this is not clear from the linux dvb api, so i've done some tests and it appears that once the CSA keys are set to the proper PIDs in the CA device (CA_SET_DESCR to /dev/dvb/card0/ca0), those PIDS already appear descrambled when demuxing them from the frontend device. if that's the case, is there any way to use the CSA descrambler device on arbitrary user data (such a pre-recorded stream), instead of just descrambling what's coming through frontend?

i hope i've made myself clear.