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[mkgmap-dev] Please try and report results of Huffman compression

From Gerd Petermann gpetermann_muenchen at hotmail.com on Sun Jan 16 09:38:14 GMT 2022

Hi all,

see https://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4866
and https://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4867

Please use https://www.mkgmap.org.uk/download/mkgmap-mdr2-r4867.zip for further tests.


Von: 7770 <7770 at foskan.eu>
Gesendet: Samstag, 15. Januar 2022 18:53
An: mkgmap-dev at lists.mkgmap.org.uk
Cc: Gerd Petermann
Betreff: Re: [mkgmap-dev] Please try and report results of Huffman compression


ALLVARLIG (MultiPolygonRelation): folder/77700046.osm.pbf: Internal error:
Failed to render MultiPolygonRelation 2970267
that was with --latin1

mkgmap version 4839 works well.


On lördag 15 januari 2022 16:59:24 CET Gerd Petermann wrote:
> Hi all,
> during the last weeks Ticker and I decoded Garmin's String compression of
> the global index for the PC (the *_mdr.img) . In the mdr2 branch I've coded
> support for that in mkgmap and I think its ready for a first beta test.
> It works with codepages 1250 ..1258 or 65001.
> I've no idea how the 2-byte pages work, but Garmin seems to support that,
> too. Maybe I'll work on this later.
> The branch version produces around 200 lines of diagnostic output to show
> what happens when compression is enabled. This will be changed to debug
> level later.
> The encoding is enabled by default, special option --x-no-mdr15-compression
> can be used to turn it off.
> Note that the size of the *_mdr.img file will be smaller (which is esp.
> intersting for those who get close to the 2G limit) Note also that a zipped
> *_mdr.img can and will be larger since zip cannot remove as much
> redundancy. Note also that this branch includes the changes from the
> faster-mp branch and introduces a few changes which are relavant for
> --lower-case maps.
> How to test?
> Install the map in MapSource and check if you see any unexpected characters
> in the result lists or maybe even crashes while searching. If so, please
> try the same input files with the --x-no-mdr15-compression to verify if
> this is caused by compression or maybe other changes.
> Please don't yet publish the maps, but let me know if you see anything
> unexpected. Some changes reg. lower-case in this branch are still
> experimental.
> The binary is here:
> https://www.mkgmap.org.uk/download/mkgmap-mdr2-r4865.zip
> If you see errors which are caused by compression, please attach the
> diagnostic output.
> @Ticker: Please review the source.
> Gerd
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
> https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev

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