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<p>Looking at <a href="https://trac.osgeo.org/gdal/browser/trunk/gdal/frmts/openjpeg/openjpegdataset.cpp?rev=40418" class="OWAAutoLink" id="LPlnk16710" previewremoved="true">https://trac.osgeo.org/gdal/browser/trunk/gdal/frmts/openjpeg/openjpegdataset.cpp?rev=40418</a></p>
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<p>I now see the GDAL made changes to enable multi-threading.</p>
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<p>Thanks</p>
<p>Noureddine Farah</p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> N. Farah <nfarah@hotmail.com><br>
<b>Sent:</b> Tuesday, October 31, 2017 3:50:15 PM<br>
<b>To:</b> Even Rouault; gdal-dev@lists.osgeo.org<br>
<b>Subject:</b> Re: [gdal-dev] Open Jpeg 2.3.0 and OPJ_NUM_THREADS</font>
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<p>Thanks for the quick response. I'm not using latest GDAL and was curious where that multi-threading enabling was made ? Was it some where in GDAL code or through an option in the openjpeg 2.3.0 API ?</p>
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<p>Thanks</p>
<p>Noureddine Farah</p>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Even Rouault <even.rouault@spatialys.com><br>
<b>Sent:</b> Tuesday, October 31, 2017 3:47:01 PM<br>
<b>To:</b> gdal-dev@lists.osgeo.org<br>
<b>Cc:</b> N. Farah<br>
<b>Subject:</b> Re: [gdal-dev] Open Jpeg 2.3.0 and OPJ_NUM_THREADS</font>
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On mardi 31 octobre 2017 19:39:23 CET N. Farah wrote:</p>
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> Hi,</p>
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> </p>
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> In http://gdal.org/frmt_jp2openjpeg.html under 'Thread Support' section</p>
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> there is the following:</p>
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> </p>
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> "Starting with GDAL 2.3, this multi-threading at code-block level is</p>
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> automatically enabled by GDAL".</p>
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> </p>
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> </p>
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> Was meant "Starting with OpenJpeg 2.3, ..." ?</p>
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No, was meant starting with GDAL 2.3 (the current dev version). And that requires openjpeg >= 2.2 as well.</p>
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> </p>
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> If yes, was that enabling made in the 'OpenJpeg 2.3' library or was made in</p>
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> GDAL ?</p>
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openjpeg >= 2.2 (actually 2.1.2, but I restricted to 2.2 or later) brings multithreading decoding at codeblock level, and GDAL trunk automatically enables it.</p>
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So the doc is correct I think, but I know that those similar version numbers between GDAL and openjpeg can be confusing.</p>
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Bottom line: use the latest and greatest of both to get the better performance.</p>
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Even</p>
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-- </p>
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Spatialys - Geospatial professional services</p>
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http://www.spatialys.com</p>
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