MemTest86 showed me my RAM is defect at exactly 1 bit: whatever you wrote to this bit, you got 0 back. During video conversion HandBrake used this part of RAM and could not cope with false data read from RAM... and froze...
Since I used this machine to backup my data on DVDs I got many errors in my data on backup. But since I had a copy of everything on another HDD I throw the DVDs away and backed up everything again (after replacing defective RAM module and reinstalling OS and SW on my machine).
> HandBrake used this part of RAM and could not cope with false data read from RAM
Which in itself alludes to the encoding stream itself (or one of the intermediate streams during the encoding process) having some form of strong channel coding - in error detection - either by design or not. Detect 1-bit error in a gig+ stream, perhaps without easily being able to locate it, beyond saying it's in such or such chunk (the current frame(s) being processed).
Since I used this machine to backup my data on DVDs I got many errors in my data on backup. But since I had a copy of everything on another HDD I throw the DVDs away and backed up everything again (after replacing defective RAM module and reinstalling OS and SW on my machine).