[gdal-dev] Open Jpeg 2.3.0 and OPJ_NUM_THREADS

Even Rouault even.rouault at spatialys.com
Tue Oct 31 12:47:01 PDT 2017

On mardi 31 octobre 2017 19:39:23 CET N. Farah wrote:
> Hi,
> In http://gdal.org/frmt_jp2openjpeg.html under 'Thread Support' section
> there is the following:
> "Starting with GDAL 2.3, this multi-threading at code-block level is
> automatically enabled by GDAL".
> Was meant "Starting with OpenJpeg 2.3, ..." ?

No, was meant starting with GDAL 2.3 (the current dev version). And that requires openjpeg 
>= 2.2 as well.

> If yes, was that enabling made in the 'OpenJpeg 2.3' library or was made in
> GDAL ?

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.

So the doc is correct I think, but I know that those similar version numbers between GDAL 
and openjpeg can be confusing.

Bottom line: use the latest and greatest of both to get the better performance.


Spatialys - Geospatial professional services
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