Author Topic: 2 versions for Corel Metafile Exchange Image (Legacy) (*.cmx)  (Read 69 times)

jenderek

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2 versions for Corel Metafile Exchange Image (Legacy) (*.cmx)
« on: October 11, 2019, 03:51:56 PM »
Hello trid users,

some days ago i run TrID on riff based Corel examples with name extension
cmx. Such files are identified correctly by cmx.trid.xml as "Corel Metafile
Exchange Image (Legacy)" ( see appended output/trid-old.txt).

According to reference URL it is possible to distinguish between version
"Presentation Exchange 5.0" and "Presentation Exchange 6+" by PRONOM
"x-fmt/34" or "x-fmt/35".

So i run DROID (Digital Record and Object Identification) on CMX files.
This is a software tool developed by The National Archives to perform
automated batch identification of file formats. See
https://digital-preservation.github.io/droid/ .

The CMX files inside directory cmx-v5 are described here as "Corel
Presentation Exchange File" with version 5.0. ( see appended
cmx-v5/output/DROID-cmx-v5.csv).

The other CMX files are described as "Corel Presentation Exchange File" with
version 6 and Later. ( see appended output/DROID-cmx-v6.csv).
So i run tridscan on version 6 samples and get definition file cmx-v6.trid.xml.
After deleting null patterns, approximating cmx.trid.xml and comparing with
DROID skeleton sample x-fmt-35-signature-id-731.cmx the resulting definition
has one additional byte pattern expressed by XML construct:
   <Bytes>32</Bytes>
   <ASCII> 2</ASCII>
   <Pos>74</Pos>
So mention this fact by remark line:
   <Rem>2 at position 74 indicates version 6 and later</Rem>
I am not sure, but this file format seems to be used til version 15. Since
version 16 then another file format is used.
And this version are now described by line:
   <FileType>Corel Metafile Exchange Image (v6)</FileType>

Then i do the same procedure for version 5 samples to get cmx-v5.trid.xml
with 1 other byte pattern expressed by XML construct:
   <Bytes>31</Bytes>
   <ASCII> 1</ASCII>
   <Pos>74</Pos>

With the new 2 definition files the Corel CMX samples are now described more
precisely ( see appended output/trid-new-v.txt and
cmx-v5/output/trid-new-v.txt). TrID definitions, some examples and output are
stored in archive cmx.zip. I hope that my 2 XML files can be used in future
version of triddefs as replacement for cmx.trid.xml.

With best wishes
Jörg Jenderek

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Re: 2 versions for Corel Metafile Exchange Image (Legacy) (*.cmx)
« Reply #1 on: October 11, 2019, 08:45:59 PM »
Thanks!