[File] [PATCH] Magdir/riff Microsoft Flight Simulator *.MDL described only generic

[Jörg Jenderek (GMX)]

Hello,
some weeks ago i handled some RIFF based video files. When i run
file command version 5.45 on more RIFF based samples with MDL file name
suffix i get an output like:

XL5.mdl: RIFF (little-endian) data
tb1.mdl: RIFF (little-endian) data

With --extension option only ??? is displayed for MDL samples.
Furthermore with option -i for inspected MDL samples only generic
application/octet-stream is shown.

For comparison reason i also run the file format identification
utility DROID ( See https://sourceforge.net/projects/droid/). This
does not recognize the the MDL examples.

For comparison reason i run the file format identification utility
TrID ( See https://mark0.net/soft-trid-e.html). This identifies also
all my MDL examples with low priority as "Generic RIFF container" by
riff.trid.xml. The examples are described with high rate as "Microsoft
Flight Simulator 3D model (generic)" by mdl-fs-gen.trid.xml (See
appended trid-v-mdl.txt.gz).
This tool list the used file name extension and with -v option the
related URL pointing to used software company. Luckily with shown
information i found page about "MDL file format". That informations are
expressed by comment lines inside Magdir/riff like:
# URL:	https://en.wikipedia.org/wiki/Microsoft_Flight_Simulator
# Ref.:	https://www.fsdeveloper.com/wiki/index.php
#	?title=MDL_file_format_(FSX)
#	http://mark0.net/download/triddefs_xml.7z
#	defs/m/mdl-fs-gen.trid.xml

All detected MDL samples are at least general described by Magdir/riff
with line like:
0	string		RIFF		RIFF (little-endian) data

For other RIFF samples the sub classification is done by considering 4
byte string at offset 8. According to references this is 3 byte MDL
string. So this is now done by additional lines inside Magdir/riff like:
   >8	string		MDL
   >>12	string		MDLH	\b, Microsoft Flight Simulator 3D model
   !:mime	application/x-ms-mdl
   !:ext	mdl

Instead of generic mime type application/octet-stream or
application/x-riff i show an user defined one.

After applying the above mentioned modifications by patch
file-5.45-riff-mdl.diff then all my inspected Microsoft Flight Simulator
   examples are now described with more details. This now looks like:

XL5.mdl: RIFF (little-endian) data, Microsoft Flight Simulator 3D model
tb1.mdl: RIFF (little-endian) data, Microsoft Flight Simulator 3D model

I hope my diff file can be applied in future version of file
utility.

Unfortunately the MDL file name suffix is also used for other file formats.

With best wishes,
Jörg Jenderek
--
Jörg Jenderek
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--- file-5.45/magic/Magdir/riff.old	2022-08-16 13:15:19.000000000 +0200
+++ file-5.45/magic/Magdir/riff	2023-08-06 20:29:02.666751300 +0200
@@ -354,6 +354,17 @@
 >>0x31	search/256	inst		by
 # probably manufacture name like: "Unspecified Company" "NVidia Corporation"
 >>>&0x24	string	x		"%s"
+# From:		Joerg Jenderek
+# URL:		https://en.wikipedia.org/wiki/Microsoft_Flight_Simulator
+# Reference:	https://www.fsdeveloper.com/wiki/index.php?title=MDL_file_format_(FSX)
+#		http://mark0.net/download/triddefs_xml.7z/defs/m/mdl-fs-gen.trid.xml
+# Note:		called "Microsoft Flight Simulator 3D model (generic)" by TrID
+>8	string		MDL
+>>12	string		MDLH		\b, Microsoft Flight Simulator 3D model
+#!:mime	application/x-riff
+!:mime	application/x-ms-mdl
+!:ext	mdl
+#>>>8	string		MDL8		\b, version 8?
 # AVI == Audio Video Interleave
 # Reference:	http://fileformats.archiveteam.org/wiki/AVI
 >8	string		AVI\040		\b, AVI
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