several data types that are used within its TREs. These
> data types are defined in this section. Table 8 introduces an unsigned
> integer type that is used in the MIE4NITF TREs. The UINTn nomenclature is
> somewhat standardized in the computing world but it is included here to
> unambiguously define its use. All bytes in the UINTn data type are stored
> in big endian order and all bits within those bytes are stored most
> significant bit first.

ok, as the UINT name comes from this doc, let's keep it (perhaps with a 
comment in the xsd to explain the difference with the integer type)

> 
> > Not sure to have understood the structure of those TREs and couldn't find
> > any
> > public resource describing them.
> 
> Sorry, should have linked to those in the initial email. In the spec
> (above), see
> 5.9.3.6 Freespace TRE (FREESA)
> 5.9.4.8 Frame-Synchronous Metadata Wrapper TRE (FSYNWA)
> 5.9.4.9 Frame-Asynchronous Metadata Wrapper TRE (FASYWA)
> 
> I would caution that it's a bit confusing the first time.

OK, that's clearer with the doc. When you say "I'm planning to open code the 
FSYNWA / FASYWA case", do you mean hard-code ? Sounds OK. Could still be 
retrofitted later into something more general purpose if such constructs are 
found to be common.

Even

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