I demand that Luis Palacios may or may not have written...
Softdevice seems not to be the cause of the problem, GRAB doesn't work either without it.
cDevice::GrabImage (the default) returns NULL, i.e. grab always fails, so cSoftDevice needs to override this (much as cXineDevice in vdr-xine does for older VDR or, with a patch which I posted here a few weeks ago, for current VDR).
vdr/dvbdevice.c contains code which you can probably adapt for this.
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