I’ve previously been successful in importing ecw into QGIS 2.0 but the same methods (for example Adding *.ecw files to QGIS on Windows) have failed with a fresh install of QGIS 2.2 with OSGeo4W on W7 64. Seems to be a GDAL version issue. The OSGeo4W shell tells me I have GDAL version 1.11 but this new installed QGIS is “compiled against GDAL/OGR" version 1.10 according to 'about'. I’ve successfully got the ecw format listed by ‘gdalinfo –formats’ but that’s version 1.11 which I assume QGIS 2.2 can’t see. I note that OSGeo4W64/bin has both gdal110.dll and gdal111.dll.
How do I force QGIS to use gdal 1.11 and not 1.10 and so be able to read ecw rasters (which I assume is the problem)?
I find that I have a different folder structure from my fresh QGIS2.2 install from OSGeo4W which has no less than 50 gdal files (from “gdal_auth.bat” to “gdalwarp.exe”) in C:/OSGeoW64/bin and one file “gdal_ECW_JP2ECW.dll” which is in C:/OSGeoW64/bin/gdalplugins. No “gisinternals” folder exists for me. I have followed the instructions on the GDAL website and also other answers on gis.stackexchange by manually copying the various ERDAS_ecw_SDKfiles to the appropriate folders. This worked with QGIS2.0 but fails with QGIS2.2. I've put C:/OSGeo4W/bin as the path in the Gdal Tools executables dialog box but QGIS2.2 still fails to recognise ecw rasters.
Success! QGIS2.2 64bit now importing all my ecws perfectly. @AndreJ's advice to manually roll back the default Gdal1.11 to Gdal1.10 and reinstall using the OSGeo4W advanced options works. Either OSGeo4W should default to Gdal1.10 on express install or QGIS should compile against Gdal1.11.