Missing c-blosc dependency for GDAL

[rouault]

From GDAL IRC: "I just realized that gdal embedded in qgis for windows, up to v3.9.2, doesn't include blosc compression for zarr format"

GDAL could potentially be built against ​https://github.com/Blosc/c-blosc

<arkanoid> by hacking a little into qgis, I figure out that the included gdal 3.7.2 DOES support zarr (run gdalinfo --formats from within gui), but open raster layer with ZARR:"<my zarr path>/var" ends with error "Decompressor blosc not-handled"

[jratike80]

For checking which compressions are built-in and supported by the GDAL version that is in use, do

gdalinfo --format zarr

...
  <Option name="COMPRESS" type="string-select" description="Compression method" default="NONE">
    <Value>NONE</Value>
    <Value>ZLIB</Value>
    <Value>GZIP</Value>
    <Value>LZMA</Value>
    <Value>ZSTD</Value>
    <Value>LZ4</Value>
  </Option>

[jef]

What about ​https://github.com/Blosc/c-blosc2 ?

[jef]

Replying to jef:

What about ​https://github.com/Blosc/c-blosc2 ?

-- libblosc cannot be used as it lacks blosc_cbuffer_validate()

[jef]

Fixed in gdal-3.9.3-2